JPH0321843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical position detection device that detects the position of an object using a light emitting/receiving means, and particularly in an atmosphere where mist droplets, dust, soot, flying objects, etc. are present. This invention relates to a water film plate position detecting device configured to detect the position of a plate to be detected.

Prior Art and its Problems Conventionally, a position detection device for detecting the position of a plate moving in a furnace, a plating tank, etc. using light emitting/receiving means has been configured as follows, for example. In other words, the light emitting part and the light receiving part are installed in the movement path of the detection plate so as to face each other through a transparent plate, and the amount of received light when the light is blocked by the movement of the detection plate is measured. It was configured to detect changes. In a device configured in this manner, foreign matter such as dust in the tank is transported by the gas and adheres to the transparent plates provided in the light projecting section and the light receiving section. For this reason, the light emitted from the light projecting section is blocked by the foreign matter, making it impossible to accurately detect the position of the detection target plate.

In order to solve the above problems, measures such as blowing dust purging gas (for example, air or nitrogen gas) around the transparent plate, flowing water over the surface of the transparent plate, or spraying high-pressure cleaning liquid are used. Measures have been taken to prevent foreign matter from adhering to the surface of the transparent plate (see, for example, Japanese Patent Laid-Open No. 53-39204).

However, even if the above-mentioned measures were taken, a uniform water film was not always formed on the transparent plate, so adhesion of foreign matter was unavoidable. In addition, when water is poured through a transparent plate, a large amount of water is required, which is not only uneconomical, but also cannot be used in a liquid tank, where the water scatters around, diluting the concentration of the liquid and causing adverse effects. Furthermore, there is a method for removing foreign matter adhering to the transparent plate using mechanical parts such as wipers, but this method has drawbacks such as the need to add special parts and the device becomes larger.

Purpose of the Invention The present invention has been made to solve the above-mentioned drawbacks of the prior art.It constantly forms a uniform water film on the surface of a transparent plate to prevent foreign matter from adhering to it, thereby improving detection sensitivity. It is an object of the present invention to provide a water film-covered plate position detection device that does not cause water to scatter and adversely affect the surrounding area even when washed with running water.

Means for Solving the Problems Overview of the Invention The present invention provides a light projecting section having a transparent plate covering a light projecting surface, and a transparent plate covering a light receiving surface and facing the light projecting section and spaced apart from each other by a predetermined distance. A position detection device that detects the position of a detected object by determining a change in the amount of received light when a moving detected object blocks the light emitted from the light projecting section. , a water supply mechanism unit that supplies a predetermined flow rate of water to the transparent plates of the light projecting unit and the light receiving unit to form a water film on the surface of the transparent plate; and a drainage mechanism that drains water that has passed through the surface of the transparent plate. By installing an air purge to eliminate the influence of fumes between the projector, transmitter, and receiver, it prevents foreign matter from adhering to the sensor, improves detection sensitivity, and prevents water from scattering and negatively impacting the surrounding area. It is characterized by being configured as follows.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 2a and 2b show a schematic configuration of the water film plate position detection device of the present invention, and FIG. 2a is a plan view. In this figure, reference numeral 1 denotes a light projector that emits light based on a signal from a light projector (not shown). Reference numeral 2 denotes a light receiving section provided at a position facing the light projecting section 1 at a predetermined distance apart. The light receiving section 2 receives the light emitted from the light projecting section 1 and outputs the optical signal to a light receiver (not shown). Reference numeral 3 denotes a detection plate that moves through the gap between the light projecting section 1 and the light receiving section 2 in a direction perpendicular to the direction in which light travels. By moving this detection target plate 3 and blocking the light emitted from the light projecting unit, the amount of light received by the light receiving unit 2 changes, and the position of the detection target plate 3 can be detected. Reference numeral 4 denotes an air purge nozzle that blows air supplied from the air duct 5 toward the detection target plate 3 to prevent foreign matter from entering from the outside. The air purge nozzles 4 are provided at the ends of the light projecting section 1 and the light receiving section 2, respectively, as shown in the left side view of FIG. 2b. Reference numeral 6 denotes a water supply pipe for supplying water to a water supply tank, which will be described later, provided in the light projector 1 and the light receiver 2. Reference numeral 7 denotes a drain pipe for draining water from a drainage tank, which will be described later, provided in the light projecting section 1 and the light receiving section 2. The light projecting section 1 includes a transparent plate that covers the light projecting surface, and the light receiving section 2
A transparent plate is provided to cover the light-receiving surface, and these transparent plates, the water supply tank, and the drainage tank are arranged as shown in FIG. FIG. 1 is a view taken along the line B-B' in FIG. be.
A water supply tank 9 is provided at the upper end of the transparent glass plate 8. The upper end of the water supply tank 9 and the end of the water supply pipe 6 are connected. A needle valve 10 is provided at the end of the water supply pipe 6 to adjust the amount of water supplied. A drainage tank 11 is provided at the lower end of the transparent glass plate 8. The drain tank 11 and the ends of the drain pipe 7 are connected.

