Patent Publication Number: US-2022230822-A1

Title: Switch device and switch system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims priority of Japanese Patent Application No. 2021-006322 filed on Jan. 19, 2021. 
     FIELD 
     The present disclosure relates to a switch device and a switch system. 
     BACKGROUND 
     Patent Literature (PTL) 1 discloses a switch device provided on a steering wheel. 
     PATENT LITERATURE 
     
         
         PTL 1: Japanese Unexamined Patent Application Publication No. 2011-210581 
       
    
     SUMMARY 
     However, the switch device according to PTL 1 can be improved upon. 
     In view of this, the present disclosure provides a switch device capable of improving upon the above related art. 
     A switch device according to one aspect of the present disclosure is a switch device including: a voltage dividing circuit that includes a plurality of switches including a first switch and a second switch, an output line, and a plurality of resistors connected in series to the output line, and outputs a voltage dividing value corresponding to a conduction state of each of the plurality of switches to the output line; an operation interface that includes a dial which rotates in accordance with a user operation; a rotation detection circuit that detects (i) rotation of the dial by a predetermined angle and (ii) a rotation direction of the dial, and generates an angle signal and a direction signal, the angle signal including a pulse that indicates detection of the rotation by the predetermined angle, the direction signal indicating whether the rotation direction is a first direction or a second direction different from the first direction; and a selection circuit that selects whether to output the pulse of the angle signal to control the first switch or to output the pulse of the angle signal to control the second switch, according to whether the direction signal indicates the first direction or the second direction. 
     A switch system according to one aspect of the present disclosure is a switch system including: the above-described switch device; and a determination device that determines a switch in a conducting state among the plurality of switches based on the voltage dividing value transmitted from the output line. 
     Note that this general or specific aspect may be implemented using any combination of, for example, systems, methods, or integrated circuits. 
     A switch device according to one aspect of the present disclosure is capable of improving upon the above related art. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       These and other advantages and features of the present disclosure will become apparent from the following description thereof taken in conjunction with the accompanying drawings that illustrate a specific embodiment of the present disclosure. 
         FIG. 1  is a block diagram illustrating a configuration example of a switch system according to Embodiment 1. 
         FIG. 2  is a diagram illustrating an arrangement example of an operation interface and a rotation detection circuit in  FIG. 1 . 
         FIG. 3  is a diagram illustrating a specific example of a rotation detection circuit, a pulse generation circuit, and a selection circuit in  FIG. 1 . 
         FIG. 4  is a timing chart showing an operation example of the switch system of  FIG. 1 . 
         FIG. 5  is a block diagram illustrating Variation 1 of a switch device in  FIG. 1 . 
         FIG. 6  is a block diagram illustrating Variation 2 of the switch device in  FIG. 1 . 
         FIG. 7  is a block diagram illustrating a configuration example of a switch device in a switch system according to Embodiment 2. 
         FIG. 8  illustrates examples of the number of polar pairs of a dial in the switch system according to Embodiment 2. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The switch device of PTL 1 includes a plurality of resistors connected in series and a voltage dividing circuit having a plurality of switches connected to ends of the resistors. The switch device outputs a voltage dividing value corresponding to a position of a switch pressed by a user to one output line. An ECU (Electronic Control Unit) connected to the switch device detects which switch among the plurality of switches has been pressed, by the voltage dividing value communicated from the one output line. The switch device is suitable for reducing the manufacturing cost because the number of output lines is one. 
     As an operation switch mounted on the steering wheel of an automobile, the need for a dial-type operation switch is increasing. The dial-type operation switch is used, for example, for adjustment of audio volume, or adjustment or selection of information displayed on a display portion of an instrument panel and can realize a simpler operation in comparison with a press-type operation switch. 
     For example, a dial-type switch device can be realized by microcomputer control. However, since radiation noise due to a clock signal that causes the microcomputer to operate occurs, it is necessary to perform radiation noise tests at the development stage. Moreover, a large number of man-hours are required for system development and system tests, and there is a problem that the development cost increases. 
