JP2002247302A - Image reader and image reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image input unit in which an image can be detected surely while reducing the cost. SOLUTION: A line sensor camera 11 is provided in order to pick up the image of a print material 45. A pulse generator 12 generates a pulse every time when the print material 45 is carried by a predetermined distance. Upon receiving the pulse, the line sensor camera 11 accumulates charges for a predetermined time and converts the accumulated charges into image data which is displayed on a liquid crystal display 33. Since the charges of an image picked up are stored for a predetermined time every time when the print material 45 is carried by a predetermined amount, images of constant exposure time can be detected continuously at a constant interval.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading an image of an object and a method thereof, and more particularly to an image reading apparatus and a method for use in textile inspection by textile printing, product inspection of a sheet-fed printing machine and the like. .

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus for a textile print inspection apparatus using a textile as a subject,
A two-dimensional sensor such as a television camera reads a still image using a strobe light or a shutter function of a camera while the textile is stopped or during driving.

On the other hand, using a line type CCD camera,
There is also a method of reading only an image of a textile area driven at a constant speed.

[0004]

However, in the method using the two-dimensional sensor, a large number of cameras are required to obtain a desired image resolution due to the limitation of the number of pixels of the two-dimensional sensor. However, there is a problem that it is difficult to obtain uniform illumination over a wide range.

According to the latter method, there is a problem that images during acceleration and deceleration cannot be used due to uneven sensitivity or image distortion.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and reduces the number of cameras.
It is an object of the present invention to provide an image reading apparatus and an image reading method capable of reading an image even during acceleration or deceleration.

[0007]

An image reading apparatus according to the present invention comprises a one-dimensional photoelectric conversion means for photoelectrically converting and reading an image of a subject, and a pulse for generating a pulse each time the subject moves a predetermined distance. Generating means, photoelectric conversion control means for controlling the photoelectric conversion means to accumulate electric charges for a certain period of time in accordance with the pulse generated by the pulse generating means, and image data creating means for converting the accumulated charges of the photoelectric conversion means into image data And

According to the present invention, the one-dimensional photoelectric conversion means accumulates electric charges for a certain period of time in accordance with a pulse generated each time the subject moves a certain distance, and creates image data based on the electric charges. An image exposed for a certain period of time at each distance is read. As a result, image data of a moving subject can be read with a small number of cameras.

Preferably, the specimen is moved in a first direction, the specimen has a predetermined width in a second direction intersecting the first direction, and a plurality of photoelectric conversion means are arranged in the second direction. The plurality of photoelectric conversion units arranged in the second direction simultaneously read the subject.

[0010] More preferably, it is determined whether or not the image pattern storage means for storing a predetermined image pattern and the image data read from the photoelectric conversion means substantially match the predetermined pattern stored in the storage means. It further includes determination means by pattern matching.

Since it can be determined whether or not the read image data substantially matches a predetermined image pattern stored in advance, it can be used for an image inspection apparatus.

According to another aspect of the present invention, there is provided an image reading method, comprising the steps of: generating a pulse each time a subject moves a predetermined distance; and performing one-dimensional photoelectric conversion in accordance with the pulse generated by the pulse generating means. Means for photoelectrically converting and reading the image of the subject by means, and at the time of reading, controlling the photoelectric conversion means to accumulate electric charges for a certain time;
Converting the stored charge into image data.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a main part of an image reading apparatus according to one embodiment of the present invention. 1A is a side view of the image reading apparatus, and FIG. 1B is an arrow view of a portion indicated by an arrow IB-IB in FIG.

Referring to FIG. 1A, an image reading apparatus 10
Is the print material (fabric) that is the subject
45, a pulse generator 12 for generating a pulse each time the print material 45 moves a predetermined distance, an image signal from the line sensor camera 11 and the pulse generator 1
And a photoelectric conversion control device 20 that receives a pulse from the second and performs image processing based on the signal.

The printing material 45 includes a driving roll 4
In the state of being stuck on the blanket (belt) accurately driven in 1, it is intermittently driven in the driving direction indicated by the arrow in the figure. The pulse generator 12 comes into contact with a part of the drive roll 41 and detects the amount of movement of the print material 45.

