US 6,067,236 AGrant
Power Supply for Providing High Voltage Power From a Low Voltage Source
Issue Date:2000-05-23
•27 Claims
•15 Drawing Sheets
Abstract
A power supply device provides high voltage power from a low voltage source. The power supply device can be manufactured so as to have a thin profile and therefore is particularly well-suited for use as a power supply for a flat screen CRT (cathode ray tube). The power supply device includes a voltage regulator, a DC-to-AC converter, and a multiplier. The voltage regulator is connectable to the low-voltage source and is arranged so as to step-down a source voltage level of the low-voltage source to produce an input voltage at a lower voltage level than the source voltage level. The DC-to-AC converter is connected to the input voltage from the voltage regulator and is arranged so as to convert the input voltage into an AC voltage. The multiplier is connected to the AC voltage from the DC-to-AC converter and is arranged so as to convert the AC voltage into a substantially DC output signal having a DC voltage level which is significantly higher than the source voltage level. Preferably, the multiplier includes an assembly of capacitors and diodes which are interconnected to form a voltage multiplier. A regulator controller can be connected, at least indirectly, to the multiplier so that when the multiplier is connected to an electrical load, a voltage indicative of current flowing between the multiplier and the electrical load and the input voltage itself dynamically controls the voltage regulation provided by the regulator.
Metadata
Assignee
- Rantec Microwave & Electronics Inc.
Inventor
- Robert Keith White
Application Information
Application Number:US 9627626
Filing Date:1997-11-03
Priority Date:1997-11-03
Art Unit:288
Classifications
IPC:
H02M 3335H02M 324G05F 140
Field of Search:
36332315;16;80;97;98;17;131;132265;266;268
Patent Drawings (15 sheets)
Description
Background of the Invention
The present invention relates to a power supply for providing high voltage power from a low voltage source. The present invention can be manufactured so as to have a thin profile and therefore is particularly well-suited for use as a power supply for a flat screen CRT (cathode ray tube).
Although the general concept of providing power conversion is known, the recently developed technology of flat screen CRTs has presented a greater need for power conversion circuitry capable of providing high voltage power from a low voltage source (e.g., 8,000 volts from a 5 volt source). In order to maximize the compactness of such flat screen CRTs, it is important that their power supplies also be compact. Further, in the highly competitive market for consumer electronics, it is important that the power supply be constructed at the lowest cost possible and therefore in a manner which permits automated manufacturing.
Summary of the Invention
It is therefore a primary object of the present invention to provide a power supply device capable of providing high voltage power from a low voltage source.
Another object of the present invention is to provide such a power supply device using components which facilitate automated manufacturing of the power supply device.
Yet another object of the present invention is to provide a power supply device which can be manufactured using "surface-mount" electrical components which are mounted to a printed circuit board and provide a thin overall profile.
Another object of the present invention is to provide a power supply device having a high output-to-input voltage ratio (e.g., at least 1000), compact size, and a relatively steady output voltage which remains within 10%, and preferably within 5%, of a desired voltage level, even if the load on the power supply varies significantly.
Yet another object of the present invention is to provide a power supply device having a high output-to-input voltage ratio, and also capable of providing power conversion in a relatively efficient manner (e.g., with a power efficiency of at least 75%).
A power supply device according to the present invention therefore includes a voltage regulator, a DC-to-AC converter, and a multiplier. The voltage regulator is connectable to a low-voltage source (e.g., a 5 volt battery) and is arranged so as to step-down a source voltage level of the low-voltage source to produce an input voltage at a lower voltage level than the source voltage level.
The DC-to-AC converter is connected to the input voltage from the voltage regulator and is arranged so as to convert the input voltage into an AC voltage.
The multiplier is connected to the AC voltage from the DC-to-AC converter and is arranged so as to convert the AC voltage into a DC output signal having a DC voltage level which is significantly higher than the source voltage level. Preferably, the multiplier includes an assembly of capacitors and diodes which are interconnected to form a voltage multiplier.
According to a preferred embodiment, the power supply device further includes a regulator controller connected, at least indirectly, to the multiplier. The regulator controller is arranged so that when the multiplier is connected to an electrical load, a voltage indicative of current flowing between the multiplier and the electrical load is applied to the regulator controller. In response to this voltage, the regulator controller provides a control signal to the regulator. Preferably, the control signal is dependent, at least in part, on the voltage indicative of current. The regulator then dynamically regulates the input voltage level in a manner dependent upon the control signal.
The power supply device may also include sampling circuitry connected electrically between the multiplier and the regulator controller. The sampling circuitry provides the voltage indicative of current without drawing more than 0.003% of the power flowing to the electrical load.
Preferably, the regulator controller is connected also to the input voltage. As a result, the control signal is provided to the dynamic regulator in a manner dependent on both the input voltage and the voltage indicative of current.