     Furthermore, in microcomputer control, it is difficult to realize compatibility with the method of notifying a voltage dividing value to an ECU by one output line like the method of PTL 1. Measures such as mounting a microcomputer and changing to a LIN (Local Interconnect Network) communication method are necessary, and it is also necessary to make a change on the connection destination ECU side. In this case also, a large number of man-hours are required for system development and system tests, and there is a problem that the development cost increases. 
     To address the above, a switch device according to one aspect of the present disclosure is a switch device including: a voltage dividing circuit that includes a plurality of switches including a first switch and a second switch, an output line, and a plurality of resistors connected in series to the output line, and outputs a voltage dividing value corresponding to a conduction state of each of the plurality of switches to the output line; an operation interface that includes a dial which rotates in accordance with a user operation; a rotation detection circuit that detects (i) rotation of the dial by a predetermined angle and (ii) a rotation direction of the dial, and generates an angle signal and a direction signal, the angle signal including a pulse that indicates detection of the rotation by the predetermined angle, the direction signal indicating whether the rotation direction is a first direction or a second direction different from the first direction; and a selection circuit that selects whether to output the pulse of the angle signal to control the first switch or to output the pulse of the angle signal to control the second switch, according to whether the direction signal indicates the first direction or the second direction. 
     Accordingly, the switch device can facilitate cost reduction and can respond to dial operations by the user. Specifically, the switch device replaces a user operation of rotating the dial in the first direction by a predetermined angle with an operation of pressing the first switch. Further, the switch device replaces a user operation of rotating the dial in the second direction by a predetermined angle with an operation of pressing the second switch. Therefore, the voltage dividing circuit can have an inexpensive circuit configuration similar to a conventional circuit configuration. Further, the rotation detection circuit and the selection circuit can be configured as logic circuits and can be inexpensively configured. 
     Here, the switch device may further include a pulse generation circuit between the rotation detection circuit and the selection circuit, and the pulse generation circuit may generate a one-shot pulse of a predetermined width upon receiving the pulse included in the angle signal, and output the one-shot pulse to the selection circuit. 
     Accordingly, the pulse width of the one-shot pulse can be set to a predetermined width. For example, it is sufficient so long as the predetermined width is set larger than the minimum pulse width required for a target circuit (for example, an ECU), which is a connection destination of the output line, to determine that the first switch has been pressed. Thereby, the switch device can be easily compatible with an existing ECU. 
     Here, the switch device may further include a first pulse generation circuit and a second pulse generation circuit. The first pulse generation circuit may put the first switch in a conducting state by supplying the first switch with a one-shot pulse of a predetermined width according to the pulse output from the selection circuit, and the second pulse generation circuit may put the second switch in a conducting state by supplying the second switch with a one-shot pulse of a predetermined width according to the pulse output from the selection circuit. 
     Accordingly, the predetermined width of the one-shot pulse can be set to any width. For example, the predetermined width can be set larger than the minimum pulse width required for a target circuit (for example, an ECU), which is a connection destination of the output line, to determine that the first switch has been pressed. Thereby, the switch device can be easily compatible with the specifications of an existing ECU. 
     Here, the switch device may have a configuration that does not include a central processing unit (CPU) that runs a program. 
     Thereby, it is possible to make the manufacturing cost of the switch device inexpensive. For example, it is possible to make costs of the circuit elements inexpensive, and eliminate the necessity of man-hours and costs of program development. Furthermore, it is possible to eliminate radiation noise due to a clock signal of the CPU. 
     Here, the operation interface may include: a rotation member that receives a user operation; the dial; and a converter that converts one rotation of the rotation member into R rotations of the dial, where R is a positive real number. 
     Accordingly, for example, in the case of R=4, it is possible to cause one rotation of the rotation member to correspond to four rotations of the dial. Further, in the case of R=0.25, it is possible to cause one rotation of the rotation member to correspond to a quarter rotation of the dial. Thus, by appropriately combining the size of the predetermined angle described above and the value of R, convenience of a rotation operation by the user can be improved. 
     Here, the dial may be in a shape of one of a cylinder and a disc. 
     Accordingly, it is possible to make the rotation operation simple for the user. 