The print material 45 is fed by the drive roll 41 for a certain distance in the drive direction, stopped, printed, and then driven again. By repeating this, a continuous pattern is printed in the driving direction. During this driving, the image reading device 10 inputs the image of the already printed portion by the line sensor camera 11, and determines the quality of the print by a pattern matching method.

A portion of the print material 45 where an image is taken by the line sensor camera 11 is provided with a lighting device 1 connected to the light source box 14 in order to secure a predetermined illuminance.
3 are provided. The print material 45 is printed in a predetermined color by the plurality of printing frames 15a and 15b.

Referring to FIG. 1B, two line sensor cameras 11 are provided in a direction intersecting the transport direction of the print material 45, and each of the line sensor cameras 11 is provided.
An image corresponding to the entire width of the print material 45 is detected by two units 1a and 11b.

The photoelectric conversion control device 20 includes match engines 29a and 29b for matching images of the line sensor cameras 11a and 11b provided on the left and right sides, and a user interface (hereinafter, referred to as "match") for performing predetermined processing described below. Computer 30). An image signal from the UI computer 30 is sent to the liquid crystal display 33, where the detected image is displayed. The liquid crystal display 33 is provided with a keyboard 31 and a mouse 32 for performing predetermined inputs.

When the print material 45 is in the stopped state, as described above, printing is performed for a predetermined length in the flat type printing frame 15, and when the printing material 45 is completed, the printing material 45 is fed and driven by that length to move to the next position. The printing is repeated. The feed distance is typically 25 inches (635 mm), but may exceed 1 m and varies depending on conditions. There are a plurality of (up to 24) printing frames 15 for performing multicolor printing. In this embodiment, the maximum width of the fabric is 1800 mm. The field of view of the line sensor camera 11 is set to about 1000 mm per unit, and a field of view of 1800 mm is secured using two units.
There is a 150 mm overlap between them. Each of the line sensor cameras 11a and 11b has 2048 elements, and has a lateral resolution of 0.5 mm. The vertical resolution is determined by the conduction ratio between the pulse generator 12 and the driving roll 41, the number of pulses per rotation of the pulse generator 12, and the pulse division ratio of the timing circuit. The conduction ratio and the number of pulses of the pulse generator 12 are appropriately selected to be about 25 μm per pulse,
By dividing the frequency by 0 and photographing an image of one line at about 0.5 mm, the aspect ratio of the pixel is approximately 1: 1.

Further certain exposure time for accumulating charges after receiving a pulse from the pulse generator 12 is determined from the direction resolution ΔL feed and maximum speed V _max of the belt conveyor 40. In this example, since in V _max is 100 m / min (meters per second 1.7 m), [Delta] L is 0.5 mm, 0.5
mm / 1700 seconds, that is, the exposure time needs to be set to 290 μs or less. On the other hand, since the sensitivity of the camera is proportional to the exposure time, it is advantageous to take as long as possible. Therefore, in this example, the exposure time is set to 300 μs to suppress the maximum speed of the belt conveyor.

FIG. 2 is a block diagram showing a main part of the match engines 29a and 29b constituting the photoelectric conversion control device 20. Referring to FIG. 2, an image signal from line sensor camera 11 is amplified by video amplifier 21, converted into a digital signal by A / D converter 22, passed through buffer memory circuit 23, and converted into a main memory circuit 24 as image data.
Is stored in The match engines 29a and 29b have a CPU 28 for controlling the entire device, and the CPU 28 receives a pulse input from the pulse generator 12 and sends a signal to the camera drive circuit 26 to drive the line sensor camera 11 at a predetermined timing. .

The timing generation circuit 27 also supplies a predetermined timing pulse to the A / D converter 22 and the buffer memory circuit 23.

The CPU 28 sends the result of pattern matching of the image data stored in the main memory circuit 24 via the input / output circuit 25 to the UI computer 30.

FIG. 3 shows a pulse signal (a) generated by the pulse generator 12, a sensor timing signal (b) supplied to the camera drive circuit 26, and a photocurrent accumulation time (c).
6 is a timing chart showing the relationship between the two.

Referring to FIG. 3, pulse generator 12
Is accumulated for a certain period of time a by the photocurrent.