In particular, the regulator controller is arranged so as to selectively determine a level of the control signal such that 1) when the voltage indicative of current indicates that the current flowing between the multiplier and the electrical load is increasing, the dynamic regulator increases the input voltage, and 2) when the voltage indicative of current indicates that the current flowing between the multiplier and the electrical load is decreasing, the dynamic regulator decreases the input voltage.
Preferably, the regulator controller is responsive to the input voltage such that the increases and decreases of the input voltage also are dependent upon a present level of the input voltage.
According to a preferred embodiment of the regulator, as the low-voltage source becomes depleted, the regulator continues to provide the input voltage at progressively decreasing voltage levels, at least until the source voltage decreases to one half of the source voltage of a fully charged low-voltage source. A more preferred arrangement continues to provide the input voltage at progressively decreasing voltage levels, at least until the source voltage decreases to 20% of the source voltage of a fully charged low-voltage source.
Preferably, the DC voltage level is at least one thousand times the source voltage level, and according to a more preferred embodiment applicable to flat-screen CRT's, the DC voltage level is between 1440 and 1760 times the source voltage level.
Preferably, the regulator, DC-to-AC converter, and the multiplier are packaged together such that a profile of the power supply device is less than one half inch in thickness, and can be even less than 0.40 inch in thickness.
A preferred multiplier according to the present invention includes first and second capacitor arrays spaced apart from each other, each capacitor array defining a plurality of capacitors; a diode located on a surface of each capacitor; and a terminal assembly. The terminal assembly itself includes a first set of conductive leads arranged so as to electrically connect respective diodes on the first capacitor array to respective capacitors of the second capacitor array, and a second set of conductive leads arranged so as to electrically connect respective diodes on the second capacitor array to respective capacitors of the first capacitor array.
Preferably, the first and second capacitor arrays are substantially parallel to one another, and a diode is arranged on a top surface of each capacitor.
The terminal assembly further may include first and second ends, the conductive leads defining the first and second set of conductive leads being alternatingly arranged between the first and second ends. In addition, each conductive lead of the first and second set of conductive leads may include a substantially straight terminal and an oppositely arranged, downwardly projecting terminal.
Preferably, the downwardly projecting terminal is connected to one of the capacitors and the substantially straight terminal is connected to one of the diodes.
The first and second sets of conductive leads preferably are arranged within an electrically insulative body, and the first and second set of conductive leads have terminal portions over the capacitor arrays which extend out from the insulative body.
Brief Description of the Drawings
FIG. 1 is a block diagram illustrating a power supply device according to a preferred embodiment of the present invention.
FIG. 2 is a circuit diagram illustrating a power supply device according to a preferred embodiment of the present invention.
FIG. 2A schematically illustrates a six-pin connector which is connected to the circuit illustrated in FIG. 2.
FIG. 3 is a plan view of a power supply device in accordance with the preferred embodiment illustrated in FIG. 2.
FIG. 3A is a plan view of an alternative power supply device in accordance with the preferred embodiment illustrated in FIG. 2.
FIG. 4 is a circuit diagram of a multiplier in accordance with a preferred embodiment of the circuitry illustrated in FIG. 2.
FIG. 5 is a perspective view of a preferred multiplier in accordance with the embodiment illustrated in FIG. 4.
FIG. 5A is a top view of preferred molded terminal assembly for the multiplier shown in FIG. 5.
FIGS. 5B and 5C are orthogonal side views of the molded terminal assembly shown in FIG. 5A.
FIG. 6 is a circuit diagram of an alternative multiplier for the circuitry illustrated in FIG. 2.
FIG. 7 is a circuit diagram of an alternative circuit according to the present invention.
FIG. 8 is a circuit diagram of yet another alternative circuit according to the present invention.
FIG. 8A schematically illustrates a nine-pin connector which is connected to the circuit illustrated in FIG. 8.
FIG. 9 is a circuit diagram of still another alternative circuit according to the present invention.
FIG. 10 is a circuit diagram of yet another alternative circuit according to the present invention.
FIG. 10A is a schematic of the four pin connector illustrated in FIG. 11.
FIG. 11 is a plan view of a preferred physical arrangement of the circuit illustrated in FIG. 10.
FIGS. 12 and 12A schematically illustrate a diode array block according to a preferred embodiment of the circuit illustrated in FIG. 10.
FIG. 13 is a perspective view of a multiplier similar to that which is illustrated in FIGS. 10-12, except that the multiplier of FIG. 13 has only six diodes and twelve capacitors.
Description of the Preferred Embodiments
With reference to FIG. 1, a power supply device according to a preferred embodiment of the present invention will now be described.
The illustrated power supply device includes a voltage regulator 10, a DC-to-AC converter 20 connected to the voltage regulator 10, and a multiplier 30 connected to the DC-to-AC converter 20. The multiplier 30 may be electrically connected to an apparatus (hereinafter "the load" or "the electrical load") which requires high-voltage power.
