JPS63212264A - Picture reader - Google Patents

Abstract

PURPOSE:To optimizingly and automatically adjust a focus and magnification of an optical system by providing a prescribed mark, a mark detection means and a moving mechanism moving at least one of a lens or a photoelectric converting element in the direction of optical axis. CONSTITUTION:A reference white board 106 having reference mark lines M1-M3 is provided to one end in the subscanning direction of an original platen 101 and the reference white board 106 is irradiated with a fluorescent lamp 102 at adjustment mode. A reflected light is formed on a CCD image sensor 105 via a mirror 103 and a condenser lens 104, and a CCD output SEN corresponding to the mark lines M1-M3 is given to an image processor. The image processor obtains an optimum position of the condenser lens 104 and the CCD image sensor 105 to send a movile command signal, and the condenser lens 104 and the CCD image sensor 105 are reciprocated by a direct mechanism 115. Thus, focusing and magnification are attained automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to an image reading device, and is particularly applicable to a configuration for adjusting focus, magnification, etc. of an optical system.

[Prior Art] For example, in a copying machine, if the optical system is out of focus or the magnification is not a predetermined magnification, a good copy image cannot be obtained and the performance of the machine will be significantly reduced. Become. Therefore, conventionally, steps such as focusing and magnification adjustment have been provided during assembly to adjust the focus and magnification.

Conventionally, such adjustments were made using an adjustment jig to adjust the working opening to one position.
They went one by one. Therefore, it takes a lot of adjustment time,
This lengthens the cycle time (takt time) in which products are sent out on the line, slowing down the pace of mass production. Furthermore, if the optical system changes over time and the focus and magnification change slightly, AM must be performed at the location where the device is installed, making maintenance complicated.

Furthermore, regarding the magnification, the copying magnification may change depending on the paper used due to its expansion and contraction, and it is also desired that the optical system be able to cope with such changes.

[Object of the Invention] The present invention has been made in consideration of the above points, and an object thereof is to provide an image reading device that can automatically and optimally adjust the focus and magnification of an optical system.

[Structure of the invention] The present invention has been made to achieve the above object,
In an image reading device that optically reads an image in a reading area and focuses the reading beam onto a photoelectric conversion element through a lens, a predetermined mark attached outside the reading area of the original or the main body of the device and a reading signal are used. a mark detection means for detecting the mark; a movement mechanism for moving at least one of the lens or the photoelectric conversion element in the optical axis direction; and a control means for controlling the movement mechanism based on the mark information signal from the mark detection and output means. It is characterized by having the following.

The present invention will be specifically described below based on one embodiment.

FIG. 2 shows the general configuration of a digital copying apparatus.

The digital copying apparatus includes an image scanner section 100, an image processor section 200, and a printer device 300.

In the image scanner unit 100, the original is placed on the original platen 10.
1 and illuminated by a fluorescent lamp 102. The reflected light from the original is reflected by a mirror 103 and a condensing lens 104.
are sequentially activated to form an image on the COD image sensor 105, and the image signal photoelectrically converted in the COD image sensor 105 is given to the image processor section 200.

The image processor section 200 processes image signals coming from the image scanner section 100 in response to input signals from an operation section (not shown). In this way, the image conversion processing signal is transmitted to the laser light source 3 of the printer unit 300.
01 as an on/off control signal. The laser beam emitted from the laser light source 301 passes through the polygon mirror 30
2, the fθ lens 30 is deflected and scanned in the main scanning direction.
3, is converted to scan at a constant speed, is deflected by a mirror 304, and is irradiated onto a photosensitive drum 305.

- A charging unit 306, a laser beam irradiation unit 307, a developing unit 308, a transfer unit 309, and a cleaning unit 310 are arranged around the photosensitive drum 305, and electrophotography is applied to the paper conveyed from the paper feed unit 311. The image signal from the image processor section 200 is transferred to the fixing section 3.
After fixing the toner through the paper 12, the paper is discharged from a paper discharge section 313.

In addition to the configuration for reading and transferring images as described above, this embodiment has an "A alignment configuration" for focusing the optical system and adjusting the magnification of the transferred image to a predetermined magnification.

