JPH05191565A - Picture reader - Google Patents

Abstract

PURPOSE:To obtain a picture reader which can read a picture at a high speed by suppressing the increase of a cost, without damaging a reliability. CONSTITUTION:A light source part 4 scans an original 2, and a reflected light from the original 2 is made incident through reflecting mirrors 5, 6, and 7 to an image forming lens 8, and condensed. The condensed reflected light is made incident to a half mirror 11, and a light path is divided into two directions. Then, CCD line sensors 9a and 9b are arranged at the image forming point of the reflected light whose light path is divided. The CCD line sensors 9a, 9b reads the picture by each main scanning line in a different timing. A control part 20a parallel-processes the signals of the CCD line sensors 9a, 9b, and converts the signals into picture signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for reading an image by a photoelectric conversion element, and more particularly to an image reading device capable of reading an image at high speed.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing the structure of a conventional image reading apparatus.

Document 2 placed on contact glass 1
Are pressed by the document cover 3. The light source unit 4 for irradiating the original 2 on the contact glass 1 and the reflecting mirror 5 move in the direction of arrow A, and the light source unit 4 irradiates the light from the end to the end of the original 2, The reflected light is reflected by the reflection mirror 5 to the reflection mirror 6. The reflected light of the original 2 via the reflecting mirrors 6 and 7 enters the image forming lens 8 and is condensed by the image forming lens 8. At the image forming point of the image forming lens 8, a charge coupled device which is a photoelectric conversion device line sensor.
A (CCD) line sensor 9 is arranged, and in order to read an image formed on the original 2 for each main scanning line at a constant interval in the sub-scanning direction, photoelectrically converts the reflected light that has been imaged, Output as an electric signal. CCD line sensor 9
Is mounted on the printed circuit board 10.
About 5000 pixels of m CCD are arranged on a straight line in the main scanning direction. The electric signal obtained by photoelectrically converting the reflected light is output to the control unit 20 via the printed board 10, processed by the control unit 20, and output to the outside via the interface unit 12 as an image signal.

[0004]

In the above-mentioned image reading apparatus, in order to read an image, the light source unit 4 irradiates the original 2 with light at a constant speed in the sub-scanning line direction, and the reflected light is emitted. This is achieved by detecting with a CCD line sensor 9 in which CCDs are arranged linearly in the main scanning line direction at a constant cycle.

Here, in order to increase the image reading speed per document, it is necessary to increase the moving speed of the light source unit 4 and shorten the cycle for detecting the image of the CCD line sensor 9. However, by shortening the detection cycle, the CCD
The time allotted to the processing of the signal for each main scanning line of the line sensor also becomes short. Therefore, the signal processing speed in the control unit 20 must be increased. However, the circuit for performing image processing in the control unit 20 is a relatively large-scale electronic circuit, and increasing the speed of this image processing circuit over the entire area poses problems in terms of cost and circuit reliability. Many.

An object of the present invention is to provide an image reading apparatus capable of reading an image at high speed while suppressing an increase in cost and without impairing reliability.

[0007]

In order to achieve the above object, the present invention provides an imaging lens that collects reflected light reflected by a document and an optical path of reflected light collected by the imaging lens in two directions. The image is formed on the original by reading the image formed on the original for each main scanning line which is arranged at each of the image forming positions of the optical path splitting section which is divided into two and the reflected light which is split in two directions. The image reading timing of the first photoelectric conversion element line sensor and the second photoelectric conversion element line sensor, the image reading timing of the first photoelectric conversion element line sensor, and the image reading timing of the second photoelectric conversion element line sensor are made different. And a control unit that performs parallel processing of the signals output from the first and second photoelectric conversion element line sensors and converts the signals into image signals.

Further, the control section controls the image reading timing of the first photoelectric conversion element line sensor from the image reading timing of the second photoelectric conversion element line sensor.
The photoelectric conversion element line sensor is provided with an adjusting circuit for adjusting the time until the image reading timing.

Further, a first trigger signal for inputting a first trigger signal for causing the first photoelectric conversion element line sensor to start reading an image in the adjustment circuit, and a first trigger signal are provided. A memory for setting the time from the output to the time when the second photoelectric conversion element line sensor outputs the second trigger signal for starting the reading, the time measured by the counter and the time set in the memory And a comparator that outputs a second trigger signal if they match each other.

[0010]

According to the above-mentioned means, the optical path splitting unit that splits the reflected light from the original document into two directions and the image forming position of the reflected light split into the two directions are arranged, and the image is main-scanned at regular intervals. The first and second photoelectric conversion element line sensors, which are read line by line, and the two photoelectric conversion element line sensors are controlled to have different image reading timings, and output from the two photoelectric conversion element line sensors. And the control unit that processes the generated signals in parallel and converts them into image signals, the control unit processes the signals output from the two photoelectric conversion element line sensors in parallel, so that the signals corresponding to one main scanning line are processed. The time allotted to do this can be increased.