In operation, the voltage regulator 10 steps down a DC voltage V.sub.DC (from a voltage source such as a battery) to provide an input voltage V.sub.IN at a lower voltage level than V.sub.DC. The input voltage V.sub.IN is then applied to the DC-to-AC converter 20. The DC-to-AC converter 20 converts the voltage V.sub.IN into an AC voltage V.sub.AC (for example, having a peak-to-peak voltage of 677 volts to 1333 volts and a frequency of about 85 kHz). The AC voltage V.sub.AC is then applied to the multiplier 30. The multiplier 30 converts the AC voltage V.sub.AC into a high-voltage output V.sub.OUT (for example, having a voltage level of 4,000 volts to 8,000 volts) which, in turn, can be applied to the load.
The current being drawn by the load is sampled by sampling circuitry 40. The sampling circuitry 40, in response to the current being drawn, provides a current-indicative voltage V.sub.program which is indicative of the current being drawn by the load. The current-indicative voltage V.sub.program is applied to a regulator controller 50. The regulator controller 50 is connected to the input voltage V.sub.IN and provides a control voltage V.sub.control at its output. The control voltage V.sub.control is applied to the regulator 10 at a level which is dependent upon both the input voltage V.sub.IN and the current-indicative voltage V.sub.program. The regulator then adjusts the input voltage V.sub.IN in a manner dependent upon the control voltage V.sub.control. The regulator 10 thereby provides dynamic voltage regulation in a manner dependent upon V.sub.control. Such dynamic control advantageously prevents significant deviations in the high-voltage output V.sub.OUT which might otherwise occur when the current being drawn by the load changes.
If, for example, the current being drawn by the load increases, this increase in current is detected by the regulator controller 50 via the current-indicative voltage V.sub.program. Upon detecting the increase, the regulator controller 50 adjusts the control voltage V.sub.control to cause an upward change in the voltage regulation provided by regulator 10. This, in turn, causes a corresponding increase in the input voltage V.sub.IN.
As a result of this regulated increase in the input voltage V.sub.IN, the combination of the DC-to-AC converter 20 and the multiplier 30 are able to maintain the desired high-voltage output V.sub.OUT, even when the load connected thereto demands more current.
Similarly, if the current being drawn by the load decreases, this decrease is detected by the regulator controller 50 via the current-indicative voltage V.sub.program. Upon detecting the decrease, the regulator controller 50 adjusts the control voltage V.sub.control to cause a downward change in the voltage regulation provided by regulator 10. This, in turn, causes a corresponding decrease in the input voltage V.sub.IN.
As a result of this regulated decrease in the input voltage V.sub.IN, the combination of the DC-to-AC converter 20 and the multiplier 30 are able to keep the high-voltage output V.sub.OUT from rising too far above the desired voltage level when the current being drawn by the load suddenly decreases.
The regulator controller 50 thereby achieves dynamic control of the regulator 10 in a manner dependent on the current being drawn by the load. Since the regulator controller 50 is responsive also to the input voltage V.sub.IN, the dynamic control of the regulator 10 is dependent also upon the present input voltage V.sub.IN.
In this regard, at different times, the control voltage V.sub.control can be at two different levels for the same amount of current being drawn by the load if the input voltage V.sub.IN at those times is at different levels. In the preferred embodiment of FIG. 2, for example, the current being drawn by the load can be at the same level in two different instances in time, and in one of those instances, the control voltage V.sub.control will be higher than in the other if the input voltage V.sub.IN is also higher. Such dynamic control of the regulator 10 advantageously provides a way of regulating the voltage V.sub.IN in a manner which is more accurate than arrangements which provide output regulation based only on the amount of current being drawn by the load.
The foregoing arrangement also achieves better efficiency than conventional voltage feedback loops because the latter usually cause a substantial power loss in the sensing network, whereas the arrangement described above performs the dynamic regulation control using a current-indicative voltage requiring very little power.
A preferred implementation of the embodiment illustrated in FIG. 1 is shown in FIGS. 2 and 3. The following chart provides details regarding the individual circuit elements shown in FIGS. 2 and 3:
As illustrated in FIG. 3, the aforementioned circuit components preferably are mounted on a printed circuit board PCB made at least partially of fiberglass and having a high dielectric strength. The illustrated printed circuit board PCB has a thickness of about 0.093 inch, and includes conductive traces CT which interconnect the circuit components so as to define the circuit illustrated in FIG. 2.
At one end of the circuit board PCB, the six-pin connector P2 is mounted. The six-pin connector P2, shown in FIG. 2A, includes a 1MON1 pin, a PS OK pin, a GND3 pin, an INPUT4 pin, a SHUTDOWN5 pin, and a VADJ6 pin. The source voltage V.sub.DC appears at the INPUT4 pin of connector P2 and is applied across the ground pin GND3 (-) and the INPUT4 pin (+). The potentiometer R14 may be electrically connected across the VADJ6 pin and the ground pin GND3. The SHUTDOWN5 pin is connected to the S/D terminal. The PS OK and 1MON1 pins are connected to appropriate monitoring and/or indicating devices.
At an opposite end of the circuit board PCB, the high-voltage connector 60 is connected to the resistor 15. The high-voltage connector 60 therefore is used to connect the circuit board PCB to the electrical load, such as a flat screen CRT.
The current flowing from the multiplier Z1 through the resistor R15 and the load, returns to the multiplier Z1 by flowing through ground, through the source voltage and the INPUT4 pin, then through the resistor R9 and back to the multiplier Z1.
Preferably, the circuit board PCB illustrated in FIG. 3 is less than three inches long and has a width no greater than one inch. The illustrated circuit board PCP has a preferred length of about 2.95 inches and a preferred width of about one inch. It is understood, however, that other dimensions can be provided depending on the needs of an end user of the power supply device.
An alternative arrangement for the components in FIG. 3 which are to the right of the transformer T1 is illustrated in FIG. 3A.
The dual op-amp U3 shown in FIG. 1 (the LT 1490 manufactured by Linear Technology) achieves two functions, a monitoring function and a control function. With regard to the monitoring function, the dual op-amp U3 monitors the input voltage V.sub.IN being applied to the DC-to-AC converter 20 and provides a PS OK (power supply OK) voltage to a PS OK terminal when the input voltage V.sub.IN is present. This permits an external indicator and/or monitoring device to indicate and/or record whether the power supply is operating. An indicator light or LED, for example, can be connected to the PS OK terminal so that the indicator light or LED is illuminated whenever the PS OK voltage is present. This provides a simple and effective warning device indicating the presence of a high voltage at the output from the power supply device.
As illustrated in FIG. 2, the monitoring function is provided by connecting the pins 2U3 and 3U3 of the dual op-amp U3 to the 3U1 pin of the DC/DC converter U1 and to the DC-to-AC converter side of the inductor L2, respectively. In addition, the output pin 1U1 of the dual op-amp U3 is connected via the resistor R13 to the PS OK terminal of the power supply.
The second function achieved by the dual op-amp U3 relates to providing control of the dynamic regulation. In particular, the dual op-amp U3 is responsive to the current flowing between the multiplier 30 and the electrical load. Since this current flows through the resistor R9, the dual op-amp U3 detects a voltage drop across the resistor R9. Based upon this current-indicative voltage drop, the dual op-amp U3 provides an output voltage at its output terminal 7U3. This output voltage corresponds to the current-indicative voltage V.sub.program and therefore is applied to the regulator controller 50. The regulator controller 50 then uses this current-indicative voltage V.sub.program to provide dynamic control of the regulator 10, as indicated above.
Such indirect, dynamic regulation of the output voltage based, in part, on the current being drawn by the load provides a regulation arrangement of increased efficiency compared to arrangements which feedback electrical voltage from the high-voltage output.
In the embodiment of FIG. 2, the control function of the dual op-amp U3 is achieved by connecting the 5U3 pin of the dual op-amp U3 between resistors R7 and R2, by connecting the 6U3 pin between resistors R10 and R11, and by connecting the 7U3 pin of the dual op-amp U3 to the regulator controller 50. The voltage drop across resistor R9 therefore is detected via the 5U3 and 6U3 pins of the dual op-amp U3, and the current-indicative voltage V.sub.program is supplied via the 7U3 pin.
The resistances R7, RB, R9, R10 and R11 are selected to provide a desired scaling factor required for V.sub.program based on the multiplier's dynamic performance. The multiplier's dynamic performance is determined primarily by the number of multiplier stages, the per-stage capacitances, and the frequency of the AC signal.
Since the DC source voltages may vary between 4.5 volts and 5.5 volts, the DC/DC converter of the regulator 10 regulates the source voltage down to approximately 3 volts, and thereby provides a more stable input voltage V.sub.IN. Preferably, the DC/DC converter has a high conversion frequency (preferably greater than 200 KHz) and a 100% (or very close to 100%) duty cycle. The DC/DC converter, therefore, does not suddenly shut down like other converters when the source voltage (e.g., battery) drops below a certain value which is significantly higher than one volt. This advantageously increases the usable operating time in portable applications of the power supply device.
The transformer T1 illustrated in FIGS. 2 and 3 has primary windings W1, W2, and W3 and a secondary winding W4. In the preferred transformer T1 commercially available from Toko, the numbers of turns in the windings W1, W2, W3 and W4 are six, six, three, and eight-hundred, respectively.
The primary winding W1 extends electrically between terminals ST1 and 4T1 and has an inductance of 6.85 .mu.H, +/-15%, at 0.1 volt and 10 kHz. Winding W1 has a resistance of no more than 110 m.OMEGA..
The primary winding W2 extends electrically between terminals 4T1 and 3T1 and exhibits the same inductance as winding W1. The resistance of winding W2, however, is no more than 125 m.OMEGA..
The primary winding W3 extends electrically between terminals 2T1 and 1T1 and has an inductance of 1.73 .mu.H, +/-15%, at 0.1 volt and 10 kHz. Winding W3 has a resistance of no more than 202 m.OMEGA..
The secondary winding W4 extends electrically between terminals 10T1 and 6T1 and has an inductance of 114 mH at 0.1 volt and 10 kHz. Winding W3 has a resistance of 331 .OMEGA., +/-20%.
Advantageously, the sampling circuitry 40 provided by the embodiment illustrated in FIG. 2 draws 25 microwatts of power at the full output load current, less than 0.003% of the power being transmitted to the load by the multiplier. By keeping the amount of power drawn by the sampling circuitry to such low levels, the illustrated embodiment enhances the overall efficiency of the system in a manner which is significantly better than arrangements wherein current from the output loop is fed back into a voltage regulator and advantageously does not lo require a high-voltage-rated/high ohmic value output sensing resistor.
The exemplary embodiment shown in FIG. 2 can be manufactured using surface-mount components on a printed circuit board. The components and the circuit board advantageously can be arranged so that the overall thickness of the power supply device is less than 0.5 inch. Preferably, the components and circuit board are arranged to have a thickness of less than 0.4 inch, a length of no more than 2.5 inches and a width of no more than one inch. Such dimensions make the exemplary embodiment compatible with the limited space in flat screen CRTs.
After manufacturing, the components of the circuit illustrated in FIG. 2 and the circuit board preferably are encapsulated using a known encapsulation technique. A preferred encapsulation technique utilizes a two part heat cure and a material which is commercially available from Dow Chemical and commonly known as "SYLGUARD".
Modifications to the circuit illustrated in FIG. 2 will become readily apparent to those of ordinary skill in the art based on the teachings in the present disclosure. Even more modifications will become readily apparent as smaller and more compact circuit elements capable of achieving the functions carried out by the circuit illustrated in FIG. 2 become available. In this regard, the present invention is not limited to the exemplary circuit illustrated in the drawings, but rather encompasses the full range of modifications which fall within the scope of the appended claims.
The illustrated circuitry can be manufactured using automated manufacturing techniques. In addition, the illustrated circuitry is powered by a 5 volt source (e.g., a battery, or battery pack) and provides an output voltage of about 8,000 volts. This voltage conversion is advantageously provided with a power efficiency of at least 75% (when delivering only 1.25 watts). In addition, the "no-load" or quiescent dissipation of the circuitry is no more than 0.1 Watt, measured at zero output loading.
A significant advantage of the illustrated circuitry is that the high-voltage output power does not terminate immediately as the 5 volt input power diminishes. Instead, the output power gradually decreases until the input voltage is very close to zero (e.g. at 1 volt or less). Also, the illustrated circuitry is able to withstand, without damage, repeated momentary external short circuits of the high-voltage output V.sub.OUT and ground.
Thus, when the illustrated circuitry is used to apply high-voltage power to a flat screen CRT, the display gradually looses intensity as the low voltage input power diminishes, thereby warning the user of the eventual loss in power and also preventing sudden loss of display. This also extends the usable time of the display.
Preferably, as illustrated in FIG. 4, the multiplier Z1 is defined by an assembly of capacitors C21, C22, C23, C24, C25, C26, C27, C28, C29, C30 and diodes D20, D21, D22, D23, D24, D25, D26, D27, D28, D31 which are interconnected to form a voltage multiplier. In order to achieve a high-voltage output V.sub.OUT of about 8,000 volts, the capacitors C21-C30 preferably have capacitances as high as physical space permits. To achieve the greatest size reduction and maintain acceptable electrical performance, C21-C30 preferably have capacitances of 75 pFarad to 150 pFarad. Also, because of the monolithic construction of the capacitor assemblies, preferably all of the capacitors are rated for the full output voltage. This tends to enhance reliability.
The resulting arrangement of capacitors converts the AC voltage V.sub.AC provided by the DC-to-AC converter 20 to a DC high-voltage output of about 8,000 volts.
With reference to FIG. 5, a preferred physical embodiment of the multiplier Z1 is defined by two monolithic capacitor arrays CA1, CA2 arranged spatially in parallel to one another and spaced apart from each other, a chip diode D20-D31 located on a top surface of each capacitor C21-C30 in each capacitor array CA1, CA2, and a molded terminal assembly 100 containing conductive leads which interconnect the capacitor arrays CA1, CA2 and the diodes D20-D31 such that the voltage multiplier circuit illustrated in FIG. 4 is achieved. In FIG. 3, the location of each capacitor array CA1, CA2 is apparent from the elongated parallel traces on the left side of the drawing.
The chip diodes D20-D31 are commercially available, as are the monolithic blocks which define the capacitor arrays CA1, CA2. Each capacitor array CA1, CA2 is defined by a ceramic block, preferably less than 0.150 inch in height, having a metalized bottom surface connected to the conductive traces CT of the circuit board PCB and also having a metalized top surface. The top surface has parallel lines of the metalization removed or etched away to define an electrically insulative space between the top plates of the individual capacitors. Preferably, the insulative space is about 0.025 inch wide and each of the top plates of the capacitors is about 0.110 inch wide from one gap to the next.
