JP2003098793A - Color alignment control system for image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive color alignment control system which does not take the traces of connection as the noise of detection of a pattern for position detection even when using a transfer belt having the traces of connection in a color image forming apparatus and prevents the malfunction based on erroneous detection of the flaws of the belt or omission of pattern detection and realizes accurate color slippage correction control. SOLUTION: A detection means is provided which has an optical sensor separately arranged in a position where the pattern for position detection is not added in the width direction of the belt and detects a pattern other than the pattern which is extended in the width direction of the belt like a joint. A means for excluding positional information obtained by the detection means from positional information obtained with a pattern detection means is further provided to remove noise information caused by a pattern other than marks which is extended in the width direction of the belt like a joint. The number of patterns in a pattern group is checked, and information is excluded in the case that this number does not coincide with a prescribed number.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for a technique for improving reliability in detecting position information of a long moving object, and particularly for preventing malfunction in color matching control of electrophotography in an image forming apparatus of a tandem type color developing system. Regarding technology.

[0002]

2. Description of the Related Art In a tandem type image forming apparatus of this type which executes multiple transfer for each color component of cyan, magenta, yellow, and black, image registration technology for each color, so-called resist technology, is used for finishing a color image. In the above, various methods have been conventionally used to detect the positional relationship between the drums of each color. For example, Japanese Patent Laid-Open No. 8-
Japanese Patent No. 44134 discloses a plurality of image forming means for forming an image corresponding to image information and a position detecting pattern image corresponding to position detecting pattern information, and the image forming means of the plurality of image forming means. And a transfer means for sequentially transferring the position detection pattern image onto the same transfer material, a background distribution detecting means for detecting a background distribution on the transfer material, and the above-mentioned value based on the value detected by the background distribution detecting means. Threshold value setting means for setting a threshold value when detecting the position detection pattern image, pattern image detecting means for detecting the position detection pattern image based on the value set in the threshold value setting means,
And a recognition unit for recognizing the transfer image shift based on the detection result of the pattern image detection unit. With this configuration, a threshold value or an operating state is set so that the fluctuation of the background portion of the belt does not appear in the output. Since the position detection pattern image is detected without performing shading correction in this way, it is possible to reduce the memory and the processing amount while preventing the detection accuracy from deteriorating due to deterioration of the belt over time. In addition, it is possible to provide an image forming apparatus having a high commercial value such as cost reduction, productivity improvement, and color misregistration correction accuracy improvement.

In Japanese Patent Laid-Open No. 10-78734, the phase difference between the latent image writing position and the transfer position of the image carrier is approximately 1
The pattern for detection formed on the endless carrier or the like is set to 80 degrees, and by the pattern detection means and the information of the vibration component regarding the periodical rotation fluctuation obtained by the detection means,
Drive control means is provided for finely adjusting the rotational speed of the image bearing member, the endless bearing member, or the like so as to cancel the year-to-year fluctuation. Suitable for eccentricity caused by various types of rotating bodies themselves such as body drums, transfer belts, intermediate transfer body belts or their mounting, eccentricity due to clearance error of the drive shaft of the rotating body, and periodical rotation fluctuation caused by uneven belt thickness, etc. The present invention provides an image forming apparatus capable of sufficiently and sufficiently suppressing the AC color registration deviation.

In Japanese Patent Application No. 2000-231235, a plurality of image forming units form images of different colors on a plurality of image carriers arranged side by side, and each color formed on each of the image carriers. In an image forming apparatus capable of forming a multicolor image by superimposing images, a positional deviation amount detecting means for detecting an arrangement positional deviation amount of each image carrier and a density control processing for each image forming unit are performed. Density control means, control for controlling the positional deviation amount detection means and the density control means so that the positional deviation amount detection processing for each image carrier and the density control processing for each image forming unit are executed in parallel. A plurality of drum units 41 that are arranged side by side.
Indispensable in an image forming apparatus capable of forming a multicolor image by a plurality of image carriers by the CPU controlling the Y, 41M, 41C and 41Bk arrangement position deviation amount detection processing and the density control processing to be executed in parallel. It is possible to significantly reduce the time until the apparatus starts up by simultaneously performing the arrangement position displacement amount detection processing of each image carrier and the density control processing for each image forming unit.

