JPS588853B2 - Light control method in welding mask equipped with liquid crystal glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling light in a welding mask provided with liquid crystal glass.

BACKGROUND OF THE INVENTION BACKGROUND OF THE INVENTION Welding masks are known in the art, as described below with reference to FIG. 1, which are provided with liquid crystal glass to protect the eyes of the operator.

In FIG. 1, 1 is a main light receiving element that receives light emitted during welding work (hereinafter referred to as "welding light"), and is made of, for example, a phototransistor, and includes a resistor R1, a Zener diode ZD, a variable resistor VR1, a resistor R2 This constitutes a bridge circuit.

2 is a switching transistor, and when the main light receiving element 1 receives a predetermined amount of welding light or more, the impedance on the side of the main light receiving element 1 decreases, the base potential of the switching transistor 2 rises, and the voltage between the collector and emitter is increased. is turned on, thereby cutting off current to the liquid crystal glass (not shown), and the liquid crystal glass protects the eyes of the worker from the welding light by maintaining a predetermined transparency for the welding light. .

In this case, the switching operating point of the switching transistor 2 is set by the resistance value of the variable resistor VR, and if the resistance value of the variable resistor VR is made large, the switching transistor 2 will be turned on by a relatively small amount of received light. , if the resistance value is small, it will turn on due to a large amount of received light.

However, such a conventional welding mask has a drawback in that the switching transistor 2 operates unnecessarily when the main light receiving element receives natural light such as sunlight, other than welding light.

In order to avoid this, the mounting position and mounting direction of the main light receiving element should be designed so that it does not receive sunlight as much as possible.
Alternatively, measures have been considered to install filters, shading canopies, etc. to avoid receiving sunlight, etc.
At present, sufficient results have not been achieved.

The main objective of the present invention is to eliminate such difficulties in welding masks using liquid crystal glass.

The present invention will be explained according to the embodiment shown in FIG.

The symbols shown in FIG. 2 that are the same as those shown in FIG. 1 indicate the same components.

The present invention is one aspect of the bridge circuit.

It consists of connecting a series circuit of an auxiliary light receiving element 3 and a resistor R3 in parallel to a series circuit of a variable resistor VR and a resistor R2.

As the auxiliary light-receiving element 3, for example, a cadmium sulfide element having a characteristic that its resistance value decreases depending on the amount of light received is used.

In this case, the main light-receiving element 1 is placed in a place where it has to receive welding light and, for example, sunlight at the same time, as in the conventional case, but the auxiliary light-receiving element 3 receives only sunlight. Alternatively, the direction of the light-receiving surface may be changed to the light-receiving direction of the main light-receiving element 1 so that only sunlight is received.

With such a configuration, when the auxiliary light receiving element 3 receives natural light such as sunlight, its resistance value decreases in accordance with the amount of light received.

On the other hand, the main light receiving element 1 receives welding light and natural light at the same time, but a voltage equal to the difference between the amount of light received by the main light receiving element 1 and the amount of light received by the auxiliary light receiving element 3, that is, equivalent to the amount of received welding light. The on/off operation of the switching transistor 2 can be avoided depending on the voltage applied.

This is because the switching operating point of the auxiliary light-receiving element is changed by receiving sunlight, so unlike the conventional method, it is possible to ensure a switching operation that is not affected by natural light.

In the above embodiment, an example was described in which the series circuit of the auxiliary light receiving element 3 and the resistor R3 was connected in parallel to the series circuit of the variable resistor VR and the resistor R2, but the series circuit of the auxiliary light receiving element 3 and the resistor R3 was The same purpose can be achieved by connecting vR and R2 in series.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining the operation of a conventional light receiving device for a welding mask equipped with liquid crystal glass, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 1... Main light receiving element, 2... Switching transistor, 3... Auxiliary light receiving element.

Claims (1)

[Claims] 1 Welding light is received by the main light receiving element, and when the intensity of the welding light exceeds a predetermined amount, a switching element is activated to cut off the power to the liquid crystal glass to protect the eyes of the worker from the welding light. When sunlight, etc. other than welding light enters the main light-receiving element in a product, an auxiliary light-receiving element arranged to receive the sunlight, etc. is provided, and the component of the light incident on the main light-receiving element and the auxiliary light-receiving element are A light control method for a welding mask provided with a liquid crystal glass in which a switching element is operated depending on a component different from an incident component of the element.