JPH09282073A - Switch circuit and arithmetic unit with switch circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switch circuit with no malfunction caused by the touch resistance of switches by parallelly connecting plural switching elements, which are turned on when the outputs of correspondent switches get higher than a prescribed voltage, through resistors. SOLUTION: Resistors (ladder resistors) 7-9 respectively having a prescribed resistance value are provided and a constant voltage is supplied from a power supply terminal 10 to depression type switches 1-3 and transistors 4-6. When a user depresses the switch 2, for example, with the increase of pressure, the contact resistance is reduced and at the same time, the voltage to be applied to the base terminal of the correspondent transistor 5 is increased. Then, at the time point when the contact resistance becomes the prescribed resistance, the prescribed voltage is applied to the base terminal of the transistor 5, the transistor 5 is turned on, and a resistance divided voltage is inputted from an output terminal 11 to the A/D input port of a microcomputer. The microcomputer executes microcomputer processing corresponding to the switch 2 by judging it from this voltage value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit including a plurality of switches and an arithmetic unit with a switch circuit.

[0002]

2. Description of the Related Art FIG. 6 is a circuit diagram showing a switch circuit for setting an A / D voltage value input to a microcomputer by conventional resistance division, as disclosed in Japanese Patent Laid-Open No. 6-51893.

In this figure, 100a, 100b, 1
00c is a push-type switch, and 200a, 200
Reference numerals b and 200c are resistors each having a predetermined resistance value. 300 is a power supply terminal to which a constant voltage V (REF) is supplied from a power supply, and 400 is an A / D of a microcomputer (not shown).
It is an output terminal connected to the input port.

Next, the operation will be described. Switch 10
By pressing 0a to 100c, V (REF) is resistance-divided corresponding to the pressed switch. This resistance-divided voltage is input to the A / D input port of the microcomputer via the output terminal 400, the microcomputer determines which switch is turned on in response to the voltage, and performs microcomputer processing corresponding to that switch. To do.

[0005]

Since the conventional switch circuit is configured as described above, the voltage input to the A / D input port of the microcomputer changes due to the contact resistance of the switch, A malfunction of the microcomputer, such as determining that a different switch was pressed, sometimes occurred. In particular, when the switch is a switch with a large PUSH stroke and an excellent feel, the change in contact resistance becomes large, and there is a high possibility of malfunction.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a switch circuit free from malfunction due to the contact resistance of the switch.

[0007]

A switch circuit according to the present invention is provided corresponding to a plurality of switches having contacts, and the respective switches of the plurality of switches, and the output of the corresponding switches has a predetermined voltage. A plurality of switching elements that are turned on when the above is reached, a power supply terminal to which the plurality of switching elements are connected in parallel via a resistor and a predetermined voltage is input, and a power supply terminal and a plurality of switching elements And an output terminal connected between them and outputting a voltage value based on opening and closing of a plurality of switches.

Also, a plurality of switches are connected in parallel to a power supply terminal to which a plurality of switching elements are connected.

The switching element is a transistor, and the output of the switch corresponding to this transistor is input to the base terminal of the transistor.

Further, a plurality of switches having contacts, a power supply terminal connected to each of the plurality of switches and inputting a predetermined voltage, and a resistance value between the power supply terminal and the plurality of switches are different from each other. As described above, a resistor provided between the power supply terminal and the plurality of switches and an output terminal connected between the power supply terminal and the plurality of switches and outputting a voltage value based on the opening and closing of the plurality of switches are provided. The switch is provided such that the maximum load required for displacement of the contact of the switch before the contact of the contact of the switch is larger than the load required for displacement of the contact at the start of contact of the contact.