In Japanese Patent Application No. 2000-284561, a set of resist patterns of each color is formed in the transfer belt 1
It is formed repeatedly so that it becomes the circumference. By detecting these resist patterns, color shift amount data for cyan, magenta, and yellow with respect to black is obtained for one round of the belt, and from the color shift amount data, components due to uneven rotation of the photosensitive drum and transfer belt Extract and save the components that are caused by uneven driving. At the time of image formation, the phases of the photoconductor drum and the transfer belt are detected, the color shift data of each of the above components is combined in accordance with the phase, and the photoconductor of each color is corrected so as to eliminate the combined color shift. A correction pulse in which the writing timing for each scanning line to the drum is corrected is generated, and each LED array is driven according to the correction pulse. Based on the extracted color misregistration components, the color misregistration correction unit continuously corrects color misregistration during image formation due to the multiple transfer so that color misregistration components do not occur during image formation. It is possible to execute highly accurate color misregistration correction that faithfully reflects the change in the phase.

[0006]

As shown in the above example, the conventional positional relationship detection method for each color drum for color misregistration correction is an optical method in which the position detection pattern on the belt is reflected or transmitted. The position is detected by means of a means, but if there are joints (connection marks) on the belt itself, it is difficult to detect it with the pattern for position detection, so a seamless belt is used as the transfer belt. Was required to do. However this seamless belt whereas setting the peripheral length and the like dimensional accuracy of manufacturing the rotational direction is determined, which is assumed to its correspondence costly bothersome for absolutely manufacturing cost. Also, when a pattern is detected, if there is a scratch on the transfer belt, it may be mistakenly recognized as a pattern, or if the patterns are overlapped and imaged or the pattern cannot be detected for some reason, a malfunction may occur in the adjustment amount indexing work. I had to wake up. In view of such a problem of the conventional technique, an object of the present invention is not to use a transfer belt having a connection mark in a color image forming apparatus as the detection noise of a pattern for position detection, and An object of the present invention is to provide a low-priced color matching control method capable of preventing erroneous detection of a scratch on a belt and erroneous operation due to omission of pattern detection and realizing accurate color misregistration correction control.

[0007]

A method of removing noise information due to a pattern other than marks extending in the belt width direction such as a joint in a color matching control system of a color image forming apparatus for executing color matching control according to the present invention is In a color image forming apparatus that forms a color matching pattern on a transfer belt, obtains positional relationship information of each photosensitive drum from a color matching pattern detection signal converted into an electric signal by an optical sensor, and executes color matching control, An optical sensor is separately arranged at a position not provided with the pattern in the belt width direction, and means for detecting a pattern other than the pattern extending in the belt width direction such as a joint is provided, and the position information obtained by the means is By providing a means for excluding the position information obtained by the pattern detection means, a pattern other than a mark extending in the belt width direction such as a joint is provided. It was to remove the noise information by. Further, in the color matching control method of the color image forming apparatus that executes the color matching control of the present invention, a method for preventing malfunctions based on erroneous detection of a scratch on the belt and omission of pattern detection is a method of preventing a specific reference color pattern from being provided at predetermined intervals. Has a means for forming a predetermined number of different patterns on the belt and a means for counting the number of patterns detected by the optical sensor, and detects between the specific reference color pattern detection and the next specific reference color pattern detection. When the count value of the different pattern is different from the predetermined amount, the reliability of the detection position signal is low and it is not adopted as the detection signal for executing the color matching control.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, even if a transfer belt having joints is used, the joints (connection marks) are processed so as not to become noise in pattern detection. Depart from releasing the conditions for using the belt. In this type of color image forming apparatus, as shown in FIG. 1, a transfer belt 1 is endlessly provided between driving rollers and is driven to rotate in one direction. Meanwhile, magenta, cyan, yellow, black 4
The color photosensitive drums 2m, 2c, 2y, 2k are arranged in tandem, and the images are applied and overlapped for each color according to the driving of the belt, and a color image is formed on the transfer belt. that time,
It is well known that if the images do not match for each color, a so-called color shift phenomenon occurs and the quality of the image is degraded. As described above, conventionally, a color matching pattern is formed on the transfer belt 2,
The photosensitive drum 2m, 2c, 2y, 2k for each color can be detected from the gap
A method is adopted in which a gap is calculated and the timing of writing the image information for each color to the drum is adjusted. It is common to use an optical sensor to detect the above color matching pattern, but if there is a joint in the belt during this detection, it will be detected together with the color matching pattern, so it is necessary to use a seamless belt. It is said that.