     Here, the dial may have at least one pair of a north (N) pole and a south (S) pole. The rotation detection circuit may include two magnetic sensors that detect a change in magnetic fields of different directions in the vicinity of the dial. The rotation detection circuit may generate the angle signal and the direction signal from outputs of the two magnetic sensors. 
     Accordingly, the rotation detection circuit can be inexpensively configured as a magnetic sensor. 
     Here, the first switch may be a transistor switch, and the second switch may be a transistor switch. 
     Accordingly, since the first switch and the second switch are configured not as mechanical switches but as circuit elements, cost reduction can be realized. 
     Here, each of the plurality of switches may correspond to a different one of the plurality of resistors, and may be located between one end of a corresponding resistor and a reference potential line. 
     Accordingly, it is possible to make the voltage dividing circuit a simple circuit. 
     Also, a switch system according to one aspect of the present disclosure is a switch system including: the above-described switch device; and a determination device that determines a switch in a conducting state among the plurality of switches based on the voltage dividing value transmitted from the output line. 
     Accordingly, the switch device can suppress the manufacturing cost and can respond to dial operations by the user. Specifically, the switch device replaces a user operation of rotating the dial in the first direction by a predetermined angle with an operation of pressing the first switch. Further, the switch device replaces a user operation of rotating the dial in the second direction by a predetermined angle with an operation of pressing the second switch. Therefore, the voltage dividing circuit can have an inexpensive circuit configuration similar to a conventional circuit configuration, and a target circuit which determines the voltage dividing circuit transmitted from the output line can also have a configuration similar to a conventional configuration. Further, the rotation detection circuit and the selection circuit can be configured as logic circuits and can be inexpensively configured. 
     Note that these general or specific aspects may be implemented using a system, a method, or an integrated circuit, or any combination of systems, methods, or integrated circuits. 
     The following specifically describes embodiments with reference to the drawings. 
     Note that the following embodiments each illustrate a general or specific example. The numerical values, shapes, materials, elements, the arrangement and connection of the elements, steps, the processing order of the steps etc. illustrated in the following embodiments are mere examples, and are not intended to limit the present disclosure. Among the elements in the following embodiments, those not recited in any of the independent claims representing the most generic concepts are described as optional elements. 
     Embodiment 1 
       FIG. 1  is a block diagram illustrating a configuration example of switch system  10  in Embodiment 1. 
     As shown in the figure, switch system  10  includes switch device  1  and determination device  2 . A part on the right side of a broken line in the figure is provided mainly on the steering wheel of an automobile. A part on the left side of the broken line is provided to the body of the automobile as a part of an ECU. 
     Reference line o 0  in the figure is a ground wire with reference voltage VO and connects reference terminal T 0  of switch device  1  and input terminal IN 0  of determination device  2 . 
     Output line o 1  communicates an output of switch device  1  to input terminal IN 1  of determination device  2 . For example, reference line o 0  and output line o 1  are provided as a part or all of a spiral cable provided to the rotation shaft of the steering wheel. 
     Switch device  1  includes voltage dividing circuit  3 , operation interface  4 , rotation detection circuit  5 , pulse generation circuit  6 , and selection circuit  7 . 
     Voltage dividing circuit  3  includes a plurality of switches including first switch  21  and second switch  22 , output line o 1 , and a plurality of resistors including first resistor  11  and second resistor  12  connected in series to output line o 1 , and outputs a voltage dividing value corresponding to a conduction state of each of the plurality of switches to output line o 1 . Switch device  1  of  FIG. 1  further includes third switch  23  and third resistor  13 . As for terminal names of the circuit elements in the figure, a terminal on the left side or the upper side will be called a first terminal, and a terminal on the right side or the lower side will be called a second terminal. 
     First resistor  11  and second resistor  12  are inserted in output line o 1  in series. Specifically, the first terminal of first resistor  11  is connected to the second terminal of second resistor  12  and the first terminal of second switch  22 . The second terminal of first resistor  11  is connected to the first terminal of first switch  21 . 