In addition, the control unit includes an adjusting circuit for adjusting the time from the image reading timing of the first photoelectric conversion element line sensor to the image reading timing of the second photoelectric conversion element line sensor. The reading interval of the image in the sub-scanning direction by the individual photoelectric conversion element line sensors can be adjusted to be constant.

Further, a counter for inputting a first trigger signal for causing the first photoelectric conversion element line sensor to start reading an image to the adjustment circuit, and starting counting.
A memory for setting the time from the output of the first trigger signal to the output of the second trigger signal to the second photoelectric conversion element line sensor, the time measured by the counter and the time set in the memory And a comparator that outputs a second trigger signal if the two coincide with each other. Therefore, from the reading timing of the first photoelectric conversion element line sensor to the reading timing of the second photoelectric conversion element line sensor. Time can be set in memory.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the configuration of one embodiment of the present invention. In the constituent members, the members corresponding to those described with reference to FIG.

The reflected light of the original 2 collected by the image forming lens 8 is divided into two optical paths by the half mirror 11 and imaged at two points on the CCD line sensor 9a and the CCD line sensor 9b, respectively. To do.

FIG. 2 is a block diagram showing the arrangement of a signal processing circuit for processing the signal output from the CCD line sensor of the control unit of this embodiment.

The detection signals detected and output by the CCD line sensors 9a and 9b at a constant cycle are input to an analog / digital (A / D) converter 21, which converts the analog signal into a digital signal for shading correction. It is stored in the shading line memory (not shown) of the circuit 22. The shading line memory is composed of a random access memory (RAM) corresponding to CCDs arranged linearly on the CCD line sensors 9a and 9b, and the shading correction circuit 22 refers to the contents of the shading line memory. By doing so, in order to correct the variation in the output of each CCD for the same image density,
Correction processing is performed on the digital output based on the signal of each CCD.

The CCD line sensors 9a and 9b read the main scanning lines of the image scanned by the light source unit 4 at a constant cycle, but are controlled so that the respective image reading timings are different.

The digital signal shading-corrected by the shading correction circuit 22 is subjected to gradation correction, dither processing for halftone processing, edge enhancement processing, etc. in the image processing circuit 23 based on the set processing parameters. Are converted into image signals.

The image signal converted by the image processing circuit 23 is
Input to the line buffer memory circuit 24.

FIG. 3 is a block diagram showing the configuration of the line buffer memory circuit, and FIG. 4 is a timing chart of signal writing and reading in the line buffer memory circuit.

The line buffer memory circuit 24 includes a write selection circuit 25 and line buffer memories (LM) A26a and LMB2.
6b, LMC26c, LMD26d and read selection circuit 27,
LMA26a and LMB26b are CCD line sensor 9a
LMC26c and L are assigned to store the signals output by
The MD 26d is assigned to store the signal output by the CCD line sensor 9b. As shown in FIG. 4, the signal corresponding to one main scanning line output from the CCD line sensor 9a at a constant cycle is alternately written to the LMA 26a and the LMB 26b by the switching operation of the write selection circuit 25, The signal from the CCD line sensor 9b is also L
It is written alternately in MC26c and LMD26d. CC here
D line sensor 9a signal output timing and CC
Since the output timings of the signals of the D line sensor 9b are controlled to be deviated by a fixed time, the writing of these signals is also performed at a timing deviated by a fixed time.

The read selection circuit 27 includes LMA26a and LMB26.
b, LMC26c, LMD26d, the signals are read out in the order in which they are stored, and the combined signal obtained by combining the signals is output to the interface unit 12.

FIG. 5 is an enlarged view showing the structure of the main part of this embodiment.

The reflecting mirror 11 is configured to be rotatable with respect to the rotating shaft 11a, and by rotating in the direction of arrow B, the direction of the split optical path is adjusted. The adjustment of the direction of the optical path is performed so that the CCD line sensors 9a and 9b read the same main scanning line when the images are read at the same timing. FIG. 6 is a timing chart of the read trigger signal for causing the CCD line sensor to read, but the CCD line sensors 9a and 9b are
When it is adjusted to read the completely same main scanning line at the same timing, C after the reading trigger signal a for causing the CCD line sensor 9a to read is output.
If the time T ₁ until the read trigger signal b for causing the CD line sensor 9b to read is output and the time T ₂ from the read trigger signal b to the read trigger signal a are made equal, Images can be read at equal intervals. However, the diameter of the CCD linearly arranged on the CCD line sensors 9a and 9b is about 7 μm, and two C
It is very difficult to adjust the CD line sensors 9a and 9b to read the same main scanning line completely.

FIG. 7 is a block diagram showing the arrangement of a timing adjusting circuit for adjusting the output timing of the read trigger signal in the control section of this embodiment.

