WO2018220894A1

WO2018220894A1 - Microcomputer input switch

Info

Publication number: WO2018220894A1
Application number: PCT/JP2018/002168
Authority: WO
Inventors: 明彦山下; 達也古▲瀬▼; 知里中田; 章平鈴木
Original assignee: 本田技研工業株式会社
Priority date: 2017-05-31
Filing date: 2018-01-24
Publication date: 2018-12-06
Also published as: JP6783930B2; MY194498A; CN110692117B; PH12019502368A1; CN110692117A; JPWO2018220894A1

Abstract

This microcomputer input switch exhibits little contact point electrical corrosion even when exposed to water and can detect an OFF state of a switch with certainty. The microcomputer input switch has a one-side contact point (6) and another-side contact point (7) that constitute a switch (5), wherein a constant current output with a pulsed waveform is applied to the switch (5) as a current for detecting an OFF state of the switch (5). The constant current is a very small current of 100 mA or less. The one-side contact point (6) or the other-side contact point (7) is connected to a voltage threshold detection means (4) that detects the OFF state of the switch (5). A control unit (8) is provided that determines the OFF state of the switch (5) on the basis of an output signal of the voltage threshold detection means (4). The control unit (8) determines that the switch (5) is in the OFF state if the applied current exceeds a predetermined threshold (Va).

Description

Microcomputer input switch

The present invention relates to a microcomputer input switch, and more particularly to a microcomputer input switch applied to a manual switch for operating a vehicle electrical device or the like.

2. Description of the Related Art Conventionally, in manual switches such as horn switches and starter switches that operate vehicle electrical equipment, attempts have been made to prevent malfunction of electrical equipment when the switch contacts are exposed to moisture such as rain.

In Patent Document 1, in a brake switch electric circuit that operates a brake lamp using an LED as a light source, a contact point of a manual switch is wetted to generate a leak current, and the brake lamp is turned off even though the manual switch is off. In order to prevent the operation of the semiconductor switch, a configuration in which the ground of the semiconductor switch in the electric circuit is shared with the ground of the manual switch is disclosed.

Japanese Patent No. 5955727

However, the switch circuit disclosed in Patent Document 1 has a problem that the cost increases because two semiconductor switches are required. In addition, there has been no study on prevention of contact corrosion caused by current for detecting the open / close state of the switch.

An object of the present invention is to solve the above-described problems of the prior art and provide a non-waterproof switch with a microcomputer input switch that can detect the OFF state of the switch reliably with little contact corrosion even when wet.

In order to achieve the above object, the present invention detects an OFF state of the switch (5) in a microcomputer input switch having one contact (6) and the other contact (7) constituting the switch (5). The first characteristic is that a constant current for outputting a pulse waveform is applied to the switch (5) as a current for the switching.

The second feature is that the constant current is a minute current of 100 mA or less.

The one side contact (6) or the other side contact (7) is connected to a voltage threshold value detection means (4) for detecting an OFF state of the switch (5), and the voltage threshold value detection means (4) The control unit (8) determines the OFF state of the switch (5) based on the output signal of the output signal, and the control unit (8) causes the applied current to exceed a predetermined threshold (Va). A third feature is that it is determined that the switch (5) is in an OFF state.

The pulse width (T1) of the current applied to the switch (5) has a fourth feature in that the detected voltage value is set to a minimum value including a range exceeding a threshold value (Va). .

Further, there is a fifth feature in that the detection of the off state of the switch (5) is executed a plurality of times within the pulse width (T1) of the current flowing through the switch (5).

Further, the sixth feature is that the application of current is stopped when the detected voltage value exceeds a threshold value (Va).

Further, the control unit (8) performs detection of the OFF state of the plurality of switches in a predetermined order, and the order is such that the detection interval of the OFF state of the switch requiring a fast response speed is shortened. There is a seventh feature in that it is set.

