JPH10250142A - Led array printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent white or black streaks from being formed in printed results by correcting a shift of pitches and uniforming to a regulated pitch even when the pitch of spots on a photosensitive body by each LED element is different from the regulated pitch. SOLUTION: Under a preset required image formation condition, correction data for correcting a spot diameter by each LED element 3 to make a pitch of spots by the LED element 3 in an LED array 4 a preset required pitch are stored in a memory part 15 beforehand. At the image formation time, correction data corresponding to each LED element are read out from the memory part 15 by a correction data read means, so that a driving control means controls with using the correction data to turn ON each LED element 3. Accordingly, optical writing with the pitch of spots uniformed to a regulated pitch is ensured, and white or black streaks are not given rise to in printed results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED array printer for forming an image by electrophotography using an LED array as optical writing means.

[0002]

2. Description of the Related Art Generally, in a printer for forming an image by electrophotography, a laser scanning optical system including a laser light source and a polygon mirror for deflecting and scanning the laser light is mainly used as an optical writing means. In recent years, in order to reduce the size and simplification of the entire device, an L
LED array printers using ED arrays have also attracted attention. The LED array has a large number of LED elements arranged in a line. By controlling the lighting of each LED element according to image data, optical writing is performed on the photoconductor, and an electrostatic latent image is formed. Is done.

[0003] An LED array is usually formed by arranging a plurality of chips in which a large number of LED elements are arranged in a straight line on a substrate. In such a case, the interval between the chips is not appropriate, and the LE
The pitch between LED elements is defined as the pitch between LED elements (6
In the case of 00 dpi, it often differs from 42.3 μm). This is because it is difficult to accurately control the pitch between the chips when mounting the chips on the substrate. Here, the LED at the end of the adjacent chip
If the elements are too far apart, there will be a gap in the irradiation area of the LED element to the photoreceptor, resulting in white streaks in the printed result. Conversely, if the LED elements at the ends of the adjacent chips are too close to each other, the irradiation area of the LED elements to the photoconductor overlaps, and black streaks occur in the printed result.

For this reason, with respect to the LED array printer, in order to improve the printing quality at the joint between the LED elements at the ends of the adjacent chips (to prevent the occurrence of white or black streaks), for example, 1-201
As disclosed in Japanese Patent Application Laid-Open No. H06-26 and Japanese Patent Application Laid-Open No. HEI 8-118722, there is an apparatus in which a current flowing through an LED element located at an end of a chip and a current supply time are adjusted.

[0005]

However, since the LED array irradiates the light emitted from the LED array onto the photoreceptor through the lens array, the characteristics of the lens itself and the light of the lens array not only between the chips but also within the same chip. Deviation from the axis,
The pitch between the prescribed LED elements often differs from the prescribed pitch between the LED elements due to various factors such as inclination and variation in the optical path length. As a result, a white streak or a black streak is generated in the printing result due to a variation in the pitch between the spots by the adjacent LED elements in the same chip. Actual fairness 1 above
In JP-A-201226 and JP-A-8-118722, measures against such a phenomenon are not considered.

Accordingly, the present invention corrects the deviation of the pitch even if the pitch between the spots on the photoreceptor by each LED element is different from the prescribed pitch, makes the pitch uniform, and provides a printing result. It is an object of the present invention to provide an LED array printer that can prevent occurrence of white streaks and black streaks.

[0007]

SUMMARY OF THE INVENTION The present invention provides an LED array printer which forms an image by electrophotography using an LED array in which a large number of LED elements whose lighting is controlled in accordance with image data are arranged in a line. Is assumed. Claim 1
The LED array printer according to the invention described above corrects a spot diameter of each LED element in order to set a pitch between spots of each LED element in the LED array to a predetermined desired pitch under a predetermined image forming condition. Storage unit storing correction data to be read, correction data reading means for reading out the correction data corresponding to each LED element from the storage unit at the time of image formation, and LE using the read correction data.
Drive control means for controlling the lighting operation of each LED element of the D array. Here, the “pitch” in the present invention means not only the interval between spots that are separated from each other, but also the degree of overlap when adjacent spots overlap (the same applies to the following inventions).