     The first terminal of second resistor  12  is connected to input terminal IN 1  of determination device  2 , the second terminal of fourth resistor  14 , and the first terminal of third resistor  13  via output line o 1 . The second terminal of second resistor  12  is connected to the first terminal of first resistor  11  and the first terminal of second switch  22 . 
     The first terminal of third resistor  13  is connected to output line o 1 . The second terminal of third resistor  13  is connected to reference line o 0 . 
     The first terminal of fourth resistor  14  is connected to a power supply line with power supply voltage V 1 . The second terminal of fourth resistor  14  is connected to output line o 1 . 
     Each of first switch  21  and second switch  22  is a transistor switch and has, in addition to the first and second terminals, a control terminal for controlling conduction and non-conduction. Note that, though a bipolar transistor may be used as the transistor switch, a field-effect transistor with a small ON resistance, which does not easily influence the resistance values of first resistor  11  and second resistor  12  and which does not require a base current and enables power saving, may be used. 
     The first terminal of first switch  21  is connected to the second terminal of first resistor  11 . The second terminal of first switch  21  is connected to reference line o 0 . Switch control signal C 1  output from selection circuit  7  is input to the control terminal of first switch  21 . First switch  21  is in a conducting state when switch control signal C 1  is at a high level and is in a non-conducting state when switch control signal C 1  is at a low level. 
     The first terminal of second switch  22  is connected to the second terminal of second resistor  12  and the first terminal of first resistor  11 . The second terminal of second switch  22  is connected to reference line o 0 . Switch control signal C 2  output from selection circuit  7  is input to the control terminal of second switch  22 . Second switch  22  is in a conducting state when switch control signal C 2  is at a high level and is in a non-conducting state when switch control signal C 2  is at a low level. 
     Third switch  23  is a mechanical switch that becomes conductive, for example, when being pressed by a user. The first terminal of third switch  23  is connected to the first terminal of second resistor  12 , the first terminal of third resistor  13 , and the second terminal of fourth resistor  14  via output line o 1 . Third switch  23  can be used, for example, to decide or finalize a menu item selected by a dial operation. Note that third switch  23  may be two or more switches connected in parallel and interlocked in order to enhance reliability. 
     Voltage dividing circuit  3  outputs a voltage dividing value according to conduction states of the plurality of switches to output line o 1 . That is, the voltage dividing value differs depending on which switch among first switch  21  to third switch  23  is in a conducting state. For example, voltage dividing circuit  3  can be configured the same as FIG. 2 of PTL 1 except for first switch  21  and second switch  22 . 
     Operation interface  4  includes a dial which rotates in accordance with a user operation. The dial is, for example, in a shape of a cylinder having a rotation shaft. 
     Rotation detection circuit  5  detects rotation of the dial by a predetermined angle and a rotation direction of the dial, and generates angle signal S 1  and direction signal S 2 , angle signal S 1  including a pulse that indicates detection of the rotation by the predetermined angle, direction signal S 2  indicating whether the rotation direction is a first direction or a second direction different from the first direction. 
     When receiving the pulse included in angle signal S 1  from rotation detection circuit  5 , pulse generation circuit  6  generates one-shot pulse P 1  with a predetermined width. Here, the predetermined width is set so that the minimum duration time of a voltage dividing value that enables determination device  2  to determine that a switch has been pressed is satisfied. 
     Selection circuit  7  selects whether the pulse of angle signal S 1  is to be output for control of first switch  21  or for control of second switch  22  according to whether direction signal S 2  indicates the first direction or the second direction. Specifically, selection circuit  7  is a switch circuit as a one-input two-output demultiplexer to which one-shot pulse P 1  from pulse generation circuit  6  is input, and selects any one of first switch  21  and second switch  22  as an output destination of one-shot pulse P 1  according to direction signal S 2 . 
     Next, a specific example of operation interface  4  will be described. 
