JP3218114B2 - Reading sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for optically receiving and detecting a binarized signal formed on a surface as unevenness, and more particularly, for example, a bar-shaped sensor on the surface of a door key. The present invention relates to an unevenness detection reading sensor for optically receiving and determining an unevenness code.

[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 reading sensor capable of determining and reading OFF.

[0005]

The above object is achieved by the present invention. That is, the reading sensor of the present invention
A transmission signal generation circuit that outputs a transmission pulse signal, a transmission circuit that irradiates and scans an object with light by the transmission pulse signal, and receives, as an optical signal, a change in the amount of reflected light received due to a change in the object as an electrical signal. Circuit that converts the data to an output signal
And a comparison circuit that compares an output from the reception circuit with a predetermined threshold value and outputs a binary signal composed of OFF and ON, and outputs a binary signal output from the comparison circuit with a transmission pulse signal. When the same type of binarized signal is detected continuously for a predetermined number of times , O is detected in accordance with the same type of binarized signal.
A pulse number check circuit that outputs a FF or ON signal
It is characterized by comprising. In addition, the reading section
In a preferred embodiment, the sensor is provided for each reset signal input.
To the initial value, and then the maximum output value from the receiving circuit
A peak hold circuit that stores and outputs the highest output value,
Based on the maximum output value from the peak hold circuit,
The ON / OFF determination level is calculated from the split ratio, and this level is calculated.
ON / OFF determination level that outputs a threshold value signal
Output from the pulse generation circuit and pulse number confirmation circuit is OFF
When the signal changes from ON to ON, the peak hold
A reset signal generation circuit for sending a reset signal to the circuit;
And the comparison circuit is an ON / OFF determination level generation circuit
The threshold signal output from the CPU is used as a threshold.

[0006]

The present invention having the above configuration operates and operates as follows. A transmission pulse signal is output from the transmission signal generation circuit. The transmission circuit emits light using the transmission pulse signal.
For example , an object having an uneven surface is irradiated and scanned. 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, and the peak hold circuit stores the highest output value from the receiving circuit since the reset signal is input,
The maximum output value is output to the ON / OFF determination level generation 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 a comparison circuit as a threshold signal.

[0007] The comparison circuit compares the output from the reception circuit with the threshold value and outputs a binary signal consisting of OFF and ON. Pulse number check circuit, when the output binary signal of the comparator circuit detects in synchronization with a transmission pulse signal, detects the binary signal of the same type in succession a predetermined number of times, the 2
Concave (OFF) or convex (ON) signal according to the digitized signal
To output. This output is a binarized signal corresponding to the uneven code on the surface.

On the other hand, the reset signal generation circuit sends a reset signal to the peak hold circuit when the output from the pulse number check circuit changes from a concave signal to a convex signal. 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.

[0009]

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 includes an oscillation circuit that outputs a pulse signal, a transmission signal generation circuit that outputs a transmission pulse signal based on the pulse signal, and a device that transmits light from a light emitting element by using the transmission pulse signal. The light is transmitted to the reflection-type sensor head via the optical fiber for light, from which the unevenness is detected (for example
A transmission circuit that irradiates and scans the uneven surface of the key), and receives a change in the amount of received light of reflected light due to the unevenness as an optical signal,
A receiving circuit that converts and outputs an electric signal, a peak hold circuit that stores the highest output value from the receiving circuit after returning to an initial value each time a reset signal is input, and a peak hold circuit that outputs the highest output value ON / OFF judgment level is calculated by a predetermined division ratio based on the maximum output value from the microcomputer, and this level is output as a threshold signal.
A decision level generation circuit, a comparison circuit that compares an output from the reception circuit with a threshold signal and outputs a binarized signal composed of OFF and ON, and outputs a binarized signal of the comparison circuit;
Number of pulses to output a concave (OFF) or convex (ON) signal corresponding to the binarized signal when the same type of binarized signal is detected three times in a row by detecting in synchronization with the transmission pulse signal. The reset circuit includes a check circuit and a reset signal generation circuit that sends a reset signal to the peak hold circuit when the output from the pulse number check circuit changes from a concave signal to a convex signal.