Therefore, when a desired pitch between spots by each LED element is determined, the LE used
Even if there is variation in the pitch between the spots due to the LED elements on the D array, correction data for correcting the spot diameter of each LED element in order to set the pitch between the spots to a preset desired pitch is stored in the storage unit in advance. Remembered,
At the time of image formation, the correction data reading unit reads the corresponding correction data from the storage unit, and the drive control unit controls the lighting operation of the LED element using the correction data. Is done. Therefore, the pitch between the spots on the photoreceptor by each LED element is corrected so as to be uniform at a desired pitch, and white streaks and black streaks do not occur in the printing result. This is L
This means that the pitch accuracy between each LED element in the ED array may be lower, and the manufacturing cost may be reduced.

In the LED array printer according to the present invention, the spot diameter of each LED element is set so that the pitch between the spots of each LED element in the LED array can be various pitches under predetermined image forming conditions. A storage unit for storing correction data to be corrected; a designation unit for designating a desired pitch between spots; and a correction data reading unit for reading correction data corresponding to each LED element from the storage unit in accordance with the designated pitch And drive control means for controlling the lighting operation of each LED element of the LED array using the read correction data.

Therefore, the present invention is also basically the same as the LED array printer according to the first aspect of the present invention, but additionally, since correction data is stored in the storage unit for each pitch. When the desired pitch between the spots is changed, each LED element can be turned on so as to be uniform at the pitch.

According to a third aspect of the present invention, there is provided an LED array printer, wherein each LED element is arranged to set a pitch between spots of each LED element in the LED array to a predetermined desired pitch for each of various image forming conditions. A storage unit for storing correction data for correcting the spot diameter of the image forming apparatus, a specifying unit for specifying a desired image forming condition, and a storage unit for storing correction data corresponding to each LED element according to the specified image forming condition. Correction data reading means for reading data from each of the LEDs of the LED array using the read correction data.
Drive control means for controlling the lighting operation of the element.

Therefore, the present invention is also basically the same as the LED array printer according to the first aspect of the present invention. In addition, correction data for obtaining a desired pitch is provided for each image forming condition. Therefore, even when the image forming conditions are changed, each LED element can be turned on so as to be uniform at a desired pitch.

According to the LED array printer of the present invention, each LE in the LED array is provided for each of various image forming conditions.
A storage unit that stores correction data for correcting the spot diameter of each LED element so as to make the pitch between spots of the D element various pitches, a specifying unit for specifying a desired image forming condition and a desired pitch, Correction data reading means for reading out the corresponding correction data for each LED element from the storage unit according to the image forming conditions and the pitch, and driving for controlling the lighting operation of each LED element of the LED array using the read correction data Control means.

Therefore, the present invention is basically the same as the LED array printer according to the first aspect of the present invention. In addition, the pitch is set for each image forming condition and each pitch. Is stored in the storage unit, so that even if the image forming condition or the desired pitch is changed, each L is adjusted so as to be uniform at the desired pitch.
The ED element can be turned on. That is, the present invention has the functions of the second and third aspects of the present invention.

[0015] The invention according to claim 5 is based on claims 1, 2, 3
In the LED array printer according to the fourth aspect, after the correction data stored in the storage unit corrects the spot diameter of each LED element to a desired spot diameter, a pitch between spots of each LED element becomes a desired pitch. As described above, the value is obtained by correcting the spot diameter of each LED element. Therefore, since the spot diameter is made uniform by giving priority to the correction of the spot diameter, correction data obtained by correcting so as to have a desired pitch between the spots is used. Correction can be made so that the pitch between the spots has a desired pitch in a state where there is no variation in the spot diameter of the LED element.

The invention according to claim 6 is the invention according to claim 5,
In the ED array printer, there are a plurality of types of desired spot diameters, and each spot diameter has correction data. Therefore, it is possible to perform printing such that the pitch between the spots is made uniform at not only one spot diameter but also various desired spot diameters.