The illustrated interconnection of chip diodes D20-D31 and capacitor arrays CA1, CA2 may be achieved using conventional surface-mount soldering techniques, or using conductive epoxy. The capacitor arrays CA1, CA2 may be connected to the circuit board and its associated conductive traces CT using similar techniques.
As illustrated in FIGS. 5A-5C, the molded terminal assembly 100 interconnects the components of or on the capacitor array CA1 with components of or on the capacitor array CA2. In particular, the straight-projecting terminals 100d are connected to the tops of the diodes, the short, downwardly extending terminals 100c are connected to respective top plates of the capacitors, and the long, downwardly extending terminals of the molded terminal assembly 100 serve as the 1Z1 and 3Z1 terminals of the multiplier Z1.
Except for the terminal 100c connected by a conductive lead CL to the 1Z1 multiplier terminal and the terminal 100d connected by another conductive lead CL to the 3Z1 multiplier terminal, each of the terminals 100d is connected by a respective conductive lead CL to one of the terminals 100c located on an opposite side of the rectangular body 102. The conductive leads CL may be defined by conductive foil, metal deposition, and the like. The connection of the various terminals to the circuit components may be achieved using conventional soldering techniques, conductive epoxy, or the like.
Preferably, the substantially rectangular body 102 of the molded terminal assembly is defined by molded "KAPTON". It is understood, however, that other electrically insulative materials can be used to form the rectangular body 102, so long as such materials are mechanically and dielectrically strong.
Preferably, the rectangular body 102 is less than one inch long, the illustrated body 102 having a length of about 0.90 inch. The short, downwardly extending terminals 100c preferably extend down a distance of about 0.04 inch to the top of the capacitors, while the long, downwardly extending terminals of the molded terminal assembly 100 extend down a distance of about 0.19 inch.
The terminals 10c, 1Z1 and 3Z1 preferably extend laterally out from the rectangular body 102 for a distance of about 0.03 inch, while the terminals 100d extend laterally out from the rectangular body 102 for a distance of about 0.08 inch. The preferred rectangular body 102 is less than 1/4 of an inch wide, preferably about 0.23 inch wide.
With reference to FIG. 5, since a high-voltage is achieved at the left-most end of the multiplier Z1, the spacing between circuit elements must be such that no short circuits occur. Additional insulation and smaller spacing may be provided by encapsulating the multiplier assembly in a strong insulative material.
In addition, as illustrated in FIG. 5, a gap 110 may be formed in the circuit board PCB, which gap 110 extends between the capacitor array CA1 and the high-voltage trace extending from the 3Z1 terminal to resistor R15 and then to the connector 60. The gap 110 also may extend between the capacitor arrays CA1, CA2, for a distance corresponding to the high voltage portions of the capacitor arrays CA1, CA2. The additional insulation described above may be applied so as to fill the void defined by the gap 110.
As illustrated in FIG. 6, an alternative multiplier Z1' can be constructed using two additional diodes and two additional capacitors. In particular, the multiplier Z1' is defined by an assembly of capacitors C21', C22', C23', C2', C25', C26', C27', C28', C29', C30', C31', C32' and diodes CR20', CR21', CR22', CR23', CR24', CR25', CR26', CR27', CR28', CR29', CR30', CR31' which are interconnected to form a voltage multiplier. Additional diodes and capacitors can be added or removed to develop a higher or lower output voltage for different applications.
In order to achieve a high-voltage output V.sub.OUT, of about 8,000 volts, the capacitors C21'-C32' preferably have capacitances which provide acceptable ripple at the output and minimize voltage regulation requirements. Typical values for 8,000 volts are between 75 pFarad and 150 pFarad for the ceramic monolithic capacitor banks, with one common plate (parallel configuration). Generally, when the voltage rating is higher, the capacitance is lower for the same size "block" due zo increased thickness of the dielectric.
Structurally, the alternative multiplier Z1' can be defined by an arrangement similar to that of FIGS. 5 and 5A-5C, except that an additional course of conductive lead pairs is provided in the rectangular body 102, as well as an additional capacitor for each capacitor array CA1, CA2.
Alternatively, the circuit board can be constructed using a ceramic material and the multiplier Z1 can be arranged so that the capacitive elements thereof are defined, in part, by the ceramic material of the circuit board. In particular, the ceramic material of the circuit board could be used as the dielectric which separates conductive capacitor plates defined by a conductive film or foil on the top surface of the circuit board from conductive parallel strips located on the bottom surface of the ceramic circuit board. The parallel strips on the bottom can be electrically connected to the transformer T1 using, for example, conductive traces which extend around an edge of the circuit board toward the appropriate terminals of the transformer T1. The diodes therefore would be located on the top surface of the conductive film or foil, thereby providing a surface mounting arrangement for the diodes of the multiplier.
The foregoing alternative arrangements, of course, are only examples of the many modifications which can be made to the preferred embodiment without departing from the scope and spirit of the present invention.
Still other examples of such modifications include, among other things, alternative circuitry for replacing the circuitry illustrated in FIG. 2.