Next, the operation of the circuit according to this embodiment will be described with reference to FIG. Based on the pulse signal generated by the oscillation circuit, a transmission signal generation circuit outputs a transmission pulse signal of Duty1: n as shown in FIG.
The transmission circuit uses the transmission pulse signal to radiate outgoing light to the uneven surface using the light transmitting optical fiber and the sensor head, and receives the reflected light due to the change in the unevenness by the sensor head and the light receiving optical fiber. . 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 of the receiving circuit is, as shown by the solid curve in FIG.
While corresponding to the transmission pulse signal, the surface level increases when the surface state is convex, and decreases when the surface state is concave.

The output from the receiving circuit is transmitted to a peak hold circuit, which stores the maximum output value from the receiving circuit and outputs the maximum output value to the ON / OFF determination level generation circuit. As shown by the dotted 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 based on the maximum output value from the peak hold circuit, and outputs this level to a comparison circuit as a threshold signal. . ON / O
The output of the FF determination level generation circuit is shown by the one-dot chain line curve in FIG. The comparison circuit compares the output from the reception circuit with the threshold value of the threshold signal, and outputs a binary signal consisting of OFF and ON as shown in the output of the comparison circuit in FIG.

The number-of-pulses confirming circuit outputs the output of the comparing circuit.
The digitized signal was detected in synchronization with the transmission pulse signal, 3 times continuously when detecting a binary signal of the same type, the binary
Signals concave corresponding to the signal (OFF) or convex (ON) <br/> outputs. In this embodiment, since it is set to three times,
When the output of the comparison circuit has been in the convex state three times, the output is changed from the “concave” state to the “convex” state. To maintain. The output becomes 'convex' when it becomes concave three consecutive times.
The state is changed from the state to the “concave” state, and the “concave” state is maintained until the output of the comparison circuit continues the convex state three times. As a result, the adverse effects of spike noise and disturbance light can be removed, and extremely stable detection can be performed. The output of this pulse number confirmation circuit is a binary signal shaped on the surface as a concavo-convex code.

On the other hand, the reset signal generation circuit sends a reset signal to the peak hold circuit when the output from the pulse number confirmation circuit changes from a concave signal to a convex signal. 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.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, by setting the hold time of the peak hold circuit to an appropriate length,
Holds enough time for the key insertion / removal speed, and if the key is released for more than a certain period of time, the hold is released and the next time the key is inserted, a new value is applied regardless of the previous hold value. , The dirt on the key is not affected by the dirt on the end face of the sensor and the decrease in the amount of light due to the deterioration of the light emitting element, so that stable detection can be always performed.

[0017]

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 reading sensor according to an embodiment of the present invention.

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

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

[Explanation of symbols]

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

Continuation of front page (56) References JP-A-57-6304 (JP, A) JP-A-60-231110 (JP, A) JP-A-61-198085 (JP, A) JP-A-54-84789 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 102 G01D 5/26-5/38

Claims (2)

(57) [Claims] 1. A transmission signal generating circuit for outputting a transmission pulse signal, a transmission circuit for irradiating and scanning light on an object by the transmission pulse signal, and an optical signal for detecting a change in a received light amount of reflected light due to a change in the object. Received as, a receiving circuit that converts to an electrical signal and outputs , comparing the output from the receiving circuit with a predetermined threshold,
A comparison circuit that outputs a binary signal consisting of OFF and ON, and synchronizes the output binary signal of the comparison circuit with a transmission pulse signal
Is not detected by, upon detecting a binary signal of the same type in succession a predetermined number of times, OFF also <br/> in response to the binary signal of the same type and number of pulses verify circuit for outputting a signal of ON , A reading sensor. 2. The method returns to an initial value every time a reset signal is input.
Thereafter, the highest output value from the receiving circuit is stored and the highest output value is stored.
A peak hold circuit that outputs an output value, Based on the maximum output value from the peak hold circuit,
The ON / OFF determination level is calculated based on the division ratio, and the level is determined.
ON / OFF determination level that outputs a threshold value signal
File generation circuit, The output from the pulse number confirmation circuit turns ON from the OFF signal
Reset to the peak hold circuit when the signal changes to
A reset signal generation circuit for transmitting a signal;
The road is output from the ON / OFF judgment level generation circuit.
2. The reading method according to claim 1, wherein a threshold signal is used as a threshold value.
Sensor.