FIG. 4 is a flowchart showing the operation of the image reading apparatus 10. Referring to FIG. 4, image reading device 10
, First, the photoelectric conversion control device 20 and the lighting device 13
Then, the power of the light source box 14 is turned on. It takes about 5 to 10 minutes to stabilize this illumination. (Step S11,
(Steps are abbreviated below.) Next, the inspection level, the print size in the feed direction, the minimum defect size to be detected, and the like are set (S12). This set value is stored.

Next, when a new inspection is started, an inspection standard is created (S13). When the product number changes (type change, color change), it is always necessary to create an inspection standard.

Next, an inspection is performed (S14). Since then
Inspect continuously. If you detect a setting flaw,
Notify the operator by buzzer ON and lamp ON.

Next, the inspection is stopped (S15). When printing is stopped due to type change or color change, the inspection is stopped. The processing after the stop differs depending on the processing to be performed next.

The program is terminated and shut down (S16). Next, the power supply of the photoelectric conversion control device 20 is turned off.
F (S17).

Next, the procedure of the reading process performed in the "execute" process shown in S14 of FIG. 4 will be described with reference to the flowchart of the "execute" process shown in FIG.

Referring to FIG. 5, in the reading process, the input pulse interval Tp from the pulse generator 12 that generates a pulse every time the print material 45 moves by a predetermined minute distance is detected. This input pulse interval Tp
Is determined to be larger than a predetermined maximum pulse interval Tm during the predetermined feeding, that is, whether the print material 45 is being conveyed at a predetermined speed or more (S21).

Print material 45 at a predetermined speed or higher
Is transported, that is, the input pulse interval T
When p is equal to or longer than the predetermined maximum pulse interval Tm (YES in S21), the pulse is divided by the pulse divider circuit built in the timing generation circuit 27 (S22), and whether the pulse reaches a predetermined value, that is, the pulse It is determined whether or not the frequency dividing circuit has counted up (S23). When the pulse divider circuit counts up (YES in S23), the drive timing of the image sensor camera is taken by the pulse generation circuit, and the photoelectrically stored charge is flashed (the unnecessary charge stored up to that point is discarded and newly stored). (S2)
4). Data is read out after a certain period of time in response to the image reading pulse (S25), and the image for one line is transferred to the main memory 25. Then, the line counter is counted up by one (S26), and the process returns to S22 for reading the image of the next line.

Here, the reason why the stop of the conveyance of the print material 45 is not determined by using the number of pulses is that the number of pulses from the pulse generator 12 input by one drive depends on the machine precision, and the frequency division is performed. This is because there is an error of about several pulses as the number of subsequent pulses, so that the number of pulses cannot be specified. Therefore, when the pulse does not arrive for a certain period of time Tm (about 10 msec), it is determined that the state has shifted to the stop state, and it is determined that the image input is completed.

If the pulse dividing circuit has not counted up in S23 (NO in S23), the condition is that the print material 45 is being conveyed at a predetermined speed, that is, the pulse interval Tp is equal to the maximum pulse interval Tm. If it is smaller (YES in S27), the flow returns to S22, and the frequency division of the pulse is continued. When the print material 45 is no longer conveyed at the predetermined speed (NO in S27), the process ends.

As described above, when acceleration of the stopped print material 45 starts, a pulse starts to be input from the pulse generator 12 to the timing generation circuit. Print material "moving" when the pulse interval falls below a certain level
Then, an image for one line is read every fixed number of pulses. This is repeated, and when the pulse interval becomes equal to or longer than a certain value, it is determined that the apparatus has stopped, and the image reading is terminated. As described above, almost all images of the print material being moved can be read. Further, the pulse from the pulse generator 12 is a pulse corresponding to the moving distance. Since the pulse is frequency-divided and an image for one line is captured, no geometric distortion occurs. Further, since the exposure time is controlled to be constant when one line is taken in, reading can be performed with a constant sensitivity.

As a result, the print material accelerates from the stopped state, reaches the highest speed, travels a certain distance, and then decelerates to the stopped state. Reading can be performed with a fixed sensitivity.

FIG. 6 is a diagram showing the timing relationship between printing and reading. Referring to FIG. 6, time is taken in the X-axis direction, and the conveyance speed of the conveyed object is taken in the Y direction. Referring to FIG.
The conveyed material is stopped during printing (speed v = 0), and is moved at a maximum speed of v = 100 m / min during movement. During this time, the printed conveyed material is read.

