JPH07117627A - Rotational position detection device for switch - Google Patents

Abstract

PURPOSE:To detect the rotational position of a rotor in a rotational position detection device for a switch in a stator by a small current. CONSTITUTION:A rotational position detection device for a switch is provided with a terminal base 13, a driver 11 installed rotatably in relation to the terminal base 13, a metal thin film resistance body 15 formed in an arc shape on the surface of the driver 11 and conductive brushes 17, 18 provided on the terminal base 13 and electrically connected to two points of the metal thin film resistance body 15. An electric resistance value between the conductive brushes 17, 18 is changed by the change of the length of the current passage of the metal thin film resistance body 15 between the conductive brushes 17, 18 in accordance with the rotation of the driver 11. The metal thin film resistance body dispersed like dots in an arc shape is provided on the surface of the driver 11. The resistance value of the metal thin film resistance body between the conductive brushes 17, 18 is changed in accordance with the rotation of the driver 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational position detecting device for a switch, and more particularly to a rotational position detecting device for a switch applied to an automobile ignition switch.

[0002]

2. Description of the Related Art For example, as disclosed in Japanese Unexamined Patent Publication No. 1-220319, a conventional automobile ignition switch has a power supply terminal, an accessory terminal, an ignition terminal, and a starter provided on three circles from a central axis. A fixed contact board having five fixed contact terminals consisting of terminals and resistance terminals, a case attached to the fixed contact board, rotated to a lock position, an ACC position, an on position and a start position and facing the fixed contact board. And a movable panel that is rotatably arranged, and three movable contact terminals that are rotatably disposed with the drive panel between the fixed contact panel and the movable panel and that can contact different fixed contact terminals of the fixed contact panel. And a first movable contact point board and a second movable contact point board. The first movable contact point board and the second movable contact point board are arranged in a stacked state. Fixed contact panel power supply terminal and ignition terminal,
The accessory terminal and the ignition terminal, the ignition terminal and the starter terminal, the power supply terminal and the resistance terminal are provided on different circles.

[0003]

By the way, the conventional ignition switch for an automobile connects a circuit for each rotational position of OFF-ACC-ON-START by a mechanical contact type, and makes it conductive. There was a problem in durability and reliability due to wear due to friction and melting loss due to arc current when the contacts were opened and closed. Also, because it directly opens and closes large currents,
There is a high risk that other electronic devices may malfunction due to the influence of noise due to the generation of back electromotive force.

Therefore, an object of the present invention is to provide a rotational position detecting device for a switch which can detect the rotational position of a rotor in a stator with a small current.

[0005]

A rotary position detecting device for a switch according to the present invention comprises a stator incorporated in a steering lock device, a rotor rotatably arranged with respect to the stator, and an arc on the surface of the rotor. The metal thin film resistor formed is provided with a conductive brush provided on the stator and electrically connected to two points of the metal thin film resistor. As the rotor rotates, the length of the current path of the metal thin film resistor between the conductive brushes changes, so that the electric resistance value between the conductive brushes changes.

In another embodiment of the present invention, the rotor is provided with metal thin film resistors formed in a circular arc and scattered. The resistance value of the metal thin film resistor between the conductive brushes changes as the rotor rotates.

[0007]

With the rotation of the rotor, the current path of the metal thin film resistor becomes longer. The rotational position of the rotor with respect to the stator is detected by measuring the potential difference across the metal thin film resistor using a small current flowing through the metal thin film resistor.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary position detecting device for a switch of the present invention applied to an automobile ignition switch will be described below with reference to FIGS.

