JPH03189541A - Method for checking action of transmission type photosensor - Google Patents

Abstract

PURPOSE:To rapidly check the action of a photosensor in a short waiting time previous to regular detection by interposing a liquid crystal board at a middle position between a light receiving part and a light emitting part which is in an on-state at the time of checking, changing the light transmissivity of the liquid crystal board and measuring the output of the photosensor in accordance with the change. CONSTITUTION:The light emitting part 1 is turned on/off by a driving circuit 4 and the light transmissivity of the liquid crystal board 3 is changed by a control circuit 6. An output signal from the light receiving part 2 is outputted to the outside through an output circuit 5. At the time of checking, the action of the light emitting part 1 already being in the on-state is stable and the light transmissivity of the liquid crystal board 3 is changed with almost no waiting time, so that the output from the light receiving part 2 through the output circuit 5 in accordance with the change of the light transmissivity of the liquid crystal board 3, that means, the output from the photosensor is directly stabilized. Whether the action of the photosensor is normal or abnormal is confirmed without waiting time. Since the light emitting part need not be turned on/off at the time of checking, the waiting time required for stabilizing the output is unnecessary and the regular detection is started earlier by as much as the unnecessary waiting time.

Description

[Detailed description of the invention] [Industrial application field]

This invention provides normal operation of an optical sensor that includes a light emitting part and a light receiving part and detects the displacement, thickness, composition, concentration, etc. of an object according to the degree of light transmission by the object located between the two. The present invention relates to a method for checking the operation of a transmission type optical sensor to check for abnormalities.

[Conventional technology]

A first method for checking the operation of a conventional transmission type optical sensor is to turn on and off a light emitting section, for example, a light emitting diode, and measure the corresponding output of the light receiving section, that is, the output of the optical sensor. Second, there is a method in which a light shielding plate is mechanically moved between a light emitting part and a light receiving part, and the output of the light receiving part is measured accordingly. By the way, when this optical sensor is used in a device that requires high dryness, such as a bill validating device, the operation check of the optical sensor is always performed before starting the actual bill validating, to check whether the optical sensor is operating properly or not. Abnormality is confirmed. Note that the optical sensor in the bill validating device changes the output of the light receiving section based on the light transmittance of the pattern at each predetermined location of the bill, and the bill denomination is discriminated based on the pattern of this output change.

[Problem to be solved by the invention]

In the first method as explained above, when a light emitting unit, for example a light emitting diode, is turned on, the current flowing through it is:
Since it takes time for the operation of the drive circuit to stabilize, the operation is unstable during that time. Therefore, the time required for this stabilization becomes the preparation or waiting time for the check, prolonging the total time required for the check. Note that this waiting time is usually about 10 seconds. Furthermore, since the second method includes a movable part called a moving light shielding plate, the structure is complicated, which impedes reliability and space saving. An object of the present invention is to provide a method for checking the operation of a transmission type optical sensor, which can be performed quickly with a short waiting time prior to actual detection, and which solves the problems of the conventional techniques.

[Means to solve the problem]

In order to solve this problem, a method for checking the operation of a transmissive optical sensor according to the present invention includes a light emitting section and a light receiving section, and a light transmission method according to the degree of light transmission by an object located between the two. In the method of checking whether the operation of an optical sensor that detects a predetermined amount is normal or abnormal, a liquid crystal plate is interposed at an intermediate position between the light receiving part and the light emitting part in an on state at the time of checking; and measuring the output of the optical sensor according to the change in the light transmittance.

[Effect]

At the time of check, the operation of the light emitting part that is already on is in a stable state, and the change in the light transmittance of the liquid crystal board occurs with almost no waiting time, so the light receiving part output according to the change in the light transmittance of the liquid crystal board. , that is, the optical sensor output is immediately stabilized.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS A bill validator which is an application example of the method for checking the operation of a transmissive optical sensor according to the present invention will be described with reference to FIG. In FIG. 1, 1 is a light emitting section, and 2 is a light receiving section, and the light emitting section 1 and the light receiving section 2 constitute a transmission type optical sensor. Reference numeral 3 denotes a liquid crystal plate, which is arranged between the light emitting section 1 and the light receiving section 2. The light emitting section 1 is turned on and off by a drive circuit 4, and the light transmittance of the liquid crystal plate 3 is changed by a control circuit 6. Also,
The output signal of the light receiving section 2 is outputted to the outside via the output circuit 5. At the time of checking, the operation of the light emitting unit 1, which is already in the ON state, is in a stable state, and the change in the light transmittance of the liquid crystal plate 3 occurs with almost no waiting time. Output from the light receiving section 2 via the output circuit 5,
In other words, the optical sensor output is immediately stabilized. Therefore, you can check whether the optical sensor is operating normally or abnormally without waiting.
It will be possible soon. By the way, FIG. 2 is a block diagram of the main parts of a bill validating device using a transmission type optical sensor after applying the method of the present invention. In FIG. 2, the liquid crystal panel 3 used during the check is removed, and the banknotes 9 are conveyed in the direction of the arrow in the direction of the arrow so as to cross the axis connecting the light emitting section 1 and the light receiving section 2 in a perpendicular direction. During the conveyance process of the banknote 9, the output of the light receiving section 2 via the output circuit 5 changes depending on the light transmittance of the pattern at a predetermined location. Based on this output pattern, the denomination of the banknote 9 is determined by a determination circuit (not shown).

【Effect of the invention】

As explained above, in this invention, at the time of checking, the operation of the light emitting part that is already in the on state is in a stable state, and the change in the light transmittance of the liquid crystal plate occurs with almost no waiting time. The output of the light receiving section, that is, the output of the optical sensor, corresponding to the change in the light transmittance is immediately stabilized. Therefore, the present invention has the following advantages over the conventional technology: (1) Since there is no need to turn on and off the light emitting section during checking, the time required for stabilizing the output is reduced. This eliminates the need for waiting time, speeds up the process, and allows the original detection to begin earlier. (2) Since it does not include any moving parts, the structure is simpler, improving reliability, saving space, and reducing costs. can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an example of application of the method of the present invention, and FIG. 2 is a block diagram of main parts of a detection device using a transmission type optical sensor after the method of the present invention is applied. Symbol explanation: Light emitting part, 2: Light receiving part, 3: Liquid crystal plate, 4: Drive circuit, 5: Output circuit, 6: Control circuit, 2 diagrams on the back

Claims (1)

[Claims] 1) A method for checking whether the operation of an optical sensor is normal or abnormal, and which includes a light emitting part and a light receiving part and detects a predetermined amount of light from an object located between the two according to the degree of light transmission by the object, A liquid crystal plate is interposed at an intermediate position between the light receiving part and the light emitting part in an on state at the time of checking; the light transmittance of this liquid crystal plate is changed; the output of the optical sensor is measured in accordance with this change in light transmittance. A method for checking the operation of a transmission type optical sensor, characterized in that: