JPH0792400B2 - Color optical sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is irradiated with light from a light source relative to the object to be detected, a color light Gakuse capacitors which is adapted to measure the light intensity for each of the three primary colors.

[0002]

2. Description of the Related Art In an inspection device and various image input devices on a printed matter production line, it is necessary to divide the color of an object to be detected such as a printed matter or an original document into three primary colors for measurement. Was used. A conventional color optical line sensor generally decomposes reflected light from an object to be detected into a desired color through a filter, receives this by a sensor such as a phototransistor, a photodiode, or a CCD, and outputs a signal according to the amount of received light. Was output. However, in the case of separating into a desired color using a color filter, filters and sensors are required for the number of colors to be separated, which makes the apparatus expensive and large. Therefore, conventionally, there has been proposed a color optical line sensor provided with a light source corresponding to each color to be detected and switching a driving light source to measure a reflected light amount corresponding to each color.

[0003]

However, in the conventional color optical line sensor in which the color of the light source for irradiating the object to be detected with light is switched, the light source cannot be switched at high speed in practical use, and particularly in real time. In the field where measurement is required, it is necessary to switch the light source in microsecond units. For green and red, it is feasible by using light emitting diodes, but for blue, light emitting diodes are technically incomplete. However, since it is expensive, has low luminance, and has a short life, there is a problem that a practical device cannot be realized. A method using a blue laser and a method switching the blue light source with a liquid crystal shutter are also conceivable. However, the use of a laser causes an increase in cost and size of the device, and a method using a liquid crystal shutter is sufficient. There was a problem that high speed could not be obtained.

It is an object of the present invention to use a continuous light source for continuously irradiating an object to be detected with respect to a color such as a blue light source which is not suitable for high speed switching, and a relatively high speed such as red or green. For colors that can be easily switched, a switching light source that turns on / off the light at a predetermined timing is used, and the output signal of the light receiving sensor is taken out at a predetermined timing, and the component of the continuous light source is output from the output signal of the light receiving sensor by subsequent electrical processing. by decomposing the desired color to remove is to provide an inexpensive and compact color light Gakuse capacitors meet the real-time measurement.

[0005]

Means for Solving the Problems] color light Gakuse <br/> capacitors of the present invention as shown in FIG. 1, Oyo first color with respect to the object to be detected
And the light of the second color are turned on at different predetermined timings.
First and second switching light sources for turning on / off and irradiating
And continuously irradiate the detected object with the light of the third color.
The continuous light source, the single light receiving means for receiving the reflected light of the light from the light source in the object to be detected and outputting the signal according to the received light amount, and the first and second switching light sources are both turned off.
Read the output of the light receiving means when there is
The continuous light intensity reading means and the first switching light source are
The amount of continuous light from the output of the light receiving means when it is on
The first is obtained by subtracting the received light amount of the third color read by the reading means.
Determine the amount of received light of the color, the second switching light source is turned on
The continuous light quantity reading means from the output of the light receiving means when
Received the second color by subtracting the amount of received light of the third color read by
It is characterized in that an arithmetic means for obtaining the quantity is provided.

[0006]

[Action] In this invention, the reflected light from the third color of the detected object of light emitted from the continuous light source during the switching light source is turned off by receiving the receiving means, the third color
It outputs a signal according to the amount of reflected light. A signal corresponding to the reflected light amount of the continuous light source is read by the continuous light amount reading means. On the other hand, when the first or second switching light source is on, the light receiving means is the continuous light source and the first light source .
Alternatively, the reflected light of the light emitted from both the second switching light source is received, and the light of the third color and the third light from the continuous light source are received .
It outputs a signal according to the amount of reflected light of both the first color and the second color by the first and second switching light sources. The output signal of the light receiving means while the switching light source is on is input to the calculating means together with the output signal of the light receiving means read by the continuous light amount reading means while the switching light source is on, and the switching light source is The output signal while the switching light source is off is subtracted from the output signal while it is on.
As a result, the calculation means outputs a signal corresponding to the amount of light of the first color or the second color emitted from the switching light source, which is reflected by the object to be detected.

