JP4185320B2 - Image recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image recording apparatus that forms an image by synthesizing a plurality of images on an intermediate transfer medium.
[0002]
[Prior art]
Conventionally, this type of image recording apparatus has, for example, four color recording units such as C (cyan), M (magenta), Y (yellow), and K (black), and each color image formed by each recording unit. Is transferred onto a belt-like intermediate transfer medium (hereinafter referred to as an intermediate transfer belt), and the color image superimposed thereon is transferred onto a recording medium.
[0003]
[Problems to be solved by the invention]
However, according to such a conventional technique, the following problems have occurred.
[0004]
That is, it is generally difficult to form the intermediate transfer belt with a uniform thickness. Therefore, the belt conveyance speed increases when a thick region of the intermediate transfer belt is in contact with the drive roller, but relatively when the thin region of the intermediate transfer belt is in contact with the drive roller. The phenomenon that the speed becomes slow occurs. As shown in FIG. 27, if the rotation speed of the drive roller is constant, the belt transfer of the intermediate transfer belt is proportional to the distance from the rotation center of the drive roller to the belt center of the intermediate transfer belt (belt thickness center). The speed changes. In the example shown in the figure, the portion where the thickness of the intermediate transfer belt is thin is R1 because the length from the rotation center to the belt center is R1, and the belt conveyance speed is VR1, but the portion where the thickness of the intermediate transfer belt is thick is Since the length from the rotation center to the belt center is R2 (> R1), the belt conveyance speed is as high as VR2 (> VR1).
[0005]
As described above, even if the driving roller is driven at a constant speed, the belt conveyance speed fluctuates due to non-uniformity of the thickness of the intermediate transfer belt, so that color misregistration occurs when each color is superimposed on the intermediate transfer belt. The problem of degrading the image quality of color images has arisen.
[0006]
The present invention has been made in view of the above-described circumstances, and has a simple configuration, performs drive control of the intermediate transfer medium in consideration of uneven thickness of the intermediate transfer medium, prevents color misregistration, and achieves high quality. An object is to provide an image recording apparatus capable of forming an image.
[0007]
[Means for Solving the Problems]
In the present invention, first, the recording means records between the first position information and the second position information at a predetermined time interval (ts), and then the detection interval time between the first position information and the second position information. (Tr) is measured, and then the ratio between ts and tr is determined. When tr / ts> 1, the drive speed of the intermediate transfer medium is decelerated between the time of recording position information and the time of detection. Judgment Record The means obtains the first position information Record And then the second location information Record The motor speed of the interval until Deceleration On the other hand, if tr / ts <1, it is determined that the driving speed of the intermediate transfer medium has increased between the time of recording the position information and the time of detection. Recording means First position information Record And then the second location information Record The motor speed of the interval until Speed increase The speed information to be determined was determined.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, a plurality of recording units, a belt-shaped intermediate transfer medium that combines images formed by the plurality of recording units, a driving roller that drives the intermediate transfer medium, and the driving roller A position information detecting means for detecting position information formed by the recording means as position information used for image alignment, a speed information determining means for determining speed information for accelerating / decelerating the motor, Control means for registering the speed information, and control for controlling a motor speed in a section from when the recording means records the first position information to when the second position information is recorded at the time of recording based on the registered speed information The speed information determination means first records the first position information and the second position information at a predetermined time interval (ts) by the recording means, and then records the first information. The detection interval time (tr) between the position information and the second position information is measured, and then the ratio between ts and tr is determined. When tr / ts> 1, the position information is recorded and detected. It is determined that the driving speed of the intermediate transfer medium has decreased with time Record The means obtains the first position information Record And then the second location information Record The motor speed of the interval until Deceleration On the other hand, if tr / ts <1, it is determined that the driving speed of the intermediate transfer medium has increased between the time of recording the position information and the time of detection. Record The means obtains the first position information Record And then the second location information Record The motor speed of the interval until Speed increase This is an image recording apparatus that determines speed information to be transmitted.
[0010]
According to this, the predetermined time interval (ts) for recording the position information and the interval time for actually detecting the position information using the existing means called the position information detecting means for detecting the position information using the plurality of images for alignment. (Tr) is used to detect a change in the driving speed of the intermediate transfer medium, and based on this, the motor speed for driving the intermediate transfer medium is controlled to increase the thickness unevenness of the intermediate transfer medium without increasing the number of parts. As a result, it is possible to correct the unevenness of speed caused by the above, and thus it is possible to appropriately prevent image misalignment with a simple configuration and form a high-quality image.
[0011]
First of the present invention 2 The aspect of the 1 In this aspect, the control means determines increase / decrease in the motor speed according to a ratio of the predetermined time interval (ts) to the detection time interval (tr).
[0012]
According to this, it is possible to appropriately correct the uneven speed due to the uneven thickness of the intermediate transfer medium, and it is possible to appropriately prevent the image shift and form a high quality image.
[0015]
First of the present invention 3 The aspect of the first Or First 2 In the aspect, the distance that the position information moves from the recording means at the substantially predetermined time interval (ts) corresponds to a substantially integral multiple of the circumference of the drive roller.
[0016]
According to this, even when the movement distance of the intermediate transfer medium at the predetermined time interval (ts) cannot be set substantially equal to the circumferential length of the driving roller due to the constraints on the mechanism, the predetermined time interval (ts) Since the moving distance of the intermediate transfer medium at this time is an integral multiple of the circumferential length of the driving roller, the output of the position information detecting means is not affected by the eccentricity of the driving roller and causes image shift. Only the influence of the uneven thickness of the intermediate transfer medium can be detected, and a higher quality image can be formed.
[0017]
First of the present invention 4 The aspect of the first Or First 2 In the aspect, a length obtained by multiplying each of the circumference of the driving roller, the circumference of the photosensitive member constituting the recording unit, and the distance from the recording unit to the position information detection unit is approximately integer times. It corresponds to the distance moved from the recording means at the substantially predetermined time interval (ts).
[0018]
According to this, the eccentricity of the driving roller and the eccentricity of the photosensitive member can be canceled even when the speed unevenness due to the eccentricity of the photosensitive member as well as the eccentricity of the driving roller occurs. An image shift including unevenness due to the eccentricity of the body can be appropriately prevented, and a higher quality image can be formed with a simple configuration.
[0023]
First of the present invention 5 The embodiment includes a plurality of recording units, a belt-shaped intermediate transfer medium that combines images formed by the plurality of recording units, a driving roller that drives the intermediate transfer medium, and a motor that drives the driving roller. Position information detecting means for detecting position information formed by the recording means as position information used for image alignment for each predetermined block obtained by dividing the intermediate transfer medium into a plurality of areas, and a speed at which the motor is accelerated or decelerated Speed information determining means for determining information, registration means for registering the speed information for each block, and control means for controlling the motor speed of each block based on the speed information at the time of recording, The speed information determining means first records the position information at predetermined time intervals (tbs) by the recording means to make an area between the position information one block, and then The lock detection interval time (tbr) is measured, then the ratio between tbs and tbr is determined to detect the change in the speed of the intermediate transfer medium for each block. Next, when tbr / tbs> 1, It is determined that the drive speed of the intermediate transfer medium has decreased between the time of recording and the time of recording information, and speed information for decelerating the motor speed in the section forming the block is determined by the recording means, while tbr / If tbs <1, it is determined that the driving speed of the intermediate transfer medium has increased between the time of recording and detecting the position information, and the motor speed of the section for forming the block is increased by the recording means. This is an image recording apparatus for determining speed information.
[0024]
According to this, even if an error occurs in the detection of the position information by the position detection means, the error is distributed to the speed control values in the preceding and succeeding blocks, so the driving speed of the intermediate transfer medium is an error on average. Can be controlled so that there is little image misalignment, ie, a small image shift.
[0027]
First of the present invention 6 The embodiment includes a plurality of recording units, a belt-shaped intermediate transfer medium that combines images formed by the plurality of recording units, a driving roller that drives the intermediate transfer medium, and a motor that drives the driving roller. Position information detecting means for detecting position information formed by the recording means as position information used for image alignment for each predetermined block obtained by dividing the intermediate transfer medium into a plurality of areas, and a speed at which the motor is accelerated or decelerated Speed information determining means for determining information, registration means for registering the speed information for each block, and control means for controlling the motor speed of each block based on the speed information at the time of recording, The speed information determining means first records the position information at predetermined time intervals (tbs) by the recording means so that the area between the position information is one block, and then the nth position. Detection interval time (tbr) measured from the information (n + 1) block n length to the position information of the th (Ln),
Next, the ratio of each block length is obtained by the following formula,
tbr / tbs = Ln / {L (n + 1)}
This is an image recording apparatus for determining speed information for controlling the motor speed for driving the block (n + 1) to tbr / tbs times the motor speed for driving the block n in order to make L (n + 1) the same length as Ln. .
[0028]
According to this, a distance ratio between each position information is calculated from a fixed time (ts) for recording the position information and an interval time (tr) at which the position information is actually detected, and the intermediate transfer medium is driven based on this. By controlling the speed of the motor, the speed control value can be easily calculated.
