JPH02217835A - Image reader - Google Patents

Abstract

PURPOSE:To enable a copy to be taken if a step-out is fine by judging whether or not the extent of the step-out is a value where an image can be read under restricted conditions where a step-out hardly occurs in judging the step-out by a comparing means by detecting the extent of the step-out. CONSTITUTION:A scanner 10 is moved actually at certain timing, the number of movement steps from the scan starting home position to the position where a sensor 100 turns on is counted, and the range is found. At this time, the scanner 10 is driven at the speed which is slow enough not to cause a step-out and whether the scanner 10 is in a step-out state or not is judged from the difference between the found range and predetermined value. Thus, a scanner position detecting means detects the difference of the scanner from a specific initial position, i.e. the extent of the step-out, the comparing means decides the extent of the difference, and a scan condition restricting means judges whether or not the image can be read under the restricted conditions where the step-out hardly occurs. Consequently, when the step-out is fine, the image can be read under the conditions where the step-out hardly occurs.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an image reading device that reads a document while scanning the document by moving the scanner and the document relative to each other. The present invention relates to an image reading device that performs abnormality detection.

[Prior Art] In a copying machine using a conventional image reading device, a scanner scans an original, forms an image on a photoreceptor drum, and copies the original by transferring the image onto copy paper. I am doing it.

Normally, a scanner takes a predetermined initial position, reads the document based on that position, and synchronizes with the supplied copy paper. Therefore, for the copying machine to operate properly, the scanner must always be set at the initial position before starting copying. In order to reliably set the scanner at the initial position, a home position sensor is usually provided to set the scanner at the initial position, and a stepping motor is used as the scanner motor. Particularly in a color copying machine using a field-sequential printing method, since multiple scans are performed for each color, registration alignment is important to match the edges of the images in each scan.

For this reason, a stepping motor is also used as a scanner motor. That is, a stepping motor is used and numerically controlled to ensure positioning.

However, tax adjustments may occur in stepping motors. Step-out means that the motor does not follow the numerical control pulses sent from the controller. This tax adjustment occurs in the following cases:

(1) There is a certain relationship between the rotational speed of the stepping motor and the load torque at that speed, but this occurs when the load torque exceeds the limit. Cases in which the load torque exceeds the limit are shown below (2) and (3).
Due to reasons such as.

(2) This problem occurs when dust gets into the slider of the stepping motor when the scanner motor is left in a dusty place for a long period of time.

(3) Normally, a scanner motor is moved along a rail fixed to a document table on which a document is placed. At this time,
When a heavy object is placed on the document table, the document table may bend. As a result, the rail of the scanner motor is bent, resulting in distortion.

When the above-mentioned tax adjustment occurs, the position of the scanner cannot be controlled and the scanner does not stop at a predetermined stop position.

[Problem to be Solved by the Invention] Since a conventional copying machine using a scanner is configured as described above, when a step-out occurs in the scanner, the scanner is not stopped at a predetermined position and other parts are There is a risk that the copying machine itself will be destroyed. To deal with this, conventionally, overrun sensors have been provided at both ends of the scanner in the movement direction to prevent the scanner from overrunning a predetermined movement range. Therefore, when the overrun sensor detects an overrun of the scanner, it is determined that the copying machine is in trouble with the tax adjustment, and subsequent copying operations are disabled. For this reason, there is a problem in that even if the tax adjustment is small and there is no problem with copying if only the scanning conditions of the copying machine are restricted, copying becomes impossible.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an image reading device that can perform copying under conditions in which tax adjustments are difficult to occur, even if the tax adjustments are minute.

[Means for Solving the Problems] An image reading device according to the present invention includes an image reading scanner that uses a stepping motor to scan an image while reciprocating it relative to a document; The scanner starts scanning the document from a predetermined first initial position and returns to a second position after scanning, and the scanning is performed under a plurality of conditions, the plurality of conditions being variable, and a gap position detection means for detecting a difference between an initial position and a second position; a comparison means for comparing the difference with a predetermined first value and a predetermined second value; scanning condition reduction means for constraining the scanning condition to some of the plurality of conditions when it is determined that the scanning condition is between the first value and the second value.

[Operation 1] The detection means in this invention detects the difference from the predetermined position of the scanner, that is, the degree of step-out, and the comparison means determines that the difference is not a normal value but a tax adjustment, but under constraint conditions in which tax adjustment is difficult to occur. It is determined whether the value is such that it is possible to read the image.

