JP3204787B2 - Detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for optically receiving and binarizing and detecting irregularities and the like on the surface. More specifically, for example, a bar-like irregular code on the surface of a door key is optically detected. And an unevenness detecting circuit for receiving and judging this.

[0002]

2. Description of the Related Art There is known a technique in which a bar-shaped concavo-convex code is formed on the surface of a door key of an apartment or the like, and the key is inserted into a keyhole of a door to read the code and open and close the door key. Here, light is irradiated from the reflection type optical sensor to the uneven surface, and the change in the amount of light reflected light received due to the change in the unevenness is received as an optical signal. As shown in the light amount fluctuation curve A in FIG. By adjusting the sensitivity so that the ON / OFF determination level becomes the threshold level, the key code can be read accurately.

[0003]

However, in the conventional detection circuit, the amount of received light is reduced due to the adhesion of dirt on the sensor head and the deterioration of the transmission power of the photoelectric switch.
As shown in the light-receiving amount variation curve B in FIG. 3, a portion that should be ON is determined to be OFF and cannot be accurately read. In addition, the distance from the sensor head when the key is inserted changes, and the surface state of the key changes over time, thereby deviating from the ON / OFF determination level, which causes a problem that accurate reading cannot be performed.

The present invention has been made on the basis of the above-mentioned background, and has as its object to prevent contamination of the sensor head, deterioration of the transmission power of the photoelectric switch, etc. Accurately turns ON / OFF even when the distance to the sensor head changes or the key surface condition changes over time.
An object of the present invention is to provide an unevenness detection circuit which can determine and read OFF.

[0005]

The above object is achieved by the present invention. That is, the detection circuit of the present invention
A receiving circuit that receives a change in the amount of light as an optical signal, converts the signal into an electric signal, and outputs the signal, and returns the initial value each time a reset signal is input, and then stores the highest output value from the receiving circuit and outputs the highest output value A peak hold circuit and a predetermined division ratio based on the highest output value from the peak hold circuit provide O
An ON / OFF determination level generation circuit that calculates an N / OFF determination level and outputs this level as a reference signal, compares the output from the receiving circuit with the reference signal.
A comparison circuit that outputs a binary signal composed of OFF and ON, and a binary signal of the comparison circuit that is input to change from OFF to O
And a reset signal generation circuit for detecting a change to N and sending a reset signal to the peak hold circuit.

[0006]

The present invention having the above configuration operates and operates as follows. For example, by using a reflection type optical fiber sensor, the outgoing light is applied to the uneven surface, and the reflected light due to the change in the unevenness is received. The receiving circuit converts the light signal of the change in the amount of received light into an electric signal and outputs the electric signal. The output from the receiving circuit is transmitted to the peak hold circuit, the peak hold circuit stores the highest output value from the receiving circuit from the time the input of the reset signal, and outputs the highest output value in ON / OFF determination level generating circuit . The ON / OFF determination level generation circuit calculates an ON / OFF determination level by a predetermined division ratio based on the highest output value from the peak hold circuit, and outputs this level to the comparison circuit as a reference signal.

[0007] The comparison circuit compares the output from the reception circuit with the reference signal, and turns off the OFF and the OFF corresponding to the concave and convex.
And an ON signal. This binarized signal becomes a binarized signal corresponding to surface irregularities . On the other hand,
The comparison circuit sends the binarized signal of the comparison circuit to the reset signal generation circuit. The reset signal generation circuit detects a change from OFF to ON from this signal and sends a reset signal to the peak hold circuit. The reset signal clears the maximum output value and starts storing the maximum output value from the receiving circuit again. As described above, the maximum output value is updated each time the unevenness is detected once.