[0029]
First of the present invention 7 The aspect of the 5 or First 6's In the aspect, the length of one block corresponds to a substantially integral multiple of the circumferential length of the drive roller.
[0030]
According to this, even if it is not possible to provide the position information detection means in the area from the recording means to the first block due to mechanical restrictions, the length of one block is approximately an integral multiple of the circumference of the drive roller. Therefore, the output of the position information detecting means is not affected by the eccentricity of the driving roller, and can detect only the influence of the thickness unevenness of the intermediate transfer medium that causes the image shift, thereby further improving the quality. Images can be formed.
[0031]
First of the present invention 8 The aspect of the 5 or First 6's In the aspect, the length obtained by multiplying the circumference of the driving roller, the circumference of the photosensitive member constituting the recording unit, and the distance from the recording unit to the position information detecting unit substantially corresponds to one block length. It is what you do.
[0032]
According to this, the eccentricity of the driving roller and the eccentricity of the photosensitive member can be canceled even when the speed unevenness due to the eccentricity of the photosensitive member as well as the eccentricity of the driving roller occurs. An image shift including unevenness due to the eccentricity of the body can be appropriately prevented, and a higher quality image can be formed with a simple configuration.
[0033]
First of the present invention 9 The aspect of the 5 or First 6's In the aspect, the length of the intermediate transfer medium is approximately an integral multiple of the one block.
[0034]
As a result, if the speed control of the motor for driving the intermediate transfer medium is performed in units of blocks, the speed control for one round of the intermediate transfer medium can be performed uniformly. Can be prevented appropriately, and a high-quality image can be formed.
[0042]
First of the present invention 10 The first to the second aspects 9 In any of the above aspects, the position information detection means is provided at a position on the peripheral surface of the drive roller where the intermediate transfer medium from the recording means to the position information detection means maintains a linear state. did.
[0043]
According to this, since the position information detecting means is arranged at a position where the driving roller is not easily affected by the fluctuation of the driving roller when driving the intermediate transfer medium, the interval time (tr) which is the basis of the control of the motor speed is set. High accuracy and speed control can be realized.
[0044]
First of the present invention 11 The first to the second aspects 9 In any of the above aspects, the circumference of the drive roller is substantially equal to the distance from the recording means to the position information detection means.
[0045]
According to this, even if speed unevenness due to the eccentricity of the drive roller occurs due to the circumference of the drive roller corresponding to the distance from the recording means to the position information detection means, the position information detection means The output is not affected by the eccentricity of the drive roller, but only the influence of the uneven thickness of the intermediate transfer medium that causes image shift can be detected, and a higher quality image can be formed.
[0046]
First of the present invention 12 The first to the second aspects 11 In any of the above aspects, the position information detection means is provided opposite to both ends in the width direction of the intermediate transfer medium, and the control means uses an average value of two detection time intervals (tr). did.
[0047]
According to this, it is possible to correct the uneven transport of the intermediate transfer medium in consideration of the skew of the intermediate transfer medium, and therefore it is possible to appropriately prevent image shift with a simple configuration and form a higher quality image.
[0048]
First of the present invention 13 The first to the second aspects 11 In any one of the above aspects, the position information detecting means is provided to face a central portion in the width direction of the intermediate transfer medium. Has been It was supposed to be.
[0049]
As a result, the positional information can be detected at a position where the influence of the skew of the intermediate transfer medium is the least, and the unevenness in transport of the intermediate transfer medium can be corrected. Can be formed.
[0050]
First of the present invention 14 The first to the second aspects 13 In any of the above aspects, the control means rotates the intermediate transfer medium two or more times and predicts each block length from the average value.
[0051]
Thereby, the thickness unevenness of the intermediate transfer medium can be predicted with higher accuracy and the motor speed can be controlled, so that a higher quality image can be guaranteed.
[0052]
Hereinafter, an image recording apparatus according to an embodiment of the present invention will be specifically described with reference to the drawings.
[0053]
First, the principle of correcting the driving speed for the driving roller will be described. The present invention intends to eliminate the speed fluctuation caused by the uneven thickness of the intermediate transfer belt by driving correction for the driving roller, and is based on the following method. In addition, the same code | symbol is used for the part corresponding to the component of the image recording apparatus shown in FIG.
[0054]
FIG. 5 schematically shows the positional relationship among the intermediate transfer belt 10, the driving roller 11, the photoconductor 18, and the registration sensor 41. In this positional relationship, with the drive roller 11 rotated at a predetermined angular velocity, the recording means (consisting of the LSU 34, the charging device 30, the developing device 22, the photoconductor 18, and the primary transfer device 26) has a predetermined time interval ( A block position mark (including a start position mark) that becomes position information at ts) is recorded on the intermediate transfer belt 10, and a relationship with a detection interval time tr in which the block position mark is detected by the registration sensor 41 is considered.
[0055]
Next, the correction principle of the present invention will be described in more detail. As shown in FIG. 4A, in a state where the intermediate transfer belt 10 is conveyed at a constant speed, a block position mark recording pulse is generated 10 times at a constant time interval ts after the start position pulse is generated, and at a time interval ts. The block position mark is recorded on the intermediate transfer belt 10. At this time, the time interval ts is set so that the intermediate transfer belt 10 is equally divided into 10 blocks by the block position mark.
[0056]
On the other hand, it is assumed that the registration sensor 41 is installed at a position downstream by one block length from the recording position of the block position mark. The registration sensor 41 outputs a block position mark detection pulse every time the block position mark passes. FIG. 4B shows detection interval times t1 to t10 at which block position mark detection pulses are generated.
[0057]
The relationship between the recording time interval ts and the detection interval times t1 to t10 shown in FIGS. 4A and 4B will be described with reference to FIGS. A start position mark Ms is recorded in synchronization with the start position pulse (FIG. 5), and after the time ts has elapsed, the block position mark M-1 of block 1 is recorded (FIG. 6). The position mark M-2 is recorded (FIG. 7), and the block position mark M-3 of the block 3 is recorded after the elapse of time ts (FIG. 8).
[0058]
On the other hand, as shown in FIG. 4B, after the registration sensor 41 outputs a block position mark detection pulse in synchronization with the detection of the start position mark Ms, the block position mark M-1 as the next position information is output. It is assumed that time t1 is required until detection and output of a block position mark detection pulse. Similarly, it takes time t2 from detecting the block position mark M-1 to detecting the block position mark M-2. After detecting the block position mark M-2, the block position mark M-3 is detected. It is assumed that time t3 is required until detection.
[0059]
If the thickness of the intermediate transfer belt 10 is uniform over the entire circumference (design value), time ts = time t1 from the above assumption. However, since the thickness of the intermediate transfer belt 10 is actually non-uniform, the time ts is different from the time t1. The relationship between the time ts and the times t2, t3,..., T10 is the same. This causes the color shift described above.
[0060]
If the length of the block 1 (distance between Ms and M-1) is a1, and the speed of the intermediate transfer belt 10 until the start position mark Ms reaches the registration sensor 41 from the recording position is Va1,
a1 = Va1 × ts (1)
It can be expressed. Also, assuming that the speed of the intermediate transfer belt 10 until the block position mark M-1 of the block 1 reaches the registration sensor 41 from the recording position is Vb1,
t1 = a1 / Vb1 (2)
It can be expressed.
[0061]
Similarly, the length of the block 2 (the distance between M-1 and M-2) is a2, and the speed of the intermediate transfer belt 10 until the block position mark M-1 reaches the registration sensor 41 from the recording position. Assuming Va2,
a2 = Va2 × ts (3)
It can be expressed. Here, the speed Vb1 during which the block position mark M-1 of the block 1 reaches the registration sensor 41 from the recording position, and the block position mark M- of the block 2 after the block position mark M-1 of the block 1 is recorded. Since the speed Va2 while 2 is recorded is the same
Vb1 = Va2 (4)
It becomes. Therefore, from equations (2) and (4),
t1 = a1 / Va2 (5)
From equations (5) and (3)
t1 = a1 / (a2 / ts) = (a1 / a2) × ts (6)
It becomes. (6)
t1 / ts = a1 / a2 (7)
Can be obtained. Since the detection interval time t1 can be actually measured and the recording interval time ts is a set time, the ratio of the block lengths of the adjacent blocks 1 and 2 can be expressed by the ratio of the actually measured value t1 and the known set value ts. I understand.
[0062]
When the intermediate transfer belt 10 is divided into n blocks, the block 1 and the block n are continuous and are expressed by the relationship of the following equation.
[0063]
(T1 / ts) × (t2 / ts) ×... (Tn / ts)
= (A1 / a2) x (a2 / a3) x ... (an / a1)
= 1 (8)
Further, when the length per block when the intermediate transfer belt is divided into n equal parts (hereinafter referred to as standard block length) is as, the average thickness of the intermediate transfer belt is a design value.
(A1 / as) + (a2 / as) +... + (An / as) = 1 · n (9)
It becomes.