In the detection of the pattern of the present invention, an optical sensor 3 having a light receiving portion composed of a light source and a photoelectric element is used to receive the reflected light on the belt surface. When a pattern is formed on the belt surface, the reflectance of that portion changes and the received light intensity also changes. Since a voltage corresponding to the intensity of received light is generated in the light receiving portion formed of a photoelectric element, this voltage value is used as the pattern detection signal. This detection signal becomes a voltage value signal corresponding to the position of the belt, and as shown in FIG. 2, the amount of reflected light starts to decrease from the position where the pattern is approaching the optical sensor 3, and a low voltage value is shown in the pattern width portion, and the end portion It begins to rise from the position approaching and gradually returns to the high voltage value corresponding to the reflected light of the belt. Next, a method for specifying the position of the pattern is provided. In the present invention, a category control means for determining the rising and falling tendency of the voltage of the color matching pattern detection signal is provided, which is, for example, via a delay means. It can be realized by a simple means such as providing a means for comparing the generated signal and a real-time signal and determining the positive / negative of the signal. Then, an appropriate reference voltage value L is set in advance, and the time point at which the reference voltage value L crosses when rising or falling tends to be specified as a count value and stored in time series. This count value corresponds to the time signal from the time when the reference position of the belt (for example, the joint of the belt) is detected, but it corresponds to the position signal from the reference position on the assumption that the belt is driven at a constant speed. To do. The count value between falling and rising is color-matched by subtracting the count value Td when the reference voltage value L when falling is crossed from the count value Tu when the reference voltage value L when falling is rising The center point position information of the pattern is obtained by executing the calculation used as the width information of the pattern and adding the count value of the point where the pattern width obtained by this calculating means is divided by 2 and the reference voltage value L in the downward tendency. It is obtained as a count value for the reference position of. That is, the center position is Td + (Tu
-Td) / 2. Further, in the present invention, as shown in FIG. 3, an optical sensor 4 separate from the optical sensors 3a and 3b for pattern detection is arranged at a position where the pattern 6 is not formed in the width direction of the belt 1, and the joint 5 is formed. A means for detecting a pattern other than the pattern extending in the width direction of the uniform belt is provided. The count position information obtained by the means is also detected as the center position of the width similarly to the center point position information of the pattern 6 described above, but this information corresponds to the position of the joint (connection mark) 5 of the belt. Therefore, since the position information of the connection mark is mixed as noise in the pattern center position information obtained by the detecting means, the information is specified and deleted from the stored information. According to the present invention, these means are provided to remove noise information due to patterns other than marks extending in the belt width direction such as joints. Although the present invention has been described as being related to the color matching control system in the color image forming means, the technical idea is not limited to this, and an optical sensor that receives reflected light or transmitted light from the belt surface faces the belt surface. In which the optical sensor detects a mark indicating the position on the belt to obtain position information, the optical sensor is separately arranged at a position not marked in the belt width direction, and a joint or the like is provided. By providing a means for detecting a pattern other than the mark extending in the belt width direction and by removing the position information obtained by the means from the position information obtained by the mark detecting means, the belt width direction such as the seam The present invention can be widely applied to a belt position detection method capable of removing noise information due to patterns other than extended marks.

Further, the present invention also provides a color matching control system for preventing an erroneous operation based on an erroneous detection of a scratch on a belt or a pattern detection failure in a color image forming apparatus.
In the apparatus of the present invention, when horizontal and diagonal pattern groups 6a and 6b of four colors are formed on the transfer belt as shown in FIG. 4, the pattern is detected by the optical sensor 3 and the number of the patterns is counted. And means for doing so. The reference pattern is, for example, a black horizontal line pattern, and M, C, and Y horizontal lines and K, M, C, and Y horizontal line patterns exist between that and the next black horizontal line pattern. Therefore, when the pattern is normally detected, the counting means should show a value of 7 between the reference pattern and the next reference pattern. In the color image forming apparatus, the control method of the present invention for preventing the erroneous detection of the scratch 8 on the belt and the erroneous operation based on the omission of the pattern detection is the count value of the pattern detected between the detection of the specific reference pattern and the detection of the next specific reference pattern. Is different from the predetermined amount, the detected position signal has low reliability and is not used as a detection signal for executing color matching control. For example, when the optical sensor 3 erroneously detects the flaw 8 on the transfer belt as a pattern and detects it, the count value increases by the number of flaws that are erroneously recognized and counted. Also, if patterns are overlapped and imaged, they are detected as one pattern, and position information for each color cannot be obtained, but in this case, the count value is reduced by the number of overlaps. . Furthermore,
The count value also decreases when the pattern cannot be detected for some reason. Such an abnormality detection is performed by the optical sensor 3 between the reference pattern and the next reference pattern.
By providing a means for counting the number of patterns detected in step 1, there is provided a color matching control method for preventing an erroneous detection of a scratch on the belt and an erroneous operation based on the omission of pattern detection in the color image forming apparatus. Although the present invention has been described above as being related to the color matching control system in the color image forming means, the technical idea is not limited to this, and a long length that optically detects a mark provided as position information and runs. In the one that detects the position of the body, the added marks are specific marks at predetermined intervals, and a predetermined number of different marks are added between them, and between the specific mark detection and the next specific mark detection. The present invention can be widely applied to a position detecting method for a long body characterized in that when the detected count values of different marks are different from a predetermined amount, the detected position signal is treated as having low reliability.

