Apparatus for Making Tactile Impressions on Paper

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

The present invention relates generally to printers and more particularly to an apparatus for making tactile impressions, such as a Braille matrix, on paper. The tactile impressions may be felt through the skin by visually impaired persons. A variety of systems for representing letters, words, or thoughts with tactile impressions on paper now exist. For example, a commonly used system, developed by Louis Braille in the early 1800's, uses predetermined combinations of raised circular dots, or "dimples," to represent letters of the alphabet.

In the Braille system, for example, each English language letter is represented by a combination of 1-6 raised dots. Dots for a particular letter are grouped together in two vertical columns, each column having up to three dots.

Communications using tactile impressions on paper are an important vehicle for allowing visually handicapped persons to communicate with others. Unfortunately, many of the printers available to make such tactile impressions are complex and expensive machines, which many visually handicapped persons cannot afford to own. Furthermore, the available machines are

o often simply too large, noisy and unreliable to be a workable tool for the visually impaired.

Moreover, many of such tactile printers can only use particular types of paper, further increasing the cost of providing Braille material to the blind. Also, many printers are large, heavy to transport, and difficult and expensive to maintain.

Many tactile printers use impact technology to create raised dots, and thus are very noisy and mechanically unreliable. Such printers are often too noisy to function effectively in an office environment that a blind person may wish to work in.

In addition, many of the tactile printers commonly available give poor quality impressions on paper. Others cannot use standard paper that is commonly available and used by sighted persons. Still other printers may only use particular sizes of paper, which, in some applications, may be inappropriate or difficult to use. This is particularly true if, for example, a visually impaired person wishes to do a large spread sheet or to print or "read" graphics. Still further, some printers take too long to operate, such that when connected to a word processor, a blind typist may spend a considerable period of time before being able to "read" what he or she has typed by touching the tactile impressions. Other printers are difficult for the visually impaired to load with paper.

Overall, tactile printers should be more widely available to visually handicapped persons. The large size, complexity, high-cost and poor performance of many commonly available tactile printers reduce the amount of "written" material that is available for the visually handicapped. This, in turn, may preclude the blind from obtaining jobs that they otherwise are capable and willing to perform. The lack of "readable" material and reduced opportunities for jobs further isolates the blind from the rest of society and prevents them from assimilating into the environment and work places of sighted persons.

In a principal aspect, the present invention is an improved apparatus for making tactile impressions on paper. The apparatus includes a plurality of pins, a driver, and a print wheel. The driver selectively extends a pin toward the paper. The print wheel then presses the paper and pin in close contact. As a result, the pin is forced against the paper by the print wheel and leaves a tactile impression on the paper.

According to another feature of the present invention, the apparatus includes a plurality of drivers and a controller. The controller receives an input signal and responsively provides activation signals to the driver so that selected pins are raised to create tactile impressions when the print wheel passes over the paper and the extended pins. The controller may receive inputs from a variety of sources, including, for example, a word processor, optical scanner, computer, or modem.

Accordingly, an object of the present invention is an improved apparatus for making tactile impressions on paper. Another object is a tactile printer that has that has fewer parts. Thus, still another object is a tactile printer that is less expensive to manufacture and that will be less expensive for the visually handicapped to purchase. A further, related object is a tactile printer that is more durable and reliable. Yet another object is a tactile printer that prints faster, is smaller and lighter, and has fewer maintenance requirements.

A further object is a tactile printer that is more useful in an office environment. Thus, it is also an object to provide a tactile printer that is quieter and creates a higher quality of tactile impressions. Yet a further objective is a tactile printer that more readily accepts and uses a variety of different papers. Still another object is a printer that will be easier to load with paper. A further object is a tactile printer that is more easily connected to a word processor and, when so connected, will allow a blind typist to quickly "read" what has been typed.

Yet a further object is a printer that may accept and use a large variety of different sized of papers. Such a printer, for example, may more easily allow graphics or spread sheets to be set forth in a tactile form. A further object is a tactile printer that more readily utilizes inexpensive "used" paper, which may be obtained for use by the blind at a substantially lower cost than the more conventional "thick" paper traditionally used for Braille printing.