[0064]
If an intermediate transfer belt having a total length of 100 mm is equally divided into 10 blocks, the length per block is 10 mm (design value). The recording interval time between each block of block 1 to block 10 is Ts, and the detection interval time from the detection of the block position mark of the previous block (x-1) to the detection of the block position mark of the next block x is Tx, Tx / Ts. = Dx, the relationship between dx and a (x + 1) / as is expressed as shown in FIG.
[0065]
In FIG. 9, d1 to d10 can be obtained by calculation from actual measurement values, a (x + 1) / as can be calculated from (ax / as) / dx from the equation (7), and from a1 / as from the equation (9). The average value of a10 / as is 1.
[0066]
For example, assuming that a1 / as = 1.00000, d1 to d9 can be calculated from actual measurement values, so (ax / as) / dx can be sequentially calculated for blocks 2 to 10. As a result, if the average value from a1 / as to a10 / as is 1.00000, the current driving roller is controlled so that the belt conveyance speed is uniform over the entire circumference close to the design value. Become.
[0067]
Therefore, by changing the temporary setting value of a1 / as, the above-described simulation is performed for each temporary setting value, that is, the calculation of a10 / as from a1 / as and the addition average thereof are performed, and the average value is the highest design value (= 1.00000). Find a1 / as (temporary setting) that approximates.
[0068]
When the optimum temporary setting value for a1 / as is determined as described above, motor speed control setting values are determined for the individual blocks 1 to 10. As a basic idea, when am / as is smaller than 1, the block length am of the block m is shorter than the standard block length as, so the motor drive speed is set so that the block length am of the block m is longer. On the contrary, when am / as is larger than 1, the block length am of the block m is longer than the standard block length as, so the motor speed control setting value is set so that the block length am of the block m is shortened. decide.
[0069]
The motor speed control set value can be obtained from the ratio between the block length and the standard block length as. For example, when the motor speed is inversely proportional to the set value, if the motor speed control standard set value is C, the motor speed control set value Cx of the block x is
Cx = C × ax / as (10)
It becomes.
[0070]
FIG. 9 shows a calculation formula of the motor speed control set value Cx for each block. As described above, since the value of a10 / as is obtained from a1 / as, the motor speed control set value of each block can be calculated from equation (10).
[0071]
FIG. 10 is a diagram showing a simulation example when the intermediate transfer belt 10 is equally divided into 10 blocks. A value obtained by measuring Tx which is a block position mark detection interval time for each block and calculating Tx / Ts is shown. As a result of simulation using four values of 1.00000, 0.999800, 0.999900, and 0.999886 as temporary setting values of a1 / as, the case of a1 / as = 0.99886 is an example that is closest to the setting value. For each block, the motor speed control set value is obtained by calculation from equation (10).
[0072]
FIG. 11 shows a setting example when speed control is performed in inverse proportion to the motor standard speed setting value C using the data shown in FIG. The motor speed control set value Cx is the same data as in the example of FIG. A speed ratio with the standard speed after speed correction is calculated for each block, and motor drive control is performed for each block based on the speed ratio.
[0073]
(Embodiment 1)
FIG. 1 is a schematic overall configuration diagram of a tandem color image recording apparatus according to the present embodiment. As shown in the figure, an intermediate transfer belt 10 having a predetermined width is stretched between a driving roller 11 and a driven roller 12. A motor 14 is connected to the drive roller 11 via a gear mechanism 13. The control system of the motor 14 will be described later.
[0074]
On the intermediate transfer belt 10, photoconductors 15 to 18 of the respective colors are arranged close to each other in a straight line. Developing units 19 to 22 are installed for the respective photoconductors 15 to 18, primary transfer units 23 to 26 are installed with the intermediate transfer belt 10 interposed therebetween, and chargers 27 to 30 are further installed. Further, LSUs (laser scanning units) 31 to 34 are provided for the respective photoconductors 15 to 18. The charger 27 charges the surface of the photoconductor 15 to a predetermined potential, the LSU 31 exposes the surface of the photoconductor 15 so that a latent image corresponding to the first color is formed, and the developer 19 removes the first color toner. The primary transfer unit 23 is attached to the surface of the photoconductor 15 and primarily transfers the first color image formed on the surface of the photoconductor 15 to the intermediate transfer belt 10. The first color recording means includes a photoconductor 15, a charger 27, an LSU 31, a developing device 19, and a primary transfer device 23. The recording means for the second color, the third color, and the fourth color are also composed of similar components provided corresponding to the respective colors.
[0075]
Note that the present invention is not limited to the four-color tandem system, and can be applied from one color. Further, although the LSUs 31 to 34 are provided corresponding to the respective colors, it is not always necessary to provide the numbers corresponding to all the colors.
[0076]
On the other hand, a paper feed roller 35 for feeding the recording medium into the paper feed mechanism is provided. The recording timing of the recording medium fed into the paper feeding mechanism is controlled by the registration roller 36 to the secondary transfer unit. The secondary transfer unit is composed of a driven roller 12 and a transfer roller 37. The recording medium that has passed through the secondary transfer portion fixes the transferred image by the fixing device 38 and is then discharged to the tray 40 by the discharge roller 39.
[0077]
In addition, a registration sensor 41 that detects an alignment mark (for example, a resist pattern such as a diagonal line) formed on the surface of the intermediate transfer belt 10 is provided. In general, a resist pattern is drawn on the surface of the intermediate transfer belt 10 (both sides and / or the center in the main scanning direction), and lateral and oblique deviations are corrected from the output of the resist sensor 41 installed at a position where the resist pattern can be detected. Yes. An origin position mark for detecting the belt origin position is formed on the back surface of the intermediate transfer belt 10, and this origin position mark is detected by the belt origin sensor 42.
[0078]
In the present embodiment, it is assumed that the registration sensor 41 is also used as position information detection means for detecting a block position mark to be described later. As a result, since the registration sensor 41 is used to detect the block position mark M recorded at the timing described later, it is possible to take measures to prevent color misregistration only by operation control described later without adding new components. The structure is simple and color misregistration can be prevented.
[0079]
In the present embodiment, the registration sensor 41 is provided at a position separated from the photosensitive member 18 as a recording means by an integral multiple of one block length (an example of a single multiplication is shown).
[0080]
As a result, the output of the registration sensor 41 is not affected by the eccentricity of the driving roller 11, and only the influence of the uneven thickness of the intermediate transfer belt 10 that causes the image shift can be detected, thereby forming a higher quality image. it can. In addition, the motor speed control set value can be calculated by comparing the block lengths and can be easily obtained.
[0081]
The registration sensor 41 is preferably provided at a position on the peripheral surface of the drive roller 11 where the intermediate transfer belt 10 from the photosensitive member 18 as the recording unit to the registration sensor 41 maintains a linear state.
[0082]
According to this, since the registration sensor 41 is disposed at a position where the driving roller 11 is not easily affected by the vibration of the driving roller 11 when the intermediate transfer belt 10 is driven, the detection interval time (which is a basis for controlling the motor speed) ( tr) can be taken in with high accuracy, and speed control with high accuracy can be realized.
[0083]
In addition, it is desirable that the distance between the registration sensor 41 and the photosensitive member 18 as a recording unit be equal to the circumferential length of the driving roller 11.
[0084]
According to this, the peripheral length of the driving roller 11 is made to correspond to the distance from the photosensitive member 18 serving as a recording unit to the registration sensor 41, so that even if the speed unevenness due to the eccentricity of the driving roller 11 occurs, the registration sensor 41 The output is not affected by the eccentricity of the drive roller 11, and only the influence of the uneven thickness of the intermediate transfer belt 10 that causes image shift can be detected, and a higher quality image can be formed.
[0085]
FIG. 2 is an example in which a pair of registration sensors 41-1 and 41-2 are installed at both ends of the intermediate transfer belt 10 in the width direction. Block position marks M1 and M2 are recorded on both sides of the intermediate transfer belt 10 and detected by the registration sensors 41-1 and 41-2.
[0086]
In this way, by installing the registration sensors 41-1 and 41-2 at both ends in the width direction of the intermediate transfer belt 10, the unevenness of the conveyance of the intermediate transfer belt 10 is corrected in consideration of the skew of the intermediate transfer belt 10. As a result, image misalignment can be appropriately prevented with a simple configuration, and a higher quality image can be formed. Specifically, a value obtained by averaging two detection interval times based on the detection results of the registration sensors 41-1 and 41-2 is used as the detection interval time.
[0087]
Further, if the recording apparatus can handle A3 size, the registration sensor 41-3 may be installed at the center in the width direction of the intermediate transfer belt 10 as shown in FIG. In this case, the block position mark M3 may be recorded at the center in the width direction of the intermediate transfer belt 10 and detected by the registration sensor 41-3.
[0088]
In this way, by installing the registration sensor 41-3 in the center in the width direction of the intermediate transfer belt 10, position information is detected at a position where the influence of the skew of the intermediate transfer belt 10 is the least, and the intermediate transfer belt 10 is detected. Therefore, image misalignment can be prevented with a simple configuration, and a higher quality image can be formed.
[0089]
Next, a specific operation of the image recording apparatus according to the present embodiment will be described.