The timing adjustment circuit is a counter that starts counting based on the clock signal when the read trigger signal a output to the CCD line sensor 9a is input.
28, a setting memory 29 that variably sets the time T _1, and a comparator 30 that outputs a signal when the counting time of the counter 28 and the setting time of the setting memory 29 match. The signal of the comparator 30 becomes a reset signal for the counter 28 to reset the count value, and the CCD
The read trigger signal b is supplied to the line sensor 9b.

Since the time T ₁ can be set by the setting memory 29, the interval between the main scanning lines read by the CCD line sensors 9a and 9b in the sub-scanning direction can be made constant by adjusting the time T ₁ .

In the image reading apparatus of this embodiment, the two CCD line sensors 9a and 9b alternately read the document scanned by the light source unit 4 at different timings.
By processing the signals output from the CCD sensors 9a and 9b by the control unit 20a by different circuits, the processing time of each signal can be lengthened, which is an expensive and high-speed process for configuring the circuit. As a result, it is possible to provide an image reading apparatus that can read an image at high speed with low cost and high reliability.

[0029]

As described above, according to the present invention, the optical path splitting section and the optical path splitting unit 2 disposed at the image forming position of the split optical path.
Photoelectric conversion element line sensors and a control unit that controls the image reading timings of the two photoelectric conversion element line sensors and that processes the output signals in parallel to convert them into image signals. Since it is possible to lengthen the processing time of the signal output from the element line sensor, it is not necessary to use an expensive device capable of high-speed processing in the circuit that constitutes the control unit, resulting in low cost and high reliability. Two photoelectric conversion elements are provided, and the control unit includes an adjustment circuit that adjusts the time from the read timing of the first photoelectric conversion element line sensor to the read timing of the second photoelectric conversion element line sensor. Since it can be adjusted so that the reading interval of the image in the sub-scanning direction by the line sensor is constant, good images can be reproduced and adjusted. A counter that starts counting time when the first trigger signal is output, a memory that sets the time from when the first trigger signal is output until the second trigger signal is output, and a time counting time of the counter. And a set time of the memory are compared, and if they match each other, a comparator for outputting a second trigger signal is output.
Since the time from the reading timing of the photoelectric conversion element line sensor to the reading timing of the second photoelectric conversion element line sensor can be set in the memory, the reading interval of the image in the sub-scanning direction by the two photoelectric conversion element line sensors is simple. It is possible to provide an image reading device that can be adjusted to a high speed and can read an image at high speed.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a signal processing circuit that processes a signal output from a CCD line sensor of a control unit of the present embodiment.

FIG. 3 is a block diagram illustrating a configuration of a line buffer memory circuit of a control unit according to the present exemplary embodiment.

FIG. 4 is a timing chart of signal writing and signal reading in the line buffer memory circuit of the present embodiment.

FIG. 5 is an enlarged view showing a configuration of a main part of this embodiment.

FIG. 6 is a timing chart of a read trigger signal for causing the CCD line sensor of the present embodiment to read.

FIG. 7 is a block diagram illustrating a configuration of a timing adjustment circuit that adjusts the output timing of the read trigger signal of the control unit according to the present exemplary embodiment.

FIG. 8 is a cross-sectional view showing a configuration of a conventional image reading device.

[Explanation of symbols]

9a, 9b ... CCD line sensor, 11 ... Half mirror, 20a ... Control section, 21 ... A / D converter, 22 ... Shading correction circuit, 23 ... Image processing circuit, 24 ... Line buffer memory circuit, 25 ... Write selection Circuit, 26a, 2
6b, 26c, 26d ... Line buffer memory (LM) A, B,
C, D, 27 ... Read selection circuit, 28 ... Counter, 29 ...
Setting memory, 30 ... Comparator.

Claims (3)

[Claims] 1. An image forming lens that collects reflected light reflected by a document, an optical path splitting unit that splits an optical path of reflected light collected by the image forming lens into two directions, and reflected light split into two directions. The first photoelectric conversion element line sensor and the second photoelectric conversion element line which are arranged at respective image forming positions for reading the image formed on the document for each main scanning line at a constant interval in the sub-scanning direction. The sensor and the first photoelectric conversion element line sensor are controlled so that the image reading timing of the first photoelectric conversion element line sensor is different from the image reading timing of the second photoelectric conversion element line sensor, and the first and second photoelectric conversion elements are controlled. An image reading apparatus comprising: a control unit that processes signals output from a line sensor in parallel and converts the signals into image signals. 2. The control unit includes an adjusting circuit for adjusting a time from an image reading timing of the first photoelectric conversion element line sensor to an image reading timing of the second photoelectric conversion element line sensor. The image reading apparatus according to claim 1, which is characterized in that. 3. A counter for inputting, to the adjustment circuit, a first trigger signal for causing the first photoelectric conversion element line sensor to start reading an image, and a counter for starting timing.
A memory for setting the time from the output of the first trigger signal to the output of the second trigger signal for starting the reading by the second photoelectric conversion element line sensor, the time counted by the counter, and the memory The image reading apparatus according to claim 2, further comprising: a comparator that compares the time set in the memory and outputs a second trigger signal if they match each other.