       FIG. 2  is a diagram illustrating an arrangement example of operation interface  4  and rotation detection circuit  5  in  FIG. 1 . In  FIG. 2 , operation interface  4  includes dial  40 . The figure schematically illustrates a section obtained by cutting dial  40  in a shape of a cylinder with a plane vertical to the rotation shaft. Dial  40  is a magnetic body that includes six pairs of N-pole and S-pole. Rotation detection circuit  5  is a magnetic detection sensor and detects a change in the magnetic field accompanying rotation of dial  40 . In the example of the figure, rotation detection circuit  5  is capable of detecting twelve polarity changes by one rotation of dial  40 . In this case, the predetermined angle described above is 30 degrees. 
     Next, a more detailed circuit configuration example of switch device  1  will be described. 
       FIG. 3  is a diagram illustrating a specific example of rotation detection circuit  5 , pulse generation circuit  6 , and selection circuit  7  in  FIG. 1 . 
     In the figure, rotation detection circuit  5  is provided with hall elements  51  and  52 , switching circuit  53 , amplifier  54 , comparator  55 , signal generation circuit  56 , and timing circuit  57 . 
     Two hall elements  51  and  52  are sensors that detect magnetic fields in directions that are different from each other. Hall elements  51  and  52  detect, for example, magnetic fields in directions that are orthogonal to each other. 
     Switching circuit  53  alternately selects one of two detection signals from hall elements  51  and  52  and outputs the detection signal to amplifier  54 . 
     Amplifier  54  amplifies the detection signal from switching circuit  53 . 
     Comparator  55  determines whether the polarity has been reversed or not by making a threshold determination of the detection signal amplified by amplifier  54 . For example, in the example of  FIG. 2 , the polarity is reversed each time dial  40  rotates by 30 degrees as the predetermined angle. Comparator  55  generates one pulse each time dial  40  rotates by the predetermined angle according to each of hall elements  51  and  52 . 
     Signal generation circuit  56  detects rotation of the dial by a predetermined angle and a rotation direction of the dial from a determination result of comparator  55  corresponding to each of hall elements  51  and  52 , and generates angle signal S 1  and direction signal S 2 , angle signal S 1  including a pulse that indicates detection of the rotation by the predetermined angle, direction signal S 2  indicating whether the rotation direction is the first direction or the second direction different from the first direction. 
     Timing circuit  57  is a sequencer circuit that controls operation timings inside rotation detection circuit  5 , such as operation timings of switching circuit  53  and the like. 
     Further, pulse generation circuit  6  of  FIG. 3  is provided with one-shot circuit  60 , resistor Re and capacitor Ce. 
     When a pulse occurs in angle signal S 1  from rotation detection circuit  5 , one-shot circuit  60  generates one-shot pulse P 1  with a predetermined width. A retriggerable monostable multivibrator or the like can be used for one-shot circuit  60 . In the example in the figure, angle signal S 1  from signal generation circuit  56  is input to input terminal B of one-shot circuit  60 , and one-shot circuit  60  generates one-shot pulse P 1  with the predetermined width, being triggered by a rising edge included in angle signal S 1 . 
     Resistor Re and capacitor Ce are a time constant circuit that defines the predetermined width of one-shot pulse P 1 . The time constant can be set as follows. For example, when determination device  2  performs 10 ms interval sampling three times in determination of the voltage dividing value, the predetermined width may be about 30 to 40 ms. 
     Selection circuit  7  is a one-input two-output switch circuit. For example, selection circuit  7  selects first switch  21  as an output destination of one-shot pulse P 1  from pulse generation circuit  6  when direction signal S 2  indicates the first direction, and selects second switch  22  as the output destination of one-shot pulse P 1  from pulse generation circuit  6  when direction signal S 2  indicates the second direction. In other words, selection circuit  7  outputs one-shot pulse P 1  as switch control signal C 1  to the control terminal of first switch  21  when direction signal S 2  indicates the first direction, and outputs one-shot pulse P 1  as switch control signal C 2  to the control terminal of second switch  22  when direction signal S 2  indicates the second direction. 
     Description will be made on an operation of switch system  10  according to Embodiment 1 configured as described above. 
