JP2000137567A - Key switch circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a key switch circuit to discriminate whether the circuit itself is connected or not, not depending on increasing the number of input ports for a CPU or the like in electronic equipment or increasing the number of connection lines to the electronic equipment. SOLUTION: Short circuits are provided by plural resistors R1 to R4 and plural key switches S1 to S4. A hold circuit consisting of a resistor 8 and a holding switch 9 is connected to the key circuit 2. Which key switch is depressed is discriminated by an output voltage change outputted from the circuit 2 to the input port Vin of electronic equipment 7. Fixed voltages corresponding to the ON/OFF of the switch 9 are applied to the input port Vin of the equipment 7, and the depression/non-depression of each of the key switches S1 to S4 and a holding/non-holding state are selected by discriminating the voltage outputted to the input port Vin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key switch circuit, and more particularly to an improvement in a key switch circuit that outputs which key switch of a key switch group is operated in association with a change in voltage value.

[0002]

2. Description of the Related Art A key switch circuit of this type can transmit a large amount of key information to an electronic device with a small number of connections, so that a remote controller for operating commands in an electronic device such as a CD player or a cassette tape player can be provided. It is widely used. An example will be described as a first conventional example with reference to FIG.

[0003] In FIG. 5, C
A PU (not shown) is provided with an input port Vin, a power supply output Vdd, and a ground terminal G, and a key switch circuit composed of a key circuit 2 and a hold switch 3 is detachably connected to these three lines. For example, it is configured as a remote controller for giving four operation commands such as “stop, playback, fast forward, and fast reverse”.

That is, in the key circuit 2, a resistor R0 is connected to an end of the power output Vdd and an end of the input port Vin, and four resistors R1 to R4 are connected in series to the input port Vin. One end of each of the four key switches S1 to S4 is connected to each of the connection point of the resistances R1 and R2, the connection point of the resistances R2 and R3, the connection point of the resistances R3 and R4, and the end of the resistance R4. The other end is connected in common and grounded via the hold switch 3.

The hold switch 3 is provided to prevent erroneous operation of the key, and is turned on as shown in the drawing and connected to the ground terminal during normal life, and is moved downward and turned off during hold to turn the key circuit 2 on and off. It is made to float.

Therefore, when the hold switch 3 is in the position shown in FIG.
The input voltage to in changes to four types according to which of the key switches S1 to S4 is operated, and this change is identified based on ROM data (FIG. 7 described later) provided in the electronic device 1. It is required by doing.

When the process is started as shown in the flowchart of FIG. 6, first, the voltage (A) to the input port Vin taken into the electronic device 1 in step S1 is stored in a memory (not shown). In step S2, it is determined whether or not the difference between the data and the previous data is large, in other words, whether or not the key input has changed. If NO, the voltage (A) is stored in the memory as step S3. Is done.

If YES in step S2, the flow advances to the next step S4, where the data of the voltage (A) already taken in in step S1 is stored as a voltage (B) in a memory, and in step S5 similar to step S2 described above. It is determined whether or not the difference between the data and the previous data is large, in other words, whether or not there has been a key input change. If NO, the voltage (B) is stored in the memory in step S6.

If YES in step S5, the process proceeds to the next step S6, where a function to be executed is selected based on ROM data built in the electronic device 1, and after the selected function is executed, Returning to step S1, the following steps S2 to S7 are repeatedly executed.

The function selection performed in step S7 is as shown in FIG. 7 which conceptually shows ROM data built in the electronic device 1.

As is apparent from the ROM data 1a shown in FIG. 7, when the hold switch 3 is turned on, the key input is validated, which corresponds to the operation of any one of the key switches S1 to S4. As a result, the input voltage to the input port Vin changes to four voltages V1 to V4. By determining which of the functions 1 to 4 according to the input voltage to the input port Vin at this time, it is possible to recognize which function has been commanded to be executed.

On the other hand, when the hold switch 3 is turned off, the input voltage to the input port Vin changes to the power output Vdd.
The execution function is fixed to the function 0,
That is, the current state is maintained as it is.