An arithmetic unit with a switch circuit according to the present invention includes a plurality of switches having contacts, a power supply terminal connected to each of the plurality of switches and receiving a predetermined voltage, and the power supply terminal and the plurality of switches. So as to have different resistance values between the power supply terminal and the plurality of switches, an output terminal that outputs a voltage value based on the opening and closing of the plurality of switches, and the output terminal And a calculating unit that determines whether the plurality of switches are opened or closed based on the voltage value, and the calculating unit determines that one of the plurality of switches is closed if the voltage value of the output terminal is within a predetermined range. , And the voltage value in the predetermined range is the same as the maximum value of the load required for the displacement of the contact of the one switch before the contact of the one switch contacts Point is intended to be set to include the voltage value of the output terminal varies due to contact resistance at the position in the after contact.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1. 1 is a circuit diagram showing the first embodiment, and FIG. 2 is an explanatory diagram showing a relationship between a push width of a switch (a displacement amount of a contact) and a contact resistance. In these figures, 1, 2 and 3 are push-type switches, and these switches 1 to 3 have the characteristics of a relatively large PUSH stroke (push width) as shown in FIG. It is a switch. Further, the switches 1 to 3 have contacts, and when the contacts are pressed and come into contact with each other, conduction is obtained. Reference numerals 4, 5 and 6 are transistors as switching elements provided corresponding to the switches 1 to 3, base terminals of the transistors 4 to 6 are connected to the switches 1 to 3, and collector terminals or emitter terminals are output terminals. 11 (described later) or is connected to the ground terminal. Reference numerals 7, 8 and 9 are resistors having a predetermined resistance value (also called ladder resistors due to their arrangement). Reference numeral 10 denotes a power supply terminal to which a constant voltage V (REF) is supplied from a power supply unit (not shown). The power supply terminal 10 supplies a constant voltage to the switches 1 to 3 and the transistors 4 to 6. 11 is an A / D of a microcomputer (not shown)
It is an output terminal connected to the input port. Further, the microcomputer incorporates an arithmetic unit such as a CPU as an arithmetic means or an arithmetic unit, and the output from the A / D input port is input to this arithmetic unit to determine which switch is pressed. It is a thing.

Next, the operation will be described. First, when the user presses any one of the switches 1 to 3 (herein, referred to as switch 2 for explanation), when the user presses the switch in FIG.
As shown in (3), the contact resistance becomes smaller as the pressing pressure becomes larger, and at the same time, the voltage applied to the base terminal of the transistor 5 corresponding to the switch 2 becomes larger. Then, when the contact resistance reaches a predetermined resistance (for example, indicated by Rs in FIG. 2), a predetermined voltage is applied to the base terminal of the transistor 5, so that the transistor 5 is turned on and the collector terminal and the emitter are connected. When a current flows between the switch and the terminal, a resistance-divided voltage is input from the output terminal 11 to the microcomputer A / D input port, and switch 2 of switches 1 to 3 is turned on (closed state) from this voltage value. The microcomputer judges that this has been done, and the microcomputer processing corresponding to this switch 2 is executed.

As described above, even if a voltage lower than a predetermined voltage is applied to the base terminals of the transistors 4 to 6 due to the voltage drop due to the contact resistance of the switches when the user starts pressing the switches 1 to 3, Since 4 to 6 are not turned on, they are not output from the output terminal 11 to the A / D port of the microcomputer, but when the user presses the switches 1 to 3 sufficiently and the contact resistance of the switches becomes sufficiently low, A voltage higher than a predetermined voltage is applied to the base terminals of the transistors 4 to 6, the transistors are turned on, and the voltage corresponding to the switch pressed by the A / D port of the microcomputer is output from the output terminal 11. The voltage value input to the A / D port of the microcomputer is not affected by the contact resistance of the switches 1 to 3. Further, there is almost no change in the resistance value in the transistors 4 to 6 when the transistors 4 to 6 are turned on and off, and the influence on the voltage input to the microcomputer A / D port is negligible.

Here, the voltage corresponding to the switch means that when the resistance values of the resistors 7, 8, and 9 are R7, R8, and R9, respectively, and when the switch 1 is pressed, the output terminal 1
The voltage value output from 1 is 0, and when switch 2 is pressed, V (REF) · R8 / (R7 + R8)
And when switch 3 is pressed, V (REF)
・ (R8 + R9) / (R7 + R8 + R9)

Further, in the first embodiment, in order to prevent the processing from being confused when a plurality of switches are simultaneously pressed, when the plurality of switches are simultaneously pressed, the voltage at the output terminal 11 is increased. If the value is lower, for example, when the switch 1 and the switch 2 are pressed at the same time, the switch 1 is given priority and the switch 1 is pressed, and one switch is pressed. If another switch is pressed while the switch is still on, the microcomputer waits until the user releases the switch and detects that the switch is turned off after detecting that the switch is turned on. Since I am not accepting input,
Another switch that is pressed later will not be detected.