[0017]

FIG. 1 shows a first embodiment of the present invention.
7 will be described with reference to FIG. FIG. 1 shows a configuration example of an optical writing device 1 in an LED array printer, which is mainly configured by an LED array drive circuit 2. The LED array drive circuit 2 includes a large number (for example, N) of LED elements 3
Are arranged in a line, and an LED array drive unit 5 that controls the lighting of each LED element 3. Specifically, the LED array driving unit 5 has a well-known configuration as shown in FIG. 2, and includes a shift register 6, a latch 7, an AND gate 8, and an LED driver 9. However, in the present embodiment, an eight-division synchronization signal / HSYNC (a signal obtained by dividing the line synchronization signal / LSYNC into eight) for performing light amount control as described later by lighting time control is used. As shown in FIG.
It is configured to be reset by the NC. The shift register 6 operates to input binary image data of one dot “0” or “1” in order from the dot 1 by the clock signal CLOCK, and internally send each dot data to each register. When all the dot data of N pieces are sent, the latch 7 latches the data, and when the strobe pulse STB is input to the AND gate 8, the dot (LED) to which "1" of the image data is sent
Basically, only the element) is turned on by the LED driver 9 for the width of the strobe pulse STB.

L in such an LED array drive circuit 2
A strobe pulse generator 10 is connected to the ED array driver 5 via a selector 11. The strobe pulse generator 10 is constituted by, for example, a counter, a comparator and the like, and generates eight types of strobe pulses STB0 to STB7. These strobe pulses STB0 to STB7 are different from each other, and when the width of strobe pulse STB0 is t, STB1 =
2t, STB2 = 4t, STB3 = 8t, STB4 = 1
6t, STB5 = 32t, STB6 = 64t, STB7
= 128t. The selector 11 divides one line into eight divided synchronization signals / HSY.
The divided timings divided into eight by the NC are sequentially denoted by T0 to T
7, at timing T0, the strobe pulse ST
B0, at timing T1, the strobe pulse STB1,
.., At the timing T7, the select operation is performed so as to output the strobe pulse STB7 to the AND gate 8, respectively.

The LED in the LED array driving circuit 2
For the array drive unit 5, the multi-value conversion unit 1 is provided as a separate system.
2 are connected via a selector 13. The multi-level conversion unit 12 is configured by, for example, an AND gate, and outputs 8-bit data b0 to b7 to the selector 13. The selector 13 outputs these 8-bit data b0 to b7 to the shift register 6 every time during the timing T0 to T7. A FIFO is provided on the input side of the multi-level conversion unit 12 in order to capture one line of binary image data for one line.
A (First-In First-Out) memory 14 and a correction data storage unit 15 as a storage unit are connected in parallel.
The correction data storage unit 15 has, for example, a ROM configuration, and each of the LEs in the LED array 4 is measured by a measurement method described later.
For the D element 3, the spot diameter of each LED element 3 is corrected so that the pitch between dots (spots) by each LED element 3 is set to a predetermined desired pitch P under a predetermined desired image forming condition C. The correction data for the light amount correction to be performed is stored. Here, at the time of the image forming operation, a function of a correction data reading unit for reading out the correction data corresponding to each LED element 3 from the correction data storage unit 15 and outputting the same to the multi-value conversion unit 12 is provided. In addition, the multi-level conversion unit 12, the selector 13, and the LED array driving unit 5 function as drive control means for controlling the lighting operation of each LED element 3 of the LED array 4 using the read correction data.

Next, the acquisition of correction data written and stored in advance in the correction data storage unit 15 will be described. As shown in FIG. 4, the correction data is acquired before shipment from the factory by the optical writing device 1 and the dot pitch correction data generation device 21.
And is performed using The dot pitch correction data generation device 21 is detachably connected to the multi-level conversion unit 12 of the optical writing device 1 by an interface (not shown).
A controller 22 containing a microcomputer;
A dot pitch measuring device 23 for measuring a pitch between dots when each LED element 3 is turned on and outputting the measurement result to a controller 22;
Condition setting unit 24 for setting measurement conditions by
A correction data setting unit 25 that outputs 8-bit correction data to the multi-value conversion unit 12 of the optical writing device 1 under the control of the controller 22, and a data storage that stores the correction data when the correction data is determined And the device 26.