Although not all of the alternative circuitry may achieve all of the objects of the invention, at least some of the objects are achieved by the alternative circuitry. An example of such alternative circuitry is illustrated in FIG. 7. The following chart describes the various circuit elements shown in FIG. 7.
Although the circuitry illustrated in FIG. 7 is generally effective, it does not provide the low-power, indirect dynamic voltage regulation control provided by the circuitry of FIG. 2.
Yet another example of alternative circuitry is illustrated in FIG. 8. The following chart describes the various circuit elements shown in FIG. 8.
The circuit illustrated in FIG. 8 is functionally very similar to that of FIG. 2. The individual op-amps, however, are shown separately in FIG. 8. The individual op-amps are replaced in FIG. 2 by the better performing LT 1490 which provides lower quiescent current and is less expensive. Also, U1 in FIG. 2 is implemented using the MAX 887 chip which is more efficient than what is illustrated in FIG. 8.
Still another example of such alternative circuitry is illustrated in FIG. 9. The following chart describes the various circuit elements shown in FIG. 9.
Although the circuitry in FIG. 9 is generally effective, it requires a negative voltage V.sub.EE for the op-amps to operate correctly, it utilizes a voltage feedback from the high-voltage output and it therefore fails achieve some of the advantages of the circuitry illustrated in FIG. 2.
FIG. 10 is a circuit diagram of yet another alternative circuit according to the present invention. FIG. 11 is a plan view of a preferred physical arrangement of the circuit illustrated in FIG. 10. The following chart describes the components of the circuit illustrated in FIGS. 10 and 11.
The four pin connector P2"" is illustrated schematically in FIG. 10A and includes an unused pin AGND 1, a ground pin AGND2, a source input pin SOURCE INPUT 3, and a shut-down pin SHUTDOWN 4.
FIGS. 12 and 12A schematically illustrate an epoxy-molded diode array block 200 according to a preferred embodiment of the circuit illustrated in FIGS. 10 and 11. All of the diodes CR20-CR27 are connected electrically in series, but physically in parallel. A node is defined electrically between each pair of diodes. Such nodes are electrically connected to respective terminals 202 which project out from the epoxy-molded diode array block 200 and are connected to respective pairs of the capacitors C21, C21A through C28,C28A.
The epoxy-molded diode array block 200 of FIGS. 12 and 12A advantageously can be manufactured so that the block 200 is about 0.15 inch thick, about 0.75 inch long, and about 0.275 inch wide.
FIG. 13 is a perspective view of a multiplier similar to that which is illustrated in FIGS. 10-12, except that the multiplier of FIG. 13 has only six diodes and twelve capacitors.
While the present invention has been described with reference to the above exemplary embodiments, it is understood that the present invention is not limited to such embodiments. To the contrary, the present invention is limited only by the scope of the appended claims.
Claims
I claim:
1. A power supply device for providing high-voltage power from a low-voltage source, said power supply device comprising: a voltage regulator for connection to said low-voltage source, said voltage regulator being arranged so as to step-down a source voltage level of said low-voltage source to produce an input voltage at a lower voltage level than said source voltage level wherein said input voltage has a variable voltage level; a DC-to-AC converter connected to said input voltage from said voltage regulator, said DC-to-AC converter being arranged so as to convert said input voltage into an AC voltage; a multiplier connected to the AC voltage from said DC-to-AC converter, said multiplier being arranged so as to convert the AC voltage into a substantially DC output signal having a DC voltage level which is significantly higher than said source voltage level.
2. The power supply device of claim 1, wherein said multiplier comprises an assembly of capacitors and diodes which are interconnected to form a voltage multiplier.
3. The power supply device of claim 1, wherein said regulator is a single dynamic regulator.
4. The power supply device of claim 3, and further comprising a regulator controller connected, at least indirectly, to said multiplier, said regulator controller being arranged so that when said multiplier is connected to an electrical load, a voltage indicative of current flowing between said multiplier and the electrical load is applied to said regulator controller, said regulator controller being connected to said dynamic regulator so as to provide a control signal to said dynamic regulator, the control signal being dependent, at least in part, on said voltage indicative of current, said dynamic regulator being arranged so as to regulate said input voltage level in a manner dependent upon said control signal.
5. The power supply device of claim 3, and further comprising sampling circuitry connected electrically between said multiplier and said regulator controller, said sampling circuitry being arranged so as to provide said voltage indicative of current without drawing more than 0.003% of power flowing to said electrical load.
6. The power supply device of claim 3, wherein sahd regulator controller is connected to said input voltage, said regulator controller being responsive to said input vol age so that said control signal is provided to said dynamic regulator in a manner dependent on both of said input voltage and saud voltage indicative of current.
7. The power supply device of claim 3, wherein said regulator controller is arranged so as to selectively determine a level of said control signal such that: when said voltage indicative of current indicates that the current flowing between said multiplier and said electrical load is increasing, said dynamic regulator increases the input voltage, and when said voltage indicative of current indicates that the current flowing between said multiplier and said electrical load is decreasing, said dynamic regulator decreases the input voltage.
