Digital Signal Generator

This invention relates to a digital signal generator for producing an accurate digital signal according to the detected state of a combination consisting of mechanical and electrical elements, and its object is to provide a digital signal generator, which comprises a signal section consisting of a predetermined conductor pattern including a digital signal pattern and a timing signal pattern and a contact group slidable over the signal section to take out the digital signal and the timing signal, and in which a digital signal is selectively taken out from a digital signal generator circuit in correspondence to the relative position of the signal section relative to the contact group when a timing signal is provided.

The accompanying drawings illustrate one embodiment of the digital signal generator according to the invention, and in which:

FIG. 1 is a schemative representation of the entire system;

FIG. 2 is a perspective view of the signal section;

FIG. 3 is an electric connection diagram of the digital signal generator circuit;

FIG. 4 is a developed view of the signal section; and

FIGS. 5a and 5b are pattern views given to illustrate features of the system according to the invention.

The invention will now be described in conjunction with an embodiment thereof with reference to the drawings.

FIG. 1 shows an outline of a digital signal generator which is adapted to produce a digital signal according to the throttle position of a vehicle. Reference numeral 1 generally disignates a detector comprising a cylindrical drum 1b serving as signal section and provided on the periphery with a predetermined conductor pattern including a digital signal pattern and a timing signal pattern and a contact group 1a consisting of 6 contacts 1a.sub.1 to 1a.sub.6 in slidable contact with the signal section. A digital signal can be taken out from the contact group 1a in accordance with the position of the signal section relative to the contact group. The cylindrical drum 1b is integral with a rotative shaft 1c serving as drive means, and the position of the drum relative to the contact group is shifted with the rotation of the rotative shaft 1c. Numeral 2 designates a digital signal generator circuit having input terminals 2a.sub.1 to 2a.sub.6 and output terminals 2a.sub.7 to 2a.sub.10. Signals from the contact group 1a are led to the input terminals 2a.sub.1 to 2a.sub.7, and a digital signal coupled from the digital signal contacts 1a.sub.1, 1a.sub.2, 1a.sub.4 and 1a.sub.5 to the input terminals 2a.sub.1, 2a.sub.2, 2a.sub.4 and 2a.sub.5 and corresponding to the afore-mentioned relative position appears at the output terminals 2a.sub.7 to 2a.sub.10 at an instant of appearance of a timing signal from the timing contact 1a.sub.3 at the input terminal 2a.sub.3. The rotative shaft 1c is rotated by depressing an accelerator pedal 3, and its position is determined by the position of the accelerator pedal. The conductor pattern provided on the periphery of the drum 1b is arranged such that one of 16 different 4-bit digital signals may be taken out from the output terminals 2a.sub.7 to 2a.sub.10 according to the relative position of the drum 1b, that is, the position of the accelerator pedal 3.

FIG. 2 shows in detail the conductor pattern printed on the periphery of the drum 1b. It consists of 6 parallel or axial divisions 1b.sub.1 to 1b.sub.6 to provide for digital signals, timing signal and a common signal. The divisions 1b.sub.1, 1b.sub.2, 1b.sub.4 and 1b.sub.5 have their respective conductor patterns for respective 2.sup.3, 2.sup.1, 2.sup.0 and 2.sup.2 portions of a digital signal. The division 1b.sub.3 is provided for a timing signal, and the division 1b.sub.6 is provided for a common signal. These conductor pattern divisions 1b.sub.1 to 1b.sub.6 are in contact with the respective contacts 1a.sub.1 to 1a.sub.6 in the contact group 1a shown in FIG. 1, and which contacts are connected to the respective input terminals 2a.sub.1 to 2a.sub.5 of the digital signal generator circuit 2 by means of six conductive wires.