Here, the correction data of the light amount of each LED element 3 is 8-bit (b0 to b7) data for changing the lighting time, and the lighting in one line is divided into eight divided synchronization signals / HS.
With respect to timings T0 to T7 divided into eight according to the YNC, the least significant bit b0 is assigned to T0, b1 is assigned to T1,..., And the most significant bit b7 is assigned to T7. ) Is data for lighting only the strobe pulse STBx at the timing Tx. FIG. 5 shows an example in which dot 1 (the LED element 3 of No. 1) is corrected with the correction data “12”.
8 "(=" 10000000 ") indicates the drive timing. One line synchronization signal / LSYNC
Are output from the strobe pulse generator 10 and the selector 11 in accordance with the timings T0 to T7 of the 8-divided synchronization signal / HSYNC obtained by dividing the signal into eight. The lighting signal for dot 1 is output every time the eight-segment synchronization signal / HSYNC is received, and the multi-value conversion unit 12 performs an AND process to set a bit indicating the correction data “128”.
7 (= T7), the strobe pulse STB7
The lighting is performed in the lighting width according to. In this case, if the correction data is “127” (= “01111111”), the lighting is performed with the lighting width corresponding to each of the strobe pulses STB0 to STB6 at the timing of b0 to b6 (= T0 to T6) where the bit is set. . Further, for example, when the correction data is “12”
9 "(=" 10000001 "), lighting is performed at a lighting width corresponding to each of the strobe pulses STB0 and STB7 at two timings of b0 and b7 (= T0 and T7) where bits are set. The variable light amount method is known as a method for obtaining a multi-valued light amount of one dot in the gradation method based on the multi-valued representation of one dot (see “LED array writing color electrophotographic printer”, p.
206, see Journal of the Society of Electrophotography, Vol. 24, No. 3 (1995)),
The correction data for changing the dot diameter (spot diameter) in the one-dot binary expression of the present embodiment can be easily applied as it is.

Under these assumptions, all N LEDs
FIG. 6 is a flowchart showing a process of acquiring light amount correction data for correcting a dot diameter (spot diameter) by each LED element 3 in order to set a pitch between dots (spots) by the element 3 to a desired pitch P. I will explain.
Here, a desired measurement condition corresponding to an image forming condition such as an exposure condition is C. First, it is checked whether a desired prescribed pitch P has been set (step S1). The specified pitch P means a pitch between dots which are aimed at at the time of actual image writing, and means not only an interval between separated dots but also an overlapping condition when adjacent dots overlap. is there. When the specified pitch P is set by the measurement condition setting unit 24 (Y in S1), it is checked whether a desired measurement condition C has been set (S2). The reason for setting these conditions is that the dot diameter (spot diameter) changes depending on which light amount is used as the threshold value. Therefore, the measurement condition setting unit 2 matches one of the exposure conditions at the time of actual image writing.
4 is set. When the measurement condition C is set (S2
Y), n = 1 is set to target the dot 1 (the LED element 3 of No. 1) (S3). Next, the correction data M _n (meaning the correction data for the n-th LED element 3) is provisionally set to “128” (= “10000000”) (S4). However, there is no meaning limited to the numerical value “128”, and “1” to
Any numerical value within the range of "255" is arbitrary, but as in the present embodiment, it is set to an intermediate value "128" to facilitate increase / decrease adjustment, or a desired dot diameter based on existing experimental data and the like. It is preferable to use a value expected to be closest to D. Then, in order to use the correction data for dot 1 as correction data used when actually writing an image, the correction data M _n (M ₁ ) for dot n (here, dot 1) is stored in the data storage device 26 (S
5). Since the correction data _Mn is set in the correction data setting unit 25 and supplied to the multi-value conversion unit 12, the dot n, here, the dot 1, is turned on by the LED array driving unit 5 (S6). The lighting timing at this time is shown in FIG.

Next, the next correction data M _{n + 1} (meaning correction data for the (n + 1) th LED element 3: here, n + 1 = second) is temporarily set to “128” (S).
7). Since the correction data M _{n + 1} is set in the correction data setting unit 25 and supplied to the multi-value conversion unit 12, the dot n + 1, here, dot 2, is turned on by the LED array driving unit 5 (S8). The lighting timing at this time is shown in FIG.
This is the same as the case shown in FIG.