As described above, according to the first embodiment, even if the voltage of the switch portion is lowered due to the voltage drop due to the contact resistance of the switch, the transistor does not turn on below the predetermined voltage, so that the voltage value of the output terminal is It does not change and the contact resistance of the switch does not cause the microcomputer to malfunction.After that, when the contact resistance of the switch decreases and the voltage reaches the specified voltage, the transistor is turned on and the voltage value of the output terminal is It changes normally and is output to the microcomputer. In this way, the user feels good,
Even when a push-type switch is used, it is possible to prevent malfunction due to contact resistance of the switch.

Embodiment 2. In the second embodiment, the transistor is provided in the above-described first embodiment to prevent malfunction due to the influence of the contact resistance. On the other hand, due to the characteristics of the switch and the processing of the microcomputer, the transistor is not provided. , To prevent malfunction due to contact resistance. 3 is a circuit diagram showing the second embodiment, FIG. 4 is a diagram showing the relationship between the load applied to the switch and the displacement amount of the switch, and FIG. 5 is a line showing the relationship between the contact resistance of the switch and the displacement amount of the switch. It is a figure. In these figures, components having the same configurations as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

A and A in FIGS. 4 and 5 show the amount of displacement of the switch (the amount of displacement of the contact) when the contact of the switch begins to make contact, and B shows before the contact of the switch begins to make contact. , The maximum load required for switch displacement. Further, C indicates the amount of displacement of the switch in which the load required for displacement of the switch is B after the contact of the switch begins to contact, and D indicates before the contact of the switch begins to contact. Is a displacement amount of the switch at the peak point of, and E is a resistance value of the contact resistance when the displacement amount of the switch is C.

Here, 20 is a switch as shown in FIG. 3, and this switch 20 is, as shown in FIG. 4, a load required for displacement of the switch before the contact starts contact. Has a peak point at which is once increased. In such a switch 20, due to the peak point before contact of the contacts, the user is required to have at least a load indicated by B in FIG. 4, and even after the peak point is exceeded, the user remains in the load. In B, the switch 20 is continuously pressed. Therefore, the contact is instantaneously moved while the displacement amount of the switch 20 is between D and C, and the influence of the contact resistance between the displacement amount of the switch 20 and D is very small. From this, the maximum resistance value of the switch 20 is that the contact displacement amount in FIG.
It is not the contact resistance at point C, but the contact displacement becomes the resistance value E at point C.

Therefore, when the contact resistance of the switch 20 is the maximum resistance value, the voltage value of the output terminal 11 is V (R
EF) ・ (R8 + R9 + E) / (R7 + R8 + R9 +
If the microcomputer determines that the switch 20 is pressed when this voltage value is output, it can determine that the switch 20 is pressed as quickly as possible while preventing malfunction due to contact resistance. It is possible. Further, the microcomputer divides the range of voltage values input to the output terminal 11, 0 to V (REF) into the number of switches, here, three, and allocates to each switch.
When a voltage value in the voltage value range corresponding to each switch is output from the output terminal 11, it is determined that each switch is pressed. When (REF) / 3 is assigned, it is the voltage value of the output terminal 11 when the contact resistance of the switch 20 is the maximum resistance value.
V (REF) ・ (R8 + R9 + E) / (R7 + R8 + R
9 + E) is included in this range, R7, R8, R
As described in the first embodiment, by setting the respective resistance values of No. 9 so as to satisfy the above-mentioned relation, and by using the switch having the characteristic that the maximum contact resistance E satisfies the above-mentioned relation as the switch 20. It is possible to prevent a malfunction of the microcomputer due to contact resistance without providing a transistor in the.

On the contrary, the voltage value of the output terminal 11 when there is no contact resistance, V (REF)  (R8 + R9) /
(R7 + R8 + R9), with the maximum contact resistance, the voltage value of the output terminal 11, V (REF) · (R8 + R9 +
E) / (R7 + R8 + R9 + E) is switch 2
It may be set so that the microcomputer determines that 0 is pressed.

According to the second embodiment, the switch 20
Is connected directly to the resistor 9 so that the variation of the voltage value due to the contact resistance of the switch is within the range in which the microcomputer determines that the switch 20 is turned on. Since it is not necessary to provide the like, the circuit can be simplified.

Conductive organic material (mixture of insulating organic material (rubber or the like) and conductive inorganic material (carbon or the like))
Since the switch configured by means of the contact has a large elastic force, the touch feeling when pressed by the user is improved, but the contact resistance is increased. Here, in each of the above embodiments, even if the contact resistance of the switch is large, it is possible to prevent malfunction due to this contact resistance. Therefore, when a switch made of a conductive organic material is used, It is possible to further improve the feeling of pressing.