[0090]
FIG. 12 is a diagram showing functional blocks related to speed control of the image recording apparatus. The CPU 100 is a part that executes control related to speed control. When the CPU 100 gives a command to the drive roller motor control circuit 101, the motor drive circuit 102 rotates the motor 14 under the control of the drive roller motor control circuit 101.
[0091]
Further, pattern data of the block position mark (including the start position mark) is stored in the position information pattern storage unit 103, and the block position mark is read out by the recording control circuit 104 given a command from the CPU 100 and recorded. 105. In this embodiment, the recording unit 105 includes an LSU 34, a charger 30, a developing unit 22, a photosensitive member 18, and a primary transfer unit 26.
[0092]
The position information recording timer 106 is a timer for measuring a time interval ts for generating a block position mark recording pulse in FIG. The position information detection timer 107 is a timer for measuring the generation interval of the block position detection pulse in FIG. The registration sensor 41 as position information detection means is a sensor that outputs a block position detection pulse when a block position mark is detected.
[0093]
Further, the first memory 108 stores the position information detection timer value of each block measured using the position information detection timer 107. The second memory 109 stores the standard speed set value C and the motor speed control set value Cx of each block determined as a result of simulation. The first memory 108 and the second memory 109 may be physically separate storage media, or may be address spaces managed separately on the same storage medium.
[0094]
As in the example described above, the intermediate transfer belt 10 is equally divided into n blocks and motor speed control is performed in units of blocks.
[0095]
First, a block position mark is recorded on the intermediate transfer belt 10. Note that data required after the recording interval time Ts (corresponding to ts in FIG. 4A), the standard speed setting value C, and the like when recording the block position mark is first and second memories 108 and 109. Is stored.
[0096]
FIG. 13 is a flowchart for recording a block position mark on the intermediate transfer belt 10. As shown in the figure, the CPU 100 retrieves the standard speed set value C from the second memory 109 and sets the standard speed set value C as the speed target value of the motor 14 (step S1). Next, the CPU 100 gives an operation start command to the drive roller motor control circuit 101, and starts the rotation operation of the drive roller 11 by driving the motor 14 at the standard speed setting value C (step S2). Thereafter, the speed of the intermediate transfer belt 10 is controlled at the designed standard speed setting value C until the block position mark recording operation is completed and the motor 14 is stopped.
[0097]
When the rotation operation of the drive roller 11 is started, the count number of the block counter is reset (step S3), and the output of the belt origin sensor 42 of the intermediate transfer belt 10 is monitored to wait for the origin position mark to be detected (step S3). S4).
[0098]
When the belt origin sensor 42 detects the origin position mark, the drive amount counter that measures the drive amount P of the intermediate transfer belt 10 is reset (step S5), the drive amount counter is operated (step S6), and the block starts. Wait until the position is reached (step S7). The position after a predetermined count after the origin position mark is detected is determined as the block start position. Of course, since the block start position can be freely determined, the origin position mark detection time can also be set as the block start position.
[0099]
When the intermediate transfer belt 10 reaches the block start position, the recording unit 105 records a start position mark (same as the block position mark) on the intermediate transfer belt 10 (step S8). Block 1 starts from the start position mark.
[0100]
When the start position mark is recorded, the block count is incremented (step S9). It is checked whether the recording of the block position marks of all the blocks has been completed (step S10). If there are remaining blocks, the position information recording timer 106 is reset (step S11), and the position information recording timer 106 is activated (step S12). . As shown in FIG. 4A, after the start position mark is recorded, the block position mark is recorded at a constant recording interval time ts (= Ts). For this reason, the position information recording timer 106 measures the time when the time Ts which is the standard one block time interval has elapsed (step S13). When the time Ts has elapsed from the previous recording time of the block position mark (including the start position mark), the recording means 105 is operated again to record the block position mark on the intermediate transfer belt 10 (step S8), and the block count number is incremented. (Step S9). If it is determined in step S10 that the recording of block position marks has been completed for all blocks, the position information recording process is terminated. In this way, block position marks are recorded on the intermediate transfer belt 10 at the time interval Ts.
[0101]
In the present embodiment, the length of one block is set as follows. The length of one block is set so as to correspond to a substantially integer multiple of the circumferential length of the drive roller 11. Thus, even if the registration sensor 41 cannot be provided within one block length from the recording means due to mechanical limitations, the one block length is substantially an integral multiple of the circumferential length of the drive roller 11. The output of the registration sensor 41 is not affected by the eccentricity of the drive roller 11, and only the influence of the uneven thickness of the intermediate transfer belt 10 that causes the image shift can be detected, so that a higher quality image can be formed.
[0102]
Further, the length of one block corresponds to the length obtained by multiplying the circumferential length of the driving roller 11, the circumferential length of the photosensitive member 18, and the distance from the photosensitive member 18 serving as a recording unit to the registration sensor 41 by an integer. Set as follows. As a result, the eccentricity of the driving roller 11 and the eccentricity of the photosensitive member 18 can be canceled even if the speed unevenness due to the eccentricity of the photosensitive member 18 as well as the eccentricity of the driving roller 11 occurs. In addition, it is possible to appropriately prevent image misalignment including unevenness due to the eccentricity of the photosensitive member 18, and it is possible to form a higher quality image with a simple configuration.
[0103]
The length of the entire circumference of the intermediate transfer belt 10 is preferably set so as to be approximately an integral multiple of the length of one block. As a result, if the speed control of the motor 14 for driving the intermediate transfer belt 10 is performed in units of blocks, the speed control for one rotation of the intermediate transfer belt 10 can be performed without unevenness. By eliminating it, it is possible to properly prevent image shift and to form a high-quality image.
[0104]
Next, the block position mark recorded on the intermediate transfer belt 10 at the recording interval time Ts is detected by the registration sensor 41, and the detection interval times t1 to t10 (T1 to T10 in FIG. 9) shown in FIG. 4B are measured. To do.
[0105]
FIG. 14 is a flowchart for measuring the interval between the block position marks recorded on the intermediate transfer belt 10 with a counter. The drive roller 11 is driven and controlled so that the intermediate transfer belt 10 reaches the standard speed set value C.
[0106]
As shown in the figure, the block count for reading is reset (step S100), and the presence or absence of a block position mark detection pulse that becomes a position information detection signal is monitored from the output signal of the registration sensor 41 (step S101). When the block position mark detection pulse is detected, the position information detection timer 107 is reset (step S102), and then the position information detection timer 107 is operated (step S103). When the next block position mark recorded on the intermediate transfer belt 10 reaches the position of the registration sensor 41, the block position mark detection pulse is detected again (step S104). When the block position mark detection pulse is detected, the timer value Tx of the position information detection timer 107 at that time is acquired (step S105) and stored in the first memory 108 (step S106).
[0107]
Until the block count reaches the number of divisions of the intermediate transfer belt 10, the block count is incremented every time the timer value Tx is registered (step S108), and the processing from step S102 to step S108 is repeated. When it is determined in step S107 that the block count has reached the number of divisions, the mark interval timer value Tx has been acquired and registered for all the block position marks recorded on the intermediate transfer belt 10, so that the position information The detection process ends. As a result of executing the position information detection process, the position information detection timer values T1 to T10 shown in FIG.
[0108]
Next, a process of calculating a motor speed control set value for each block from the position information detection timer value and registering it in the second memory 109 is executed.
[0109]
FIG. 15 is a flowchart for calculating and obtaining a motor speed control set value for each block. As shown in the figure, the position information detection timer values T1 to T10 are read from the first memory 108 (step S200), and the ratio dx between the position information detection timer values T1 to T10 and the recording interval time Ts of one standard block is obtained. Each is calculated (step S201). As a result, d1 to d10 in FIG. 9 are obtained by calculation.
[0110]
Next, an initial value (= 1.000000) is set as a temporary setting value (step S202). The temporary setting value set in step S202 is set to the block interval ratio of block 1 (step S203). Then, the block interval ratio (a2 / as) of block 2 is provisionally calculated by calculating (a1 / as) / d1 for block 2, and the block interval ratio of block 3 by calculating (a2 / as) / d2 for block 3 (A3 / as) is provisionally calculated, and thereafter the block interval ratio is provisionally calculated up to the block 10 (step S204).
[0111]
Next, an average value of the provisional setting value of the block interval ratio of the block 1 and the provisional calculation values of the block interval ratios of the blocks 2 to 10 temporarily calculated in step S204 is calculated (step S205). If the average value = 1, the provisional setting values and the provisional calculation values acquired for block 1 to block 10 are adopted (step S210).
[0112]
On the other hand, if the average value = 1 is not satisfied in step S206, the size of the average value is determined (step S207). If the average value> 1 is not satisfied, the provisional setting value used as the block interval ratio of block 1 is increased (step S208). On the other hand, if the average value> 1, the temporary setting value used as the block interval ratio of block 1 is reduced (step S209).
[0113]
In this way, when the temporary setting value is changed in steps S208 and S209, the process returns to step S203, and the block interval ratio is temporarily calculated again for each block using the changed temporary setting value (steps S203 to S209).