In this case, the passage of time and the key switches S1 to S1
The following can be said between the operation of S4.

When none of the key switches S1 to S4 is pressed, the input voltage to the input port Vin is Vdd
When any one of the key switches S1 to S4 is pressed, the voltage changes from Vdd to "any of V1 to V4", and when released, the voltage returns from "any of V1 to V4" to Vdd.

Therefore, by operating the key switches S1 to S4, the function corresponding to the operation is executed.

In the above examples, the hold operation is performed by hardware, but there is also an example in which the hold operation is performed by software. This example will be described as a second conventional example with reference to FIG.

As shown in FIG. 8, the input ports of the electronic device 4 are configured as two systems, that is, a first input port Vin-a and a second input port Vin-b. To S4 are grounded, and the connection point of the resistors R0 and R1 is connected to the first input port Vin-a.

The power supply output Vdd is connected to the second input port Vin-b via the pull-up resistor 5, and the second input port Vin-b
And the ground switch G are connected to the hold switch 6.

The hold switch 6 is provided to prevent erroneous operation of the key, and is turned on at the time of hold and connected to the ground terminal as shown in FIG.
The in-b input is forcibly set to the L level (ground potential), and is moved downward during normal life to form the key circuit 2 and the power supply output Vdd
H level.

Then, which one of the key switches S1 to S4 is pressed and the function corresponding to it are as ROM data 4a conceptually shown in FIG.

As is apparent from the ROM data 4a shown in FIG. 9, when the hold switch 6 is turned off, the input voltage to the second input port Vin-b is fixed at Vdd, so that key input is effective. And the input voltage to the first input port Vin-a changes to four, V1 to V4, in response to the operation of any of the key switches S1 to S4.

If it is determined which of the functions 1 to 4 according to the input voltage to the first input port Vin-a at this time, it is possible to recognize which function is instructed to be executed. .

On the other hand, when the hold switch 6 is turned on, the input voltage to the second input port Vin-b is fixed to the ground potential, so that any signal (V1 to V1) is applied to the first input port Vin-a. Even if V4) is supplied, this is ignored and the execution function is function 0, that is, the current state is maintained.

In the first conventional example as described above, the key is simply disabled, so that it cannot be used to assign another function, and whether the key is pressed during hold or not held is determined. The second conventional example is generally used to determine the value on a microcomputer.

[0025]

In the first prior art, since the output signal of the key circuit is not transmitted to the input port of the electronic device at the time of hold, the state is described as "the state in which no key is operated". There is a problem that it is not possible to discriminate between the “hold state” and the “state where the key switch circuit itself is not connected”.

In the second conventional example, at the time of hold, the hold signal is transmitted to the input port of the electronic device, so that "the key switch circuit itself is not connected".
However, since the second input port is added, if this circuit is used in a remote control device or the like, the number of signal lines increases by one, and the cost increases, and the signal line is disconnected. There is a problem that the probability of an accident increases.

Therefore, an object of the present invention is to determine whether a key switch circuit is connected or not by increasing the number of input ports of a CPU or the like in an electronic device or increasing the number of connection lines to the electronic device 1. It is an object of the present invention to provide a key switch circuit that can be performed without performing any operation.

[0028]

In order to solve the above-mentioned problems, the key switch circuit according to the present invention employs the following characteristic configuration.

(1) A key switch group composed of a plurality of key switches, a hold switch for holding an operation command by the key switch, and which of the key switches in the key switch group is operated is determined by a voltage value change. By operating the key circuit to output in association with the hold switch, the output of the key circuit is changed to an output voltage generated in the key circuit when none of the key switches in the key switch group is operated. And a hold circuit for fixing to a specific voltage value different from the above.

(2) A key switch group consisting of a plurality of key switches, a mode switch for switching a plurality of modes, and which key switch of the key switch group is operated is associated with a voltage value change. And a key circuit for outputting a plurality of modes that can be switched by operating the mode switch, and
A mode circuit set to a voltage value different from an output voltage generated in the key circuit when none of the key switches in the key switch group is operated.