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

FIG. 1 is a front view showing the overall configuration of a digital color copying machine to which the present invention is applied.

This copying machine converts a document image read by an image sensor into image data, which is a digital signal, and prints (forms) an image on paper using an electrophotographic method in accordance with this image data.

Referring to FIG. 1, the digital color copying machine includes an image reading section 71 for reading an image of a document and processing the read image, and a laser for recording an image signal read by the image reading section 71. A scanning exposure unit 72 for converting the image into an optical signal, and an image recording unit 7 for copying the original image onto copy paper using the laser beam output from the scanning exposure unit 72.
3. The image reading unit 71 is provided with a document table 16 for placing a document and below the document table 16.
6, a scanner 10 including an image sensor for reading an image of a document placed on the scanner 10, a scanner motor 11 for driving the scanner 10, a sensor 100 for detecting the home position of the scanner 10, and the scanner 10. Overrun sensor 101 for detecting the position of the scanner 10 to prevent overrun to the scanner motor 11 side
and a signal processing unit 20 for processing signals read by the scanner 10. The scanning exposure section 72 includes the signal processing section 20
It includes a printer radar 31 for converting the processed signal into a laser beam for recording, and a reflecting mirror 37 for reflecting the laser beam. The image recording section 73 is provided with the photoreceptor drum 41 for forming an electrostatic latent image with a laser beam reflected by the reflecting mirror 37, and on the outer periphery of the photoreceptor drum 41, and for charging the photoreceptor drum 41. A charging charger 43, developing devices 45a to 45d for developing the electrostatic latent image on the photosensitive drum 41, a transfer drum 51 for transferring the image on the photosensitive drum 41, and copying by the transfer drum 51. A fixing device 48 for fixing the image transferred to paper, a paper cassette 50 for holding the copy paper sent to the transfer drum 51, and a paper discharge for holding the copy paper fixed by the fixing device 48. and a tray 49.

The scanner 10 includes an exposure lamp 12 that irradiates the original, a rod lens array 13 that collects reflected light from the original, and
Close-contact CCD for converting focused light into electrical signals
and a color image sensor 14 consisting of a color image sensor 14 and the like.

In this embodiment, an image reading apparatus is shown in which the document table is fixed and the scanner is moved, but the scanner may be fixed and the document table is moved. In this case, the document table is driven by a stepping motor.

Next, the operation of the digital color copying machine shown in FIG. 1 will be explained. The scanner 10 is driven by a motor 11 to scan the original on the original table 16 when reading the original image. Here, the moving direction of the scanner 10 (direction of the arrow in FIG. 1) is the scanning direction, and the direction in which the image sensors 14 are arranged (direction perpendicular to the plane of the paper in FIG. 1) is the main scanning direction.

The original image illuminated by the exposure lamp 12 is photoelectrically converted by the image sensor 14 and sent to the read signal processing section 20.
is converted into a print signal of yellow, magenta, cyan, or black.

In the printer head section 31, the LD drive circuit 33 is operated according to the print signal for each color from the signal processing section 20, and the semiconductor laser 34 blinks (see FIG. 2).

A laser beam generated from the semiconductor laser 34 is reflected by the reflecting mirror 37 and exposes the photosensitive drum 41. The surface of the photosensitive drum 41 is uniformly charged by a charging charger 43, and an electrostatic latent image is formed by receiving the above-described exposure.

This electrostatic latent image is developed into yellow, magenta, cyan, or black by any one of the developing devices 45a to 45d. The developed image is transferred by the transfer charger 46 onto a sheet of paper wrapped around the circumferential surface of the transfer drum 51. After the above-mentioned process is repeated for at least one color of yellow, magenta, cyan, or black, the paper is separated from the transfer drum 51 by the separation claw 47, fixed by the fixing device 48, and ejected to the paper ejection tray 49. It is papered. During these periods, the scanner 10 repeats the scanning operation in synchronization with the rotational operations of the photosensitive drum 41 and the transfer drum 51. The transfer drum 51 is provided with a position sensor 53, and is controlled to synchronize with the scanner 10 based on a detection signal from the position sensor 53. The diameter of this transfer drum 51 is larger than the diameter of the photosensitive drum 41. This is because large size paper can be set by wrapping it around the circumferential surface of the transfer drum 51. Of course, both diameters may be the same.