According to the first feature, in the microcomputer input switch having the one side contact (6) and the other side contact (7) constituting the switch (5), the current for detecting the OFF state of the switch (5) As described above, since a constant current that outputs a pulse waveform is applied to the switch (5), it is possible to reduce the amount of energization when detecting the open / closed state of the switch, thereby minimizing contact erosion when wet. It becomes possible. In addition, since the pulse waveform is output as the current, it is possible to accurately detect the OFF state of the switch by monitoring the pulse waveform of the current. Furthermore, when the resistance is increased by the oxide film when the constant current is used, the voltage between the contacts rises and the oxide film is destroyed by trying to pass the specified current, thereby suppressing the generation of the oxide film. it can. As a result, the on-resistance can be kept low.

According to the second feature, since the constant current is a minute current of 100 mA or less, it is possible to minimize the progress of contact electrolytic corrosion.

According to a third feature, the one-side contact (6) or the other-side contact (7) is connected to voltage threshold value detection means (4) for detecting an off state of the switch (5), and the voltage A control unit (8) that determines an off state of the switch (5) based on an output signal of the threshold detection means (4), and the control unit (8) has a predetermined threshold ( Since it is determined that the switch (5) is in an off state by exceeding Va), it is possible to reliably detect the off state of the switch using the pulse waveform mode.

According to the fourth feature, the pulse width (T1) of the current applied to the switch (5) is set to a minimum value including a range in which the detected voltage value exceeds a threshold value (Va). The detection time of the switch off state can be shortened, and the electric corrosion at the time of flooding can be minimized.

According to the fifth feature, since the detection of the OFF state of the switch (5) is executed a plurality of times within the pulse width (T1) of the current flowing through the switch (5), It becomes possible to improve detection accuracy.

According to the sixth feature, when the detected voltage value exceeds the threshold value (Va), the current application is stopped, so the current application time is shortened to minimize the contact corrosion at the time of water. It becomes possible.

According to a seventh feature, the control unit (8) performs detection of the OFF state of a plurality of switches in a predetermined order, and the order is detection of an OFF state of a switch that requires a fast response speed. Since the interval is set to be short, the response speed of the horn switch, the brake lamp switch, etc. can be increased.

It is a schematic diagram of the switch circuit to which the switch structure according to the present embodiment is applied (switch on state). It is a schematic diagram of the switch circuit to which the switch structure according to the present embodiment is applied (switch off state). It is a graph which shows transition of the voltage of the input signal to the voltage threshold value detection means in a switch-off state. It is a flowchart which shows the procedure of the OFF state detection control 1 of a switch. It is a flowchart which shows the procedure of the OFF state detection control 2 of a switch. It is a figure which shows the change of a switch contact at the time of using it for a long time in a flooded state.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 are schematic diagrams of a switch circuit 1 to which the switch structure according to the present embodiment is applied. FIG. 1 shows an on state in which the switch 5 is closed, and FIG. 2 shows an off state in which the switch 5 is opened.

The switch circuit 1 includes a switch 5 such as a horn switch that is switched on and off by a human operation, a transformer 2 that converts a power source current into a minute constant current, and a low voltage applied to the gate toward the drain from the source. A P-type FET 3 through which a current flows, a voltage threshold value detection means 4 for detecting a threshold value of the output voltage of the FET 3, and a control unit (microcomputer) 8 that determines the on / off state of the switch 5 based on the output signal of the voltage threshold value detection means 4 Including.

The switch 5 which is a microcomputer input switch includes a first contact 6 located on the voltage threshold detection means 4 side and a second contact 7 located on the ground side. The present embodiment is characterized in that a constant current that outputs a pulse waveform is applied as a current for detecting the OFF state of the switch 5. The constant current can be applied immediately before the detection timing.

Conventionally, in order to detect the OFF state of the switch 5, a method of continuously applying current to the switch has been adopted. For this reason, when the conductive liquid W is filled between the one side contact 6 and the other side contact 7, a leakage current flows through the conductive liquid W, and it becomes difficult to detect the OFF state of the switch 5. There was a problem that electric corrosion occurred at the contact point due to the current. In addition to seawater, such a conductive liquid W may be generated by, for example, rain water that has entered a steering wheel switch case of a motorcycle, water at the time of car washing, or the like.

