JP5814409B2 - Operation switch detection system - Google Patents

Description

  The present invention relates to detection of switch operation of an electronic device having a plurality of switches.

  When an electronic device having a plurality of switches is realized by a system having a CPU (Central Processing Unit), it is necessary for the CPU to detect which switch is operated. In order to perform this detection, an operation switch detection circuit is provided. Here, the CPU includes general-purpose main processor devices for embedded systems including SoC (System-on-a-chip).

  FIG. 5 shows a configuration of a known operation switch detection circuit and an operation switch detection system for an electronic apparatus including the same. The operation switch detection system 30 includes an operation switch detection circuit 300 incorporated in an operation panel and the like, and a CPU 309, a ROM 314, and a RAM 315 incorporated in the control board 301. The operation switch detection circuit 300 and the CPU 309 are connected by a connection cable 302.

  The operation switch detection circuit 300 is mounted with a plurality of switches. Here, a case where there are three switches will be described as an example. The switch here assumes a push button type switch.

  The three switches 303, 304, and 305 are connected to the reference voltage 309 and the input port 311, input port 312, and input port 313 of the CPU 309 via a resistor 306, a resistor 307, and a resistor 308, respectively. Here, since the voltage detected by each input port is either the reference voltage level or the ground voltage level, the resistance value of each resistor may be the same.

  The control board 301 includes a CPU 309 that is a processor of the system, a ROM 314 that stores control software, and a RAM 315 that expands and executes the control software. The CPU 309 reads control software for detecting depression of the switch, that is, ON, from the ROM 314 to the RAM 315 and executes it. The CPU 309 monitors the input port to which each switch is connected by the control software.

  Here, for example, when the switch 303 is turned on, the voltage detected at the port 311 changes from the reference voltage level to the ground voltage level. At this time, the CPU 309 can specify that the switch 303 is turned on by the control software.

Japanese Patent Laid-Open No. 4-112267

  However, in the operation switch detection system 30 of FIG. 5, when the number of switches is to be increased, as many input ports of the CPU 309 are required as the number of switches. In general, since the CPU becomes more expensive as the number of input ports increases, it is necessary to reduce the number of input ports in order to reduce the cost. Further, if the number of input ports is reduced, the number of connection cables 302 is also reduced, and further cost reduction effects are expected.

  Patent Document 1 discloses an operation switch detection device having a plurality of switches and a small number of input ports. However, in the configuration of Patent Document 1, the resistors are connected in series, and when some of the plurality of switches are simultaneously turned ON, it is not possible to specify each ON switch.

  The present invention has been made in view of the above problems, and its object is to reduce the number of CPU input ports even when the number of switches increases, and to identify a plurality of switches that are turned on simultaneously. An operation switch detection system is provided.

  An operation switch detection system according to the present invention is based on an operation switch detection circuit in which a plurality of switch resistor structures having a switch and a resistor connected in series to the switch are connected in parallel, and a voltage generated by the operation switch detection circuit. Detecting means for identifying the switch that is turned on, and the voltage is generated based on a resistance value of the resistor connected to the switch that is turned on, and the resistance values of all combinations when the switch is turned on Is different.

  According to the present invention, it is possible to provide an operation switch detection system in which the number of CPU input ports can be reduced even when the number of switches increases, and a plurality of switches that are turned on simultaneously can be specified.

It is a figure which shows the structure of the operation switch detection circuit of the 1st Embodiment of this invention, and the operation switch detection system provided with the same. It is a figure which shows the structure of the operation switch detection circuit of the 2nd Embodiment of this invention, and the operation switch detection system provided with the same. The voltage which arises when the operation switch of the operation switch detection circuit of the 2nd Embodiment of this invention is turned ON is shown. It is a figure which shows the structure of the operation switch detection circuit of the 3rd Embodiment of this invention, and the operation switch detection system provided with the same. It is a figure which shows the structure of a known operation switch detection circuit and an operation switch detection system provided with the same.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the preferred embodiments described below are technically preferable for carrying out the present invention, but the scope of the invention is not limited to the following.
(First embodiment)
FIG. 1 is a diagram illustrating a configuration of an operation switch detection circuit and an operation switch detection system including the operation switch detection circuit according to the first embodiment of the present invention. The operation switch detection system 1 of this embodiment includes an operation switch detection circuit 2 in which a plurality of switch resistor structures 6 each having a switch 4 and a resistor 5 connected in series to the switch 4 are connected in parallel. Furthermore, a detection means 3 for specifying the operation switch 4 that is turned on based on the voltage generated by the operation switch detection circuit 2 is provided. Further, the voltage is generated based on a resistance value of the resistor 5 connected to the switch 4 that is turned on. Furthermore, the resistance values of all combinations when the switches are turned on are different.