[0024] sends the pitch P _p between the dots n dot n + 1 at this time was measured by the dot pitch measurement device 23 (S9), the measurement result to the controller 22. Measurement results in the controller 22 receives a pitch P _p between the dots checks almost equal or not to the provision of a pitch P (S10). If it is still not almost equal (S
10) N), the correction data M according to the magnitude relationship between the two.
By increasing or decreasing the value of _{n + 1} (for example, M
Change _{n + 1} = “129” or change M _{n + 1} = “127” ... However, the increment / decrement width is not limited to one (S11), and the dots lit according to the correction data again measuring the pitch P _p between the n and the dot n + 1 (S9), and repeats this until the pitch P _p is almost equal to the prescribed pitch P.

Here, the determination in step S10 should originally be a determination as to whether or not the two are completely equal. However, the number of bits of the correction data M _{n + 1} and the pitch P
_Since it is considered that the data may not always be equal due to the measurement error of _p and the like, it is determined that the data is normal when the data is within the allowable approximation range. The approximate range is the number of bits of the correction data M _{n + 1} , the pitch P
The determination is made in consideration of the measurement error of _p, the range of pitch variation that can be accepted as the target image quality when an image is actually formed, and the like.

The measured pitch P _p may become approximately equal to the prescribed pitch P (S10 of Y), the stored correction data M _{n + 1} in the data storage device 26 for the dot n + 1 (S12). The correction data M _{n + 1} at this time is the numerical value set in the correction data setting unit 25 at that time. Thereafter, dot n, here, dot 1 (LE of No. 1)
D element 3) is turned off (S13), and n is incremented by +1 to target the next dot n, here, dot 2 (LED element 3 of No. 2) (S14).
At this point, it is checked whether or not the number of new dots n exceeds the total number N (S15), and if not, the processes of steps S7 to S14 are repeated for dot n in the same manner.

That is, while the dot n (here, dot 2) is lit with the corrected data, the correction data M _{n + 1} (here, the third LED element 3) is temporarily set to “128”. It is set (S7). This correction data M _{n + 1}
Is set in the correction data setting unit 25 and given to the multi-value conversion unit 12 side, so that the dot n + 1, here, dot 3, is lit by the LED array driving unit 5 (S8). The pitch P _p between the dots n dot n + 1 at this time was measured by the dot pitch measurement device 23 (S9), and sends the measurement result to the controller 22. Measurement results in the controller 22 receives a pitch P _p between the dots checks almost equal or not to the provision of a pitch P (S10).
If the measured pitch P _p is substantially equal to the prescribed pitch P (S10 of Y), the stored correction data M _{n + 1} in the data storage device 26 for the dot n + 1 (S1
2). The correction data M _{n + 1} at this time is the numerical value set in the correction data setting unit 25 at that time.

Thereafter, dot n, here dot 2
(No. 2 LED element 3) is turned off (S13), and n is incremented by +1 to target the next dot n, here, dot 3 (No. 3 LED element 3) (S14). . At this point, the new dot n is the total number N
Is checked (S15). If not, steps S7 through S14 are performed for dot n.
Is repeated in the same manner.

[0029] Hereinafter, by repeating the same processing for each dot, the correction data M _n for light amount correction for the pitch P of defining the pitch P _p for all the dots n (n = 1~N) The data is stored in the data storage device 26.

Therefore, after all the measurements are completed, the data storage device 26 stores No. of each LED element 3 as shown in FIG. Is used as an address, and the correction data _Mn for each LED element 3 is stored. The correction data _Mn stored in the data storage device 26 is written into the correction data storage unit 15 in the optical writing device 1 using a ROM writer or the like, and is used at the time of actual image writing.