[0114]
In step S206, the temporary set value is sequentially changed until the average value = 1 is satisfied, and the processes in steps S203 to S209 are repeated. As a result, the average value of the provisional calculation values (including provisional setting values) of the block interval ratio of each block is 1, or the block interval ratio of each block that approaches 1 to the allowable range is obtained. The block interval ratios a1 / as to a10 / as thus obtained are temporarily stored in the first memory 108 or the second memory 109 (step S210).
[0115]
Here, in steps S206 and S207, the design value (= 1) of the average value of the ratio of each block length (ax) to the standard block length (as) is set as the standard value. As a result, the image transfer due to the uneven thickness of the intermediate transfer belt 10 is surely brought close to the state where the image shift is not caused. Therefore, even when the image shift due to other elements is corrected, the influence of the uneven thickness of the intermediate transfer belt 10 is affected. This can be performed without consideration, and image shift control can be simplified as a whole.
[0116]
It is desirable that the standard value can be set to an arbitrary value. If the actual block length (ax) is the standard block length (as), the average value of the ratios of the predicted block lengths (ax) to the standard block length (as) is 1. However, the image shift is not only caused by the unevenness of the conveyance due to the unevenness of the thickness of the intermediate transfer belt 10, but is caused by a complex combination of other elements.
[0117]
Therefore, when the average value is set as a standard value, and this standard value can be arbitrarily set, even when the conveyance unevenness due to the thickness unevenness of the intermediate transfer belt 10 is corrected, image deviation still occurs. Since the color shift caused by other elements can be corrected by a simple means of changing the standard value, the image shift can be appropriately prevented with a simple configuration, and a high-quality image can be formed.
[0118]
Further, it is desirable that the standard value can be changed manually. According to this, since the standard value can be changed even after the apparatus is shipped, even if the thickness of the intermediate transfer belt 10 changes due to secular change, it can be appropriately handled and high-quality image formation can be maintained. .
[0119]
Next, the block interval ratio at the temporary setting value is read sequentially from block 1 (step S211), the calculation shown in the equation (10) is executed to calculate the motor speed control setting value Cx (step S212), and the calculated value is calculated. The motor speed control set values C1 to C10 for each block are registered in the second memory 109 (step S213).
[0120]
In this way, the motor speed control set value Cx is set in the second memory 109 so that the speed of the intermediate transfer belt 10 does not fluctuate over the entire circumference in consideration of the uneven thickness of the intermediate transfer belt 10 or the fluctuation becomes extremely small. It will be remembered.
[0121]
The operation for registering the motor speed control set value Cx of each block in the second memory 109 as described above is performed once before the image recording apparatus is shipped from the factory, and when the intermediate transfer belt 10 is replaced. It will be done at the time of exchange.
[0122]
Next, an operation in the case where image recording is actually performed using the motor speed control setting values (C1 to C10) for each block prepared as described above will be described.
[0123]
FIG. 16 is a flowchart relating to motor speed control when image recording is performed. As shown in the figure, the CPU 100 retrieves the standard speed setting value C from the second memory 109, and sets the standard speed setting value C as the speed target value of the motor 14 (step S300). Next, the CPU 100 gives an operation start command to the drive roller motor control circuit 101, and starts the rotation operation of the drive roller 11 by driving the motor 14 at the standard speed setting value C (step S301). Further, the motor speed control set values (C1 to C10) of the respective blocks are sequentially called from the second memory 109 (step S302), and the motor speed control set values (C1 to C10) corresponding to the respective blocks are set (step S303). ).
[0124]
Next, the block counter is reset (step S304), and the output of the belt origin sensor 42 of the intermediate transfer belt 10 is monitored to detect the origin position mark (step S305). When the origin position is detected in the process of step S305, the drive amount counter for measuring the drive amount of the intermediate transfer belt 10 is reset (step S306), and then the drive amount counter is operated (step S307). When the value of the drive amount counter becomes P = Pdo (step S308), it is determined that block 1 has started, and motor speed control is started with the motor speed control set value C1 of block 1 (step S309).
[0125]
In this example, the length of one block (count value converted value) is set as a counter value P = Pdo.
[0126]
Therefore, in step S309, every time the drive amount counter reaches the counter value P = Pdo, the motor speed control set value Cx of the next block is changed, and the counter value of the drive amount counter is reset.
[0127]
Thus, according to the present embodiment, the block position mark is recorded at a predetermined recording interval time (Ts) so as to divide the intermediate transfer belt 10 into n equal parts, and the detection interval time (Tx) of the block position mark is set. Since the block interval ratio ax / as is measured based on Tx / Ts, and the motor speed control set value Cx of each block is acquired from the block interval ratio, the entire circumference of the intermediate transfer belt 10 is used. The motor speed control set value that absorbs the speed fluctuation caused by the belt thickness can be set over a long period of time, and extremely accurate positioning can be realized.
[0128]
Further, even if an error occurs in the detection of position information by the registration sensor 41, the error is distributed to the speed control values in the preceding and succeeding blocks, so the driving speed of the intermediate transfer belt 10 is averaged to have an error. It can be controlled so that there is little, that is, a small image shift.
[0129]
In the above description, the motor speed control set value Cx is changed based on the count value of the drive amount counter. However, the present invention is not limited to this, for example, every time a block position mark is detected. It is also possible to switch to the motor speed control set value of the block corresponding to, and execute the motor speed control based on the motor speed control set value Cx in units of blocks.
[0130]
In the above description, the intermediate transfer belt 10 is equally divided into 10 blocks, and the motor speed control set value Cx is obtained for each block. However, the motor speed control set value Cx is obtained for all blocks and individual control is not performed. Even if only the motor speed control set value Cx is obtained for only one block and the speed control is performed, the effect of suppressing the conveyance unevenness is recognized, and the image shift may be prevented to the extent that there is no influence.
[0131]
For example, the intermediate transfer belt 10 is equally divided into 10 consecutive blocks, and the motor speed control set value Cx is obtained only for several consecutive blocks (for example, 8 blocks), and the speed is controlled.
[0132]
That is, the block position marks of block 1 to block 8 are recorded on the intermediate transfer belt 10 in the same manner as the flowchart shown in FIG. Further, in the same manner as in the flowchart shown in FIG. 14, the position information detection timer values T <b> 1 to T <b> 8 are acquired for the blocks 1 to 8 and stored in the second memory 109.
[0133]
FIG. 17 shows the recording interval time between the blocks 1 to 8 as Ts, and the detection interval time from the detection of the block position mark of the previous block (x−1) to the detection of the block position mark of the next block x as Tx, When Tx / Ts = dx, the relationship between dx and a (x + 1) / as is shown.
[0134]
Also in this example, d1 to d8 are sequentially calculated using the measured position information detection timer values T1 to T8. Further, an average value from d1 to d8 is obtained, and some temporary setting values are set to a1 / as, and an average value from a1 / as to a8 / as is obtained for each temporary setting value. Then, a temporary setting value that approximates the average value of both is determined.
[0135]
FIG. 18 shows a specific example in which four temporary setting values are set for a1 / as and simulated. The average value from T1 / Ts to T8 / Ts is 1.000055, and it is shown that the temporary setting value closest to this average value is a1 / as = 0.999872. Therefore, in the example shown in FIG. 18, motor speed control set value Cx = C × (ax / as) is calculated for block 1 to block 8 with a1 / as = 0.999872.
[0136]
FIG. 19 shows an example in which the speed ratio with the standard speed set value after speed correction is obtained from the motor speed control set value Cx. As shown in the figure, it can be seen that when the block interval is short, the speed is controlled to increase.
[0137]
FIG. 20 is a flowchart for obtaining the motor speed control set value. As shown in the figure, the position information detection timer values T1 to T8 are read from the first memory 108 (step S400), and the ratio dx between the position information detection timer values T1 to T8 and the recording interval time Ts of one standard block is obtained. Each is calculated (step S401).
[0138]
Next, an initial value (= 1.000000) is set as a temporary setting value (step S402). The temporary setting value set in step S402 is set to the block interval ratio of block 1 (step S403). Then, the block interval ratio (a2 / as) of block 2 is provisionally calculated by calculating (a1 / as) / d1 for block 2, and the block interval ratio of block 3 by calculating (a2 / as) / d2 for block 3 (A3 / as) is provisionally calculated, and thereafter, the block interval ratio is provisionally calculated up to block 8 (step S404).
[0139]
Next, an average value of the provisional calculation values (including provisional setting values) of the block interval ratios of the blocks 1 to 8 is calculated (step S405). The calculated average value of the block interval ratio is compared with the average value of d1 to d8 calculated in step S401 (step S406), and if they do not match, the average value of d1 to d8 and each temporarily calculated value of the block interval ratio ( The size is compared with the value including the provisional setting value (step S407). If the average value of the block interval is larger than the average value of dx, the temporary setting value is increased (step S408). Conversely, if the average value of the block interval is smaller than the average value of dx, the temporary setting value is decreased. (Step S409). By repeating the processing of steps S403 to S409, a temporary setting value in which the average value of the block interval matches the average value of dx (or within an allowable range) is determined, and each block 1- 1 at the determined temporary setting value is determined. The block interval ratio (am / as) of 8 is calculated and registered (step S410).