According to the present embodiment, it is possible to provide an operation switch detection system in which the number of CPU input ports can be reduced even when the number of switches increases, and a plurality of switches that are turned on simultaneously can be specified.
(Second Embodiment)
FIG. 2 is a diagram illustrating a configuration of an operation switch detection circuit and an operation switch detection system including the operation switch detection circuit according to the second embodiment of the present invention. In the operation switch detection system 10 of the present embodiment, an operation switch detection circuit 100 having a plurality of switches and a control board 101 having a CPU that is a detection means for specifying an ON switch are connected by a connection cable 102. It has a configuration. Further, the operation switch detection circuit 100 and the control board 101 can be directly connected without the connection cable 102.

  The operation switch detection circuit 100 includes a plurality of switches, and here, a case where there are three switches will be described as an example. However, the number of switches is not limited to three and can be any number. The switch here can be a push button type switch.

  A resistor 106, a resistor 107, and a resistor 108 are connected to the three switches 103, 104, and 105, respectively. Here, each resistor has a different resistance value. A plurality of switch resistor structures composed of the switches and resistors are connected in parallel as shown in FIG.

  The control board 101 includes a CPU 109 that is a processor of the system, a ROM 114 that stores control software, and a RAM 115 that executes the control software. Furthermore, it has FET111 (Field Effect Transistor) which performs electrical circuit isolation | separation of the operation switch detection circuit 100, the reference voltage 112 and load resistance 113 for detecting ON of an operation switch. Further, the CPU 109 includes an ADC 110 (Analog Digital Converter) that is a functional block that performs analog / digital conversion.

  The CPU 109 reads out control software for detecting operation button ON stored in the ROM 114 from the ROM 114 to the RAM 115 and executes it. The CPU 109 acquires the value detected by the ADC 110 as needed by the control software, and identifies the switch that is turned on.

  In the operation switch detection operation of the operation switch detection system 10 in FIG. 2, first, initialization of the system will be described.

  In this embodiment, it is detected that the switch is turned on by comparing the voltage when the switch is turned on with the voltage before the switch is turned on. For this reason, the reference voltage 112 is acquired by the ADC 110 as an initialization process of the CPU 109 when the system power is turned on. At this time, a correct reference voltage cannot be acquired if any of the switches is turned on. Therefore, the FET 111 is turned on so as to be disconnected from the electric circuit so as not to be grounded even if the switch is turned on. Thereby, even if the switch is turned on, a correct reference voltage can be acquired. After the initialization is completed, the FET 111 is turned off so that it is electrically connected.

  After the initialization is completed, a voltage acquired by the ADC 110 is changed by turning on any of the switches during the operation of the system. The CPU 109 can identify which switch is turned on by comparing this voltage with the reference voltage obtained by initialization.

  FIG. 3 shows voltages detected by the ADC 110 when the respective switches of FIG. 2 are turned on. When neither switch is turned on, the reference voltage 112 is detected. When the switch 103 is turned on, a voltage calculated from the resistor 106 and the load resistor 113 is detected. When the switch 104 is turned on, a voltage calculated from the resistor 107 and the load resistor 113 is detected. When the switch 105 is turned on, a voltage calculated from the resistor 108 and the load resistor 113 is detected. When a plurality of switches are simultaneously turned on, a voltage generated by a combined resistance of the load resistor 113 and a resistor connected to each turned-on switch is detected.