In order to supply the water flow to the transparent glass plate 8, for example, a water flow circulation pump (not shown) is used.
Water is circulated through a loop of pump → water supply pipe 6 → water supply tank 9 → transparent glass plate 8 → drainage tank 11 → drain pipe 7 → pump.

Next, the operation of the device configured as described above is explained in the first step.
This will be explained with figures. FIG. 1 shows details of the light projecting section 1 or the light receiving section 2, and in this figure, 12 is the light projecting surface of the light projecting section or the light receiving surface of the light receiving section. The water now sent from the water supply pipe (not shown) is supplied as a water stream to the surface of the transparent glass plate 8 via the water supply tank 9. At this time, a uniform water film 13 is formed on the surface of the transparent glass plate 8, so that even if foreign matter enters from the outside, it will not adhere to the transparent glass plate 8. Therefore, the surface of the transparent glass plate 8 can be protected from mist, dust, soot, flying objects, and the like. The water flow that has passed through the surface of the transparent glass plate 8 is sent to a drain pipe (not shown) via a drain tank 11.
The thickness and flow rate of the water film 13 can be arbitrarily changed by adjusting the valve opening in the water supply pipe from the needle valve 10 or the aforementioned water circulation pump (not shown). This makes it possible to constantly form a water film or increase the amount of water to forcibly remove foreign matter that has adhered to the transparent glass plate 8. Moreover, if the air taken in from the air suction duct 5 (not shown) mentioned above is ejected to the detection target plate 3 side through the air passage 14 and the air purge nozzle 4,
Fumes and atmospheric gases that are scattered at high speed from the outside can be thrown and blown away to prevent them from entering between the light-receiving parts.

Effects of the Invention As explained above, according to the present invention, the following effects can be obtained. That is, (1) since a uniform water film can be formed on the surface of the transparent plate, it is possible to prevent foreign matter from adhering to the surface of the transparent plate, thereby significantly improving detection sensitivity.

(2) The water flow supplied to the pot clear plate forms a water film on the surface of the transparent plate and does not scatter to the outside, so even if it is used in a liquid tank, it is unlikely that the concentration of the liquid will become diluted. You can use it with care.

(3) Since the thickness of the water film formed on the surface of the transparent plate and the speed of the water flow can be arbitrarily changed, foreign matter attached to the transparent plate can be forcibly removed.

(4) Detection accuracy can be improved by preventing fume and atmospheric gas from entering between the projecting and light receiving sections.

[Brief explanation of the drawing]

FIG. 1, FIG. 2 a, b, and FIG. 3 all show one embodiment of the present invention, where FIG. 1 is an explanatory diagram explaining the details of the main part, FIG. Diagram b
is the left side view of Fig. 2a, and Fig. 3 is the left side view of Fig. 2a.
It is a view from arrow A. 1...Light emitter, 2...Light receiver, 3...Detected plate, 6...Water supply pipe, 7...Drain pipe, 8...Transparent glass plate, 9...Water supply tank, 10...Needle Valve, 11... Drainage tank, 12... Light emitting surface (light receiving surface), 13... Water film.

Claims (1)

[Scope of Claims] 1. A light projecting section including a transparent plate covering a light projecting surface, and a light receiving section provided with a transparent plate covering a light receiving surface and facing the light projecting section and spaced a predetermined distance apart. A position detection device that detects the position of the object to be detected by determining a change in the amount of light received when a moving object to be detected blocks the light emitted from the light emitting portion, the light emitting portion and the light receiving portion; A water supply mechanism unit that supplies a water flow at a predetermined flow rate to the transparent plate to form a water film on the surface of the transparent plate, and a drainage mechanism unit that drains water that has passed through the surface of the transparent plate. Water film plate position detection device. 2. The water film plate position detection device according to claim 1, wherein the water supply mechanism section has a function of arbitrarily changing the watering flow rate. 3. Claim 1, which is characterized by providing cooling of the light emitter and receiver, prevention of fogging inside the transparent plate of the light emitter and receiver, a fume between the light receivers, use of a dryer for atmospheric gas purging, and a purge nozzle. Water film plate position detection device.