Note that the paper is fed from a paper cassette 50, and its leading edge is chucked by a chucking mechanism 52 provided on the transfer drum 51, so that no misalignment occurs during transfer of each color. Further, 42 is an eraser lamp.

FIG. 2 is a block diagram showing the configuration of the read signal processing section 20. As shown in FIG. The image signals of three colors, R (red), G (green), and B (blue) photoelectrically converted by the image sensor 14 are each operationally amplified by a log amplifier 21 into a signal having a size corresponding to the image density. Ru. The reason why the log amplifier 21 is provided here is as follows. CCD
The image signal received from the original is proportional to the reflectance of the original.

Therefore, in order to convert this into an image signal, it is necessary to convert this into density. Generally, the phantom number of reflectance is proportional to density, so a log amplifier is used to convert the reflectance detected by the CCD into density. Next, it is converted into a digital signal by A/D conversion 622. This digital signal is an image signal (image data) having gradation, and is then subjected to shading correction by the shading correction circuit 23.

Next, the masking processing circuit 24 performs R and G.

Image signals (print signals) for printing corresponding to each print color of Y (yellow), M (magenta), C (cyan), and B (black) are generated from the image signals of the three colors of B by the developing device. It is generated according to the characteristics of toners 45a to 45d.

Note that the print signal for which color is generated depends on the CP.
It is determined sequentially by the control signal from U25. Further, the CPU 25 receives various key human power signals from an operation panel (not shown), and also receives a detection signal TBASE from a position sensor 53 provided on the transfer drum 51, and drives the scanner 10 based on this signal. A control signal for controlling the motor 11 is output from the CPU 25. Note that signals from a sensor 100 for detecting the home position of the scanner 10 and a sensor 101 for detecting an overrun of the scanner are also input to the CPU 25.

Note that the sensor 100 functions as a home position sensor when the power is turned on, but is not turned on at other times (when the scanner 10 is scanning).

The subsequent electric magnification/variation movement circuit 26 performs a magnification operation in the irradiation direction and a movement operation in the movement direction. In addition, by repeatedly outputting the same area multiple times within the electric magnification/movement circuit 26, it is also possible to output multiple identical images in the operating direction.

The halftone processing circuit 27 binarizes the print signal from the masking processing circuit 24 using a dither method, for example, to generate a binary pseudo halftone signal. The halftone-processed signal is sent to the LD drive circuit 3 via the I/F circuit 18.
3 is input. ! The /F circuit 28 has a line memory that stores image data line by line. This line memory has a capacity for two lines so that read and write operations can be performed in parallel. The LD drive circuit 33 blinks the semiconductor laser 34 in response to this signal data. The beam generated by the semiconductor laser 34 exposes the photosensitive drum 41 through a reflecting mirror 37, as shown in FIG. As a result, an image is drawn on the photoreceptor drum 41,
An electrostatic latent image is formed.

Next, scanner control of the digital color copying machine having the above configuration will be explained. In a digital color copying machine having a line memory but not a full screen memory as in this embodiment, it is necessary that the scanner 10 and the transfer drum 51 be driven in synchronization. In this embodiment, the photosensitive drum 41 and the transfer drum 51 rotate at a low speed, and the start-up of the scanning operation of the scanner 10 is controlled in accordance with the operation of the transfer drum, so that they are synchronized. Therefore, the rotation of the transfer drum 51 is detected by the position sensor 53 provided on the transfer drum 51, and this detection signal TBASE is input to the CPU 25. CPU2
Reference numeral 5 controls the motor 11 to drive the scanner 10 so that the leading edge of the original image can be read after a predetermined period of time has elapsed from the rise of the TBASE signal.

In this case, if the magnification in the sub-scanning direction changes, the scanner 10
The effective rise time of will vary accordingly. Therefore, it is necessary to adjust the start-up time of the scanner 10 by shifting the start-up timing of the scanner 10, shifting the home position of the scanner 10 itself, or performing a combination of these to correct the start-up time of the scanner 10 according to the magnification. .