Another object is a printer that will more easily operate off standard data ports. The enhanced ability to operate using standard data ports may allow the blind to more easily communicate in society. Thus, for example, an inexpensive (and therefore more "available") tactile printer may be attached to a personal computer. The personal computer may, in turn, be connected to a modem. Two blind persons with such equipment may thus send and receive tactile documents over a telephone line.

The availability of a cheap, reliable, tactile printer thus has tremendous implications for allowing the blind to more easily assimilate into a sighted society. A blind person may carry a lightweight, reliable, quiet printer with him or her, for example, to the work place. With a standard word processor connected to a compact tactile printer, for example, a blind typist may type a letter to be read by sighted persons while, substantially at the same time, create for himself or other blind persons, a Braille version of the typed document. The blind typist is thus enabled to readily proofread the typed line or typed page before it is distributed. Also, by simply putting a normally typed document into an optical scanner, and then connecting the scanner to the tactile printer, the visually handicapped may "read" a conventional, ink-typed memorandum or letter almost as easily as a sighted person.

Furthermore, such a printer may more readily allow blind persons to read a newspaper. The contents of a newspaper may, for example, be readily stored on a computer disc. It may be put on the disc either by a newspaper concern itself or, alternatively, could be read by an optical scanner and then put onto a disc. Such a disc could then be put into a file in a personal computer "billboard" system. In this way, a blind person, with a personal computer, modem, and printer, may simply dial up the file over the telephone line and obtain a "dump" of the current newspaper file. The visually handicapped person may then transfer the newspaper file to the printer. Thus, in a matter of minutes, a visually handicapped person can "read" about current events in an up-to-date newspaper, rather than only listening to news programs on radio or television or waiting for the delivery of possibly outdated newspaper made with conventional Braille printing techniques.

These and other objects of the present invention will be more fully understood by reference to the following detailed description of the preferred embodiment.

A preferred embodiment of the present invention is described herein with reference to the drawing wherein:

FIG. 1 is a perspective view, with a cut away portion, of a preferred embodiment of the present invention;

FIG. 2 is an enlarged perspective view of a portion of the driver assembly in the preferred embodiment shown in FIG. 1;

FIG. 3 is a right side view of a portion of the driver assembly shown in FIG. 2, with a pin in a normal, retracted position;

FIG. 4 is a right side view of a portion of the driver assembly shown in FIG. 2, with the pin in an extended position;

FIG. 5 is a perspective view of the preferred embodiment shown in FIG. 1;

FIG. 6 is a partial perspective view of the preferred embodiment shown in FIG. 1, with a cut away portion showing the channel and optical scanner assembly;

FIG. 7 is a simplified block diagram of the preferred embodiment shown in FIG. 1;

FIG. 8 is a more detailed block diagram of the preferred embodiment shown in FIG. 7;

FIG. 9 is a schematic diagram of the direct current power supply for the controller in the preferred embodiment shown in FIG. 1; and

FIG. 10 is a schematic diagram of the interface for the controller in the preferred embodiment shown in FIG. 1.

Referring to FIGS. 1-10, a preferred embodiment of the present invention is shown as an improved apparatus for making tactile impressions on paper. The apparatus hereafter shall be referred to as a "Braille printer" or "printer" 20. It is to be understood, however, that a number of alternative systems to communicate with the visually handicapped, which employ tactile impressions on paper, may be used with the present invention.

The Braille system uses series of raised dots. Other types of tactile markings, such as, for example, raised slashes or other geometric patterns, may be made on paper with the present invention. The invention may be modified to accommodate different types of raised characters or different arrangements of raised characters to represent various letters, words, or thoughts.