(3) The key circuit and the hold circuit of the above (1) are connected to a specific voltage source via a resistor at a starting end of a series connection resistor group, and each connection point of the series connection resistor group is It is configured such that it is grounded via a plurality of key switches, and the terminal of the series-connected resistor group is grounded via a resistor and a hold switch.

(4) The key circuit and the mode circuit of (2) are connected to a specific voltage source via a resistor at the beginning of the series-connected resistor group, and each connection point of the series-connected resistor group is It is configured such that it is grounded via a plurality of key switches, and the terminal of the series-connected resistor group is grounded via a resistor and a mode switch.

(5) The key circuit according to any one of (1) to (4) is connected to a specific voltage source via a resistor at a starting end of a series connection resistor group, and each connection point of the series connection resistor group is connected. Are configured to be grounded via a plurality of key switches.

[0034]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a circuit block diagram showing a circuit configuration of a key switch circuit according to a first embodiment of the present invention. There are many portions similar or similar to the configuration of FIG. The same or similar parts will be denoted by the same reference numerals as those shown in FIG. 5, and the description thereof will be omitted. The parts related to the present invention will be mainly described.

The processing operation of the key switch circuit according to this embodiment is the same as that in the flow chart shown in FIG. 6, except for the item of step S7. Therefore, the operation relating to the present invention will be mainly described.

A CPU (not shown) built in the electronic device 7 of FIG. 1 has an input port Vin, a power output Vdd, and a ground terminal G.
And a key switch circuit composed of a key circuit 2, a resistor 8, and a hold switch 9 can be detachably connected to these three lines.

The "key circuit 2" and the "hold circuit composed of the resistor 8 and the hold switch 9" connect the starting end of the series-connected resistor group to a specific voltage source via a resistor, and connect each of the series-connected resistor groups. Each of the points is grounded via a plurality of key switches, and the terminal of the series-connected resistor group is grounded via a resistor and a hold switch.

That is, in the key circuit 2, the resistor R0 is connected to the end of the power output Vdd and the end of the input port Vin, and four resistors R1 to R4 are connected in series to the input port Vin. One end of each of the four key switches S1 to S4 is connected to each of the connection point of the resistors R1 and R2, the connection point of the resistors R2 and R3, the connection point of the resistors R3 and R4, and the end of the resistor R4. The other ends are commonly connected and grounded.

The connection point between the resistor R4 and the key switch S4 is
Grounded via a resistor 8 and a hold switch 9 sequentially.

The hold switch 9 is provided to prevent erroneous operation of the key, and is turned off as shown in FIG.
At the time of hold, it is moved upward and turned on, and the key circuit 2
The connection point of the resistor R4S key switch S4 is grounded via the resistor 8.

Therefore, when the hold switch 9 is in the position shown in FIG.
The input voltage to "in" changes into four types depending on which of the key switches S1 to S4 is operated, and this change is determined by identifying the change based on the ROM data 7a shown in FIG.

As is apparent from the ROM data 7a shown in FIG. 2, when the hold switch 9 is turned off, an input to the input port Vin is made in response to any one of the key switches S1 to S4 being operated. When the voltage changes from Vdd to "V
1 to V4 ". Input port V at this time
By determining which of the functions 1 to 4 according to the input voltage to in, it is possible to recognize which function has been commanded to be executed.

On the other hand, in the hold state where the hold switch 9 is turned on, when no key is pressed, the input voltage to the input port Vin becomes Va = Vdddd (r1 + r2 + r3 + r4 + r
8) / (r0 + r1 + r2 + r3 + r4 + r8)
When any one of S4 is pressed, from Va, “V1 to V
4 ". If it is determined which of the functions 5 to 8 according to the input voltage to the input port Vin at this time, it is possible to recognize which function has been commanded to be executed.

Therefore, when the hold switch 9 is turned off, four types of functions 1 to 4 can be identified, and when the hold switch 9 is turned on, a total of eight types of functions 5 to 8 can be identified. You can do it.

