JPH03233817A - Inspection apparatus for mechanical switch - Google Patents

Abstract

PURPOSE:To improve inspection precision by counting electric signals after rectification and determining the quality from the result of the counting. CONSTITUTION:Outputs of signal rectifying means 22 during one inspection cycle are counted by a counting means 23, and the quality of a mechanical switch is determined by a determining means 25 based on the standard value of a standard value setting means 24 and the counted result. When the mechanical switch is made a dome switch SW and the standard value is set to be 1, the counted result becomes 1 if ON-state takes place only one during one inspection cycle, the counted result and standard value agree with each other and thus normality of the dome switch SW is determined. But when on times of the dome switch SW becomes 0 or over 1, the calculated result and the standard value do not agree with each other and the abnormality of the dome switch SW is determined. As a result, switches which carry out improper of/off operation are made also unsatisfactory in inspection. In this way, inspection precision can be improved.

Description

[Detailed Description of the Invention] [Summary] Regarding an inspection device suitable for application to mechanical contact type switches, the inspection accuracy is improved by counting electrical signals after shaping and determining pass/fail based on the counting results. For the purpose of this, during a predetermined inspection cycle, key operation pressure is gradually applied to the mechanical switch to be inspected, and then the applied pressure is gradually decreased, and the on/off electricity from the mechanical switch is turned off during the inspection cycle. A mechanical switch testing device that shapes a signal and tests the quality of the switch based on the shaped electrical signal, comprising: a counting means that counts the shaped electrical signal for one test cycle; and a predetermined reference value. and a determining means that compares the counting result of the counting means with the reference value of the reference value setting means to determine whether the switch is good or bad.

[Industrial application field]

The present invention relates to an inspection device for mechanical switches, and more particularly to an inspection device for keyboard switches, for example, which generates a pulse-like signal with a single key operation. This invention relates to a suitable inspection device.

In recent years, with the spread of computers, word processors, etc., there has been a trend for keyboards as input devices to be lower in price, more reliable, and more sophisticated in operation.

Generally speaking, keyboard switches (hereinafter referred to as key switches) include non-contact key switches such as optical type, Hall effect type, electromagnetic induction type, capacitance sensor type or piezoelectric effect type, reed switch type or mechanical type. There are contact type key switches such as contact type. In particular, contact key switches have been in practical use for a long time and are superior to non-contact key switches in terms of reliability and price. By the way, mechanical contact key switches have the disadvantage of malfunctions caused by contact chatter, so for example, metal contact key switches,
Various improved types have been developed, including thin film contact type and conductive rubber contact type.

FIG. 5 is a diagram showing an example of a conventional mechanical contact type key switch. This key switch (hereinafter referred to as dome switch SW) consists of a plurality of (three in the figure) fixed contacts 11 provided on a terminal board 10, and a conductive dome spring (one) placed so as to cover the fixed contacts 11. 12 (shown with a broken part) and a resilient actuator 13 for deforming the dome spring 12. Normally, as shown in FIG. 6(a), the fixed contact 11 and Although the dome spring 12 is separated from the dome spring 12 and is in the OFF state, when a key operation force is applied to the tip of the actuator 13, as shown in FIG. 6(b)
As shown in FIG.
3, the dome spring 12 and fixed contact 11 come into contact and turn on.

By the way, even with contact type key switches that have undergone various improvements, it is difficult to eradicate manufacturing errors and the like, and final inspection is essential.

[Conventional technology]

The conceptual configuration diagram in Figure 7 is an example of the above dome switch SW.
This figure shows a conventional mechanical switch inspection device applied to

That is, this inspection device has a predetermined inspection cycle T.

(for example, T1 = about 1 second), the key operation force applying means 14 gradually increases the key operation pressure P to the dome switch S-, and then gradually decreases the applied pressure P, and the test period T1 The switch includes a signal shaping means 15 for shaping the on/off electrical signal from the dome switch SW between the two, and a determining means 16 for deciding whether the switch is good or bad based on the shaped electrical signal.

If the dome switch SW is operating normally, it will go through the process of going from an OFF state to an ON state and then back to an OFF state during one test cycle. By detecting the change, it is possible to determine whether the dome switch S- is good or bad.

- Sample the electrical signal at an appropriate point during the test cycle, check its level, and if it is at the predetermined signal level,
The inspection is passed.