The Braille printer 20 includes a housing 22, paper receiver 24, plurality of pins 26, driver assembly 28, print wheel or platen assembly 30, and controller 32. The housing 22 is made of plastic and substantially encloses the other components of the printer 20. The housing 22 includes a paper slot 34, defined by two side ridges 36, 38, and a lower horizontal plate 40. The paper slot 34 defines the "front" of the printer 20. For illustrative purposes, a sheet of fan-fold computer paper 42 is shown in the printer 20 in FIG. 1. The paper 42 includes a series of side holes 44, 45 therein. Such computer paper, as well as other types of paper (including "used" paper with ink printing on it) may be used with the present printer 20.

The paper receiver 24 includes a platen 46, roller 48, and paper advance mechanism 50. The platen 46 and roller 48 are spaced apart so that the paper 42 may snugly fit between them. Each end of the platen 46 includes a series of pegs 52, 53 and a knob 54, 55. The pegs 52, 53 mesh with the series of holes 44, 45 along the sides of the paper 42. For paper not including such holes, however, the simple friction of the paper between the platen 46 and roller 48 is sufficient to hold the paper in the desired location while the printer 20 is in operation.

The knobs 54, 55 on each end of the platen 46 may be turned to manually advance the paper 42. To load the printer 20 with paper, the paper 42 is placed in the paper slot 34 and pushed forward toward the platen 46 and roller 48.

The paper advance mechanism 50 includes a stepper motor 56, interconnected via an interface in the form of a gear assembly 58, to the platen 46. Upon receiving a signal from the controller 32, the mechanism 50 rotates the platen 46 and moves the paper 42.

The pins 26 of the printer 20 are combined into groups of forty pairs. Since all of the eighty pins are substantially the same, only a single, illustrative pin 60 is discussed immediately below. The pin 60 includes upper and lower segments 62, 63, which are substantially straight, and a curved elbow portion 64, as shown in FIGS. 3 and 4. The upper and lower segments 62, 63 of the pin 60 are approximately 10 millimeters in diameter. The top of the upper segment 62 is rounded. All of the pins 26 are arranged substantially in a straight line near the platen 46. This line defines the "roller path" 65 of the printer 20.

The driver assembly 28 includes a bracket 66 holding a series of forty pairs of drivers 67. The drivers 67 comprise a group of eighty electrical solenoids 68 and a group of eighty interface blocks 70. See FIG. 2.

The bracket 66 is interconnected to the housing 22 and is substantially adjacent to the platen 46. When the printer 20 is in its normal position, as shown in FIG. 1, the solenoids 68 are in a substantially horizontal orientation, and the pins 26 are held by the bracket 66 in a substantially vertical position.

The bracket 66 includes upper and lower levels 71, 72, as shown in FIG. 2. With this arrangement, each of the forty pairs of pins 26 may be located closely to one another (despite the physical width of the solenoids 68).

Since all of the eighty driver assemblies 67 are substantially the same, only a single, illustrative driver 73, a single, illustrative electrical solenoid 74, and single illustrative interface block 76 are discussed below. The solenoid 74 is attached to the bracket 66 and includes a central shaft 78 and retracting spring 80. The spring 80 normally keeps the shaft 78 in a retracted position, as shown in FIG. 3. The block 76 is interconnected to the shaft 78 and, as shown, includes an inclined surface, 82, having an angle of approximately 30 degrees to horizontal, and an upper surface 84, which is substantially horizontal. The solenoid 74 moves the central shaft 78 approximately 0.2 inch upon receiving an electrical impulse.

The elbow portion 64 of the pin 60 rests against the inclined surface 82 of the block 76. The elbow portion 64, together with the inclined surface 82, define cooperating cam surfaces 86. See FIG. 3. Thus, when the solenoid 74 is activated and the block 76 is pushed toward the pin 60, the elbow portion 64 of the pin 60 slides upward, along the inclined surface 82 and then finally to the upper surface 84 of the block 76. See FIG. 4. The elbow portion 64 then rests on the upper surface 84 until the solenoid 74 releases the shaft 78 and the spring 80 pushes the shaft 78 back into the normal position, allowing the pin 60 to fall back to the normally retracted position shown in FIG. 3.

