JPH02228721A - Keyboard - Google Patents

Abstract

PURPOSE:To prevent a code discriminating margin in a comparator from being largely affected with the deviation of a serial resistor, and to improve the yield of products by printing-forming a pull-up resistor inside a first or a second membrane sheet where the serial resistor is formed. CONSTITUTION:A pull-up resistor Rj as well as a serial resistor Rij is formed on the same membrane sheet 22 in the same manufacturing process. In such a method, even when the resistance values of the serial resistor Rij and the pull-up resistor Rj are dispersed from a standard value, the dispersion in Rij and Rj is made comparatively smaller, and the input voltage error of the comparator is made smaller. For this reason the level discriminating margin in the comparator becomes larger, and the yield of the products can be improved.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to keyboards, and in particular to so-called image processing, in which data indicating that a key is pressed is erroneously output even though the key is not pressed. Regarding the keyboard that prevented the occurrence.

"Prior Art" As shown in FIG. 5, scanning lines X1 to X extend horizontally on the printed wiring surface of the switch board 11.

The data lines Y1 and Y1 extending in the vertical direction are arranged to intersect with each other, thereby forming a large number of meshes. Scanning line Xi (1=1~m) and data line Y.

At each intersection position with (J-1 to J-n), the S-th switch is connected between the drawing lines. One end of scanning line XI is terminal A
, to the anode of the diode DI, and its cathode is connected to the scanning circuit 12. One end of data line Y is connected to decoder 13 through terminal Bj, the other end is connected to one end of pull-up resistor RJ through terminal C4, and the other end is connected to power supply terminal B.

As shown in FIG. 6, scanning signals E+ to E are sequentially and repeatedly output from the scanning circuit 12 at high speed.

When the scanning signal E is at a low level (zero volts) and the switch Sll is on, R+
Current flows to the scanning circuit through the paths S+ and D+, and the diode DI is turned on, so that the potential of the data line Yl is set to a low level. As a result, the decoder 13 detects the on state of the switch S. The same applies to the other switch S.

In the keyboard shown in Figure 5, even if any two switches are turned on at the same time, their on states can always be detected and an image will not be generated.However, when three switches are turned on at the same time, an image will not be generated. This may occur. Switches that are currently on at the same time are SIl+
S! Ii S! ! Then, when the scanning signal E is at a low level, from the power supply terminal B, the path of R1-31+ D+ and Rz Sz□-3z+ S++ D+
Current flows through the path. Therefore, at that time, the potentials of the data lines Y1 and Y are both set to a low level, and the decoder 13 identifies the switches S and Sat as on. Next scanning signal E
, is low and healthy, the decoder 13 identifies that switches St1 and Stt are on. In this way, switch board 1
Image data is generated from 1 and the decoder 13 is switched on from switch S1! This will result in an incorrect identification signal being output if it is assumed that it is on. From such a thing,
When using the keyboard shown in Figure 5, it is prohibited to turn on three or more switches at the same time, and if this happens, the decoder 13 will not consider any of the switches to be on, that is, the current All key human power is disabled.

The switch board 11 is realized by a membrane switch (board), and m=3. An example where n=2 will be described below. 7th
As shown in the figure, first and second flexible printed wiring boards (hereinafter referred to as membrane sheets) 21 and 22 based on sheets such as PET (polyethylene terephthalate) and spacers interposed between them (for example, (made of PET) 23. As shown in FIG. 8, one contact alj of the switch Sij is formed in a circular shape on the first membrane sheet, and each contact a
ll to a1m are common scanning lines XI extending approximately horizontally.
connected to. One end of the scanning line Xl is extended to the tip of the terminal portion 24, and a terminal A is formed at the tip. on the other hand,
On the second membrane sheet 22, the other contact point of the switch Slj is formed in a circular shape (same size as the a point), and each contact point blJ to baj is connected to the data line YJ in the vertical direction.
connected to. One end and the other end of data vAYj are extended to the tips of terminal portions 25 and 26, respectively, and terminals B1 and C are formed at each tip, respectively. Note that arc pieces 27 are formed concentrically so as to surround each contact point. 1st. When the second membrane sheets are stacked facing each other, the contact point a and the arcuate piece 27 around it are arranged at a position overlapping with the contact point blJ and the arcuate piece 27 around it. 1st. The second membrane sheet 21922 is initially made of one sheet and is later folded.