[Problem to be solved by the invention]

However, such conventional inspection devices are configured to determine pass/fail based on sampled electrical signals, so they can only inspect a portion of the inspection cycle.
There was a problem that the inspection accuracy could not be fully satisfied.

In other words, as shown in Figure 8, the operating characteristics of the dome switch S- during normal operation are shown in Figure 8. After becoming A), in the process of decreasing the key operation pressure P (hereinafter referred to as the return process), it becomes OFF again! ! (B in the figure), but for example, if the dome spring 12 deviates from its normal position due to an assembly error, etc., it will be in the on state (a in the figure) during the pushing down process, as shown in Figure 9. 〉, it changed to off-state B (b in the figure), and during the return process, it changed from the on-state (C in the figure) to off-state B (d in the figure) again. Comparing Figures 8 and 9, , it can be seen that the set of on/off operations indicated by C and d in FIG. 9 is inappropriate.

In the conventional inspection apparatus, an appropriate period between A-8 in FIG. 8 is set as a sampling period, and normal operation is determined if the sampling potential is a predetermined value. Therefore, a switch with the above-mentioned inappropriate on/off operation may be erroneously passed the test, resulting in insufficient test accuracy.

[Purpose of the invention]

The present invention was made in view of these problems, and
The purpose is to improve inspection accuracy by counting electrical signals after shaping and determining pass/fail based on the counting results.

[Means for Solving the Problems] In order to achieve the above object, the present invention, as shown in FIG. During this period, the mechanical switch to be inspected (for example, the above dome switch sh)
key operation force application means 21 that gradually increases and then applies key operation pressure P to and then gradually decreases the applied pressure P; and signal shaping means 22 that shapes the on/off electrical signal from the mechanical switch during the test cycle. , a counting means 23 that counts the electrical signal after shaping for one test cycle, a reference value setting means 24 that sets a predetermined reference value, and a counting result of the counting means 23 and a reference value of the reference value setting means 24. and a determining means 25 for comparing the values and determining the quality of the mechanical switch.

[Effect]

In the present invention, the output of the signal shaping means 22 during the inspection cycle is counted by the counting means 23, and the quality of the mechanical switch is determined by the determining means 25 based on the counting result and the reference value of the reference value setting means 24. be done.

Here, connect the mechanical switch to the above dome switch S-
At the same time, if the reference value is set to 1, the counting result will be 1 if the ON state is ON only once during the inspection period, and the counting result and the reference value will match and the corresponding dome switch S- will be in the ON state. It is determined that the dome switch SW is normal, but if the number of times the dome switch S- is turned on exceeds 0 or 1, the counting result and the reference value do not match, and the dome switch SW is determined to be defective.

Therefore, the switch with the inappropriate on/off operation can also be judged as a failure of the test, and the test accuracy can be improved.

〔Example〕 Hereinafter, the present invention will be explained based on the drawings.

2 to 4 are diagrams showing an embodiment of the mechanical switch inspection device according to the present invention, and are examples in which the device is applied to a dome switch similar to the conventional example.

First, the configuration will be explained. In FIG. 2, 30 is a control circuit as a periodic signal generating means, 31 is a power mechanism as a key operation force applying means, 32 is a dome switch as a mechanical switch to be inspected, and 33 is a signal shaping circuit as a signal shaping means. , 34 is a counter circuit as counting means, 35 is a dip switch as reference value setting means, 36 is a comparison circuit as determining means, and 37 is a display circuit.

The details of each component will be explained below. During the inspection period, the control circuit 30 controls the power mechanism 31 and the counter circuit 34.
Outputs the following signals for .

Start signal T: A signal corresponding to the "inspection period signal" described in the means for solving the problem, which is repeated every predetermined period TI (for example, Tt = 1000a+s), End signal 'r , T', delayed by about half a cycle (T, /2), counter clear signal Cc: a signal synchronized with Ts, the power mechanism 31 starts rotating in the forward direction in response to the input T, and at the same time Tt A DC motor 31a that starts rotating in the opposite direction in response to a large input, a motion direction converter 31b that converts the forward and reverse rotation motion of the DC motor 31a into reciprocating motion, and a moving head 31c driven by the motion direction converter 31b.
The key operation pressure P is gradually increased to the dome switch 32 when the DC motor 31a rotates in the forward direction, and the key operation pressure P is gradually decreased when the DC motor 31a rotates in the reverse direction.