FIG. 3 shows the circuit diagram of the digital signal generator circuit. In FIG. 3, the input terminal 2a.sub.6 is grounded. Indicated at V.sub.DD is a positive bias terminal connected to the positive side of a power supply. 2.sup.0, 2.sup.1, 2.sup.2 and 2.sup.3 signals are led to the respective input terminals 2a.sub.4, 2a.sub.2, 2a.sub.5 and 2a.sub.1, and timing signal is led to the input terminal 2a.sub.3. Designated at 2R.sub.11, 2R.sub.12, 2R.sub.21, 2R.sub.22, 2R.sub.31, 2R.sub.32, 2R.sub.41, 2R.sub.42, 2R.sub.51 and 2R.sub.52 are resistors, designated at 2b.sub.11, 2b.sub.21, 2b.sub.31, 2b.sub.41 and 2b.sub.51 are inverters, and designated at 2b.sub.12, 2b.sub.22, 2b.sub.32 and 2b.sub.42 are D type flip-flops which may be "MOS IC CD4013" (a trade name by Radio Corporation of America in U.S.A.). In each of the flip-flops 2 b.sub.12 -2b.sub.42, the terminal symbol D designates data, C clock, S set, R reset, and Q output. As is known in the art, D type flip-flops are clockable bistable storage elements which change the output state thereof only when a separate pulse, i.e., clock pulse, is coupled thereto.

The operation of the above construction will now be described in connection with FIG. 4, which is a developed view of the drum 1b. Since the input terminal 2a.sub.6 is grounded, all the shaded portions of the conductor pattern represent level " ". That is, the shaded portions in the conductor pattern shown in FIG. 2 or the conductive pattern in FIG. 4 which shows a developed view of the pattern in FIG. 2 represent level "0" . As the accelerator pedal 3 is depressed the drum 1b is rotated in unison with the rotative shaft 1c relative to the contact group 1a. When the drum 1b comes to a position at which the contacts 1a.sub.1 to 1a.sub.6 are on line 31 in FIG. 4, the 2.sup.0 signal at the input terminal 2a.sub.4 is of level "1" due to the resistor 2R.sub.11, and a signal of level "0" is coupled through the inverter 2b.sub.11 to the data terminal D of the D type flip-flop 2b.sub.12. Similarly, the 2.sup.1 signal at the input terminal 2a.sub.2 is of level "1" due to the resistor 2R.sub.21, and a signal of level "0" is coupled through the inverter 2b.sub.21 to the data terminal D of the D type flip-flop 2b.sub.22. On the other hand, the 2.sup.2 signal at the input terminal 2a.sub.5 and the 2.sup.3 signal at the input terminal 2a.sub.1 are of level "0", and a signal of level "1" is coupled through the inverters 2b.sub.31 and 2b.sub.41 to the respective data terminals D of the D type flip-flops 2b.sub.32 and 2b.sub.42. Meanwhile, the timing signal at the input terminal 2a.sub.3 is of level "0", and a signal of level "1" is coupled through the inverter 2b.sub.51 to the clock terminals c of the individual D type flip-flops 2b.sub.12, 2b.sub.22, 2b.sub.32 and 2b.sub.42, so that the signal at the data terminal D of each flip-flop appears at the output terminal Q. Thus, the outputs at the output terminals 2a.sub.7 and 2a.sub.8 respectively representing the 2.sup.0 signal and 2.sup.1 signal are of level "0", while the 2.sup.2 signal and 2.sup.3 signal appearing at the respective output terminals 2a.sub.9 and 2a.sub.10 are of level "1". In this way, the extent of depression of the accelerator pedal 3, that is, the throttle aperture, can be represented by a 4-bit digital signal.

When the drum 1b is further rotated with further depression of the accelerator pedal 3 to a position at which the contacts 1a.sub.1 to 1a.sub.6 are on line 31' in FIG. 4, the signal at the input terminal 2a.sub.3 is of level "1", and the signal coupled through the inverter 2b.sub.51 to the clock terminals c of the D type flip-flops 2b.sub.12, 2b.sub.22, 2b.sub.32 and 2b.sub.42 is of level "0". Thus, the previous digital signal at the output terminals 2a.sub.7 to 2a.sub.10 is maintained.