FIG. 3A is a timing chart when the above correction is performed by shifting the home position of the scanner 10. Scanner 1 immediately starts at the rising edge of the TBASE signal.
0 is activated. The home position of the scanner 10, which is the starting position, differs depending on the magnification. For example, if the home position at 1x magnification is H7, the home position Ho at 0.5x is a quadrilateral /'+ AI/2 B+/
It moves away from the image leading edge position by 2 B+ (distance expressed in time x velocity), and the home position H2 at the time of doubling is a position closer to the image leading edge position by quadrilateral A2 A+ B+ 82 (see figure '1JBB). Here, T.B.
It goes without saying that the rise of the ASE signal does not necessarily have to coincide with time O, but may be earlier.

By controlling the activation start of the scanner 10 as described above, it is possible to start the scanning operation for the leading edge of the document image after a certain period of time from the fall of the TBASE signal, regardless of the magnification in the operating direction, and the print head unit 31 starts printing at this point. The relationship between the moving speed of the scanner and time is shown in FIG. In Figure 4,
The X-axis represents time and the Y-axis represents speed. A negative range on the Y axis also indicates a negative direction of speed. Referring to FIG. 4, scanner 1 has started up to a low scanning speed at time t.
0 is the scanner length (time t2
) at low speed. After scanning (time t
In a), the scanner 10 is immediately accelerated in the opposite direction (times t4 to 1.), returns to the home position at high speed (from time 1. to t), and stops (time t?).

Next, specific control of the scanner of the digital color copying machine during tax adjustment will be explained with reference to a flowchart.

FIG. 5 is a flowchart showing the main routine of the process for detecting the tax adjustment status of the scanner of the digital color copying machine.

Referring to FIG. 5, when the power of the digital color copying machine is turned on, initialization of the scanner 10 is first performed to bring the scanner 10 into a document reading state (S102). Next, it is determined whether or not the print switch is on (S104), and if it is, a test scan (S106) is performed to determine whether the scanner 10 is in the document reading state, and the scan The operation starts (
5108). Next, abnormality detection 1 (SllO) detects whether the scanner 10 is in an overrun state, abnormality detection 2 (S112) determines whether the scanner 10 is started normally, and the actual copying operation is performed. Each process (5114) is performed. Note that if the print switch is not turned on in step 5104, the processing flow moves to abnormality detection 1 (S110). Copy operation (5114
) is completed, the trouble flag is checked to determine whether the scanner 10 is in a trouble state due to step-out (S116), and if it is not in a trouble state (S
If YES in step 116), the end of the scan will be terminated (
3118). If the scan is completed (Y in S118)
ES), the process flow moves to a process for determining whether or not the print switch is turned on (S104). If the scan has not been completed in step 5118, the processing flow shifts to abnormality detection 1 (Silo).

Note that when it is determined in step 5116 that there is a trouble state (No in S116), it is determined whether the trouble state has been reset (5120). When the trouble state is reset in step 5120, the processing flow moves to an initialization subroutine (S102),
If the trouble status is not reset (N in S120)
(O), processing is stopped until the trouble condition is reset.

Next, details of each subroutine shown in FIG. 5 will be explained in order.

FIG. 6 is a flowchart showing details of the initialization subroutine shown in step 5102 of FIG.

The scanner 10 may not be at the home position when the digital color copying machine is powered on. Therefore, first, the operation of returning the scanner 10 to the home position is started. Here, the home position to be returned to is a position farther from the leading edge of the image than the scan start position at the minimum magnification (that is, when the scan speed is the fastest). This corresponds to the position indicated by HD in FIG. 3B. To achieve this kind of operation, scanner 1
The sensor 100 of the scanner 10 transmits a signal to the CPU 25 that indicates "L" when the position of the reading unit of 0 is at the above-mentioned Ho or further from the front edge of the image. The scanner 10 is provided at the home position (see FIG. 1).Using this sensor, when the power is turned on, the scanner 10 is first moved to the Ha position, and then moved to the home position for a predetermined magnification.

The above contents will be explained with reference to the flowchart shown in FIG. In the figure, CW indicates a forward direction (the direction in which the scanner 10 scans), and CCW indicates a reverse direction (the direction in which the scanner 10 returns).

First, it is determined whether or not the sensor 100 is outputting an "H'signal" (S202).When the sensor 100 is outputting an "H" signal, the reading section of the scanner 10 is located closer to the leading edge of the image than the HO. Therefore, the scanner motor 11 is reversed (5202), and the scanner 10 is driven by one pulse (S208).It is then determined whether the output of the sensor 100 has been reversed (S210'). When the output of the sensor 100 is inverted in step 5210, this means that the position of the reading section of the scanner 10 has reached HO, so that the scanner 10 can read.