8. The power supply device of claim 7, wherein said regulator controller is responsive to said input voltage such that said increases and decreases of the input voltage also are dependent upon a present level of the input voltage.
9. The power supply device of claim 1, wherein said regulator controller is connected to said input voltage, said regulator controller being responsive to said input voltage so that said regulator controller determines said level of the control signal in a manner which is also dependent upon the level of the input voltage.
10. The power supply device of claim 1, wherein said regulator is arranged so that, as said low-voltage source becomes depleted, said regulator continues to provide said input voltage at progressively decreasing voltage levels, at least until said source voltage decreases to one half of the source voltage of a fully charged low-voltage source.
11. The power supply device of claim 1, wherein said regulator is arranged so that, as said low-voltage source becomes depleted, said regulator continues to provide said input voltage at progressively decreasing voltage levels, at least until said source voltage decreases to 20% of the source voltage of a fully charged low-voltage source.
12. The power supply device of claim 1, wherein said DC voltage level is at least one thousand times the source voltage level.
13. The power supply device of claim 1, wherein said DC voltage level is between 1440 and 1760 times the source voltage level.
14. The power supply device of claim 1, wherein said regulator, DC-to-AC converter, and said multiplier are packaged together such that a profile of said power supply device is less than one half inch in thickness.
15. The power supply device of claim 1, wherein said regulator, DC-to-AC converter, and said multiplier are packaged together such that a profile of said power supply device is less than four tenth of an inch in thickness.
16. The power supply device of claim 1, wherein said multiplier comprises: first and second capacitor arrays spaced apart from each other, each capacitor array defining a plurality of capacitors; a diode located on a surface of each of said plurality of capacitors; and a terminal assembly having: a first set of conductive leads arranged so as to electrically connect respective diodes on said first capacitor array to respective capacitors of said second capacitor array, and a second set of conductive leads arranged so as to electrically connect respective diodes on said second capacitor array to respective capacitors of said first capacitor array.
17. The power supply device of claim 16, wherein said first and second capacitor arrays have a spatial relationship so that said first and second capacitor arrays are arranged in a substantially parallel fashion to one another, and said surface is a capacitor top surface.
18. The power supply device of claim 17, wherein said terminal assembly further comprises first and second ends, the conductive leads defining said first and second set of conductive leads being alternatingly arranged between said first and second ends.
19. The power supply device of claim 18, wherein each conductive lead of said first and second set of conductive leads includes a substantially straight terminal and an oppositely arranged, downwardly projecting terminal; the downwardly projecting terminal being connected to one of said capacitors and the substantially straight terminal being connected to one of said diode.
20. The power supply device of claim 16, wherein said first and second sets of conductive leads are arranged within an electrically insulative body, said first and second set of conductive leads having terminal portions over said first and second capacitor arrays which extend out from said insulative body.
21. A voltage multiplier capable of converting an AC voltage into a substantially DC high-voltage output signal, said multiplier comprising: first and second capacitor arrays spaced apart from each other, each capacitor array defining a plurality of capacitors; a diode located on a surface of each of said plurality of capacitors; and a terminal assembly having: a first set of conductive leads arranged so as to electrically connect respective diodes on said first capacitor array to respective capacitors of said second capacitor array, and a second set of conductive leads arranged so as to electrically connect respective diodes on said second capacitor array to respective capacitors of said first capacitor array.
22. The voltage multiplier of claim 21, wherein said first and second capacitor arrays have a spatial relationship so that said first and second capacitor arrays are arranged in a substantially parallel fashion to one another, and said surface is a capacitor top surface.
23. The voltage multiplier of claim 22, wherein said terminal assembly further comprises first and second ends, the conductive leads defining said first and second set of conductive leads being alternatingly arranged between said first and second ends.
24. The voltage multiplier of claim 23, wherein each conductive lead of said first and second set of conductive leads includes a substantially straight terminal and an oppositely arranged, downwardly projecting terminal; the downwardly projecting terminal being connected to one of said capacitors and the substantially straight terminal being connected to one of said diode.
25. The voltage multiplier of claim 21, wherein said first and second sets of conductive leads are arranged within an electrically insulative body, said first and second set of conductive leads having terminal portions over said first and second capacitor arrays which extend out from said insulative body.
26. A power supply device for providing high-voltage power from a low-voltage source, said power supply device comprising: regulator means connectable to said low-voltage source, for stepping down a source voltage level of said low-voltage source to produce an input voltage at a lower voltage level than said source voltage level wherein said input voltage has a variable voltage levels; a DC-to-AC converter means connected to said input voltage, for converting said input voltage into an AC voltage; multiplier means connected to the AC voltage from said DC-to-AC converter means, for converting the AC voltage into a substantially DC output signal having a DC voltage level which is significantly higher than said source voltage level.
27. The voltage multiplier of claim 21, wherein each capacitor forming said first capacitor array shares a first common electrode; and each capacitor forming said second capacitor array shares a second common electrode.
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