In FIG. 1, at one end of the mounting table 101 in the sub-scanning direction, there is a reference white plate 106 having reference mark lines M1 to M3 provided at predetermined intervals as shown in FIG. 3 in the main scanning direction. The reference white plate 106 is provided so as to be extended, and a fluorescent lamp 102 illuminates this reference white plate 106 during the adjustment mode. As described above, the reflected light from the reference white plate 106 is also focused on the CCD image sensor 105 via the mirror 103 and the condensing lens 104, and corresponds to the mark lines M1 to M3 as shown in FIG. 3(B). The CCD output SEN, which has a high level in the portion where the image is displayed, is given to the image processor section 200. Note that the brightness of the mark lines M1 to M3 is selected such that the level of the CCD output SEN falls within the range of signals that can be processed by the image processor section 200. The image processor unit 200 controls the condenser lens 104 and the CCD image sensor 1 in the adjustment mode.
05 and sends a movement command signal.

In the case of this embodiment, the condenser lens 104 and the CCD image sensor 105 are movable forward and backward by a linear motion Ja horizontal 115. As shown in FIG. 4, the linear motion i-lateral 115 converts the rotational force of the motors 1.07 and 108 into linear force through the rotational linear motion conversion mechanism 109 and 10, respectively, and connects the condenser lens 104 and the CCD image sensor. 105 can be moved in the optical axis direction. Each motor 10
7.108 is rotationally controlled in response to a movement command signal from the image processor unit 200 described above.

The image processor section 200 generates a movement command signal for focusing. First, the principle of focusing will be explained. Focusing on any of the reference mark lines M1, M2, M3, for example mark line M2, on the reference white board 106, since the background is white, the brightness level on the reference white board 106 is as shown in FIG. Therefore, when the focus is correct, a high level detection signal is obtained from the portion corresponding to the mark line M2 from the CCD image sensor 105 as shown in FIG. If there is a deviation, a detection signal of a small level is also sent from the part corresponding to the mark line M2.Therefore, the condenser lens 104 and the CCD image are adjusted so that the detection signal level corresponding to the mark line M2 is maximized. Determine the position of sensor 105.

Here, the distance from the reading point (the position of the reference white plate 106) to the condenser lens 104 is a, and the distance from the condenser lens 104 to the CCD
The distance to the image sensor 105 is b, and the condenser lens 10
4, the conjugate length a+b of this optical system can be expressed by the following formula (1). The focal pressure MF is difficult to vary even if a compound lens system is used, and is fixed depending on the lens, and the magnification m is fixed because the light-receiving area of the COD cell is fixed. Therefore,
Even if the distances a and b are set to the designed values, if the focal pressure IF is different from the designed values, the focus will be out of focus (
1) It becomes something that does not satisfy the formula. Therefore, if the right and left sides of equation (1) above are not equal due to a shift in focus, the left side must be varied.

In order to vary the conjugate length a+b, the position of the CCD image sensor 105 described above may be moved and varied. Therefore, the movement of the CCD image sensor 105 is controlled in response to a movement command signal from the image processor section 200.

Since only the distance changes due to this movement, the magnification also changes as shown in FIG. 6(B), but since the image formation state on the CCD image sensor 105 is important, first,
The CCD image sensor 105 was moved to focus, and then the magnification was adjusted as described below.

Moreover, the position adjustment of the CCD image sensor 105 is as follows.
This is not shown in FIG. 7 and is executed by the control device 201.

The control device 201 includes an analog/digital conversion circuit 20 that converts electrical signals photoelectrically converted by the COD image sensor 105.
2 is converted into a digital signal, and further processed through a shading correction circuit 203 to eliminate variations due to the position of the optical system, C
It is given after correcting variations in CD cell conversion. The control device 201 detects the level of the above-mentioned predetermined mark line M2 from the incoming read signal and outputs a movement command signal for the CCD image sensor 1.5 to the motor 108.

The control device 201 executes the adjustment program shown in FIG. 8 to output the movement command signal. That is,
When the H.211 setting mode is selected, the program is started in step SP1, and then the process proceeds to the next step SP2, where a level signal (Vl) corresponding to the mark line M2 is fetched. Next, in step SP3, the CCD image sensor 105 is moved back in the direction away from the condenser lens 104, and the level (V
2), sets the backward flag F1 indicating that the moving direction is the backward direction, and proceeds to the next step SP4.