When the hold switch 9 is turned off, all of the functions 1 to 4 are in the hold state.
When the hold switch 9 is used as a mode switch, it is possible to identify eight functions in which the first mode is set when the hold switch 9 is turned off and the second mode is set when the hold switch 9 is turned on.

When the key switch circuit is connected to the electronic device 7, the supply voltage to the input port Vin is Vdd or Vdd in the initial state (the state in which none of the key switches S1 to S4 is pressed). Since it is Va, it is possible to identify whether or not the key switch circuit is connected.

Next, a key switch circuit according to a second embodiment of the present invention will be described with reference to FIGS.

The CP built in the electronic device 10 shown in FIG.
U (not shown) is provided with an input port Vin, a power supply output Vdd, and a ground terminal G.
A key switch circuit composed of resistors 11, 12 and a mode switch 13 is detachably connected to the remote controller.

The "key circuit 2", the "mode circuit comprising the resistors 11, 12 and the mode changeover switch 13" connect the starting end of the series-connected resistor group to a specific voltage source via a resistor, and Are connected to ground via a plurality of key switches, and the ends of the series-connected resistor group are grounded via resistors and a mode switch.

That is, in the key circuit 2, the resistor R0 is connected to the end of the power output Vdd and the end of the input port Vin, and four resistors R1 to R4 are connected in series to the input port Vin. One end of each of the four key switches S1 to S4 is connected to each of the connection point of the resistors R1 and R2, the connection point of the resistors R2 and R3, the connection point of the resistors R3 and R4, and the end of the resistor R4. The other ends are commonly connected and grounded.

The connection point between the resistor R4 and the key switch S4 is
Grounded via a resistor 11, a resistor 12, and a mode switch 13 sequentially.

The mode changeover switch 13 is used to set three function modes. In the first mode, the resistors 11 and 12 are floated from the ground terminal as shown by reference numeral c. In the second mode, the tip of the resistor 12 is grounded as shown by reference numeral b, and in the third mode, the connection point between the resistors 11 and 12 is grounded as shown by reference numeral a.

Therefore, the mode switching switch 13 is
Or the third mode,
The input voltage to the input port Vin changes depending on which of the key switches S1 to S4 is operated, and what is the function instructed by identifying this change based on the ROM data 10a shown in FIG. Is required.

When the mode changeover switch 13 is set to the first mode indicated by the symbol c, as is apparent from the ROM data 10a shown in FIG.
Are not pressed, the input voltage to the input port Vin is Vdd, and the input voltage to the input port Vin is changed from Vdd to "Vdd" in response to any of the key switches S1 to S4 being operated. V1 to V4 ".

When the mode changeover switch 13 is set to the second mode indicated by the symbol b, the key switches S1 to S1
If none of S4 is pressed, input port Vin
The input voltage to the input port Vb is Vb, and when any of the key switches S1 to S4 is operated, the input port V
The input voltage to in changes from Vb to four “V1 to V4”. This Vb is calculated as follows: Vb = Vdd · (r1 + r2 + r3 + r4 + r11 + r12) / (r0 + r1 + r2 + r3 + r4 + r1
1 + r12).

When the mode changeover switch 13 is set to the third mode indicated by the symbol a, the key switches S1 to S1
If none of S4 is pressed, input port Vin
The input voltage to the input port Vc corresponds to the operation of any one of the key switches S1 to S4.
The input voltage to in changes from Vc to four of “V1 to V4”. This Vc is as follows: Vc = Vdddd (r1 + r2 + r3 + r4 + r11) / (r0 + r1 + r2 + r3 + r4 + r11)

Therefore, by determining the change in the input voltage to the input port Vin, that is, which of "Vdd, Vb and Vc" in the initial state, it is possible to identify which of the first to third modes. Which of the functions 1 to 12 in response to which of the key switches S1 to S4 is operated, the input voltage to the input port Vin changes to four of "V1 to V4" in response to the operation. Is determined, it is possible to recognize which function has been commanded to be executed.

When the key switch circuit is connected to the electronic device 10, the supply voltage to the input port Vin is "Vdd" in the initial state (the state in which none of the key switches S1 to S4 is pressed). And Vb and Vc ", it is possible to easily identify whether or not the key switch circuit is connected.