In operation, the solenoids 68 are activated such that a selected group of the pins 26 are driven approximately 1/32 inch above the paper slot 34. While in the upper position, the elbow portion 64 rests on the upper surface 84 of the block 76, and the pin 60 can not be depressed by applying a normal, downward pressure on the pin 60. The pin 60 is effectively "locked" in the elevated position, as shown in FIG. 4.

Accordingly, the wheel assembly 30 presses downward, forcing the paper 42 against the extended pin 60. When the print wheel assembly 30 presses paper over the pin 60, the pin 60 leaves a tactile impression on the paper 42.

As shown in FIGS. 1 and 6, the print wheel assembly 30 includes a sensor assembly 88, print wheel or platten 90, drive mechanism 92, and channel 93. The drive mechanism 92 includes a reversible stepper motor 94, as shown in FIG. 1, and an interface, in the form of an endless belt 96 attached to the print wheel 90, as shown in FIG. 6. The stepper motor 94 receives commands from the controller 32 and responsively turns the endless belt 96, allowing the print wheel 90 to roll along the roller path 65.

The print wheel or platten 90 is approximately one inch in diameter, having a rotatable central spindle 97 and a circumferential edge 98. See FIG. 4. In the preferred embodiment, the circumferential edge 98 includes an elastomeric rim 100, approximately 1/4 inch thick. Thus, when the wheel 90 rolls along the roller path 65, the wheel 90 pushes the paper 42 about the raised pin 60, and the pin 60 extends into the paper 42 and into the elastomeric rim 100 of the wheel, as shown in FIG. 4. Accordingly, a raised dot appears on the paper 42, which corresponds to the raised pin 60. Where the pin 60 has not been raised, however, the wheel 90 simply rides over the paper 42 without causing any raised dots to be made in the paper 42.

As shown by FIGS. 1 and 6, the channel 93 is located directly above the roller path 65. The channel 93 is rigid and fixedly attached to the housing 22. As shown in FIG. 6, the channel 93 allows the print wheel 90 to move unobstructed, but resists upward movement of the wheel 90, away from the paper 42.

In this way, when the wheel 90 rides over a raised pin, the wheel 90 does not ride upward over the pin. Rather, the spindle 97 of the print wheel 90 remains at a substantially constant distance above the paper slot 34, regardless of whether a pin has been raised. The wheel 90 riding over a raised pin simply pushes the paper about the pin, rather than moving the wheel 90 and spindle 97 upward.

The sensor assembly 88 includes two head detectors 102, 104, a paper sensor 105, a buzzer 106, and manual inputs 107. See FIGS. 6, 8, and 10C. The head sensors 102, 104 are mounted on either end of the-roller path 65. Each of the sensors 102, 104 includes a source of light 108, 110 and a light detector 112, 114.

When the print wheel 90 is in the center of the printer 20, away from either end of the roller path 65, each source 108, 110 sends an unobstructed beam of light to a corresponding light detector 112, 114. When the wheel 90 reaches one end of the roller path 65, however, the wheel 90 obstructs the light. The detector 112, 114 then sends a signal to the controller 32. The controller 32 may then responsively adjust the movement of the drive mechanism 92 so that the wheel 90 will not be substantially further driven toward the end, but will either stop or reverse direction.

Of course, alternative embodiments of the printer 20 may include, for example, instead of the sensors 102, 104, any of a variety of simple limit switches Such limit switches could sense the passage of the print wheel 90 and, accordingly, signal the controller 32.

The paper sensor, or button 105, is located along the paper slot 34. The sensor, or button, 105 is depressed only if there is paper in the paper slot 34. When a fault condition exists, such as, for example, the print wheel 90 does not rotate or the paper is out, the controller 32 issues an alarm signal to the buzzer 106. The buzzer 106 responsively sounds an audible alarm to alert the user of the fault condition. The manual inputs 107 allow the user to push a button and instruct the controller 32 to advance the paper one page or one line or to go "on or off line."