Therefore, by the output of the continuous light quantity reading means
The amount of reflected light of the light of the third color can be measured, and the amount of reflected light of the light of the first color and the light of the second color can be measured by the output signal of the calculation means.

[0008]

2 is a sectional view showing the structure of a color optical line sensor according to an embodiment of the present invention. The color optical line sensor 1 is provided with a blue light source 2, a red light source 3, and a green light source 4, and the red, blue, and
Light of the three primary colors of additive color mixture of green and green is emitted. The reflected light on the detected object 21 of the light emitted from these light sources is detected by the CCD line sensor 5 via the lens 6. The blue light source 2 is a discharge tube light source such as a fluorescent lamp, and both the red light source 3 and the green light source 4 are light emitting diodes. A blue light source configured by a discharge tube such as a fluorescent lamp is a continuous light source that continuously emits light to the object to be detected 21, and a blue light emitting diode suitable for switching lighting still has sufficient brightness and life at present. In view of the lack of a light source, the blue light source is a continuous light source.
On the other hand, for the red light source and the green light source, light emitting diodes suitable for switching lighting and having sufficient brightness and life are used.

FIG. 3 is a block diagram showing the configuration of the color optical line sensor. Each of the blue light source 2, the red light source 3, and the green light source 4 is driven by the lighting circuits 15-17. Of these, the blue light source 2 is constantly turned on by the lighting circuit 15 and continuously irradiates the detected object 21 with blue light. Predetermined timing pulse signals are input from the timing generation circuit 7 to the lighting circuits 16 and 17 for driving the red light source 3 and the green light source 4, and the lighting circuits 16 and 17 are only in the meantime.
Lights up. The output of the CCD line sensor 5 is input to the correction look-up table 9 via the A / D converter 8. The output of the CCD line sensor 5 is output via an amplifier or the like (not shown), but the relationship between this output and the amount of light received by the CCD line sensor 5 is not always constant for red, blue, and green, and is not linear. . Therefore, the correction look-up table 9 stores data for correction so that the relationship between the output of the A / D converter 8 and the amount of light received by the CCD line sensor 5 for each color is constant and linear. Therefore, the output of the correction look-up table 9 has a value obtained by this correction.

The output of the correction look-up table 9 is stored in the memories 10-12. A signal is input to the memories 10 to 12 from the timing generation circuit 7 at a predetermined timing, and the memories 10 to 12 capture the output of the correction lookup table 9 when the signal is input. The data stored in the memory 10 is directly extracted as an output corresponding to the amount of received blue light, and is also input to each of the subtractors 13 and 14. The data stored in the memories 11 and 12 are input to the subtracters 13 and 14, respectively. The subtracters 13 and 14 subtract the data input from the memory 10 from the data input from the memories 11 and 12, and output the subtracted data as the measurement results of the red light reception amount and the green light reception amount, respectively.

FIG. 4 is a timing chart showing signals of respective parts of the color optical line sensor. Lighting circuit 1
Reference numeral 5 continuously drives the blue light source 2 after power is supplied to the optical line sensor 1. On the other hand, the lighting circuits 16 and 17 respectively drive the red light source 3 and the green light source 4 in the cycle T during the time t1. The driving timing of the green light source 4 is longer than the driving timing of the red light source 3 by time t.
It is delayed by 2 (t2> t1). Therefore, neither the red light source 3 nor the green light source 4 is driven during the time (t2-t1). The red light source 3 and the green light source 4 are driven at their own timing.
Therefore, when the blue light source 2 and the red light source 3 are turned on,
It is divided into a state in which only the blue light source 2 is turned on and a state in which the blue light source 2 and the green light source 4 are turned on. The above lighting control of the red light source 3 and the green light source 4 is controlled by the timing pulse input from the timing generation circuit 7 to the lighting circuits 16 and 17.

On the other hand, the memory 11 has a driving timing of the red light source 3, that is, the blue light source 2 and the red light source 3.
While the are lit at the same time, the output of the correction look-up table 9 is read. The memory 10 also reads the output of the correction look-up table 9 between the driving timing of the red light source 3 and the driving timing of the green light source 4, that is, while only the blue light source 2 is on. Further, the memory 12 reads the output of the correction look-up table 9 while driving the green light source 4, that is, while the blue light source 2 and the green light source 4 are simultaneously turned on. The reading timing of the memories 10 to 12 is also controlled by the timing pulse output from the timing generating circuit 7.

By outputting the output of the correction look-up table 9 read by the memories 10 to 12 from the memories 10 to 12 at a predetermined timing as described above, the subtracter 13 stores the data stored in the memory 11 into the memory. The received data amount of the red light is obtained by subtracting the stored data of 10 and the received light amount of the blue light is obtained by directly outputting the stored data of the memory 10, and the subtractor 14 obtains the received light amount of the blue light from the stored data of the memory 12 of the memory 10. By subtracting the stored data, it is possible to obtain the received light amount of green light. The reading of the stored data in the memories 10 to 12 and the subtraction processing in the subtractors 13 and 14 can be performed after the driving of the green light source 4 is completed and before the driving of the red light source 3 is started next. For this reason, the cycle T is set with the minimum value of the time (t1 + t2) plus the time required for the storage data calculation processing of the memories 10 to 12.

As described above, according to this embodiment, the blue light source 2 is continuously turned on, and the red light source 3 and the green light source 4 are switching-driven at a predetermined timing.
When the red light source 3 is turned on, the received light amounts of the blue light and the red light are read, and then the received light amount of the blue light is read while the red light source 3 and the green light source 4 are not turned on, and the green light source 4 is turned on. The amount of received light of blue light and green light is read during the period.

Then, the received light amount of red light is detected by subtracting the received light amount of only blue light from the received light amount of blue light and red light, and the received light amount of only blue light is detected from the received light amount of green light and blue light. Subtract and detect the amount of received green light. This makes it possible to detect the amount of received light for each of red, blue and green.

By setting the times t1 and t2 when the detection object is moving to a sufficiently small value, the operation of the detection object can be approximately ignored, and the light amounts of the three colors at the same time can be ignored. Can be detected.

Further, although the subtracters 13 and 14 are used as the calculating means in this embodiment, the components of the blue light source may be removed by an equivalent process in the subsequent software.

[0018]

According to the present invention, a light source for one color among the light sources for reflected light of a plurality of colors to be read is continuously turned on, and a light source for another color is switched and turned on, thereby switching like a blue light source. Even when a light source color that is difficult to turn on is included, there is an advantage that the reflected light amount of each color can be accurately detected without causing an increase in size of the device and an increase in cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a color optical line sensor that is an embodiment of the present invention.

FIG. 3 is a block diagram of the same color optical line sensor.

FIG. 4 is a timing chart of signals in a main part of the color optical line sensor.

[Explanation of symbols]

 1-Color optical line sensor 2-Blue light source (continuous light source) 3-Red light source (switching light source) 4-Green light source (switching light source) 5-CCD line sensor (light receiving means) 10-Memory (continuous light amount reading means) 13 , 14-subtractor (calculation means)

Claims (1)

[Claims] 1. A single light receiving means for receiving the reflected light of light from a light source on an object to be detected and outputting a signal according to the amount of received light, and a single color of a first color and a second color for the object to be detected. Light each
Irradiates by turning on / off at different predetermined timings
For the first and second switching light sources and the object to be detected,
A continuous light source that continuously emits light of three colors;
Light receiving hand when both switching light sources are off
When the continuous light amount reading means for reading the output of the stage as the amount of received light of the third color and the first switching light source are on
The continuous light intensity reading means reads from the output of the light receiving means of
Subtract the amount of received light of the third color to obtain the amount of received light of the first color
To receive light when the second switching light source is on
The continuous light quantity reading means reads from the output of the means.
Color light Gakuse capacitors for 3-color calculating means for obtaining the amount of light received by the second color by subtracting the amount of light received, that was provided with the features.