In the present embodiment, in the configuration in which it is determined that the switch 5 is in the OFF state when the input signal to the voltage threshold detection unit 4 exceeds the predetermined threshold, the current of the switch 5 is detected as the current for detecting the OFF state of the switch 5. Immediately before the detection timing of the OFF state, by applying a constant current that outputs a pulse waveform, it is possible to prevent contact corrosion and to detect the OFF state of the switch 5 reliably even when the switch 5 is wet. Is possible. In addition, because of the constant current, when an oxide film is generated, if the resistance value increases due to the generated oxide film, the voltage between the contacts rises to try to pass the specified current, and the oxide film can be destroyed. .

FIG. 3 is a graph showing the transition of the voltage of the input signal to the voltage threshold detection means 4 when the switch 5 is in the OFF state. As described above, the current applied to the switch 5 via the transformer 2 is a minute current of 100 mA or less (for example, 7 mA). Thereby, the electric corrosion of a contact can be suppressed.

Furthermore, in this embodiment, this minute current is a pulse current having a pulse waveform. Thereby, it becomes easy to detect the OFF state of the switch by monitoring the pulse waveform of the current, and further, the electric amount of the applied current is suppressed, and the electric corrosion of the contact is reduced.

At time t = 0, the switch is awaiting detection of an off state. At time t1, application of the input signal to the voltage threshold value detection means 4 is started, and the first pulse of the minute constant current starts to rise. Since the determination of the OFF state of the switch 5 is performed based on whether or not the pulse voltage exceeds a threshold value Va that is smaller than the peak voltage V2, it is possible to reliably detect the OFF state even if there is an influence of leakage current. it can.

Here, the pulse width T1 of the constant current to be applied is set to the minimum value including the range in which the detected voltage value exceeds the threshold value Va based on the peak voltage V2. Thereby, it is possible to shorten the detection time of the OFF state of the switch 5. In this graph, a predetermined time T2 has elapsed from the start of constant current application at time t2, a predetermined time T3 has elapsed from the start of constant current application at time t3, and the output voltage due to the constant current has peak voltage V2 at time t4. Shows the state of reaching.

Further, in the present embodiment, in order to improve the detection accuracy of the OFF state of the switch 5, the detection of the OFF state of the switch 5 is set to be executed a plurality of times within the pulse width T1 of the current flowing through the switch 5. be able to. Thereby, for example, it is possible to improve the noise toughness by determining that the switch 5 is in the OFF state when the voltage V exceeds the threshold value Va for five consecutive times.

Furthermore, as another method, when the detected voltage value exceeds the threshold value Va, it is set so that the current application is stopped immediately, and the current application time is shortened to minimize the contact corrosion at the time of flooding. You can also

On the other hand, the control unit 8 is configured to detect the OFF state of a plurality of switches such as a horn switch and a brake lamp switch in a predetermined order. At this time, the detection order of the OFF state can be set so that the detection interval of the OFF state of the switch that requires a fast response speed is shortened. As a result, it is possible to detect the OFF state according to the required response speed of the switch.

FIG. 4 is a flowchart showing a procedure of the OFF state detection control 1 of the switch 5 according to the present embodiment. The predetermined time shown below corresponds to the graph of FIG. As switch-off state detection control, in step S1, detection of the off-states of a plurality of switches is started. In step S2, application of a minute constant current is started. In step S3, it is determined whether or not the application elapsed time T has exceeded a predetermined time T2. If a positive determination is made in step S3, the process proceeds to step S4, and voltage detection is executed. On the other hand, if a negative determination is made in step S3, the process returns to the determination in step S3.

In step S5, it is determined whether or not the detected voltage V exceeds the threshold voltage Va. If an affirmative determination is made in step S5, the process proceeds to step S6, where it is determined that the switch is in an off state, and the application of the minute constant current is stopped in step S7, and the series of controls is terminated. If a negative determination is made in step S5, steps S6 and S7 are skipped, and the series of controls is terminated.

FIG. 5 is a flowchart showing a procedure of the OFF state detection control 2 of the switch 5 according to the present embodiment. As described above, when detection is performed a plurality of times within a predetermined pulse width, for example, the energization is stopped after the switch V is determined to be off because the voltage V has exceeded the threshold value Va for five consecutive times. Therefore, highly accurate detection can be performed in a short time.

In step S10, detection of an off state of a plurality of switches is started. In step S11, application of a minute constant current is started. In step S12, it is determined whether or not the application elapsed time T has exceeded a predetermined time T2. If a positive determination is made in step S12, the process proceeds to step S13, and voltage detection is executed. On the other hand, if a negative determination is made in step S12, the process returns to the determination in step S12.

In step S14, it is determined whether or not the detected voltage V exceeds the threshold voltage Va. If a positive determination is made in step S14, the process proceeds to step S15, and the off detection counter is incremented (+1). On the other hand, if a negative determination is made in step S14, step S15 is skipped and the process proceeds to step S16.

In step S16, it is determined whether or not the application elapsed time T is less than the predetermined time T3. If a positive determination is made in step S16, the process returns to step S13. On the other hand, if a negative determination is made in step S16, the process proceeds to step S17.

In step S17, it is determined whether or not the off detection counter number Nc exceeds five. If an affirmative determination is made in step S17, the process proceeds to step S18, where it is determined that the switch is in an off state. In step S19, the off detection counter is reset. In step S20, the application of the minute constant current is stopped, and the series of controls is terminated.

FIG. 6 is a diagram showing a change in the switch contact when used for a long time in a wet condition. (A) shows the state which applied the electric current by the method which concerns on this embodiment, (b) shows the state which applied the electric current by the conventional system. In the conventional method of (b), the electric corrosion progresses quickly because the current is continuously applied to the switch in order to detect the off state of the switch, whereas in the present embodiment shown in (a), almost no switch contact is present. It can be seen that no electrolytic corrosion has occurred.

In addition, the configuration of the switch, the transformer, the FET, the voltage threshold value detection means, the shape and structure of the one side contact and the other side contact, the pulse width, the threshold value, and the like are not limited to the above embodiment, and various changes can be made. The microcomputer input switch according to the present invention is not limited to a handle switch of a motorcycle, and can be applied to switches of various vehicles and power units.

DESCRIPTION OF SYMBOLS 1 ... Switch circuit, 2 ... Transformer, 3 ... FET, 4 ... Voltage threshold value detection means, 5 ... Switch, 6 ... One side contact, 7 ... Other side contact, 8 ... Control part, V2 ... Pulse peak voltage, Va ... threshold, W ... conductive liquid

Claims

In the microcomputer input switch having one side contact (6) and the other side contact (7) constituting the switch (5),
A microcomputer input switch, wherein a constant current for outputting a pulse waveform is applied to the switch (5) as a current for detecting an off state of the switch (5).
The microcomputer input switch according to claim 1, wherein the constant current is a minute current of 100 mA or less.
The one side contact (6) or the other side contact (7) is connected to a voltage threshold value detection means (4) for detecting the OFF state of the switch (5),
A control section (8) for determining an off state of the switch (5) based on an output signal of the voltage threshold detection means (4);
The said control part (8) judges that the said switch (5) is an OFF state because the said applied electric current exceeds the predetermined threshold value (Va), The switch (5) is characterized by the above-mentioned. Microcomputer input switch.
The pulse width (T1) of the current applied to the switch (5) is set to a minimum value including a range in which the detected voltage value exceeds a threshold value (Pa). The switch for microcomputer input in any one of.
4. The microcomputer input switch according to claim 3, wherein the detection of the OFF state of the switch (5) is performed a plurality of times within a pulse width (T1) of a current flowing through the switch (5). .
4. The microcomputer input switch according to claim 3, wherein when the detected voltage value exceeds a threshold value (Va), application of current is stopped.
The control unit (8) performs detection of an off state of the plurality of switches in a predetermined order,
4. The microcomputer input switch according to claim 3, wherein the order is set so that a detection interval of an off state of a switch requiring a high response speed is shortened.