JPH06203708A - Face-to-face transmission type photoelectric switch - Google Patents

Abstract

PURPOSE:To provide a face-to-face transmissive type photoelectric switch which allows monitoring the light quantity of the light projection part even while the light is being blocked. CONSTITUTION:A frame 5a is fitted with a single light projection part 2 and two light receiving parts 3a, 3b oppositely situated while the part 2 is in the middle. An object for sensing 1 passes between the projection part 2 and the light receiving part 3a. The light generated by the projection part 2 reaches the light receiving parts 3a, 3b upon passing through a clear window 7 furnished in the frame 5a, and optical axes 4a, 4b are formed. The light receiving part 3a senses whether object 1 exists or not from change of the light quantity on the optical axis 4a resulting from passage of the object 1. The light receiving part 3b senses drop of the light quantity resulting from failure of a light emitting element belonging to the projection part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric switch used for detecting the position of a switch.

[0002]

2. Description of the Related Art FIG. 2 is a plan view of a conventional counter-transmission type photoelectric switch, in which a light projecting section 2 and a light receiving section 3 are installed facing each other on a frame 5 to form an optical axis 4. Where (A) is
When the opaque detection object 1 is located at a position that blocks the optical axis 4, (B) shows the case where the detection object 1 is located away from the optical axis 4. In this photoelectric switch, in each of the cases (A) and (B), the light receiving unit 3 can detect a change in the amount of light on the optical axis 4 and determine the presence or absence of the detection object 1.

Further, this photoelectric switch detects in advance a light quantity in the light receiving section 3 in order to detect in advance an abnormality in the light projecting section 2 such as a decrease in the light quantity due to the life of the light emitting element or an extinction due to the loss of the power source such as a disconnection. It is configured to be able to monitor.

FIG. 3 shows an example in which this photoelectric switch is applied to a switch. (A) is a plan view showing an open state of the switch,
(B) is a side view thereof. The switch rotates the main shaft 10 by electric control of an electric motor or the like to rotate the lever 11 and the link 1.
The movable contactor 13 is driven via 2 to connect and disconnect the fixed contactors 14 and 15.

When a photoelectric switch is applied to such a switch, it is necessary to surely detect the open or closed position in order to confirm the interlock condition with another switch and control the drive of the electric motor or the like. . Therefore, the light-shielding lever 9 is provided at the tip of the main shaft 10 as a detection object,
By rotating the switch in conjunction with 0, the switch is opened or closed, and one optoelectronic switch 8a or 8b is installed at the final operation position of the light-shielding lever 9.

[0006]

Here, in general, the switch is always used in either the closed or open position.
For this reason, one of the photoelectric switches 8a and 8b remains in the state of blocking the optical axis, which causes a problem that the light amount of the light projecting unit 2 cannot be monitored. Therefore, the present invention provides a counter-transmission type photoelectric switch capable of constantly monitoring the light projecting portion even in a light-shielded state.

[0007]

In the present invention, a single light projecting portion having optical axes in two directions on a straight line and a light projecting portion sandwiching the light projecting portion on the optical axis of the light projecting portion. Two light receiving portions are provided, each of which is spaced apart from each other.

[0008]

According to the present invention, it is possible to constantly monitor the light emission abnormality of the light projecting portion of the photoelectric switch even when the detected object is at the light shielding position.

[0009]

EXAMPLES The present invention will be described in detail with reference to examples. 1A and 1B show an embodiment of the present invention, wherein FIG. 1A is a plan view and FIG. 1B is an internal structural view. The frame 5a has a single light projecting section 2
And two light receiving parts 3 facing each other with the light emitting part 2 in between.
a and 3b are arranged. The light generated by the light projecting section 2 including the light emitting element reaches the light receiving sections 3a and 3b formed of photoelectric conversion elements through the transparent window 7 provided in the frame 5a, and configures the respective optical axes 4a and 4b. . Also, frame 5
In a, the light projecting portion 2, the light receiving portion 3a, and the window 7 are arranged at intervals on the optical axis 4a side so that the detection object 1 can pass therethrough and shield light.

Here, when the opaque detection object 1 interlocked with the operation of the switch or the like blocks the optical axis 4a, the light receiving section 3a senses a decrease in the light amount and an electrical switching signal is transmitted via the cable 6. To be done. Further, when the detection object 1 is separated from the optical axis 4a, the light receiving unit 3a senses an increase in the amount of light, and the electrical switching signal is transmitted again. Therefore, the detection of the amount of light by the light receiving unit 3a can be used for detecting the position of the detection object 1.

In the light receiving section 3b, the light projecting section 2 is used as a light source, and the optical axis 4 does not depend on the light blocking operation of the detection object 1.
Since b can be configured, the light amount of the light projecting unit 2 can be constantly monitored. Therefore, the detection of the amount of light by the light receiving section 3b can be used for monitoring the abnormality of the light projecting section 2.

[0012]

As is apparent from the above description, according to the present invention, it is possible to detect a failure at an early stage because the light projecting portion can be monitored both when the photoelectric switch projects light and when it blocks light. In addition, even when it is applied to a device such as a switch which is used in a light-shielded state, it is possible to constantly monitor, so that a failure of the photoelectric switch can be detected before the operation. As a result, repair work such as component replacement can be performed in advance, which greatly contributes to improvement in reliability.

[Brief description of drawings]

FIG. 1A is a plan view showing an embodiment of the present invention. (B) is an internal structure diagram for explaining the structure.

2A shows a conventional example, FIG. 2A is a plan view showing a state after a detection object shields an optical axis, and FIG. 2B is a plan view showing a state before a detection object shields an optical axis. .

FIG. 3 shows an application example of a counter-transmission type photoelectric switch to a switch, (A) is a plan view showing an open state of the switch, (B).
[Fig. 4] is a side view for explaining the structure.

[Explanation of reference numerals] 1 detection object 2 light emitting unit 3a, 3b light receiving unit 4a, 4b optical axis 5a frame 6 cable 7 window 8a, 8b photoelectric switch 9 light-shielding lever 10 main shaft 12 link 13 movable contactor 14 fixed contactor 15 fixed Contact

Claims (1)

[Claims] 1. A single light projecting unit having optical axes in two directions on a straight line, and a light projecting unit disposed on the optical axis of the light projecting unit with a distance between them. Opposed transmission type photoelectric switch having two light receiving parts.