1st. In the second membrane sheet 21, 22, as shown in FIG. 7, a conductive film 32 containing silver (for example, 7 to 8 μm thick) is placed on a PET sheet 31 having a thickness of 100 μm, for example.
is formed by printing, and a protective film 33 made of carbon (for example, thickness 7 to 8 μll) is formed by silk printing to cover it, and each contact point Aij + B4J, arc piece 27 scanning line Xi + data line Y, etc. A pattern is constructed.

The spacer 23 shown in FIG.
It is made of ET sheet, and its outer shape is the same as that of the first and second membrane sheets (excluding the terminal portion). A circular hole 28 having a size intermediate between the outer diameter of the contact and the inner diameter of the arcuate piece 27 is formed at a position facing each contact of the membrane sheet.

1st. The second membrane sheet has a pattern and arc pieces 2
Adhesive 28 is applied to a plurality of locations except for the area surrounded by 7, and they are laminated together with the pattern surfaces facing each other with spacers 23 in between.

The arcuate piece 27 serves as a breakwater to prevent the adhesive 28 from entering the contact position. A part of the arc is cut out at the same position as the arc piece 27 around the a-th contact point and that around the second contact point. When the switch is turned on or off, this notch allows the air around the contacts am J + b 5 j to freely flow in, so that the air trapped inside the arc piece does not affect the on or off operation. That's what I do.

As mentioned above, the switch board 11 in FIG. 5 generates an image when three or more switches are turned on at the same time. On the other hand, even if any number of switches are turned on at the same time,
A switch board shown in FIG. 10 in which a diode is connected in series with each switch is also used as one that does not generate images.

``Problem to be solved by the invention'' In the keyboard shown in Figure 5, the number of switches that can be turned on at the same time must be limited to two, which is not easy to use, and also makes it difficult to turn on three or more switches. The decoder requires a circuit to detect this and nullify all human power at that time, which has the drawback of increasing the circuit scale of the decoder. Furthermore, since the keyboard using the switch board shown in FIG. 10 has a large number of diodes, it is difficult to reduce the size of the keyboard, and the number of man-hours increases. Particularly in keyboards using membrane switches, because the membrane sheet is flexible, the diode chips on/adhered to the sheet tend to peel off during various work processes, resulting in a problem with poor product yield. There was also the risk that the capacitor chip would peel off due to vibrations and shocks during use, reducing the credibility of the product.

The purpose of this invention is to prevent image generation even when a practically necessary number of switches (for example, three or more) are turned on at the same time, and to prevent the generation of images when a membrane switch is used, and to reduce the size of the product. To provide a keyboard that is free from the risk of deterioration of yield or deterioration of product reliability.

[Means to solve problems] First, the keyboard according to claim (1) will be described.

A plurality of data lines and a plurality of scan lines are formed on the substrate so as to intersect with each other, and a switch and a series resistor are connected in series between the data line and the scan line at each intersection point position. .

Each of the above data lines is connected to a comparator and to a power supply via a pull-up resistor, and each of the comparators is connected to a power supply through a pull-up resistor.
In the keyboard according to claim (2), the voltage of the data line is characterized by a high level or a low level voltage by comparing the voltage with a threshold value. One contact of the switch and the data line are formed, the other contact of the switch and the scanning line are formed on a second membrane sheet, and the first . The second membrane sheets are opposed to each other and are joined together via a spacer to form a membrane switch.

The contacts, data lines, and scanning lines of the switch are formed by printing a conductive film on a membrane sheet and printing a protective film to cover the conductive film.

A predetermined section of the linear conductive film led out from each contact point is cut out, and the above-mentioned series resistor is configured by the above-mentioned protective film printed to cover the cut-out part.

The keyboard according to claim (3) is the keyboard according to claim (1), wherein the switch is constituted by a membrane switch, and the series resistor and the pull-up resistor are formed on a membrane sheet constituting the membrane switch. This is what is being done.

The keyboard according to claim (4) is the keyboard according to claim (1), wherein the switch is a membrane switch, one end of the first voltage dividing resistor is connected to the power source, and the other end is connected to the second voltage dividing resistor. The terminal voltage of the second voltage dividing resistor is connected to one end of the voltage resistor and the other end is connected to a common potential point, and the terminal voltage of the second voltage dividing resistor is supplied as a threshold value to each of the comparators. The series resistor is formed on a membrane sheet constituting the membrane switch.