At this time, a counter LCN T indicating the position of the scanner 10
+, :o is assigned. The counter LCNT is incremented by 1 when the scanner motor 11 moves by one pulse in the scan direction, and is decremented by 1 when it moves by one pulse in the return direction. Next, the number of pulses P to the home position of the scanner 10 with respect to the initial magnification inputted to the CPU 25 from the operation unit in advance,
is read (S2). Since the home position of the scanner 10 with respect to the initial magnification is always in the scan direction, the scanner motor 11 drives the scanner in the scan direction by one pulse (S218). At the same time, the counter LCNT is read.
The value of is incremented by 1 (S220). This operation causes the counter LCNT to reach the home position by the number of pulses P
, is repeated until it matches (S222).

If NO is determined in step 5202, scanner 1
Since the position of the reading unit 0 is further away from the leading edge of the image than Ho, the motor rotation direction of the scanner motor 11 is set to the scanning direction (5206), and the scanner motor 11 is driven by one pulse (S208). If the output of the sensor 100 is not reversed in step 5210, the scanner motor 11
drives the scanner 10 by one pulse in accordance with each motor rotation direction (S208).

Next, details of abnormality detection in the scanner drive indicated by 5110 and 5112 in FIG. 5 will be explained.

Since a stepping motor is used as the scanner motor 10, once the home position is determined when the power is turned on, the CPU 25 can numerically control the scanner 10 thereafter. However, if an unexpected load change occurs, a tax adjustment phenomenon will occur. In that case, it is difficult for the CPU 25 to immediately detect scanner drive abnormality. Therefore, in this embodiment, the sensor 100 and the sensor 101 shown in FIG.
is used to detect anomalies associated with tax audits, etc. The abnormality detection items are as follows.

(1) If the sensor 100 and the sensor 101 become 'L' while the scanner 10 is being driven, they stop generating pulses and apply a brake to the scanner motor 11. A trouble message is displayed on the display of the copying machine.

(2) H at the timing when the scan ends.

The scanner 10 is driven until the counter LCN at that time is
If the value of T is larger than the allowable error, it is determined that a tax adjustment has occurred, and compensation processing is performed.

The flowchart for abnormality detection 1 will be described in detail with reference to FIG. As described above, the sensor 100 is not turned on except when the power is turned on. Furthermore, the sensor 101 is also installed so that it is not normally turned on.

Referring to FIG. 7, in the flow of abnormality detection 1, it is first determined whether sensor 100 or sensor 101 is turned on (S302). Next, it is determined whether a scan is being executed (S304).

As described above, both the sensor 100 and the sensor 101 are installed so that they are not normally turned on during scanning.

Therefore, if these sensors are turned on, it may be determined that there is an abnormality. Therefore, when the determination in step 5304 is YES, the motor drive pulse of the scanner motor 11 is stopped (S306). Next, a message indicating that there is a trouble is displayed on the operation unit of the copying machine (S308). Then, 1 is assigned to a trouble flag indicating that the copying machine is in trouble (S310).

N in steps 5302 and 5304, respectively.
When it is determined that the copying machine is not in trouble, the processing flow returns.

Next, abnormality detection 2 will be explained. If no synchronization phenomenon occurs, the distance between the scan start home position and the sensor 100 at the given magnification should be constant. Therefore, the scanner 10 is actually moved at this timing, the number of movement steps from the scan start home position until the sensor 100 is turned on is counted, and the distance is measured.