[0011]

Embodiment 1 An embodiment of a color matching control system of a color image forming apparatus of the present invention will be described. In this embodiment, as shown in FIG. 3, the color matching pattern 6 is formed on both sides of the transfer belt 1 in the width direction, and the pattern detecting photoelectric sensors 3a and 3b are arranged at positions facing the both sides. The detection mechanism is provided on both sides in order to detect the distortion of the optical system such as the mirror and the angular deviation of the photosensitive drum with respect to the traveling direction of the belt. Further, a photoelectric sensor 4 for detecting a connection mark is arranged so as to face the central portion of the belt where the color matching pattern 6 is not imaged.
Only the connection mark of the transfer belt 1 is detected without being affected by. Color matching pattern is black, yellow, cyan, magenta 4
The horizontal and diagonal lines of color are imaged, and one pattern group has eight patterns. In this embodiment, eight pattern groups are used.
In addition, only one horizontal black line that serves as a reference pattern is independently written.

The procedure for removing the connection mark noise in this embodiment will be described with reference to the flow chart shown in FIG. After the start, the transfer belt connection mark detection flag stored first is turned off, the color matching pattern sensor 3 and the connection mark detection sensor 4 on both sides are activated, and the pattern detection operation is executed. This detection is stored as position data of the central value by the above-mentioned method. If the connection mark detection flag is OFF, the connection mark detection sensor 4 detects the connection mark and the count value indicating the position at that time is stored in the memory. When the positional information of the connection mark can be detected, the transfer belt connection mark detection flag is turned on. When it is confirmed that the pattern detection of the color matching pattern sensors 3 on both sides is completed, the process proceeds to the next step. First, the position information of the pattern detected on the A side is confirmed. The numerical value n for specifying the pattern is reset to 0, it is confirmed that this n is smaller than the number of patterns in the pattern group (at first, of course), and the position of the first detected pattern is checked. The number of patterns is eight, but since the first pattern is 0, this number is seven. A calculation is performed by subtracting the previously acquired position information count value of the connection mark from the position information count value of the top mark of the pattern group, and the calculated value is set to ya. Is this ya value within the transfer belt connection mark position detection range value Δ? Check whether or not. That is, if it is outside this range, it is considered that this pattern is not a connection mark. If it is determined that it is not a connection mark, the value of n is incremented by 1 and the next detection pattern is checked. This check is sequentially executed, and if pattern detection within the range is found, it is specified as a transfer belt connection mark, the A side connection mark position detection flag is turned ON, and the process proceeds to the next step.
The next step is to confirm the positional information of the pattern detected on the B side, and the operation is exactly the same as that on the A side. In this way, in the present embodiment, the connection mark position information detected by the color matching pattern detecting optical sensor 3 as the pattern position information is the color image from the position information of the color matching pattern that is erased from the memory and acquired. The position alignment control of is correctly executed.