[0140]
Next, the registered block interval ratio (am / as) is sequentially called (step S411), and the motor speed control set value Cx of each block 1-8 is calculated (step S412). The motor speed control set value Cx of block 1 to block 8 acquired as described above is registered in the second memory 109 (step S413).
[0141]
At the time of actual recording, speed control is performed using the registered motor speed control setting values C1 to C8 for the blocks 1 to 8 according to the flowchart shown in FIG. 16, and the remaining blocks 9 and 10 are determined in advance. Control is performed using the set value, for example, the standard speed set value C or the motor speed control set value C8 of the last block 8.
[0142]
According to such an embodiment, the entire circumference of the intermediate transfer belt 10 is equally divided into blocks, and the motor speed control set value Cx is calculated for only a few of the blocks. Time for obtaining is shortened, and arithmetic processing is simplified.
[0143]
It should be noted that, instead of the entire circumference of the intermediate transfer belt 10, a partial area is equally divided into blocks, and the motor speed control set value Cx is calculated for all the divided blocks or several blocks in the divided blocks, and based on the calculation results. It can also be configured to control in the same manner as described above.
[0144]
According to this, even when the entire circumference of the intermediate transfer belt 10 cannot be divided equally, there is an advantage that the motor speed control can be performed in a partial region of the intermediate transfer belt. In the first embodiment, the motor speed control setting value Cx is obtained by multiplying the standard speed setting value C by the block interval ratio (ax / as), but the adjacent block length ratio and the motor speed control setting of the previous block are obtained. The motor speed control set value of the next block may be obtained from the value.
[0145]
Specifically, first, block position marks are recorded at predetermined time intervals (ts) by the recording means, the area between the block position marks is set to one block, and then the (n + 1) th block from the nth block position mark. The detection interval time (tnr) of the block length (Ln) of the block n formed up to the block position mark is measured, and the ratio of the block lengths is obtained by the following equation.
[0146]
tnr / ts = Ln / {L (n + 1)}
In order to make L (n + 1) the same length as Ln, a motor speed control set value Cn for controlling the motor speed for driving the block (n + 1) to tnr / ts times the motor speed for driving the block n is determined. In this way, motor speed control set values are obtained and registered for all blocks, and are read and used for each block during recording.
[0147]
According to this, a distance ratio between each block position mark is calculated from a fixed time (ts) for recording the block position mark and a detection interval time (tr) for actually detecting the block position mark, and based on this, the intermediate transfer is performed. By controlling the speed of the motor 14 that drives the belt 10, the speed control value can be easily calculated.
[0148]
(Embodiment 2)
In the first embodiment, the intermediate transfer belt 10 is divided into a plurality of continuous blocks and the motor speed control set value Cx is calculated in units of blocks. It is also possible to perform motor speed control in consideration of the thickness of the intermediate transfer belt 10 only with the sensor 41 and predetermined calculation processing. In this case, since the block division is not premised, the block interval ratio is not used, and the recording interval time (ts) of the position information recorded at the front end and the rear end of the target area and the detection interval time (tr) of the position information. The motor speed control set value for the target area is determined using only the ratio.
[0149]
Specifically, when tr / ts> 1, it is considered that the detection interval time tr is long because the drive roller 11 is decelerated, and a motor that controls the motor speed so as to increase the motor speed in that section. Use speed control setpoint.
[0150]
On the other hand, in the case of tr / ts <1, it is considered that the detection interval time tr is shortened because the driving roller 11 is accelerated, and the motor speed control setting for controlling the motor speed so as to decelerate the motor speed in that section. Use the value.
[0151]
Further, instead of increasing or decreasing the time for detecting the block position mark, the same correction can be performed by delaying or increasing the recording timing. That is, when tr / ts <1, control is performed to slow down the recording timing of the block position mark by decelerating the motor speed in the interval from recording the block position mark to recording the next block position mark. On the other hand, in the case of tr / ts <1, control is performed to increase the motor speed and increase the recording timing of the block position mark in the interval from recording the block position mark to recording the next block position mark. .
[0152]
According to this, the recording interval time (ts) for recording the position information and the detection interval time for actually detecting the position information using the existing means called the registration sensor 41 for detecting the position information using the plurality of images for alignment. (Tr) is used to detect a change in the driving speed of the intermediate transfer belt 10, and based on this, the motor speed for driving the intermediate transfer belt 10 is controlled, so that the number of parts does not increase. Since the speed unevenness caused by the thickness unevenness can be corrected, a high-quality image can be formed by appropriately preventing image shift with a simple configuration.
[0153]
Further, it is desirable not to make a determination only by comparing tr / ts with 1, but to determine the increase / decrease in the motor speed in multiple steps in detail according to the ratio of tr / ts. According to this, the speed unevenness due to the thickness unevenness of the intermediate transfer belt 10 can be appropriately corrected, and a high-quality image can be formed by appropriately preventing image misalignment.
[0154]
Hereinafter, an embodiment in which the motor speed control set value is switched in multiple steps according to the ratio of tr / ts will be described. In the present embodiment, the process for calculating the motor speed control set value Cx is simplified compared to the first embodiment. The hardware configuration of the image recording apparatus according to the present embodiment is the same as that of the first embodiment described above, and will be described using the reference numerals shown in FIG.
[0155]
In the present embodiment, the motor speed control set value Cx in the arbitrary area is calculated only by the ratio between the recording interval time ts of the position information in the arbitrary area and the detection interval time tr and the standard speed set value C.
[0156]
FIG. 21 is a conceptual diagram of recording area setting in the image recording apparatus according to the second embodiment. As shown in the figure, arbitrary non-continuous portions of the intermediate transfer belt 10 are set as recording areas for motor speed control, and a motor speed control set value Cx is obtained for the recording areas. In the example shown in the figure, recording areas 1 to 4 having arbitrary lengths are set at arbitrary four locations. A first position mark is recorded at the tip of each recording area (1-4), and a second position mark is recorded at the end.
[0157]
The motor is controlled at the standard speed setting value C to drive the intermediate transfer belt 10 at a constant speed, and the first position mark and the second position mark are recorded at an arbitrary recording interval time ts in each recording area (1-4). The detection interval time tr from the first position mark to the second position mark is measured by the registration sensor 41. A numerical value obtained by multiplying the standard speed setting value C by ts / tr is used as the motor speed control setting value Cx in the recording area x.
[0158]
Hereinafter, the operation from the recording operation of the first position mark and the second position mark to the registration of the motor speed control set value Cx of each recording area (1-4) will be specifically described with reference to a flowchart.
[0159]
22 and 23 are flowcharts relating to the recording operation of the first position mark and the second position mark from the recording area 1 to the recording area 4. Note that the recording start positions (first position mark recording positions) in the recording area 1 to the recording area 4 are respectively registered as Pw1 to Pw4 as belt drive amounts as shown in FIG. It is also assumed that recording interval times ts1 to ts4 corresponding to the lengths of the recording areas 1 to 4 are registered in advance.
[0160]
The CPU 100 reads the standard speed set value C from the second memory 109 and sets it as a target value (step S500), drives the motor 14 and rotationally drives the drive roller 11 (step S501). When the intermediate transfer belt 10 moves and the origin position mark is detected by the belt origin sensor 42 (step S502), the drive amount counter for measuring the drive amount of the intermediate transfer belt 10 is reset (step S503) and then the drive. The amount counter is activated (step S504).
[0161]
When the counter value of the driving amount counter becomes P = Pw1, it is determined that the leading end of the recording area 1 has reached the recording position of the photosensitive member 18 serving as recording means (step S505), and the first position mark is set to the intermediate transfer belt. 10 (step S506).
[0162]
After the position information recording timer is reset simultaneously with the recording of the first position mark (step S507), the position information recording timer is activated (step S508). When a time ts1 that is a predetermined time interval elapses after recording the first position mark (step S509), the second position mark is recorded on the intermediate transfer belt (step S510). As a result, the first position mark and the second position mark are recorded at the interval of time ts1 at the leading end and the trailing end of the recording area 1.
[0163]
Next, when P = Pw2, which is a counter value indicating the recording start position of the recording area 2, it is determined that the leading end of the recording area 2 has reached the recording position of the photoconductor 18 serving as recording means (step S511). The first position mark is recorded on the intermediate transfer belt 10 (step S512). After the position information recording timer is reset simultaneously with the recording of the first position mark (step S513), the position information recording timer is activated (step S514). When a time ts2 that is a predetermined time interval elapses after recording the first position mark (step S515), the second position mark is recorded on the intermediate transfer belt (step S516). As a result, the first position mark and the second position mark are recorded at the interval of time ts2 at the leading end and the trailing end of the recording area 2.