       FIG. 4  is a timing chart showing an operation example of switch system  10  of  FIG. 1 . The figure illustrates a voltage waveform of each of angle signal S 1 , direction signal S 2 , one-shot pulse P 1 , switch control signals C 1  and C 2  and the voltage dividing value. Further, the “dial operation” field at the top shows states of dial  40  by user operations. The state of “no rotation” indicates a state in which dial  40  is not rotating. It is shown that dial  40  is rotating in the first direction in period T 1 . It is shown that dial  40  is rotating in the second direction in period T 2 . 
     In the period of “no rotation” before period T 1 , all the signals are constant without changing. As for the voltage dividing value at this time, since first switch  21 , second switch  22  and third switch  23  are in a non-conducting state, the potential of output line of is voltage dividing value Vd 0  that is obtained by dividing power supply voltage V 1  by fourth resistor  14  and third resistor  13 . 
     It is assumed that, in period T 1 , dial  40  of  FIG. 2  rotates in the first direction by about 120 degrees by a user operation. Rotation detection circuit  5  generates one pulse every 30 degrees as the predetermined angle, as angle signal S 1 , and generates four pulses in total. Further, rotation detection circuit  5  maintains a high level indicating the first direction as direction signal S 2 . 
     At time ta, pulse generation circuit  6  generates one-shot pulse P 1 , being triggered by a rising edge of angle signal S 1 . At this time, since direction signal S 2  is at the high level, selection circuit  7  outputs one-shot pulse P 1  to first switch  21  as the pulse of switch control signal C 1 . First switch  21  is in a conducting state in the high level period of switch control signal C 1 , and output line of outputs voltage dividing value Vd 1  in period Tp in which first switch  21  is in the conducting state. By successively sampling that the voltage dividing value of output line of is Vd 1  a plurality of times (for example, three times), determination device  2  determines that first switch  21  corresponding to voltage dividing value Vd 1  is in the conducting state. Thus, since the potential of output line of is voltage dividing value Vd 1  in period Tp from time ta, determination device  2  determines that first switch  21  has been pressed. 
     An operation in period Tp from time tb, an operation in period Tp from time tc, and an operation in period Tp from time td are the same as the operation in period Tp from time to described above. 
     As a result, determination device  2  determines that first switch  21  has been pressed four times in period T 1 . Thus, switch device  1  causes determination device  2  to determine a rotation operation of dial  40  in the first direction by the predetermined angle as a press of first switch  21 . Further, switch device  1  causes determination device  2  to determine a rotation operation of dial  40  in the first direction by an angle larger than the predetermined angle as a plurality of successive presses of first switch  21 . 
     Furthermore, it is assumed that, in period T 2 , dial  40  of  FIG. 2  rotates in the second direction opposite to the first direction by about 90 degrees by a user operation. Rotation detection circuit  5  generates one pulse every 30 degrees as the predetermined angle, as angle signal S 1 , and generates three pulses in total. Further, rotation detection circuit  5  outputs a low level indicating the second direction as direction signal S 2 . 
     At time te, pulse generation circuit  6  generates one-shot pulse P 1 , being triggered by a rising edge of angle signal S 1 . At this time, since direction signal S 2  is at the low level, selection circuit  7  outputs one-shot pulse P 1  to second switch  22  as the pulse of switch control signal C 2 . Second switch  22  is in a conducting state in the high level period of switch control signal C 2 , and output line of outputs voltage dividing value Vd 2  in period Tp in which second switch  22  is in the conducting state. By successively sampling that the voltage dividing value of output line of is Vd 2  a plurality of times (for example, three times), determination device  2  determines that second switch  22  corresponding to voltage dividing value Vd 2  is in the conducting state. Thus, since the potential of output line of is voltage dividing value Vd 2  in period Tp from time te, determination device  2  determines that second switch  22  has been pressed. 
     An operation in period Tp from time tf and an operation in period Tp from time tg are the same as the operation in period Tp from time te described above. 
     As a result, determination device  2  determines that second switch  22  has entered a conducting state three times in period T 2 . Thus, switch device  1  causes determination device  2  to determine a rotation operation of dial  40  in the second direction by the predetermined angle as a press of second switch  22 . Further, switch device  1  causes determination device  2  to determine a rotation operation of dial  40  in the second direction by an angle larger than the predetermined angle as successive presses of second switch  22 . 