Next, a description will be given of an embodiment having a coping function in color matching control when a flaw on the belt is erroneously detected or is missed due to some cause. In this embodiment, as shown in FIG. 4, the color matching pattern is composed of one independent horizontal line of the reference color black, and four horizontal lines of four colors of black, yellow, cyan, and magenta, and eight diagonal lines, forming a group. Since the group is composed of 8 groups, the total is 8 × 8 + 1 = 65. If it operates normally, the optical sensor 3 should first detect the black independent horizontal line which is the reference line, and then detect the first black horizontal line of the color matching pattern group. Then, the line image of the group consisting of the horizontal lines K, Y, C, M of Y, C, M is detected following the black horizontal line at the beginning of the line, and then the black horizontal line that becomes the first mark of the next group is detected. Then, similarly, eight pattern groups are sequentially detected. If the detection signal is correct, the detection position (pattern interval) should be within a certain range with respect to the set value. The present invention originally detects and adjusts the positional deviation between the four-color photosensitive drums and the optical system. However, in principle, the deviation cannot be a large displacement amount, and it cannot occur in principle within a predetermined range. This is because it becomes a thing. However, when a pattern other than the pattern formed for color matching such as a scratch on the belt is detected, the position signal exceeds the above range. This embodiment is to detect the abnormality detection by checking the positional relationship between the patterns and take measures against it.

The detection control operation of the color matching pattern group in this embodiment will be described with reference to the flowchart of FIG. Starting from i (identifying the detection points by sequentially numbering them in time series), the start mark point value i is set to 0, and the stored interval detected value is reset. This i will not exceed the pattern matching limit value (the number corresponding to the total number of color matching patterns) unless a lot of noises such as scratches are detected, so it is checked whether it is smaller than that number, and i is within the limit value. In the case of, the first detected pattern is stored in the start mark detection buffer as the positional information of the pattern of i as sampling data [i]. After this, use the beginning of the sampling data as the start mark,
Find a point that fits the gap between the horizontal lines of the reference color black. This point becomes the first horizontal line of the reference color black. When it is smaller than the interval check reference value, the sampling data j + 1 is accumulated in the first mark detection buffer, the interval calculation is executed by subtracting the value of the star mark detection buffer from this value, and the result is stored in the interval calculation buffer. It is checked whether this value is an appropriate value within the range of the maximum value and the minimum value of the reference color horizontal line pattern interval. If it is unsuitable, the process is redone, and if it is a proper value, the start mark point i and the first mark point j + 1 at this time are adopted and it is set that the interval has been detected. By this operation, it is possible to specify a group having a proper interval between the reference color (black) horizontal pattern and the next reference color horizontal pattern.

Next, the operation for confirming whether a predetermined number of color matching patterns in each group divided by the horizontal color reference pattern are included will be described with reference to the flowchart of FIG. First, start with i (identify the color matching pattern sets by sequentially chronologically numbering them) to determine whether this i is smaller than the maximum number (8 in this case) of color matching pattern groups. In this case, the value obtained by adding the first mark point to the offset point for the next reference color horizontal pattern is used as the sampling data as the calculation mark of the reference color horizontal pattern. First, j (the numbers in the patterns in each group are sequentially specified in time series) is set to 0, and j is the number of patterns between the reference color patterns (in this embodiment, other than the reference color horizontal line, 7 If the following is true, the position information in the start mark detection buffer is subtracted from the position information in the first mark detection buffer to calculate the interval, and the result is stored in the interval calculation buffer. Then, in the next interval calculation buffer, as the sampling data, data obtained by subtracting the calculation mark of the reference color horizontal pattern from the sampling data of the value obtained by adding the first mark point to the offset point for the next reference color horizontal pattern Memorize Check whether this value is between the minimum and maximum values of the corresponding pattern interval, and if it is not within this range, it is not a correct pattern relationship,
That is, it is regarded as noise, and this j is incremented by 1 (next detection pattern) and returned to the beginning. If it is within the range, it is regarded as a relationship between the correct reference color horizontal patterns, and the reference color horizontal pattern point of [i] is stored as sampling data as a value obtained by adding the first mark point to the offset point for the next reference color horizontal pattern. To do. Next, confirm that the i value at this time is 7 or less, and then [i]
1 is added to the number of patterns between the reference color lateral patterns of, and the process returns to the beginning to check the next pattern j + 1. This operation is repeated in the order of patterns, and this operation is repeated. If i becomes 7 or more, it is confirmed that the value obtained by adding the first mark point to the offset point for the next reference color horizontal pattern to j is 0 or more. , At that time, the number i of the groups under the reference color is increased by one. It is confirmed that this value is 0 or more, and the point of the reference color lateral pattern of i is calculated by adding the first mark point value to the offset point for the next reference color lateral pattern and stored. Then, the j value is incremented by one and the process returns to the beginning to perform the work for the next pattern. If this j value exceeds a predetermined number between the reference color lateral patterns, it is confirmed that the count value between the reference colors at that time is 8, and it is considered that the pattern position detection of the i group is proper. Set enable of. Then, the offset value for the next horizontal pattern of the reference color is calculated by adding the count value of the points between the reference colors in this i group, and the number of j is incremented by 1 and returned to the base. When the i value reaches the maximum value of the color matching pattern group, this work is ended. By the above work, the group in which the normal number of patterns are detected in the group (usable group) and the abnormal group can be specified.