In that case, scan Scanner 1 at a sufficiently slow speed to avoid tax adjustment.
0 is driven. It is determined whether the scanner 10 is in the correct state based on the difference between the measured distance and a predetermined target value. This process will be explained with reference to the flowchart of abnormality detection 2 shown in FIG. In the flow of abnormality detection 2, it is first determined whether the scanner 10 is in a stopped state (S402). If the scanner 10 is in a stopped state (YES in S402), it is determined whether the operation request for abnormality detection 2 is not performed (5404). If there is an operation request for abnormality detection 2 (YES in S404), the scanner 10 is driven at low speed to the position of the sensor 100 by the scanner motor 11, and the distance is measured by the number of pulses at that time (S4
06). Next, a predetermined target value and step 5406
The difference ε from the a1 constant value obtained in (8408) is calculated. ε
It is determined whether or not is less than or equal to a value (L) sufficiently close to 0 within the measurement error range (S410). If ε is less than or equal to fL (YES in S410), the scanner 10 is determined to be normal, and is returned to the home position where scanning is started (5412). When it is determined in step 5410 that the difference ε is larger than a birthmark, it is determined whether the difference ε is equal to or greater than a predetermined value Q, 2 (S414). If it is determined in step 5414 that the difference ε is greater than or equal to the predetermined value q2, (S4
14: YES), it is determined that this is a non-compensable tax adjustment occurrence,
Similar to abnormality detection 1, a trouble state is displayed on the operation unit of the copying machine (8418). Then, set the trouble flag to 1 to indicate the occurrence of trouble (S420)
. When it is determined in step 5414 that the difference ε is smaller than the predetermined value 2, it is determined that the tax adjustment is compensable, and subsequent operations are restricted, and the scanner unit of the copying machine is restricted. is displayed (5416), and the scanner 10 is returned to the position before measurement (5412).

Next, the above compensation operation will be explained. FIG. 9 is a diagram showing the relationship between the rotation speed and torque of a stepping motor generally used as the scanner motor 11. The X-axis shows the rotation speed, and the Y-axis shows the torque. Referring to FIG. 9, the output torque of the stepping motor decreases as the rotational speed increases. This means that t in FIG.
This means that there is the least torque margin in the acceleration state near the time indicated by t and in the deceleration state immediately after the time indicated by t. Originally, the scanner motor 11 is selected so as to ensure a margin of torque in these respects, but it is conceivable that some tax adjustment may occur in these respects due to unexpected load fluctuations. This tax adjustment is done by reducing the acceleration and deceleration at the time of return (that is, from t4 to
t) or by increasing the time between scanner 1
This can be avoided by lowering the zero return speed itself. At this time, the disadvantage is that the time t6 at which the return ends is delayed, and the scanner operation that normally would have finished the return during one rotation of the transfer drum cannot be performed.
As a result, the transfer drum must be left idling in the next copying process. Therefore, a warning is displayed on the operation unit to inform the user of this fact.

At a small magnification during reading scan, the scanner 10 is driven with a speed curve similar to the speed curve during return. In this case, if the acceleration is reduced, the time from 0 to t becomes longer, and the acceleration of the scanner 10 cannot be completed within the time from the fall of the TBASE signal to the registration position, which causes a problem.

Furthermore, since the distance required for acceleration also increases, the copying machine must be made larger in advance. From the above points, it is necessary to restrict the use of copying machines at low magnifications. For example, if a copying machine was originally capable of being used in a variable magnification range of 0.5x to 4x, the use of the copying machine would be limited to a range of 0.7x to 4x when compensation is required under tax regulations. , the fact that this restriction has been added is displayed as a warning on the operation panel, similar to the example above.

The abnormality detection 2 measurement may be performed, for example, after a certain period of time after the end of the previous copying operation (for example, during auto-clear if the copying machine has an auto-clear mode). Alternatively, when the user looks at the image and feels that there may be a shift between colors in the sub-scanning direction, the user may request the abnormality detection 2 operation through the operation unit. Further, the above two operations may be used together.

Next, the test scan will be explained. A test scan is a scan to determine whether or not the tax adjustment phenomenon has actually been suppressed when the scanner of the copying machine is in the tax adjustment state, with restrictions on copy magnification and scanner acceleration as described above. . After the first copy switch is turned on after the restriction is applied, a scanning operation with the first magnification is performed within the restriction range before feeding the copy paper.Then, after the scanner 10 returns, the distance to the sensor 100 is is measured. If the measurement result at this time is determined to be tax-adjusted, then the process proceeds to the copying process. Further, after the restriction is applied, a briscan may be performed once in the operation mode each time the copy switch is turned on to determine the presence or absence of step-out. If it is determined that there is a step-out in the scanner 10 during the above test scan, the subsequent copying operation will be stopped as a problem.