In this step SP4, the levels corresponding to the mark line M2 captured twice before and after are compared.

As a result, if it is determined that the level captured this time is large, it is determined that the camera is moving in the direction of focus, and the process proceeds to step SP5, where it sets the up flag F2, which means that the level is moving in the direction of increasing. Then, the stored contents are updated so that the level taken in this time (■2) becomes the previous level value (Vl) in the next judgment, and the process proceeds to the next step S P 6.

In step S I) 6, the current direction of movement is determined according to the reverse flag F1 and the situation, and if the current direction is backward, the process returns to step SP3 to continue moving in the reverse direction. Then, processing for capturing the level corresponding to the mark line M2 is performed. On the other hand, if the current direction of movement is the forward direction, the process proceeds to step SP7 to continue moving forward and reach the level (V2) corresponding to mark line M2.
and set the backward flag F1. is reset and the process returns to step SP4 described above.

In step SP4 mentioned above, if the level (V2) taken in this time is smaller and a negative result is obtained, step S
Proceed to P8. In step SP4, a negative result is obtained.
There are cases in which the initial movement direction (backward direction) is the direction in which the object is out of focus, and cases in which the object has been moved in the direction in which the object is in focus, but the object is moved beyond the optimum point of focus. Therefore, in step SP8, either case is determined based on the up flag F2.

As a result of this judgment, if the initial moving direction is the direction in which the focus is going out of focus, the process proceeds to step SP7, where the CCD image sensor 105 is moved in the forward direction, and the optimal point of focus is determined by the CCD image sensor 105. I moved the 105 forward to search.

On the other hand, since the optimum point has been exceeded, step S1]4
If it is determined that a negative result has been obtained in step S1]9, the current direction of movement is determined according to the setting status of the backward flag F1, and if the current direction of movement is the backward direction, step S1 is performed. Proceeding to 5P10, move the CCD image sensor 105 by one unit in the forward direction to position the image sensor 105 at the optimum focus point; conversely, if the moving direction up to now is the forward direction, step S1
] After proceeding to Step 11, the CCD image sensor 105 is moved by one unit in the backward direction to position the image sensor 105 at the optimum focus point, and then the process proceeds to a magnification adjustment step to be described later.

In this way, the CCD image sensor 105 can be positioned at the position where the level corresponding to the mark line M2 is maximum, and the focus can be optimized.

Next, the principle of magnification adjustment will be explained. When a reference white board 106 on which three mark lines M1, M2, and M3 are spaced apart as shown in FIG. 3 is imaged on the image sensor 105, if the magnification is large, the mark lines on the image sensor 105 are If the distance between them is larger than the predetermined value, and conversely, the magnification is smaller than the predetermined value, the image sensor 105
The distance between the upper mark lines is shorter than the predetermined distance. Therefore, by detecting the distance between the mark lines on the image sensor 105, it is possible to determine whether the magnification is greater than a predetermined value. Since the distance between mark lines on the image sensor 105 is read out from the CCD cell in the third order, it can be expressed by the difference in readout time of read signals corresponding to the mark lines. Therefore, in this embodiment, the magnification is determined based on the time difference between reading signals corresponding to mark lines.

FIG. 9 shows a configuration for detecting the reading time between mark lines. 1st
The COD image sensor 105 performs a transfer operation and sequentially outputs accumulated charges in synchronization with the line synchronization signals i and syNC shown in FIG. 0(A). Thus, as shown in FIG. 10(C), the output SEN of the image sensor 105 is sent out, which rises at the time points corresponding to the mark lines M1, M2, and M3.

The line synchronization signal LSYNC is inverted via an inverter circuit 204 and given to a time counter circuit 205 as a clear signal. Therefore, the counter circuit 205 counts the number of arriving clock pulse signals CLK (FIG. 10(B)) after the first pulse signal P1 of the line synchronization signal [,5YNC falls. Further, line synchronization signal LSYNC is applied to clear circuit 206. Clear circuit 206 includes flip-flop circuits 207 and 20
8 and an AND circuit 209, line synchronization signal L
In addition to S Y N C, logic [H
An adjustment signal TEST is provided that takes the J output. The clear circuit 206 is in magnification A'M mode, and the line synchronization pulse P1 of the 19th exit to the second line synchronization pulse P
A clear signal indicating a non-clear state is output to flip-flop circuits 210 to 212 and latch circuits 213 to 215 only for a period until 2 is applied.