Finally, the function of excluding from the calculation of the color matching pattern set correction value when the number between the reference patterns does not meet the specified value will be described with reference to FIG. Starting, i is set to 0, and pattern groups are sequentially selected. Make sure that i is less than the total number of pattern groups,
It is checked that the i group at that time has available points set. If the number of patterns in the group does not match the specified value, it is not set, so the i group is skipped and the next i + 1 group is checked. When this i group is set, the pattern information of the i group is valid, and the horizontal line position information of K, horizontal line information of Y, horizontal line information of C, horizontal line information of M, and oblique line information of K of the group are valid. , Y diagonal information, C diagonal information,
The shaded information of M is sequentially set as valid information. Continued i + 1
Check each group and repeat this process for each group in sequence. This work is finished when the work for all eight groups is finished.

[0017]

According to the first aspect of the present invention, an optical sensor is separately arranged at a position where the mark is not provided in the belt width direction, and a pattern other than the mark extending in the belt width direction such as a joint is detected. By removing the position information obtained by the means from the position information obtained by the mark detecting means, noise information due to patterns other than marks extending in the belt width direction such as joints is removed. Therefore, an optical sensor that receives reflected or transmitted light from the belt surface is arranged facing the belt surface, and the optical sensor detects a mark indicating the position on the belt to obtain position information widely. It can be applied to detect the position information accurately. In the invention described in claim 2, an optical sensor is separately arranged at a position not provided with the pattern in the belt width direction, and means for detecting a pattern other than the pattern extending in the belt width direction such as a joint is provided. By providing means for removing the position information obtained by the means from the position information obtained by the pattern detection means, noise information due to patterns other than marks extending in the belt width direction such as joints can be removed. , A color image forming apparatus that forms a color matching pattern on a transfer belt, obtains positional relationship information of each photosensitive drum from the color matching pattern detection signal converted into an electric signal by an optical sensor, and executes color matching control. It enables the use of inexpensive jointed belts without using the high-cost seamless transfer belt that was required in the past. It was.

Further, in the invention of claim 3, as a constitution of the color image forming apparatus, a color matching pattern detection signal which is formed by forming an image on the transfer belt and converted into an electric signal by an optical sensor at a constant interval. Means for A / D conversion, category control means for judging the rising and falling tendency of the voltage of the color matching pattern detection signal, and a time point at which the set reference voltage value at the rising and falling tendency is crossed is specified as a count value. Colors the count value between falling and rising by subtracting the count value at the time of detecting the reference voltage reaching point on the falling tendency from the count value up to the detection of the reference voltage reaching point on the falling tendency. A calculation means used as the width information of the matching pattern, a value obtained by dividing the pattern width obtained by the above means by 2, and the count value of the reference voltage reaching point in the downward tendency are added. In a color matching control method having means for obtaining the center point position information of the pattern as a count value with respect to the reference position, an optical sensor is separately arranged at a position where the pattern is not formed in the belt width direction, and a belt such as a joint is provided. By including means for detecting a pattern other than the pattern extending in the width direction and removing the count position information obtained by the means from the pattern center position information obtained by the detecting means, a belt width direction such as a seam Since noise information due to patterns other than the marks extending to the background is removed, not only can inexpensive belts with joints be used, but the accuracy of position information can be improved, malfunctions can be prevented, and color matching control system reliability can be improved. The quality has been improved.

According to a fourth aspect of the present invention, the marks provided on the belt are specific marks at predetermined intervals, and a predetermined number of different marks are provided between them. When the count value of different marks detected during the detection of the specific mark is different from the predetermined amount, the detected position signal is treated as having low reliability. Widely applied to those that detect the position of a long body that travels by detecting
The position information can be accurately detected. The invention according to claim 5 is applied to a color image forming apparatus, and means for forming a specific reference color pattern at a predetermined interval on the belt, and a predetermined number of different patterns on the belt, and a pattern detected by an optical sensor. With a means for counting the number of different reference patterns, and the detected position signal has low reliability when the count value of different patterns detected between the detection of the specific reference color pattern and the detection of the next specific reference color pattern is different from the predetermined amount. As a result, since it is not adopted as a detection signal for executing color matching control, the reliability of the detection signal is high and the color matching control based on it is accurate.