  As described above, the resistor 106, the resistor 107, and the resistor 108 are set to have different resistance values in order to specify a switch that is turned on by the voltage detected by the ADC 110. Furthermore, the resistor 106, the resistor 107, and the resistor 108 are set so that the parallel combined resistors when the plurality of switches are simultaneously turned on have different resistance values. That is, the resistor 106, the resistor 107, and the resistor 108 are set so that the resistance values of all combinations when the switches are turned on are different. These resistance values may be set including the resistance value of the load resistor 113 based on the number of constituent switches.

  In the present embodiment, since the voltage corresponding to the ON state of the switch is detected through the ADC 110, it is not necessary to increase the CPU input port even if the number of switches increases.

  The operation switch detection system 10 of this embodiment can be incorporated into various electronic devices. Components that specify the type of electronic device are not directly related to the present invention, and are therefore omitted in FIG.

As described above, according to the present embodiment, it is possible to provide an operation switch detection system in which the number of CPU input ports can be reduced even when the number of switches increases, and a plurality of switches that are turned on simultaneously can be specified. Can do.
(Third embodiment)
FIG. 4 is a diagram illustrating a configuration of an operation switch detection circuit and an operation switch detection system including the operation switch detection circuit according to the third embodiment of the present invention. In the operation switch detection system 20 of this embodiment, switch resistor structures including switches (switch 203, switch 204, switch 205) and resistors (resistors 206, 207, 208) connected to the switches are connected in parallel. The operation switch detection circuit 200 is integrated with a control board 201 having a CPU 209 that identifies a switch that is turned on.

  Each component of this embodiment is based on 2nd Embodiment shown in FIG. Further, the ADC may be configured as an external device of the CPU 209 like the ADC 210. In FIG. 2, the FET 111 is used at the time of initialization so that the reference voltage does not change even when the switch is turned on. On the other hand, as in the present embodiment, the CPU 209 may generate a switch lock signal 211 to mechanically lock each switch so that it cannot be turned on. In this case, the switch is locked when the initialization is performed, and the switch is unlocked after the initialization is completed.

  The operation switch detection system 20 of this embodiment can be incorporated into various electronic devices. Components that specify the type of electronic device are not directly related to the present invention, and thus are omitted in FIG.

  As described above, according to the present embodiment, as in the first and second embodiments, even if the number of switches increases, the number of CPU input ports can be reduced, and a plurality of switches that are turned on at the same time can be used. An operation switch detection circuit that can be specified can be provided.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention.

1, 10, 20, 30 Operation switch detection system 2, 100, 200, 300 Operation switch detection circuit 3 Detection means 4 Switch 5 Resistor 6 Switch resistor structure 101, 201, 301 Control board 102, 302 Connection cable 103, 104 , 105, 203, 204, 205, 303, 304, 305 Switch 106, 107, 108, 206, 207, 208, 306, 307, 308 Resistor 109, 209, 309 CPU
110, 210 ADC
111 FET
112, 212, 312 Reference voltage 113, 213 Load resistance 114, 214, 314 ROM
115, 215, 315 RAM
311, 312, 313 Input port

Claims (3)

An operation switch detection circuit in which a plurality of switch resistor structures having a switch and a resistor connected in series to the switch are connected in parallel, and detection means for specifying the switch that is turned on based on a voltage generated by the operation switch detection circuit; Have
The voltage is generated based on the resistance value of the resistor connected to the switch that is turned on, and the resistance values of all combinations when the switch is turned on are different.
The detection means compares the voltage with a reference voltage, identifies the switch that is turned on based on the comparison,
One end of the parallel connection is grounded, the other end produces the voltage,
Said detecting means, said parallel connection and has a FET (field effect transistor) between the ground, the parallel connection and the ground and the electrical circuit to disconnect City, by the FET at the time of acquisition of the reference voltage,
The operation switch detection system, wherein the voltage is generated based on a load resistance connected to the reference voltage and a resistance value of the resistor. The operation switch detection system according to claim 1, wherein the detection unit acquires the reference voltage when the detection unit is powered on. The operation switch detection system according to claim 1, wherein the detection unit includes a CPU (Central Processing Unit), and the CPU performs analog / digital conversion and compares the voltages.

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