     As described above, switch device  1  can realize cost reduction and can respond to dial operations by the user. Specifically, switch device  1  replaces a user operation of rotating dial  40  in the first direction by a predetermined angle with an operation of pressing first switch  21 . Further, switch device  1  replaces a user operation of rotating dial  40  in the second direction by a predetermined angle with an operation of pressing second switch  22 . Therefore, voltage dividing circuit  3  can have an inexpensive circuit configuration similar to a conventional circuit configuration. Further, rotation detection circuit  5  and selection circuit  7  can be configured as logic circuits and can be inexpensively configured. 
     Further, the pulse width of one-shot pulse P 1  can be set to a predetermined width. For example, the predetermined width can be set larger than the minimum pulse width required for a target circuit (for example, an ECU), which is a connection destination of output line o 1 , to determine that first switch  21  has been pressed. Thereby, switch device  1  can be easily compatible with an existing ECU. 
     Furthermore, switch device  1  is configured without including a CPU that executes a program. Thereby, it is possible to make costs of the circuit elements of switch device  1  inexpensive and eliminate the necessity of man-hours and costs of program development. In this case, it is possible to eliminate radiation noise due to a clock signal of the CPU. 
     Further, since first switch  21  and second switch  22  are configured not as mechanical switches but as transistor switches, cost reduction can be realized. 
     Next, Variation 1 and Variation 2 of switch device  1  of Embodiment 1 will be described. 
       FIG. 5  is a block diagram illustrating Variation 1 of switch device  1  in  FIG. 1 . In comparison with the configuration of  FIG. 1 , switch device  1  of  FIG. 5  is different in that two pulse generation circuits  6   a  and  6   b  are provided instead of pulse generation circuit  6 . Description will be made mainly on different points, avoiding duplicate description of the same points as  FIG. 1 . 
     Selection circuit  7  of  FIG. 5  may have the same internal configuration as  FIG. 1 , but the input source and output destination of selection circuit  7  are different. Angle signal S 1  from rotation detection circuit  5  is input to selection circuit  7  of  FIG. 5 , and selection circuit  7  selects an output destination of angle signal S 1  according to direction signal S 2 . That is, selection circuit  7  outputs the pulse of angle signal S 1  to pulse generation circuit  6   a  when direction signal S 2  is at the high level, and outputs the pulse of angle signal S 1  to pulse generation circuit  6   b  when direction signal S 2  is at the low level. Each of pulse generation circuits  6   a  and  6   b  have the same configuration as pulse generation circuit  6 . 
     Effects equal to those of  FIG. 1  are obtained by Variation 1 illustrated in  FIG. 5 . 
     Next, Variation 2 will be described. 
       FIG. 6  is a block diagram illustrating Variation 2 of switch device  1  in  FIG. 1 . In comparison with the configuration of  FIG. 1 , switch device  1  of  FIG. 6  is different in that pulse generation circuit  6  is deleted. Description will be made mainly on different points, avoiding duplicate description of the same points as  FIG. 1 . 
     In  FIG. 6 , pulse generation circuit  6  is deleted, and angle signal S 1  is input to selection circuit  7  instead of one-shot pulse P 1 . The pulse width of angle signal S 1  changes depending on the rotation speed of dial  40 . When most of the pulse width included in angle signal S 1  satisfies the pulse width condition required for determination of the voltage dividing value by determination device  2 , the configuration of Variation 2 may be used in which pulse generation circuit  6  is not provided, and angle signal S 1  is input to selection circuit  7 . However, when rotation of dial  40  by the user is too fast, the pulse width of angle signal S 1  decreases, and there may be a case where the duration time of a corresponding voltage dividing value cannot be determined by determination device  2 . In this case, such specifications that it is allowed to ignore too fast rotation of dial  40  may be adopted. 
     Embodiment 2 
     In Embodiment 2, description will be made on a configuration example in which a rotation member that receives a user operation and a converter that converts one rotation of the rotation member into R rotations of the dial, where R is a real number. 