The keyboard according to claim (5) includes the above-mentioned series resistor,
The pull-up resistor or the second voltage dividing resistor is formed in the same direction.

"Example" The switch board 11 used in the keyboard of this invention is
As shown in Figure 1, each switch S- has a series resistor R1,
is connected. Now switch S + + +S, l+s
! 1 are on at the same time, and the scanning signal E1 applied to the terminal A1 becomes a low level (zero volts). The equivalent circuit of this section can be expressed as shown in FIG. The voltage of the power terminal hanger B is Eb, the resistance value of each pull-up resistor R+, Rz and series resistor Rm is R.
Then, the combined resistance R between the 22 points in FIG. 2 and the power terminal hanger B is as follows.The voltage at the 21 points (voltage at terminal B+) V+ is as follows. Therefore, if the voltage v1 across the combined resistor R7 is the voltage V2 across the terminal CZ (terminal B), then E is assumed to be 5V.

Furthermore, switch 511r S3! is S++, 3m1
+ Above Rt, V when turned on at the same time as Sty
+, V-.

If v2 is expressed by adding a dash (') to each, it is given by each. Therefore, a comparator circuit 30 is provided at the output terminals of terminals B, ~B, and its threshold voltage ■ is set to 3,5
The input voltage of each comparator CPj is set to ■, and the output ■ depends on whether j is smaller or thicker than V. If J is a low level (zero volts) or a high level (+E, -+5V), in any of the above cases, ■et-OV, VO2-
5V (of course other voltages and voltages are all 5V), and the image described in the conventional example does not occur.

The input voltage Voj of the comparator cp is the above-mentioned V+, Vz.

■＋'＋V! As is clear from the equation ', if the resistance values of the pull-up resistor R4 and the series resistor R1j are equal, it is irrelevant to the magnitude of the resistance value, so when using a membrane switch, It is desirable to form the pull amplifier resistor Rj and the series resistor R1J in the same manufacturing process on the same membrane sheet. In this way, even if the resistance values of R1 and R5 vary from the standard value, the variation in R5 and Rj will be relatively small, and therefore the error in the input voltage V will be small, and the comparator circuit This is because the reliability of the output data of No. 30 is improved. Furthermore, even if the pull-up resistor R4 and the series resistors R and J have different standard resistance values, the same effect as described above can be obtained if they are formed on the same membrane sheet.

The threshold voltage {circle around (2)} applied to the comparator CPj can be created, for example, by dividing the power supply voltage E (+5V) between resistors R and R. If the pull-up resistor Rj is to be attached externally to the membrane sheet, the voltage dividing resistor R5 on the common potential side is formed on the same membrane sheet together with the series resistor RiJ, and the voltage dividing resistor R5 on the common potential side is formed on the same membrane sheet, and It is desirable to use highly accurate individual components for the voltage resistor R1 and the pull amplifier resistor R4. In this way, the resistance value of the series resistor R1j can be made considerably smaller than, for example, the standard value, so that even if the input voltage v of the comparator CPj varies in the smaller direction, the resistance value of the voltage dividing resistor R5 can be made much smaller than the standard value. Similarly, since it is shifted toward the smaller side, the threshold voltage (2) also varies toward the smaller side, which makes it easier to obtain a margin for code identification.

When using membrane switches on the keyboard,
As shown in FIG. 3, a resistive film is formed by printing in the middle of a pattern connecting the contact point bi on the membrane sheet (the second membrane sheet in the figure) and the data line Y to form a series resistor RIJ. In the same figure, there is also a pull-up resistor R
4 is similarly formed on the second membrane sheet.

Further, when a second voltage dividing resistor R1 is provided in place of the pull-up resistor RJ on the same membrane sheet together with the series resistor R4j, the configuration is, for example, as shown by the dotted line in FIG. 3. These series resistor R and pull-up resistor R (or second voltage dividing resistor R) are preferably formed in the same direction on the membrane sheet.
In this way, each resistor is oriented in a constant direction with respect to the squeegee direction, so that variations in resistance values can be reduced τ.