[0164]
Next, when P = Pw3 which is a counter value indicating the recording start position of the recording area 3, it is determined that the leading end of the recording area 3 has reached the recording position of the photosensitive member 18 serving as a recording means (step S517). The first position mark is recorded on the intermediate transfer belt 10 (step S518). After the position information recording timer is reset simultaneously with the recording of the first position mark (step S519), the position information recording timer is activated (step S520). When a time ts3 corresponding to a predetermined time interval elapses after recording the first position mark (step S521), the second position mark is recorded on the intermediate transfer belt (step S522). As a result, the first position mark and the second position mark are recorded at the interval of time ts3 at the front end and the rear end of the recording area 3.
[0165]
Next, when P = Pw4 which is a counter value indicating the recording start position of the recording area 4, it is determined that the leading end of the recording area 4 has reached the recording position of the photosensitive member 18 serving as a recording means (step S523). The first position mark is recorded on the intermediate transfer belt 10 (step S524). After the position information recording timer is reset simultaneously with the recording of the first position mark (step S525), the position information recording timer is activated (step S526). When a time ts4 that is a predetermined time interval elapses after the first position mark is recorded (step S526), the second position mark is recorded on the intermediate transfer belt (step S527). As a result, the first position mark and the second position mark are recorded at the interval of time ts4 at the leading and trailing ends of the recording area 4 (step S528).
[0166]
While the recording of each recording area is performed, the detection interval time is measured by the position information detection shown in FIG. That is, it is started simultaneously with the execution of the recording operation. First, after resetting the recording area number (step S600), the recording area number is incremented to n = 1 (step S601). Then, it is monitored that the registration sensor 41 outputs a position information detection pulse (step S602). As shown in FIG. 21, the first detection pulse after activation is that of the first position mark in the recording area 1. When the first position mark in the recording area 1 is detected, the position information detection timer is reset (step S603), and then the position information detection timer is activated (step S604). Then, it waits for the registration sensor 41 to output the position information detection pulse (step S605). When the position information detection pulse is output, the position information detection timer value tm (= tr1) at that time is acquired (step S605). S606). As shown in FIG. 21, since the second position information detected after activation is the second position mark of the recording area 1, the timer value tr1 is detected corresponding to the length from the leading end to the trailing end of the recording area 1. It will be an interval time.
[0167]
Next, it is determined whether or not the recording area number is n = 4 (step S608). If n = 4, the processing from step S601 to step S608 is repeated, and the positional information of recording area 2 to recording area 4 is determined. Timer values tr2 to tr4, which are detection interval times, are sequentially acquired.
[0168]
When the position information detection interval times tr1 to tr4 are acquired for the recording areas 1 to 4 by the above operation, motor speed control set values C1 to C4 are calculated for the recording areas 1 to 4. That is, C1 = C × ts1 / tr1, C2 = C × ts2 / tr2, C3 = C × ts3 / tr3, and C4 = C × ts4 / tr4 are calculated.
[0169]
FIG. 25 is a flowchart when the motor speed control is performed using the calculated motor speed control set values C1 to C4. As shown in the figure, the standard speed set value C is called from the second memory 109 and set as a target value (step S700), and the drive roller 11 is driven to rotate by controlling the motor 14 with the standard speed set value C. (Step S701). Then, the detection interval time tr value of the position information of each recording area 1-4 registered from the second memory 109 is called (step S702), and the motor speed control setting values C1 to C4 are recorded for the recording area 1 to the recording area 4. Calculation is performed (step S703).
[0170]
When the belt origin sensor 42 detects the origin position mark (step S704), the drive amount counter of the intermediate transfer belt 10 is reset (step S705), and the operation of the drive amount counter is started (step S706). If there is no stop command for the driving roller 11 (step S707), the process waits until the driving amount P of the intermediate transfer belt 10 indicated by the driving amount counter becomes P = Pw1 (step S709). If a stop command for the drive roller 11 has been generated, the drive roller 11 is stopped before entering the image recording operation (step S708).
[0171]
The position where the intermediate transfer belt 10 has moved by Pw1 after detecting the origin position mark is the position corresponding to the tip (first position mark) of the recording area 1. In this example, the motor speed control set value C1 is set at the tip of the recording area 1 (step S710), and the target value of the motor 14 is changed from the standard speed set value C to the motor speed control set value C1 (step S711). .
[0172]
The motor speed control set value C1 is maintained until the driving amount P of the intermediate transfer belt 10 indicated by the driving amount counter reaches P = Pw2, and the driving amount Pw2 corresponding to the distance at which the tip of the recording area 2 reaches the registration sensor 41 is maintained. At this point (step S712), the motor speed control set value is changed from C1 to C2 (step S713), and the speed of the motor 14 is changed (step S714).
[0173]
Further, the motor speed control set value C2 is maintained until the driving amount P of the intermediate transfer belt 10 indicated by the driving amount counter reaches P = Pw3, and the driving corresponding to the distance that the leading edge of the recording area 3 reaches the registration sensor 41 is achieved. When the amount Pw3 is reached (step S715), the motor speed control set value is changed from C2 to C3 (step S716), and the speed of the motor 14 is changed (step S717).
[0174]
Thereafter, the motor speed control set value C3 is maintained until the drive amount P of the intermediate transfer belt 10 indicated by the drive amount counter reaches P = Pw4, and the drive corresponding to the distance at which the tip of the recording area 4 reaches the registration sensor 41 is achieved. When the amount Pw4 is reached (step S718), the motor speed control set value is changed from C3 to C4 (step S719), and the speed of the motor 14 is changed (step S720).
[0175]
Then, returning to step S704, when the origin position mark of the intermediate transfer belt 10 is detected, the processing from step S704 to step S720 is repeated.
[0176]
According to such an embodiment, each position mark is calculated from the recording interval time (Ts) for recording the first and second position marks and the detection interval time (Tx) for actually detecting the first and second position marks. By calculating the distance ratio and controlling the speed of the motor 14 that drives the intermediate transfer belt 10 based on this distance ratio, the speed control value can be easily calculated.
[0177]
Also in the second embodiment, it is desirable that the setting position of the registration sensor 41, the circumference of the driving roller 11, the one block length, and the like are set as in the first embodiment. That is, it is desirable that the registration sensor 41 be provided at a position away from the photosensitive member 18 serving as a recording unit by an integral multiple of the distance that the position information moves in a substantially recording interval time (Ts).
[0178]
According to this, the output of the registration sensor 41 is not affected by the eccentricity of the driving roller 11, and only the influence of the uneven thickness of the intermediate transfer belt 10 that causes the image shift can be detected, so that a higher quality image can be obtained. Can be formed.
[0179]
In the second embodiment, the distance that the position information moves from the photosensitive member 18 serving as a recording unit in a substantially recording interval time (Ts) corresponds to a substantially integral multiple of the circumference of the drive roller 11. .
[0180]
According to this, even when the moving distance of the intermediate transfer belt 10 in the recording interval time (Ts) cannot be set to be substantially equal to the circumferential length of the driving roller 11 due to the constraints on the mechanism, the recording interval time (Ts) ) Is an integral multiple of the circumferential length of the drive roller 11, and the output of the registration sensor 41 is not affected by the eccentricity of the drive roller 11 and causes image shift. Only the influence of the uneven thickness of the intermediate transfer belt 10 can be detected, and a higher quality image can be formed.
[0181]
In Embodiment 2, the length obtained by multiplying the circumference of the driving roller 11, the circumference of the photosensitive member 18 as the recording unit, and the distance from the recording unit to the registration sensor 41 by an approximately integer multiple is the position information described above. It corresponds to the distance traveled from the recording means by the approximate recording interval time (Ts).
[0182]
Accordingly, the eccentricity of the driving roller 11 and the eccentricity of the photosensitive member 18 can be canceled even if the speed unevenness due to the eccentricity of the photosensitive member 18 as well as the eccentricity of the driving roller 11 occurs. An image shift including unevenness due to the eccentricity of the photoconductor 18 can be appropriately prevented, and a higher quality image can be formed with a simple configuration.
[0183]
In the second embodiment, it is preferable that an average of the ratio of the detection interval time (Tx) to the recording interval time (Ts) is a standard value, and this standard value can be set to an arbitrary value.
[0184]
According to this, by setting the average as the standard value and setting the standard value to an arbitrary value, even if the conveyance unevenness due to the thickness unevenness in the intermediate transfer belt 10 is corrected, the image shift still occurs. In this case, since the color shift caused by other elements can be corrected by a simple means of changing the standard value, the image shift can be appropriately prevented with a simple configuration, and a high-quality image can be formed.
[0185]
In the first and second embodiments, the intermediate transfer belt 10 is rotated only once to measure the block or recording area. However, the second block or more is detected and the same block or recording area is detected twice or more. The time interval (Tx) may be measured, and the block length or recording area length may be predicted from the average value.
[0186]
Accordingly, the thickness unevenness of the intermediate transfer belt 10 can be predicted with higher accuracy, and the speed control of the motor 14 can be performed, so that a higher quality image can be guaranteed.
[0187]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to control the drive of the intermediate transfer medium in consideration of the thickness unevenness of the intermediate transfer medium with a simple configuration, thereby preventing color misregistration and forming a high-quality image. An image recording apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of an image recording apparatus according to Embodiments 1 and 2 of the present invention.