Each flip-flop circuit 210, 211, 212 latches an output signal that takes logic "H" when pulse signals PMI, PM2, PM3 corresponding to mark lines M1, M2, M3 are applied to latch circuits 213-215. Give as a command signal. Each of the latch circuits 213 to 215 receives the count value of the counter circuit 205, and latches this count value when a latch command signal is applied.

The first latch circuit 213 has the counter circuit 205 cleared by the first pulse signal P1 of the line synchronization signal LSYNC, and is latched by the latch command signal sent at the time corresponding to the first mark line M1. Because it is a thing,
A value corresponding to the time T1 from the first pulse signal P1 of the line synchronization signal LSYNC to the point corresponding to the first mark line is latched. Similarly, latch circuits 214 and 215
latches values corresponding to times T2 and T3 from the first pulse signal P1 of the line synchronization signal LSYNC to times corresponding to the second and third mark lines M2 and M3, respectively. The latch output of each latch circuit 213 - 215 is given to control device 201 .

The control device 201 executes magnification adjustment by obtaining the mutual time difference 1.4 to T6 between the points corresponding to the mark lines based on the incoming latch output. This magnification adjustment is executed after the focus adjustment is completed according to the program shown in FIG.

Note that since the magnification rn can be expressed as the ratio of the distances Ata and b, as described above, it is possible to adjust them by changing both a and b, but since this would complicate the moving configuration, in this embodiment only the distance a is used. I made it possible to adjust it by making it variable. Incidentally,
The distances Ma and b can be expressed as shown in the following formula % formula % (2), and the actual magnification (approximately 0°11
), when trying to change the magnification by 1% (0, 12>), it is necessary to change the distance I4@a by about 8%, whereas it is sufficient to change the distance gb by about 1%. It has been found that the magnification can be adjusted even if the distance is fixed for slight changes in the magnification, and the magnification can be changed even if only the distance Ata is changed as described above.

When the focus adjustment is completed, the control device 201 performs step 5.
Proceed to P1-2 and take in the inter-mark times T4 to T6,
In the next step 5P13, it is determined whether each time T4 to T6 is within a predetermined error range. As a result, if a positive result is obtained, the process proceeds to step 5P14 and the adjustment program is ended. On the other hand, if each time T4 to T6 is determined to be outside the error range, each time T4 to T6 is determined to be outside the error range.
4 to T6 is larger or smaller than the reference range.

Each time] If 4 to T6 is large, the magnification is larger than the predetermined value, so proceed to step 5P16, drive the motors 107 and 108 via the motor drivers 111 and 112, and drive the CCD image sensor 105 and the condenser lens. 1
04 is moved backward while keeping the mutual distance 1lllb constant, the distance a is increased, the magnification is lowered, and the process returns to step 5P12 described above. On the other hand, if the judgment result in step 5P15 is that each of the times T4 to T6 is small, the magnification is smaller than the predetermined magnification, so the process advances to step 5P17 to drive the motors 107 and 108 via the motor drivers 111 and 112. Then, the CCD image sensor 105 and the condensing lens 104 are moved forward while keeping the mutual distance constant, the distance 1lia is decreased, the magnification is increased, and the process returns to step 5P12 described above. After repeating such a loop operation, an affirmative result is obtained in step 5P13, and the program is terminated.

Therefore, according to the above-described embodiment, the focusing operation and the magnification adjustment operation can be performed automatically, and the adjustment work of the device at the time of shipment can be facilitated and the working time can be shortened. Further, even if the focus shifts or the magnification shifts due to changes over time, it can be easily adjusted, making maintenance work easier.

In the above embodiment, the focus adjustment is performed based on the level value corresponding to the reference mark line, but as shown in FIG. It is also possible to use a value that changes and determine the focus state based on the transition time TX until the output of the CCD image sensor 105 (FIG. 11(B)) reaches a new value.