Note that a squeegee is a brush used for silk printing, and the squeegee direction refers to the direction in which the squeegee is moved to spread the ink.

These resistors including the series resistor R1j can be made by cutting out a predetermined section of the conductive film from each contact point to the data line or scanning line, and printing a resistive film on that part. However, it is preferable to use a protective film 33 made of carbon, for example, as shown in FIG. 4 instead of using a special resistor ink.In this way, a special resistor printing process can be eliminated and the work time can be reduced. can be shortened.

Protective film 33 printed on contacts a iJ, b iJ
For example, the contact resistance between the contacts is small (
On the other hand, since the above-mentioned protective film 33 used in place of the resistive film is extremely long and the cross-sectional area can be made small, it is easy to obtain a resistance value of several Ω. .

In the explanation so far, the data line Y on the switch board 11 is
A pull-up resistor R1 is connected to one end of j, and the other end is connected to a comparator circuit, but the data line
Both terminals may be connected to one terminal.

"Effects of the Invention" According to the present invention, a series resistor is connected to each switch on the switch board, and the voltage of each data line is identified as either high level or low level by a comparator, which is relatively simple. By means of suitable means, it is possible to easily prevent the generation of images when three or more switches are turned on.

According to this invention, when a membrane switch is used in a keyboard, a series resistor can be formed by printing instead of gluing a diode chip as in the past.
Since the size of the switch board can be made smaller and no parts come off, the yield is improved, and there is no fear that the quality of the product will deteriorate during use.

If the pull-up resistor R1 (or the second voltage dividing resistor R,) is formed on the same membrane sheet along with the series resistor R, the variation from the reference value of these resistors will cause the switch to turn on/off. The impact on state identification can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the main part of the present invention, and FIG. 2 shows switches Sat, S□, and S in FIG. 1. is on and the scanning signal E1 is at a low level; FIG. 3 is a plan view of the second membrane sheet constituting the membrane switch used as the switch substrate 11 in FIG. 4A and 4B are a plan view and an AA sectional view of the main parts to show an example of the configuration of the series resistor R4j in FIG. 3, respectively, FIG. 5 is a circuit diagram of a conventional keyboard, and FIG. 7 is a cross-sectional view of the main part when the switch board of FIG. 5 is configured as a membrane switch, and FIG. 8 is a time chart of the scanning signals E to E of the scanning circuit 12 of FIG. 9 is a plan view of the spacer 23 shown in FIG. 7, and FIG. 10 is a circuit diagram showing another example of the conventional switch board 11.

Claims (5)

[Claims] (1) A plurality of data lines and a plurality of scan lines are formed on the substrate to intersect with each other, and at each intersection point, a switch and a series resistor are connected in series between the data line and the scan line. Each of the data lines is connected to a comparator and connected to a power supply via a pull-up resistor, and each of the comparators is connected to
A keyboard that compares the voltage of the data line with a threshold value and outputs a high-level or low-level voltage. (2) In the keyboard according to claim (1), one contact of the switch and the data line are formed on a first membrane sheet, and the other contact of the switch and the scanning line are formed on a second membrane sheet. The first and second membrane sheets are opposed to each other and are integrally coupled via a spacer to form a membrane switch, and the contacts, data lines and scanning lines of the switch are formed by forming a conductive film on the membrane sheet. It is formed by printing a protective film to cover the conductive film, and when a predetermined section of the linear conductive film led out from each contact point is missing, printing is performed to cover the missing part. The above-mentioned series resistor is configured by the above-mentioned protective film. (3) In the keyboard according to claim (1), the switch is constituted by a membrane switch, and the series resistor and pull-up resistor are formed by printing on a membrane sheet constituting the membrane switch. There is a keyboard. (4) In the keyboard according to claim (1), the switch is constituted by a membrane switch, one end of a first voltage dividing resistor is connected to the power supply, and the other end is connected to one end of a second voltage dividing resistor. The terminal voltage of the second voltage dividing resistor is supplied to each of the comparators as a threshold value, and the second voltage dividing resistor and the series resistor are connected to the membrane. A keyboard formed on a membrane sheet that makes up a switch. (5) Claim (2) or (5) wherein the series resistor, pull-up resistor, or second voltage dividing resistor is formed in the same direction.
3) or the keyboard described in (4).