The dome switch 32 has one end of the switch contact 32a connected to a power source at a low potential (ground potential in the figure, hereinafter referred to as G), and the other end connected to a high potential (hereinafter referred to as G) through a resistor R1.
+V) side power supply, and during one round trip of the moving head 31c, the switch contact 32a changes from the OFF state to the ON state and then to the OFF state again (during normal operation). During the OFF state, the potential +V is changed. , and during the on state, the potential G is switched to the switch signal S31. Output as l. This switch signal S5. .

corresponds to the on/off electrical signal described in the summary of the invention.

The signal shaping circuit 33 includes an integrating circuit 33a, a trigger circuit 33b, a flip-flop circuit 33C1, a differentiation circuit 33d, an inverting circuit 33e, and a multivibrator circuit 33f, and includes a resistor R2 and a capacitor CI.
After removing the impulsive noise of the switch signal SSM by the integrating circuit 33a, the Schmitt trigger circuit 33b shapes the waveform, and at the falling edge of the shaped signal, the Q output of the flip-flop circuit 33c (hereinafter referred to as QJK) to high level and resistor R3
QJ by a differentiator circuit 33d consisting of a capacitor C2 and a capacitor C2.
Detects the rising edge of K and sends it to the inverting circuit 33e.
It is output as a clock signal CP via the clock signal CP. Furthermore, the multivibrator 33f detects the falling edge of C1 (Q
After a predetermined time (td) from the setting of JX, a signal CJX is generated to reset the flip-flop circuit 33c to J-, and the predetermined time td is sufficiently longer than the duration of the chatter included in the switch signal S8,1. It is preferable to set it to a long time, for example, about 10 Ils. Note that td is set by adjusting the resistors R, , R and capacitors C, , C, which are externally attached to the multi-bi flake circuit 33f.

The counter circuit 34 counts the clock signal CP from the signal shaping circuit 33 and calculates the count value Cv.
However, when the counter clear signal Cc is input, the count value Cv is cleared to zero.

The comparison circuit 36 compares a predetermined reference value Rv (here, Rv=1) set in the dip switch 35 in advance with the count value Cv from the counter circuit 34, L, -'lt.
When (RV = C,), a determination result signal J0 that becomes high level is output. Note that the timing of the comparison is preferably, for example, immediately before the counter circuit 34 is cleared to zero.

The display circuit 37 includes an inverting buffer circuit 37a, a normal buffer circuit 37b, a pass lamp 37c, a fail lamp 37d, and resistors R& and R7, and causes the pass lamp 37c to emit light (fail) when Jo is at a high level. Pass lamp 37
d is turned off), and when Jo is at the low level, the reject lamp 37d is turned on (the pass lamp 37c is turned off).

Next, the circuit operation of this embodiment will be explained with reference to each waveform diagram in FIG. 3.4.

(I) Normal circuit operation (see Figure 3), time t. When the start signal T is generated, the DC motor 31a starts normal rotation, and the moving head 31c starts moving while gradually increasing the key operation pressure P.

Time tl: switch contact 32a of dome switch 32
changes from the off state to the on state, the switch signal Ss-
The signal potential changes from +■ to G with chuckling.
change to. This change in the switch signal SSW is shaped by the integrating circuit 33a and the Schmitt trigger circuit 33b, and then applied to the flip-flop circuit 33c at J-, thereby causing QJI[ to rise from the low level to the high level. The rising edge of QJK is detected by the differentiating circuit 33d, and the rising edge of
clock signals C2 are output.

Time 1. :1. After td elapses, CJK rises and QJx is reset.

Time t3: When approximately half a cycle (half of the inspection cycle T1) has elapsed since the start signal T and the pulse were generated, the end signal T is generated, and the DC motor 31a starts rotating in reverse. As a result, the moving head 31C starts reverse movement while gradually reducing the key operation pressure P.

Time L4: Switch contact 32a of dome switch 32
When the switch turns from the on state to the off state again, the switch signal S
3,1 changes the signal potential from G to +V with chattering.

Time to': When one inspection cycle B, l1, passes,
The start signal T and pulse for the next cycle are generated, and the process is as above.

-Repeat t4.