During operation, the printer 20 may receive an input from a variety of interfaces 108a, which receive signals from a variety of sources, such as, for example, a keyboard 109, optical scanner 110, computer 111, or telephone line 112. See FIG. 8. The controller 32 receives such signals and responsively issues signals to the driver assembly 28 and print wheel assembly 30.

The print wheel assembly 30 advances the paper 42 at a controlled rate, and the reversible stepper motor 94 responsively moves the print wheel 90 over the roller path 65. The controller 32 sends signals to the driver assembly 28 so that appropriate pins are extended. Consequently, the electrical input signals are transformed to a understandable sequence of raised dots as the paper 42 is fed through the printer 20 by the stepper motor 56. See FIGS. 7 and 8.

In the preferred embodiment, the controller 32 includes a direct (d.c.) current power supply 116 and interface 118. Schematic representations of the controller 32 are shown in FIGS. 9 and 10.

FIG. 9 shows the power supply 116 used to provide constant source of direct current electrical power to the other components of the printer 20. The power supply 116 includes a line voltage input transformer 120, two rectifiers 122, 124, six input smoothing capacitors 126, four voltage regulators 128, 129, 130, 131, and ten output smoothing capacitors 132, 133, 134, 135. The transformer 120 provides alternating current (a.c.) voltage to the rectifiers 122, 124 and to the smoothing capacitors 126. Accordingly, a low voltage d.c. current is provided to the voltage regulators 128-131.

The voltage regulator chips 128-134 provide, respectively, a substantially constant source of +5 Volts (10 ampere maximum), +5 Volts (1 ampere maximum), +24 Volts (5 ampere maximum) and -12 Volts (1 ampere maximum) for use by the other components in the rest of the controller 32. The output smoothing capacitors 132-135 help to maintain the voltage output of the voltage regulator chips 128-131 at a more constant level.

FIG. 10 discloses the interface 118 for the printer 20, which includes an input circuit 142 (FIG. 10A), microprocessor circuit 144 (FIG. 10B), paper control circuit 146 (FIG. 10C), memory circuit 148 (FIG. 10D), and driver circuit 150 (FIGS. 10C and 10E). The circuits are interconnected via a data bus 152, control bus 154, address bus 156, driver bus 158, output control bus 160, and print control bus 162.

The input circuit 142 includes a standard RS232 data port 164, to receive serial data, and parallel input lines 166, to receive parallel data. The parallel input lines 166 include eight input lines 172 to receive Centronics parallel input, four "hand shaking" lines 174, and two error signaling lines 176. The hand shaking lines 174 allow proper sequencing of the information along the eight input lines 172.

Data from the eight input lines 172 are received by the latch 168. The latch 168 responsively holds the received signals, while forwarding signals to the data bus 152 and buffer 170. The "hand shaking" lines 174 are interconnected to the control bus 154.

The buffer 170 receives the signals from the latch 168. If the input is arriving too quickly and the buffer 170 becomes full, the buffer 170 sends a signal, via one of the "hand shaking" lines 174, to inform the transmitting interface that no additional data should be sent until a clear signal is sent along the "hand shaking" lines 174.

Data from the buffer 170 is transferred to the memory circuit 148 via the data bus 152. The memory circuit 148 includes a 64K Random Access Memory (RAM) 172 as well as an Erasable Programable Read Only Memory (EPROM) 174 which holds a microprocessor program. The memory circuit 148 also includes memory data lines 176, address input lines 178, control lines 180, and address control lines 182. Data from the buffer 170 is sent via the memory data lines 176 and RAM 172.

The microprocessor circuit 144 advises the RAM 172 of where the data is to be stored, via the address bus 156 and address input lines 178. The EPROM 174 sends signals to control the operation of the microprocessor circuit 144 via the control lines 180. The location of data to be retrieved is sent via the address control lines 182. As needed, data from the RAM 172 is supplied to the microprocessor circuit 144, according to the instructions in the EPROM 174, via the memory data lines 176.

The microprocessor circuit 144 in the preferred embodiment includes an Intel 8049 microprocessor 184 with standard peripheral circuits, such as an eight megahertz crystal-driven clock 186, address output lines 188, data lines 190, and an output latch 192.