Further, in the above embodiment, the reference mark is provided on the reference white board 106 provided at the end of the mounting table, but the present invention is not limited to this, and may be provided on the original, for example.
When provided on a document, the magnification can be adjusted depending on the elasticity of the paper.

Further, the number of mark lines, the width of the mark lines, etc. are not limited to those of the above-mentioned embodiments.

Further, in the above-described embodiment, the magnification adjustment in the main scanning direction was shown, but the image scanner unit 100 provides a reference mark line in the sub-scanning direction and detects the difference in reading time of the reference mark line. The magnification in the sub-scanning direction may be adjusted by changing the scanning speed.

Furthermore, although the magnification adjustment is performed by changing only the distance a, in the case of highly accurate adjustment, both the distances a and b may be changed depending on the difference from a predetermined magnification.

Furthermore, when the variable magnification operation is manually selected, an error amount from a predetermined magnification may be used as a correction term for each variable magnification.

In the above embodiment, the reference value used as the judgment criterion when adjusting the magnification was fixed, but the paper quality of the original, the ambient temperature,
It may be changed according to the humidity and offset input value.

[Effects of the Invention] As described above, according to the present invention, it is possible to automatically perform focus adjustment and magnification adjustment, thereby obtaining a double OA reading device that further simplifies adjustment work during assembly and maintenance. be able to.

[Brief explanation of the drawing]

Fig. 1 is a layout diagram of main parts showing an embodiment of an image reading device according to the present invention, Fig. 2 is a layout diagram of each part showing the configuration of a copying machine to which the invention is applied, and Fig. 3 is a reference mark. 4 is a schematic perspective view showing the movement mechanism of the condenser lens and the CCD image sensor, and FIG. 5 is a route map showing the relationship between the reference mark brightness and the COD image sensor output. Fig. 6 is a route map for explaining the principle of focusing, Fig. 7 is a block diagram showing the configuration until the output of the CCD image sensor is given to the control device, and Fig. 8 shows the procedure for adjusting focus and magnification. Flow chart shown, No. 9
FIG. 10 is a block diagram showing a magnification detection configuration, FIG. 10 is a signal waveform diagram of each part thereof, and FIG. 11 is a route diagram for explaining the second characteristic value used for determining a focused layer. 100... Image scanner section, 102... Fluorescent lamp, 103... Mirror, 104... Condenser lens,
105...CCD image sensor, 106...Reference white board, 115-...Direct motion mtra, 201...Control device, M1-M3...Reference mark. Applicant Rico Co., Ltd. - Figure 1 Figure 2 Figure 3 Figure 4 Figure 511 Figure 6 Figure 7

Claims (9)

[Claims] (1) In an image reading device that optically reads an image in a reading area and focuses the reading beam onto a photoelectric conversion element through a lens, a predetermined mark attached outside the reading area on the original or the device body. , a mark detection means for detecting the mark from a read signal, a movement mechanism for moving at least one of the lens or the photoelectric conversion element in the optical axis direction, and the movement mechanism based on the mark information signal from the mark detection means. An image reading device comprising a control means for controlling. (2) The image reading device according to claim 1, wherein the control means controls the moving mechanism so that the lens is brought into focus based on the mark information signal. (3) The image reading device according to claim 1, wherein the mark information signal corresponds to the width of the mark. (4) The image reading device according to claim 1, wherein the mark information signal corresponds to a distance between the plurality of marks. (5) Even when the brightness of the above mark is in focus,
2. The image reading device according to claim 1, wherein the image reading device corresponds to a range of signal processing levels of the mark detection means and the control means. (6) The mark information signal is in accordance with the width of the mark itself or in accordance with the distance between a plurality of the marks, and the control means compares the mark information signal with a reference value and determines the width of the mark itself. 2. The image reading device according to claim 1, wherein the magnification of the optical system is detected and the moving mechanism is controlled based on the detected value. (7) The image reading device according to claim 6, characterized in that the width of the mark itself or the distance between a plurality of the marks is processed as time information and compared with the reference value. . (8) The image reading device according to claim 6, wherein the reference value can be corrected according to external conditions. (9) The image reading device according to claim 8, wherein the external conditions include the quality of the document paper, ambient temperature, humidity, and operation input values.