Here, the number of occurrences of the clock signal C1 during the above time t0 to t,I is a number (1) equal to the number of times the switch contact 32a is turned on, and the count value Cv of the counter circuit 34 is also (1). . Therefore, Cv
Since the condition of =Rv is satisfied, Jo becomes high level and only the pass lamp 37c lights up.

(II) Circuit operation during failure, time t. If the potential of the switch signal SSW never changes from +V to G during -t 810 (- test period),
That is, in the case of a malfunction in which the dome switch 32 never changes to the on state, the number of generated clock signals C1 is zero, and therefore the count value Cv is also zero, and Cv≠
Since it becomes Rv, J.

becomes low level and only the reject lamp 37d lights up.

Alternatively, in FIG. 4, if there is a malfunction in which the dome switch 32 changes to the on state twice or more (twice in the figure) during the test period, the number of times the clock signal CP is generated is on. The same number of changes occur, and therefore the count value Cv is also the same (in this example, CV-2), and in the same way, Cv≠Rv, so in this case too, Jo becomes low level and the rejection lamp 37 ( Only I lights up.

As described above, according to the present embodiment, the number of clock signals C equal to the number of ON changes of the switch signal SAW in the test cycle is
P is generated, and the count value Cv of this clock signal CP is compared with the reference value Rv, and only when they match, the pass lamp 3 is output.
7c is configured to light up, it is possible to pass the test only when the number of ON changes of the dome switch 32 during the - test period is the same as Rv. Therefore, a defective operation in which the number of ON changes is 0 or 2 or more can be reliably determined, and the accuracy of testing the dome switch 32 can be improved.

〔Effect of the invention〕

According to the present invention, an electrical signal from a mechanical switch is shaped, and the shaped electrical signal (in the embodiment, a clock signal C
F, CP represents the number of ON times) and pass/fail is determined based on the counting result, so only when the number of ON times matches the reference value can the inspection be passed, and all cases where there is a mismatch can be passed. It is possible to fail the test.

Therefore, if the reference value is set to 1, a switch that has been turned on 0 to 2 or more times can be determined to be defective, and the inspection accuracy can be improved by making the majority of the inspection period the inspection target.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle configuration of the present invention. 2 to 4 are diagrams showing an embodiment of the mechanical switch inspection device according to the present invention, in which FIG. 2 is a block diagram thereof, FIG. 3 is an operating waveform diagram during normal operation, and FIG. It is an operation waveform diagram at the time of the defect. Figures 5 to 9 are diagrams showing conventional examples, Figure 5 is a perspective view of a dome switch shown as an example of the key switch to be inspected, and Figures 6 (a) and (b) are OFF/ON of the dome switch. Fig. 7 is a conceptual configuration diagram of the mechanical switch inspection device, Fig. 8 is a characteristic diagram showing the switch operation during normal operation, and Fig. 9 is a characteristic diagram showing the switch operation when it is defective. It is. S-... Dome switch (mechanical switch), 20... Periodic signal generation means, 21... Key operation force applying means, 22...
- Signal shaping means, 23... Counting means, 24... Reference value setting means, 25... Judgment means, 30... Control circuit (periodic signal generation) means), 31
...Power mechanism (key operation force applying means), 32.
...Dome switch (mechanical switch), 33...Signal shaping circuit (signal shaping means), 34
...Counter circuit (counting means), 35...
...Dip switch (reference value setting means) 36...
. . . Comparison circuit (judgment means), 37 . . . Display circuit. Principle of the present invention Construction diagram 1゜Operating waveform diagram in normal operation Figure 3 Operation waveform diagram in malfunction 1゜Perspective view of the dome switch Figure 1 State diagram showing on/off of the dome switch Conceptual block diagram of mechanical switch inspection equipment Figure 8 Characteristic diagram showing switch operation when normal. Figure 9 Characteristic diagram showing switch operation when defective.

Claims (1)

[Claims] During a predetermined inspection cycle, key operation pressure is gradually applied to the mechanical switch to be inspected, and then the applied pressure is gradually decreased, and the mechanical switch is turned on/off during the inspection cycle. A mechanical switch testing device that shapes an OFF electrical signal and tests the quality of the switch based on the shaped electrical signal, comprising: a counting means that counts the shaped electrical signal for one test cycle; A mechanical switch comprising: a reference value setting means for setting a reference value; and a determining means for comparing the counting result of the counting means with the reference value of the reference value setting means to determine whether the switch is good or bad. inspection equipment.