The microprocessor and memory circuits 144, 148 function, in essence, as a "look up table." In accordance with the data received, the controller 32 determines what series of impressions should be made on the next line of paper and, accordingly, sends appropriate signals to the driver assembly 28 so that an appropriate pattern of raised dots or characters will be made on the paper.

The microprocessor 184 sends signals, via the address output lines 188 and address bus 156, to control where data is stored in the memory circuit 148 The output of the microprocessor 184, which contains information as to which pins should be elevated to cause a proper sequence of raised dots on the paper 42, is sent out, via the data lines 190, to the latch 192. The latch 192, in turn, sends the data to the address bus 156 and the driver circuit 150.

The driver circuit 150 includes a 4 to 16 decoder 194 (FIG. 10C), ten latches 196 (FIG. 10E), and ten solenoid drivers 197 (FIG. 10E). Data from the latch 192 are thus sent to the 4 to 16 decoder 194 which, in turn, transmits the output from the microprocessor 184 to the output control bus 160.

Each of the ten latches 196 receives ten inputs: eight from the driver bus 158, one from the output regulation bus 160, and one from the paper control circuit 146. Each of the ten latches 196 provides eight output lines. Each of the ten solenoid drivers 197 receives the eight output lines from one of the latches 196 and provides eight output lines 198. Each of the 80 output lines 198 is connected to one of the solenoids 68, such as the solenoid 74 shown in FIG. 3. The solenoid, in turn, when activated, pushes a pin upward against the paper.

As required, the microprocessor 184 sends signals along the print control bus 162 to activate the stepper motor 56 or the reversible stepper motor 94 to either move the print wheel 90 along the paper roller path 65 or to advance the platen 46 and thus the position of the paper 42 within the printer 20.

The paper control circuit 146 includes the buzzer 106, right head detect circuit 202, left head detect circuit 204, printer control circuit 206, and motor drive circuit 207. The right and left head detect circuits 202, 204 receive signals from the light sensors 102, 104 and responsively issue a signal to the microprocessor 184, along the print control bus 162, when the print wheel 90 has reached an end of the roller path 65.

The printer control circuit 206 includes a off/on line switch 208, form feed switch 209, and line feed switch 210, as well as the paper-out switch 105. When activated, each switch 105, 208-210 delivers a signal to the microprocessor 184, via the print control bus 162. The switches 105, 208-210 send signals to note that the printer 20 is off or on line, to activate the stepper motor 56 to advance the paper 42 an entire sheet, to activate the stepper motor to advance the paper 42 one line, and to note that no paper is in the paper slot 34. In response to a signal from the paper-out switch 105 or other fault conditions, the microprocessor 184 issues a signal to activate the buzzer 106 and thus advise the user that a fault conditions exits.

The motor drive circuit 207 includes a latch 214 and driver 216. Upon receiving a signal from the microprocessor 184, the latch 214 or 216 responsively activate the motors 56, 94.

Although the foregoing description of the preferred embodiment will enable a person of ordinary skill in the art to make and use the invention, the following detailed assembly language listing for the microprocessor 184 is included. The listing provides detailed information concerning the overall programming and operation of the controller 32. Additional features of the controller 32 will become apparent to those skilled in the art upon reviewing the assembly language listing that follows. ##SPC1##

A preferred embodiment of the present invention has been described herein. It is to be understood, however, that changes and modifications can be made without departing from the true scope and spirit of the present invention. For example, an alternative printer could include a wheel having a series of pins and a pin driver within it. The paper would then be laid on a base, and the base would include a series of depressions spaced to correspond to the pins in the wheel. A controller would activate the driver to raise selected pins. The wheel would then roll over the paper, driving any extended pins into the depressions in the base. The raised pins in the wheel would thus cause tactile impressions to be made on the paper, which is between the wheel and base.

Thus, a large variety of variations from the present invention are possible, without departing from the true scope and spirit of the invention. This true scope and spirit are defined by the following claims and their equivalents to be interpreted in light of the foregoing specification.