In each of the above-mentioned embodiments, three switches are shown, but the number of switches is not limited to three, and
Needless to say, there may be a plurality of switches, for example, two or three or more.

Although a transistor is used as a switching element in each of the above-mentioned embodiments, other switching elements such as a thyristor and TTL may be used.

In each of the above embodiments, the switches 1, 2, 3, 20 and the transistors 7 to 9 are supplied with a constant voltage from the same power supply terminal 10. May be supplied with a constant voltage from another power supply terminal.

[0028]

As described above, according to the switch circuit of the first aspect of the present invention, the fluctuation of the voltage value output from the output terminal due to the contact resistance of the switch can be prevented.

Further, according to the switch circuit of the second aspect of the present invention, since the power source terminal can be shared by the switching element and the switch, the device can be simplified.

Further, according to the switch circuit of claim 3 of the present invention, since the output of the switch is input to the base terminal of the transistor, the output of the switch is not directly output from the output terminal, and the switch contact It is possible to further prevent the fluctuation of the voltage value output from the output terminal due to the resistance.

Further, according to the switch circuit of the fourth aspect of the present invention, the maximum value of the load required for the displacement of the contact before the contact comes into contact is required for the displacement of the contact at the time of contact of the contact. Since the load is larger than the load, the contact can be quickly displaced at the start of contact of the contact having a large contact resistance, so that the fluctuation of the voltage value output from the output terminal due to the contact resistance of the switch can be reduced. .

According to a fifth aspect of the present invention, in the arithmetic unit with a switch circuit, the displacement of the contact before the contact comes into contact within a voltage value within a predetermined range in which the arithmetic means judges that the switch is in the closed state. The contact resistance of the switch is set to include the voltage value of the output terminal that changes due to the contact resistance at the position after the contact that requires the same load as the maximum load required for It is possible to prevent the malfunction of the device due to the fluctuation of the voltage value output from the output terminal.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a switch circuit according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a contact resistance and a push width of the switch according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a switch circuit according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a load and a displacement amount required for displacement of a switch according to the second embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a contact resistance and a displacement amount of a switch according to the second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a conventional switch circuit.

[Explanation of symbols]

1-3, 20: switch, 4-6: transistor, 7-
9: resistance

Claims (5)

[Claims] 1. A plurality of switches having contacts, and a plurality of switching elements provided corresponding to the respective switches of the plurality of switches and turned on when the output of the corresponding switches exceeds a predetermined voltage. And these switching elements are connected in parallel via a resistor,
A switch circuit including a power supply terminal to which a predetermined voltage is input, and an output terminal connected between the power supply terminal and the plurality of switching elements and outputting a voltage value based on opening and closing of the plurality of switches. . 2. The switch circuit according to claim 1, wherein a plurality of switches are also connected in parallel to a power supply terminal to which a plurality of switching elements are connected. 3. The switch circuit according to claim 1, wherein the switching element is a transistor, and the output of the switch corresponding to the transistor is input to the base terminal of the transistor. 4. A plurality of switches having contacts, a power supply terminal connected to each of the plurality of switches and receiving a predetermined voltage, and a resistance value between the power supply terminal and the plurality of switches, respectively. Differently, a resistor provided between the power supply terminal and the plurality of switches, and connected between the power supply terminal and the plurality of switches, and outputs a voltage value based on the opening and closing of the plurality of switches. The switch has a maximum load required for displacement of the contact of the switch before contact of the contact of the switch is required for displacement of the contact at the start of contact of the contact. A switch circuit characterized by having a load larger than that. 5. A plurality of switches having contacts, a power supply terminal connected to each of the plurality of switches, to which a predetermined voltage is input, and a resistance value between the power supply terminal and the plurality of switches, respectively. Differently, a resistor provided between the power supply terminal and the plurality of switches, an output terminal that outputs a voltage value based on opening and closing of the plurality of switches, and a plurality of the output terminals based on the voltage value of the output terminal. And a calculating means for judging whether the switch is open or closed, wherein the calculating means judges that one of the plurality of switches is in a closed state if the voltage value of the output terminal is within a predetermined range, And the voltage value in the predetermined range is equal to the maximum value of the load required for displacement of the contact of the one switch before the contact of the contact of the one switch is contacted. An arithmetic unit with a switch circuit, which is set so as to include the voltage value of the output terminal which is changed by the contact resistance at the position after the contact of the H contact.