When the drum 1b is still further rotated with the continued depression of the accelerator pedal 3 to a position at which the contacts 1a.sub.1 to 1a.sub.6 are on line 33 in FIG. 4, the level of the timing signal at the input terminal 2a.sub.3 rises again to level "1", so that at this time signals of level "1", "1", "0" and "1" at the data terminals D of the respective flip-flops 2b.sub.12, 2b.sub.22, 2b.sub.32 and 2b.sub.42 appear in that state at the respective output terminals 2a.sub.7 to 2a.sub.10 as 4-bit digital signal.

Now, the effect of providing the conductor pattern division for the timing signal at the center of the overall pattern as in FIG. 4 will be discussed. For the sake of comparison, a conductor pattern without division for the timing signal is shown in FIG. 5a. In manufacture, it is very difficult to perfectly align the tips of a plurality of contacts in contact with the pattern, and usually these tips are out of alignment as shown by dots in FIG. 5a. In this case, when the drum comes to a position at which the contacts are intended to be on line 43 in FIG. 5a, the 2.sup.0 signal is of level "1", the 2.sup.1 signal is of level --"1", the 2.sup.2 signal is of level "1", and the 2.sup.3 signal is of level "0". This results in malfunctioning since this state is the same as that in which the contact tips are on line 43' in FIG. 5a. By the provision of the conductor pattern division 1b.sub.3 for the timing signal as shown in FIG. 4, the malfunctioning that might otherwise result due to out-of-alignment of the contact tips with respect to, for instance, line 33 in FIG. 4, can be prevented by taking out the digital signal only when the timing signal is of level "0".

In the above embodiment, the conductor pattern division for the timing signal is arranged at the center of the overall pattern. FIG. 5b shows a case in which the conductor pattern division for timing signal is arranged at either end of the overall pattern, and the contact tips may be inclined as shown in line 44' due to external causes such as vibrations. In this case, the deviation of the contact tips due to such external may be increased. Actually, malfunctioning is prone if the angle .theta. of out-of-alignment line 44' exceeds

where l.sub.2 and l.sub.4 are as shown in FIG. 5b. With the pattern of FIG. 4 where the division 1b for the timing signal is arranged at the center, the malfunctioning is reduced because l.sub.3 which is given as

is smaller than l.sub.4 since l.sub.1 is smaller than l.sub.2.

While in the above embodiment the digital signal generator circuit has used D type flip-flops, similar effects may be obtained by using R-S flip-flops or J-K flip-flops. Also, entirely reverse operation can be obtained to obtain similar effects by making the common signal to be of level "1".

Further, while the above embodiment has concerned with the case of detecting the throttle aperture, this is by no means limitative, and the invention may also be applied to such cases as detecting the air flow or fuel meter level in the fuel injection control system and so forth.

Furthermore, while in the above embodiment the drum 1b is rotated for shifting the relative position between drum 1b and contact group 1a in slidable contact therewith, it is also possible to move the contact group 1a. Moreover, the signal section which is constituted by the cylindrical drum 1b in the above embodiment need not be cylindrical but it may be planar. In the latter case, the relative movement will be linear.

As has been described in the foregoing, a first feature of the invention resides in the provision of a signal section consisting of a predetermined conductor pattern including a digital signal pattern and a timing signal pattern parallel therewith, a contact group consisting of digital signal contacts slidable over the digital signal pattern to take out a digital signal and a timing signal contact slidable over the timing signal pattern to take out a timing signal, and means to shift the relative position between the signal section and contact group according to a value of a detected parameter, whereby the relative position may be shifted in accordance with the value of the detected parameters, and a digital signal corresponding to the aforesaid relative position can be taken out. Also, since a digital signal generator circuit which provides the aforesaid digital signal when the timing signal is provided from the timing signal contact is provided, it is possible to prevent malfunctioning due to out-of-alignment of the tips of the contacts in the aforesaid contact group. Thus, it is possible to obtain an excellent effect of steadily producing accurate digital signals according to the detected value of the parameter with the combination of mechanical and electrical elements.

In addition to the above first feature of the invention, it is a second feature of the invention to arrange the timing signal pattern at the center of the overall conductor pattern, whereby it is possible to eliminate malfunctioning and generate accurate digital signals, increase allowable deviation of mechanical elements and simplify the adjustment thereof.