According to a sixth aspect of the invention, as a color image forming apparatus, a color matching pattern detection signal is obtained by forming a color matching pattern on a transfer belt and converting the color matching pattern into an electric signal by an optical sensor. Means for A / D conversion at a constant interval, category control means for judging rising / falling tendency of the voltage of the color matching pattern detection signal, and counting the time when the set reference voltage value at rising / falling tendency is crossed The value that is specified as a value and stored in time series, and the count value when the reference voltage is detected when the falling tendency is subtracted from the count value when the reference voltage is detected when the falling tendency is generated By the calculation means used as the width information of the matching pattern and the value obtained by dividing the pattern width obtained by the above means by 2 and the count value at the time of detecting the reference voltage in the downward tendency. In color matching control method of a color image forming apparatus having a means for obtaining the center point position information of the pattern as a count value for the reference position, and means for imaging the lateral and diagonal pattern group on the transfer belt with four colors,
A means for counting the number of patterns detected by the optical sensor is provided, and if the count value of the pattern detected between the detection of the specific reference color pattern and the detection of the next specific reference color pattern is different from the predetermined amount, the detection position signal Since the reliability is low, it is not used as a detection signal for executing the color matching control. Therefore, the accuracy of the position information is increased, malfunction is prevented, and the reliability of the color matching control method is improved. According to a seventh aspect of the invention, in the color matching control system of the color image forming apparatus according to the sixth aspect,
Since the specification of the set of patterns from the detection of the specific reference color pattern to the detection of the next specific reference color pattern is determined by the width of the range between the maximum value and the minimum value of the offset point which is the specified value and the interval between them, the series of Since the group of color matching patterns can be specified, its reliability is improved.

[Brief description of drawings]

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

FIG. 2 is a diagram showing the principle of specifying the pattern center position in the present invention.

FIG. 3 is a diagram showing a positional relationship between an image forming pattern on a transfer belt and an optical sensor in the present invention.

FIG. 4 is a diagram illustrating a pattern form formed on the transfer belt in the embodiment.

FIG. 5 is a flowchart illustrating an operation of excluding a belt connection mark from pattern detection information according to an embodiment.

FIG. 6 is a flowchart illustrating an operation of identifying a pattern group according to the embodiment.

FIG. 7 is a flowchart illustrating an operation of checking whether or not the number of detected patterns in a pattern group is a prescribed value in the embodiment.

FIG. 8 is a flowchart illustrating an operation of excluding, from the color matching correction value calculation, a pattern detection count in a pattern group that is not a prescribed value in the embodiment.

[Explanation of symbols]

1 transfer belt 2 (2k, 2y, 2c, 2m) photosensitive drum Optical sensor for 3 (3a, 3b) pattern detection 4 Optical sensor for belt mark detection 5 Belt connection mark 6 (6o, 6a, 6b) color matching pattern 8 scratches L reference voltage value G1, G2, ... G8 pattern group

Continued front page    F term (reference) 2F065 AA02 AA03 AA14 AA15 AA17                       BB06 BB11 BB15 BB27 CC00                       DD04 FF04 QQ03 QQ08 QQ13                       QQ24 QQ31 QQ51 RR06                 2H027 DA21 DE07 DE10 ED04 ED24                       EE02 EF10                 2H030 AA01 AB02 AD17 BB02 BB16                       BB44 BB46 BB56 BB63                 2H200 FA04 GA12 GA23 GA34 GA47                       HA02 HB12 JA02 JB08 JB50                       PB13 PB39

Claims (7)