It should be noted that the present invention is not limited to the above-described embodiment, and the number of key switches constituting the key circuit and the number of modes in the mode switching switch are completely arbitrary. It is completely arbitrary based on the aspect of the electronic device.

[0060]

As described above, according to the key switch circuit of the present invention, at the time of hold, "the state where no key is operated", "the hold state", and "the key switch circuit itself" are connected. It is possible to identify which state is “no state” without adding an input port or increasing the number of lines.

Accordingly, the cost does not increase and the probability of a signal line disconnection accident does not increase.
Therefore, it is possible to provide a key switch circuit that can determine whether or not the key switch circuit is connected without increasing the number of input ports such as CPUs in the electronic device or increasing the number of connection lines to the electronic device 1. it can.

[Brief description of the drawings]

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

FIG. 2 is a ROM incorporated in the electronic device shown in FIG.
FIG. 3 is a data storage diagram conceptually showing data.

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

FIG. 4 is a ROM incorporated in the electronic device shown in FIG. 3;
FIG. 3 is a data storage diagram conceptually showing data.

FIG. 5 is a circuit diagram showing a main configuration of a first conventional example of a key switch circuit.

FIG. 6 is a flowchart for explaining a key switch detection operation shown in FIG. 5;

FIG. 7 is a ROM incorporated in the electronic device shown in FIG. 5;
FIG. 3 is a data storage diagram conceptually showing data.

FIG. 8 is a circuit diagram showing a configuration of a main part of a second conventional example of a key switch circuit.

FIG. 9 is a ROM incorporated in the electronic device shown in FIG. 8;
FIG. 3 is a data storage diagram conceptually showing data.

[Explanation of symbols]

 R0 to R4, 8, 10, 11, 12 Resistance S1 to S4 Key switch 1, 4, 7, 10 Electronic equipment 2 Key circuit 3, 6, 9 Hold switch 13 Mode switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Momose 1-14-6 Dogenzaka, Shibuya-ku, Tokyo Inside Kenwood Corporation (72) Inventor Seiki Nomata 1-14-6 Dogenzaka, Shibuya-ku, Tokyo Stock Company F-term (reference) in Kenwood 5B020 BB10 DD02 FF11

Claims (5)

[Claims] 1. A key switch group comprising a plurality of key switches, a hold switch for holding an operation command by the key switch, and which key switch of the key switch group is operated corresponds to a voltage value change. By operating the hold switch, an output voltage generated in the key circuit when none of the key switches in the key switch group is operated. A key switch circuit, comprising: a hold circuit for fixing the voltage to a different specific voltage value. 2. A key switch group comprising a plurality of key switches, a mode switch for switching a plurality of modes, and which key switch of the key switch group is operated is associated with a voltage value change. A key circuit to be output, the key circuit being associated with each of a plurality of modes that can be switched by operating the mode switch, and when no key switch in the key switch group is operated. A key switch circuit comprising: a mode circuit set to a voltage value different from a generated output voltage. 3. The key circuit and the hold circuit, wherein a starting point of a series connection resistor group is connected to a specific voltage source via a resistor, and each connection point of the series connection resistor group is connected to a plurality of key switches. The key switch circuit according to claim 1, wherein the key switch circuit is configured to be grounded via a resistor, and a terminal of the series-connected resistor group is grounded via a resistor and a hold switch. 4. The key circuit and the mode circuit, wherein a starting point of a series connection resistor group is connected to a specific voltage source via a resistor, and each connection point of the series connection resistor group is connected to a plurality of key switches. 3. The key switch circuit according to claim 2, wherein the terminal is grounded via a resistor, and the terminal of the series-connected resistor group is grounded via a resistor and a mode switch. 4. 5. The key circuit according to claim 1, wherein a starting end of the series connection resistor group is connected to a specific voltage source via a resistor, and each connection point of the series connection resistor group is grounded via a plurality of key switches. 5. The key switch circuit according to claim 1, wherein the key switch circuit is configured as described above.