FIG. 7 is a diagram showing an example of a screen display on the liquid crystal display with the settings shown in S12 of FIG.

Referring to FIG. 7, there are inspection levels from level 1 to level 5, with inspection level 1 being the loosest inspection and inspection level 5 being the tightest inspection level.
The standard is level 3.

In the print size (feed direction), the feed size of one print is specified. In setting the alarm, the minimum defect size to be detected is specified. If you want to detect defects that occur normally continuously, specify the minimum size and the number of alarms. Specifically, if the size is defined as 2 mm and the number of times is 5, the alarm is generated when the defect size occurs 2 times or more on one side and 5 times in the same place.

When it is desired to detect a serious defect that occurs,
Specify the number of times that the minimum size is set as the alarm.

For example, if the size is defined as 20 mm and the number of times is 2, the defect size is 20 mm or more on one side and 2
Generates an alarm when the alarm occurs. This detection does not detect a perforation or the like, but can detect a serious defect due to color-out or broken fabric.

The buzzer ON time setting sets the buzzer ON time (seconds). FIG. 8 is a diagram showing an example of a screen of the liquid crystal display when creating the new inspection standard shown in S13. Referring to FIG. 8, a "new" button is clicked. This makes a click when the belt stops. It takes a while to create the inspection criteria (10 seconds ~
20 seconds). The reference images captured by the two line sensors 11a and 11b are displayed on the screen. Referring to FIG. 8, a left camera reference image is displayed on the left side, and a right camera reference image is displayed on the right side. Check the reference image. Check whether the image is suitable for the standard (without defects). Check the automatically detected left and right margins (vertical black solid line). If the image does not meet the standard, the inspection standard is created again. If the left and right margins are not appropriate, change them in the margin settings. "Inspection" is performed in this state. Click "execute" at the lower part of the center of FIG.

When an image has a defect, defect information is displayed in a defect information display area. In the above embodiment, the pulse generator is provided on the drive pulley of the belt conveyor, but is not limited thereto, and may be provided at any position.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an image input device.

FIG. 2 is a block diagram showing a main part of the match engine.

FIG. 3 is a timing chart of the photoelectric conversion control device.

FIG. 4 is a flowchart illustrating an operation procedure of the image input device.

FIG. 5 is a flowchart illustrating an operation procedure of an image reading process.

FIG. 6 is a diagram illustrating a relationship between a moving time and a speed of a print material.

FIG. 7 is a diagram showing a screen display example when performing “setting”.

FIG. 8 is a diagram showing an example of a display screen when creating an “inspection standard”.

[Explanation of symbols]

10 image input device, 11 line sensor camera, 12
Pulse generator, 13 lighting device, 14 light source box, 20 photoelectric conversion control device, 21 video amplifier, 22 A / D converter, 23 buffer memory circuit,
24 main memory circuit, 25 input / output circuit, 26 camera drive circuit, 27 timing generation circuit, 28 CP
U, 29 match engine, 30 user interface computer, 33 liquid crystal display, 40 belt conveyor, 41 drive roll.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yutaka Ikeda No. 146, Katsura Asamachi, Nishikyo-ku, Kyoto, Kyoto, Japan

Claims (3)

[Claims] 1. A one-dimensional photoelectric conversion unit that photoelectrically converts and reads an image of a subject, a pulse generation unit that generates a pulse each time the subject moves a predetermined distance, and a pulse generated by the pulse generation unit An image reading apparatus, comprising: a photoelectric conversion control unit that controls the photoelectric conversion unit so as to accumulate electric charges for a certain period of time in accordance with the above, and an image data creation unit that converts the accumulated charges of the photoelectric conversion unit into image data. 2. An image pattern storage means for storing a predetermined image pattern, and a judgment for judging whether or not the image data read from the photoelectric conversion means matches the predetermined pattern stored in the storage means. The image reading device according to claim 1, further comprising a unit. 3. A step of generating a pulse each time the subject moves a predetermined distance; and performing one-dimensional photoelectric conversion on the image of the subject by one-dimensional photoelectric conversion means in accordance with the pulse generated by the pulse generating means. An image reading method, comprising: reading; controlling the photoelectric conversion unit to accumulate charges for a predetermined time during the reading; and converting the accumulated charges into image data.