       FIG. 7  is a block diagram illustrating a configuration example of switch device  1  in switch system  10  according to Embodiment 2. In comparison with the configuration of  FIG. 1 , switch device  1  in the figure is different in the configuration of operation interface  4 . Hereinafter, description will be made mainly on different points, avoiding duplicate description of the same points. 
     Operation interface  4  is provided with dial  40 , rotation member  41 , coupler  42 , converter  43 , and shaft bars  44 ,  45 , and  46 . 
     Dial  40  is a magnetic body similar to that of  FIG. 2 . However, though  FIG. 2  illustrates an example of a magnetic body with six pairs of N-pole and S-pole,  FIG. 7  illustrates an example of a magnetic body with two pairs of N-pole and S-pole. Rotation detection circuit  5  is capable of detecting four polarity changes by one rotation of dial  40  of  FIG. 7 . 
     Rotation member  41  is a cylindrical member that receives a user operation and rotates around shaft bar  44 . 
     Coupler  42  couples shaft bar  44  and shaft bar  45  at a rotation ratio of 1:1. Note that the rotation ratio need not be 1:1. 
     Converter  43  couples shaft bar  45  and shaft bar  46  at a rotation ratio of 1:R. Here, R is a positive or negative real number. Positive means that the rotation direction of rotation member  41  and the rotation direction of dial  40  are the same, and negative means that the rotation directions are opposite to each other. 
     Shaft bar  46  is fixed to dial  40  as the rotation shaft of dial  40 . 
     By this configuration, operation interface  4  converts one rotation of rotation member  41  to R rotations of dial  40 . For example, in the case of R=2, it is possible to cause one rotation of rotation member  41  to correspond to two rotations of dial  40 . Further, in the case of R=0.5, it is possible to cause one rotation of rotation member  41  to correspond to a half rotation of dial  40 . Thus, by appropriately combining the size of the predetermined angle described above and the value of R, convenience of a rotation operation by the user can be improved. Further, an inexpensive magnetic body with a small number of polar pairs can be used for dial  40 . That is, since the number of rotations is converted in the case of using dial  40  with a small number of polar pairs, the same usability as a magnetic body with a large number of polar pairs can be realized. 
     Note that the number of polar pairs of dial  40  of  FIG. 7  needs to be at least one.  FIG. 8  illustrates examples of the number of polar pairs of dial  40 . Here, (a), (b), and (c) of  FIG. 8  show examples of six pairs, two pairs, and one pair, respectively. Even if dial  40  is any of the magnetic bodies of  FIG. 8 , it is possible to appropriately set usability of rotation member  41  if the conversion rate R of converter  43  is appropriately set. Note that the number of polar pairs of dial  40  is not limited to the examples of  FIG. 8  but may be any number. 
     Further, dial  40  is not limited to the shape of a cylinder but may be in a shape of a disc. 
     Note that, though a configuration example using magnetic rotary encoders as operation interface  4  and rotation detection circuit  5  has been shown, the configuration is not limited thereto. Operation interface  4  and rotation detection circuit  5  may be, for example, optical, mechanical, or electrostatic rotary encoders. 
     Further, switch device  1  and switch system  10  may be provided to transport equipment other than an automobile. For example, they may be provided to a ship, an airplane, a game machine, or the like. 
     A switch device and a switch system according to one or more aspects have been described above based on embodiments. However, the present disclosure is not limited to the embodiments. Forms obtained by making various kinds of modifications that one skilled in the art conceives in the present embodiments or forms constructed by combining elements in the different embodiments may be included within the scope of the one or more aspects as far as not departing from the spirit of the present disclosure. 
     For example, if a plurality of other switches in addition to the switches described in the embodiments are provided to a steering wheel, a plurality of voltage dividing circuits  3  may be provided to correspond to the plurality of other switches. 
     While various embodiments have been described herein above, it is to be appreciated that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as presently or hereafter claimed. 
     The disclosure of the following patent application including specification, drawings, and claims is incorporated herein by reference in its entirety: Japanese Patent Application No. 2021-006322 filed on Jan. 19, 2021. 
     The switch device and switch system of the present disclosure can be used, for example, for a steering wheel of transport equipment and the like.