The above contents will be explained with reference to test scan flowcharts in FIGS. 10 and 11. FIG. 10 is a flowchart showing the processing of test scan part 1. In the first test scan, it is first determined whether this is the first copy request after restriction (S502). step 550
When it is determined that it is the first copy request in step 2 (YES)
, First, paper feeding is not performed (S504). Next, the scanner 10 is blisscanned at the minimum magnification within the limited range (5
506). Scanner 1 up to sensor 100 at low speed
0 is moved, and the distance of scanner deviation is measured using the number of pulses at this time (5508). The deviation value ε is expressed as the difference between a predetermined target value and a measured value (S 51
0). Next, it is determined whether the deviation ε is close to 0 within a constant error range of 4), for example, hair, or less (S 512).
. If the difference ε is 1 or less (YES in step 5512)
), the scanner 10 is returned to the position before measurement (85
1, 4), the paper feed wait suspended in step 5504 is canceled (S516). If the difference ε is larger than the hair in step 5512, a trouble flag is displayed on the operation unit of the copying machine (8518), and 1 is assigned to the trouble flag for indicating the t' syllable (S520).

Note that if it is determined in step 5502 that this is not the first print request after the restriction, the processing flow is returned.

FIG. 11 is a flowchart showing the second test scan method during compensation operation.

Referring to FIG. 11, according to the second test scan method, it is first determined whether or not any restrictions are imposed on the scanner 10 (S602), and when it is determined that there are restrictions (S602) (YES), paper feeding wait processing (S604) is performed to interrupt paper feeding, and blisscanning is performed in the operation mode (5606). Then, the scanner 10 is moved to the sensor 100 at a low speed that does not cause tax adjustment, and the number of pulses at that time is measured to measure the distance from the predetermined position (S608). Next, the difference ε between the predetermined target value and the measured value obtained in step 8608
is calculated (S610). Next, it is determined whether the difference E is less than or equal to a predetermined value fL1 close to 0 within the measurement error range (S612), and if the difference ε is less than or equal to the predetermined value (YES in step 5612), the scanner 10 is returned to the position before measurement (8614), and the paper feed wait process performed in step 5604 is canceled (S610).

In step 612, if the difference e is larger than a predetermined value (, (No), display a trouble state on the operation panel of the copying machine. 5618), and 1 is assigned to the trouble flag for displaying the trouble state. (5620).

[Effect of the Invention] As described above, according to the present invention, the scanner position detecting means detects the difference from the predetermined initial position of the scanner, that is, the degree of tax adjustment, and the comparing means detects the magnitude of the difference. The scanning condition constraint means determines whether it is possible to read the image under constraint conditions that do not easily cause tax contrast. As a result, when the tax adjustment is minute, it is possible to provide an image reading device that can read images under conditions where the tax adjustment is unlikely to occur.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the overall configuration of a digital color copying machine, FIG. 2 is a block diagram showing the configuration of the read signal processing section 20, and FIG. 3A is a correction by shifting the home position of the scanner. FIG. 3B is a diagram showing the positional relationship between the leading edge of the image and the home position at each magnification, and FIG. 4 is a graph showing the relationship between time and speed in the movement of the scanner. FIG. 5 is a main flowchart for detecting the tax adjustment status of the scanner, FIG. 6 is a flowchart showing a subroutine for initializing the scanner, FIG. 7 is a flowchart showing a subroutine for abnormality detection position, and FIG. FIG. 8 is a flowchart showing the subroutine of abnormality detection 2, FIG. 9 is a graph showing the relationship between the rotation speed and torque of the stepping motor, and FIG. 10 is a flowchart showing the subroutine of test scan part 1. FIG. 11 is a flowchart showing the subroutine of test scan part 2. 10 is a scanner, 11 is a scanner motor, 16 is a document table, 20 is a signal processing section, and 100 and 101 are sensors. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 1, Figure 38, 838, Figure 4, Figure 5, Figure 5, Figure 7, Figure 8, Figure 10, Figure 8, Q, times # comparison (pps), Figure 11

Claims (1)

[Scope of Claims] An image reading scanner for reading an image of an original while scanning the original by making a reciprocating motion relative to the original using a stepping motor; The scanning starts from a predetermined first initial position and returns to a second position after the scanning, the scanning is performed under a plurality of conditions, and the plurality of conditions are variable; scanner position detection means for detecting a difference between an initial position and the second position; and comparing the difference with a predetermined first value and a predetermined second value different from the predetermined first value. comparing means; when the comparing means determines that the difference is between the first value and the second value, changing the scanning condition to some of the plurality of conditions; An image reading device comprising a scanning condition constraining means for constraining.