[0008]

EXAMPLES The present invention will be specifically described with reference to examples. FIG. 1 is a block diagram of an unevenness detecting circuit according to an embodiment of the present invention. The circuit according to this aspect transmits light from a light emitting element controlled by a transmission circuit to a reflection type sensor head via a light transmitting optical fiber, and irradiates the uneven surface of an unevenness detection target (for example, a key) therefrom with light. A receiving circuit that receives a change in the amount of reflected light received by the unevenness as an optical signal through a light receiving optical fiber, converts the received signal into an electric signal with a light receiving element, and outputs the electric signal. And a peak hold circuit for storing the highest output value from the controller and outputting the highest output value. An ON / OFF determination level is calculated by a predetermined division ratio based on the highest output value from the peak hold circuit, and this level is used as a reference signal. O to output
An N / OFF determination level generation circuit, a comparison circuit that compares an output from the reception circuit with a reference signal, and outputs a binary signal composed of OFF and ON corresponding to the concave and convex, and A reset signal generating circuit for receiving a binary signal, detecting a change from OFF to ON, and sending a reset signal to the peak hold circuit.

Next, the operation of the circuit of this embodiment will be described with reference to FIG. The reflected light is irradiated onto the uneven surface using the reflection type optical fiber sensor, and the reflected light due to the change in the unevenness is received. The receiving circuit converts the light signal of the change in the amount of received light into an electric signal and outputs the electric signal. As shown by the thick solid curve in FIG. 2, the output of the receiving circuit increases when the surface state is convex and decreases when the surface state is concave. The output from the receiving circuit is transmitted to the peak hold circuit. The peak hold circuit stores the maximum output value from the receiving circuit when the reset signal is input, and outputs the maximum output value to the ON / OFF determination level generation circuit. . As shown by the curve in FIG. 2, the output of the peak hold circuit follows the rise of the output of the receiving circuit and maintains the value even when the output of the receiving circuit falls.

The ON / OFF determination level generation circuit calculates an ON / OFF determination level by a predetermined division ratio (for example, 50%) based on the maximum output value from the peak hold circuit, and compares this level as a reference signal. Output to the circuit. The output of the ON / OFF determination level generation circuit is shown by a thin solid line curve in FIG. The comparison circuit compares the output from the reception circuit with the reference signal and outputs a binary signal consisting of OFF and ON corresponding to the concave and convex. As shown in the output of the comparison circuit in FIG. 2, this binarized signal becomes a binarized signal shaped as irregularities on the surface.

On the other hand, the comparison circuit sends the binarized signal of the comparison circuit to the reset signal generation circuit, and the reset signal generation circuit changes the signal from OFF to ON as shown in the reset signal output of FIG. A change is detected and a reset signal is sent to the peak hold circuit. The reset signal clears the maximum output value and starts storing the maximum output value from the receiving circuit again. As described above, the maximum output value is updated each time the unevenness is detected once.

[0012]

As demonstrated in the above embodiment, according to the present invention, even if the sensor head becomes contaminated, the transmission power of the photoelectric switch deteriorates, or the distance from the sensor head at the time of key insertion changes. Also, it is possible to accurately determine ON / OFF and read the information even when the key surface condition changes over time.

[Brief description of the drawings]

FIG. 1 is a block diagram of an unevenness detection circuit according to one embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the unevenness detecting circuit according to one embodiment of the present invention;

FIG. 3 is a time chart for explaining the operation of the conventional unevenness detection circuit.

[Explanation of symbols]

 A: Normal light reception amount fluctuation curve b: Light reception amount fluctuation curve when deteriorated

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-108703 (JP, A) JP-A-57-6304 (JP, A) JP-A-3-242540 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) G01B 11/00-11/30 102 G01D 5/00-5/62

Claims (1)

(57) [Claims] 1. A receiving circuit for receiving a change in the amount of received light as an optical signal, converting the received signal into an electric signal and outputting the signal, and resetting an initial value each time a reset signal is input, and thereafter storing a maximum output value from the receiving circuit. A peak hold circuit that outputs the highest output value, and an ON / OFF determination level that calculates an ON / OFF determination level by a predetermined division ratio based on the highest output value from the peak hold circuit and outputs the level as a reference signal.
A comparison circuit that compares a decision level generation circuit, an output from a reception circuit with the reference signal, and outputs a binarized signal consisting of OFF and ON, and inputs a binarized signal of the comparison circuit to OFF A reset signal generation circuit for detecting a change from ON to ON and sending a reset signal to a peak hold circuit .