As shown in FIG. 1, an ignition switch for an automobile has a metal housing 10 and a housing 1.
Driver 1 as a rotor rotatably arranged in 0
1 and a return spring 12 which is disposed in the housing 10 and returns the driver 11 from the start position to the on position when the driver 11 is rotated to the start position,
It has a terminal base 13 as a stator fixed to the end of the housing 10. The click ball 14 that gives a feeling of rotation when the driver 11 rotates is the driver 1
1 is provided. Further, the driver 11 is provided with a metal thin film resistor 15 and a contact 16 which are arcuately and concentrically formed. The metal thin film resistor 15 has a diameter larger than that of the contact 16, and is provided outside the contact 16. The terminal base 13 is provided with a pair of conductive brushes 17 and 18.
After assembling the return spring 12, the driver 11 and the terminal base 13 in the housing 10, the housing 10 is mounted in a frame forming a steering lock device (not shown). A key cylinder is arranged in the steering lock device in a known manner, and an end portion of the key cylinder penetrates an opening 20 formed in the housing 10 and is operatively connected to the driver 11. Therefore, the driver 11 is rotated simultaneously with the rotation of the key cylinder. Figure 2
As shown in FIG. 3, the ring-shaped contact 16 and the ring-shaped metal thin-film resistor 15 are formed concentrically and are connected by the conductive connector 19. The conductive brushes 17 and 18 contact the metal thin film resistor 15 and the contact 16, respectively. When the driver 11 is rotated with respect to the terminal base 13, the positions of the conductive brushes 17 and 18 with respect to the metal thin film resistor 15 and the contact 16 are changed, and the conductive brush 1 from the conductive connector 19 is moved.
The position of the contact point of the metal thin film resistor 15 of No. 7 changes. As shown in FIG. 3, the potential difference changes depending on the position of the contact point of the metal thin film resistor 15 of the conductive brush 17 from the conductive connector 19, for example, 0V at the lock position, 1.5V at the ACC position, and at the ON position. 4V, 5 at start position
A potential difference of V is applied.

FIG. 4 shows another embodiment of the present invention, in which a plurality of metal thin film resistors 21 extend in the radial direction from arcuate contacts 16. The metal thin film resistor 21 includes six resistors 21a to 2a.
Having 1 g. The six resistors 21a to 21g are formed of metal thin film resistors having different resistance values. Therefore, the rotation angle position can be detected by rotating the conductive brush 17 in the circumferential direction and detecting a predetermined potential difference.

The rotary position detecting device for a switch according to the present invention can be used in various modes. For example, a control circuit configured by a microcomputer detects a potential difference to detect a lock position, an ACC position, an on position, and a start position of a steering lock device, and supplies a necessary electric power to a predetermined amount of an engine through a drive circuit and / or an amplifier circuit. Can be supplied to the site.

FIG. 5 shows an example applied to an automobile ignition switch according to the present invention. Conductive brush 1
The outputs of 7 and 18 are supplied to the control circuit 3 through the voltage detection circuit 30.
The output of the control circuit 31 is given to the output circuit 34 through the amplifier circuit 32 and the branch control circuit 33.
The branch control circuit 33 determines a power supply destination, and outputs the output circuit 3
4 can selectively supply electric power to a necessary portion of the engine through a power switching element such as a power transistor or a relay.

[0013]

As described above, according to the present invention, since a small current flowing through the metal thin film resistor is used to measure the potential difference of the metal thin film resistor, the rotational position can be detected, so that arc discharge occurs. There is an advantage that it does not occur and a counter electromotive force is not generated, and it becomes possible to extend the life of the rotary position detecting device for a switch.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a rotary position detecting device for a switch according to the present invention applied to an automobile ignition switch.

FIG. 2 is a front view showing a contact state between a metal thin film resistor and a conductive brush.

FIG. 3 is a graph showing the relationship between the current path length and the potential difference of the metal thin film resistor.

FIG. 4 is a front view of a metal thin film resistor showing another embodiment of the present invention.

FIG. 5 is a circuit diagram of a rotary position detecting device for a switch according to the present invention used in an ignition circuit.

[Explanation of symbols]

10 ··· Housing, 11 · · Driver (rotor), 1
2 ・ ・ Return spring, 13 ・ ・ Terminal base (stator), 15, 21 ・ ・ Metal thin film resistor, 16 ・
・ Contacts, 17, 18 ・ ・ Conductive brushes, 19 ・ ・ Conductive connectors, 20 ・ ・ Openings,

Claims (2)

[Claims] 1. A stator incorporated in a steering lock device, a rotor rotatably arranged with respect to the stator, a metal thin film resistor formed in an arc shape on a surface of the rotor, and a metal provided on the stator and provided with a metal. A conductive brush electrically connected to two points of the thin film resistor is provided, and the electric resistance value between the conductive brushes is changed by changing the length of the current path of the metal thin film resistor between the conductive brushes as the rotor rotates. A rotary position detecting device for a switch, characterized in that 2. A stator incorporated in a steering lock device, a rotor rotatably arranged with respect to the stator, metal thin film resistors formed in a circular arc on the surface of the rotor, and a stator. A rotation for a switch, comprising: a conductive brush provided and electrically connected to two points of the metal thin film resistor, wherein the resistance value of the metal thin film resistor between the conductive brushes changes as the rotor rotates. Position detection device.