FIG. 2 is a schematic perspective view showing a relationship between a block position mark and a pair of registration sensors.
FIG. 3 is a schematic perspective view showing a relationship between a block position mark and a center registration sensor.
FIG. 4A is a diagram showing a record detection pulse of a block position mark.
(B) The figure which shows the detection pulse of the block position mark by a registration sensor
FIG. 5 is a diagram illustrating a state in which a start position mark is recorded on the intermediate transfer belt.
FIG. 6 is a diagram illustrating a state in which a block position mark of block 1 is recorded on the intermediate transfer belt.
FIG. 7 is a diagram showing a state in which a block position mark of block 2 is recorded on the intermediate transfer belt.
FIG. 8 is a diagram illustrating a state in which a block position mark of block 3 is recorded on the intermediate transfer belt.
FIG. 9 is a diagram showing a correspondence table of position information detection timer value of each block, ratio to standard one block interval time, block interval ratio, and motor speed control set value.
FIG. 10 is a diagram illustrating an example of calculation using a temporary setting value.
FIG. 11 is a diagram showing a correspondence table obtained up to a speed ratio, which is an example of calculation using temporarily set values.
FIG. 12 is a functional block diagram related to motor speed control according to the first and second embodiments of the present invention.
FIG. 13 is a flowchart for recording position information in the first embodiment.
14 is a flowchart for detecting position information in Embodiment 1. FIG.
FIG. 15 is a flowchart for calculating a motor speed control set value in the first embodiment.
FIG. 16 is a flowchart of motor speed control during recording in the first embodiment.
FIG. 17 is a diagram showing a correspondence table of position information detection timer values of each block, a ratio to a standard one block interval time, a block interval ratio, and a motor speed control set value in a modification of the first embodiment.
FIG. 18 is a diagram illustrating a calculation example using a temporary setting value in the modification example;
FIG. 19 is a diagram illustrating a correspondence table obtained up to a speed ratio, which is an example of calculation using a temporary setting value in the modification example.
FIG. 20 is a flowchart for calculating a motor speed control set value in the modified example.
FIG. 21 is a diagram showing a concept of a recording area set on an intermediate transfer belt in the second embodiment.
FIG. 22A is a flowchart of the previous stage of recording the recording area 1 in the second embodiment.
(B) Flow chart for recording the recording area 1 in the second embodiment.
(C) Flow chart for recording the recording area 2 in the second embodiment
FIG. 23A is a flowchart for recording the recording area 3 in the second embodiment.
(B) Flow chart for recording the recording area 4 in the second embodiment
24 is a flowchart for detecting position information in Embodiment 2. FIG.
FIG. 25A is a flowchart of the preceding stage for starting motor speed control in the second embodiment;
(B) Flow chart of motor speed control in recording areas 1 and 2 in the second embodiment
(C) Flow chart of motor speed control in recording areas 3 and 4 in the second embodiment
FIG. 26 is a view showing a correspondence table of start position driving amount, recording interval, position information detection interval, and motor speed control set value for each recording area in the second embodiment.
FIG. 27 is a diagram for explaining the principle of fluctuation of the belt conveyance speed depending on the belt thickness.
[Explanation of symbols]
10 Intermediate transfer belt
11 Driving roller
12 Followed roller
13 Gear mechanism
14 Motor
15-18 photoconductors of each color
19-22 Developer
23-26 Primary transfer unit
27-30 Charger
31-34 LSU
35 Paper feed roller
36 Registration Roller
37 Transfer roller
38 Fixing device
39 Discharge roller
40 trays
41 Registration sensor
42 Belt origin sensor

Claims (14)

A plurality of recording means; a belt-like intermediate transfer medium that combines images formed by the plurality of recording means; a drive roller that drives the intermediate transfer medium; a motor that drives the drive roller; and the recording means Position information detecting means for detecting position information formed by the above as position information used for image alignment, speed information determining means for determining speed information for accelerating / decelerating the motor, and registration means for registering the speed information Control means for controlling the motor speed of the section from the time when the recording means records the first position information to the time when the second position information is recorded at the time of recording, based on the registered speed information,
The speed information determining means first records the first position information and the second position information at a predetermined time interval (ts) by the recording means, and then records the first position information and the second position information. The detection interval time (tr) between the information is measured, and then the ratio between ts and tr is determined. If tr / ts> 1, the intermediate transfer is performed between the time of recording the position information and the time of detection. Determining that the drive speed of the medium has been reduced and determining speed information for decelerating the motor speed in a section from when the recording means records the first position information to when the second position information is recorded, When tr / ts <1, it is determined that the driving speed of the intermediate transfer medium has increased between the time of recording the position information and the time of detection, and the recording means records the first position information before the recording means records the first position information. Speed information for increasing the motor speed in the section until the second position information is recorded is determined. The image recording apparatus according to claim and. It said control means, an image recording apparatus according to claim 1, wherein the determining in accordance with the increase or decrease of the motor speed to the ratio of the predetermined time interval (ts) and the detection time interval (tr). The distance that the location information is moved by the substantially predetermined time interval from said recording means (ts) is according to claim 1 or claim 2, wherein the image, characterized in that corresponding to approximately an integral multiple of the circumferential length of said drive roller Recording device. The circumferential length of the driving roller, the circumferential length of the photosensitive member constituting the recording means, and the length obtained by multiplying the distance from the recording means to the position information detecting means by substantially an integer number are obtained by calculating the position information from the recording means. the substantially image recording apparatus according to claim 1 or claim 2, wherein the corresponding to the distance traveled by the predetermined time interval (ts). A plurality of recording means; a belt-like intermediate transfer medium that combines images formed by the plurality of recording means; a drive roller that drives the intermediate transfer medium; a motor that drives the drive roller; and the intermediate transfer Position information detecting means for detecting position information formed by the recording means as position information used for image alignment for each predetermined block obtained by dividing the medium into a plurality of areas, and speed information for increasing and decreasing the speed of the motor are determined. Speed information determination means, registration means for registering the speed information for each block, and control means for controlling the motor speed of each block based on the speed information at the time of recording,
The speed information determining means first records the position information at a predetermined time interval (tbs) by the recording means to make the area between the position information one block, and then detects the detection interval time (tbr) of the block Next, the ratio between tbs and tbr is determined to detect the change in the speed of the intermediate transfer medium for each block. Next, when tbr / tbs> 1, the position information is recorded and detected. In this case, it is determined that the driving speed of the intermediate transfer medium has decreased, and the recording unit determines speed information for reducing the motor speed in the section forming the block. It is determined that the drive speed of the intermediate transfer medium has increased between the time of recording and the time of recording information, and the speed information for increasing the motor speed of the section forming the block is determined by the recording means. Image Apparatus. A plurality of recording means; a belt-like intermediate transfer medium that combines images formed by the plurality of recording means; a drive roller that drives the intermediate transfer medium; a motor that drives the drive roller; and the intermediate transfer Position information detecting means for detecting position information formed by the recording means as position information used for image alignment for each predetermined block obtained by dividing the medium into a plurality of areas, and speed information for increasing and decreasing the speed of the motor are determined. Speed information determination means, registration means for registering the speed information for each block, and control means for controlling the motor speed of each block based on the speed information at the time of recording,
The speed information determination means first records the position information at predetermined time intervals (tbs) by the recording means to make the area between the position information one block, and then (n + 1) pieces of information from the nth position information. Measure the detection interval time (tbr) of the block n length (Ln) to the eye position information,
Next, the ratio of each block length is obtained by the following formula,
tbr / tbs = Ln / {L (n + 1)}
In order to make L (n + 1) the same length as Ln, the speed information for controlling the motor speed for driving the block (n + 1) to tbr / tbs times the motor speed for driving the block n is determined. Image recording device. 1 The length of the block, the image recording apparatus according to claim 5 or claim 6 further characterized in that substantially corresponding to an integral multiple of the circumferential length of the driving roller. The length obtained by multiplying the circumferential length of the driving roller, the circumferential length of the photosensitive member constituting the recording means, and the distance from the recording means to the position information detection means by substantially an integer corresponds to one block length. The image recording apparatus according to claim 5 or 6, characterized in that The length of the intermediate transfer medium, the 1 block image recording apparatus according to claim 5 or claim 6, wherein it is approximately an integral multiple of. 2. The position information detection unit is provided at a position on a peripheral surface of the drive roller where the intermediate transfer medium from the recording unit to the position information detection unit maintains a linear state. The image recording apparatus according to claim 9 . The circumferential length of the driving roller, an image recording apparatus according to any one of claims 1 to 9, characterized in that substantially equal to the distance from the recording means to said position information detecting means. The position information detecting means is provided opposite to both ends in the width direction of the intermediate transfer medium, and the control means uses an average value of two detection interval times (tr). The image recording apparatus according to claim 11 . The position information detecting means, an image recording apparatus according to any one of claims 1 to 11, characterized in that provided opposite the center in the width direction of the intermediate transfer medium. The control means, said intermediate transfer medium is rotated over two turns, the image recording apparatus according to any one of claims 13 claim 1, characterized in that predicting the block length from the average value.

Images