[Claims] 1. A device in which an optical sensor for receiving reflected or transmitted light from a belt surface is arranged to face the belt surface, and the optical sensor detects a mark indicating a position on the belt to obtain position information. An optical sensor is separately arranged at a position not provided with the mark in the belt width direction, and means for detecting a pattern other than the mark extending in the belt width direction such as a joint is provided, and the position information obtained by the means is obtained as described above. A belt position detection method characterized by removing noise information due to a pattern other than a mark extending in the belt width direction such as a joint by removing the noise information from the position information obtained by the mark detecting means. 2. A color matching pattern is formed on a transfer belt, and positional relationship information of each photosensitive drum is obtained from a color matching pattern detection signal converted into an electric signal by an optical sensor,
In a color image forming apparatus that executes color matching control, means for separately arranging an optical sensor at a position not provided with the pattern in the belt width direction and detecting a pattern other than a pattern extending in the belt width direction such as a joint. Equipped with
By providing means for excluding the position information obtained by the means from the position information obtained by the pattern detection means,
A color matching control method characterized by removing noise information due to patterns other than marks extending in the belt width direction such as joints. 3. A means for forming a color matching pattern on a transfer belt and A / D converting the color matching pattern detection signal converted into an electric signal by an optical sensor at regular intervals, and a means for converting the color matching pattern detection signal. Control means for judging the rising and falling tendency of the voltage, a means for storing the time when the set reference voltage value at the rising and falling tendency is crossed as a count value, and the reference voltage for the falling tendency. By calculating the count value at the time of reaching point detection from the count value up to the reference voltage reaching point at the time of upward / downward trend, the calculating means using the count value during the falling and rising as the width information of the color matching pattern, and the above means. Count the center point position information of the pattern with respect to the reference position by adding the value obtained by dividing the obtained pattern width by 2 and the count value of the reference voltage reaching point in the downward trend In the color matching control system of the color image forming apparatus having a means for obtaining a pattern, an optical sensor is separately arranged at a position where the pattern is not formed in the belt width direction, and a pattern other than a pattern extending in the belt width direction such as a joint is provided. The pattern other than the mark extending in the belt width direction such as a joint is provided by including means for detecting the pattern and the means for removing the count position information obtained by the means from the pattern center position information obtained by the detecting means. A color matching control method for a color image forming apparatus, which is characterized in that noise information due to noise is removed. 4. A device for optically detecting a position of a traveling long object by optically detecting marks provided as position information, wherein the provided marks are specific marks at predetermined intervals, and a predetermined number of marks are provided between them. If different marks are added, and the count value of different marks detected between the detection of a specific mark and the detection of the next specific mark is different from the predetermined amount, treat it as one with low reliability of the detected position signal. A method for detecting the position of a long body, characterized by. 5. A color matching pattern is formed on a transfer belt, and positional relationship information of each photosensitive drum is obtained from a color matching pattern detection signal converted into an electric signal by an optical sensor,
In a color image forming apparatus that executes color matching control, a means for forming a specific reference color pattern at a predetermined interval, a predetermined number of different patterns on the belt, and a number of patterns detected by an optical sensor are counted. When the count value of the different pattern detected between the detection of the specific reference color pattern and the detection of the next specific reference color pattern is different from the predetermined amount, it is considered that the reliability of the detected position signal is low, and color matching control is performed. A color matching control method for a color image forming apparatus, which is not used as a detection signal for executing 6. A unit for forming a color matching pattern on a transfer belt and A / D converting the color matching pattern detection signal converted into an electric signal by an optical sensor at a constant interval, and a means for converting the color matching pattern detection signal. Control means for judging the rising and falling tendency of the voltage, a means for storing the time when the set reference voltage value at the rising and falling tendency is crossed as a count value, and the reference voltage for the falling tendency. Calculating means that uses the count value during the fall and rise as the width information of the color matching pattern by subtracting the count value at the time of detection from the count value up to the time when the reference voltage at the time of rising and falling tendency, and the pattern width obtained by the above means Is divided by 2 and the count value at the time of detecting the reference voltage when the voltage is declining is added to obtain the center point position information of the pattern as the count value with respect to the reference position. A color matching control system for a color image forming apparatus having a step, comprising means for forming four horizontal and diagonal pattern groups on a transfer belt, and means for counting the number of patterns detected by an optical sensor. If the count value of the pattern detected between the detection of the specific reference color pattern and the detection of the next specific reference color pattern is different from the predetermined amount, the detection position signal is considered to be unreliable and the detection signal for executing the color matching control is determined. A color matching control method for a color image forming apparatus characterized by not being adopted as 7. The specification of a set of patterns from the detection of a specific reference color pattern to the detection of the next specific reference color pattern is determined by an offset point which is a stipulated value and its width between the maximum value and the minimum value. Item 7. A color matching control method for a color image forming apparatus according to Item 6.