The correction data storage unit 1 in which the correction data _{Mn under} such a desired image forming condition C is written.
When optical writing is actually performed by the optical writing device 1 using the data 5, the corresponding correction data _Mn is read from the correction data storage unit 15 and output to the multi-value conversion unit 12. For example, M ₁ = “128” (= “10000000”), M
₂ = “145” (= “10010000”), M ₃ =
If "125" (= "01111101"), the lighting drive timing at this time is as shown in FIG. That is, 1-bit binary image data is input to the FIFO memory 14 for one line, and the FIFO memory 14 outputs 8 image data.
The image data is repeatedly output at the timing of the division synchronization signal / HSYNC. On the other hand, the 8-bit correction data for each dot (each LED element 3) is stored in the correction data storage unit 15 in the same manner as the image data by the 8-divided synchronization signal / HSYNC.
Is output repeatedly at the timing of. Then, the multi-value conversion unit 12 performs an AND operation on the image data and the correction data, and
The data is sent to the selector 13 as bit data (b0 to b7). The selector 13 outputs the least significant bit b0 at the timing T0, the bit b1,... At the timing T1, and the most significant bit b7 at the timing T7. On the other hand, the strobe pulse generator 10 outputs strobe pulses STB0 to STB having different pulse widths at the respective timings T0 to T7.
7 is output, and lights at the timing when AND is taken. In the case of the dot 1, the light is turned on at the timing T7 according to the strobe pulse STB7. In the case of the dot 2, the light is turned on at the timing T0, T4, T7 according to the strobe pulses STB0, STB4, STB7, and the dot 3 is turned on.
, The timings T0, T2, T3, T4,
Strobe pulses STB0, STB2, S at T5, T6
Lights according to TB3, STB4, STB5, STB6,
As a result, lighting control is performed so that the pitch between dots is uniformed at a specified pitch P in any one line.

Therefore, according to the present embodiment, each LED
The pitch between the spots of the element 3 on the photoreceptor is corrected so as to be a desired pitch P, and it is possible to prevent a white streak or a black streak from occurring in a printing result. This is LED array 4
This means that even if the pitch accuracy in manufacturing between the LED elements 3 is low, it can be dealt with by correction, and the manufacturing cost can be reduced.

FIGS. 8 and 9 show a second embodiment of the present invention.
It will be described based on. The same parts as those described in the above embodiment are denoted by the same reference numerals, and description thereof is omitted (the same applies to the following embodiments). In the present embodiment, an image writing condition setting unit 16 functioning as a designating unit is connected to the correction data storage unit 15. That is, in the above-described embodiment, the desired prescribed pitch P is uniquely specified under the preset desired image forming conditions, but in the present embodiment, the desired prescribed pitch _Px itself is specified. for but it is freely designated by the image writing condition setting section 16, and the light amount correction for correcting the spot diameter of each LED element 3 to its pitch P _x in each type of pitch P _x in the correction data storage unit 15 Are stored in advance.

Here, in the image forming operation, when a desired pitch P _x is designated by the image writing condition setting section 16, each LED element 3 is set according to the designated pitch P _x.
And a function of a correction data reading unit for reading out the corresponding correction data from the correction data storage unit 15 and outputting the same to the multi-value conversion unit 12. Further, the multi-value conversion unit 12,
The selector 13 and the LED array drive unit 5 function as drive control means for controlling the lighting operation of each LED element 3 of the LED array 4 using the read correction data.

Next, will be described acquisition of correction data for each pitch P _x which is previously written and stored in the correction data storage unit 15. The acquisition of these correction data is basically performed before the shipment from the factory, as shown in FIG.
This is executed in the same manner as in the above-described embodiment by using the dot pitch correction data generation device 21 and the dot pitch correction data generation device 21. Figure 9 is a flow chart showing the processing for obtaining the correction data in the present embodiment, differs from the process shown in FIG. 6, is a point pitch provisions may set any kind as P _x, In step S1a, the initial pitch P _x (x = 1 to
X: X is arbitrary) is determined. In this case it is shown with respect to the pitch P _x in FIG. 6 and after being processed in the same manner, it is determined whether the pitch P _x other provisions there (S
16), and repeats the process only the type X minutes of defined pitch P _x.

Therefore, after all the measurements are completed, the data storage device 26 stores As each L in the form of an address to the pitch P _x of each defined
This means that the correction data M _{nx for} each ED element 3 is stored. The correction data M _nx stored in the data storage device 26 is stored in the optical writing device 1 using a ROM writer or the like.
The data is written into the correction data storage unit 15 in the middle, and is used at the time of actual image writing.

The correction data storage unit 1 in which the correction data M _{nx under} such a desired image forming condition C is written.
5, when the optical writing is actually performed by the optical writing apparatus 1, the desired pitch _Px is specified when the image forming condition is set by the image writing condition setting unit 16, so that the correction data is stored. The corresponding correction data M _nx is read from the unit 15 and output to the multi-value conversion unit 12. This allows
Each LED element 3 is controlled to light as uniform at a pitch P _x between specified freely each dot.

[0038] Therefore, according to this embodiment, even if you want to change the desired pitch P _x, it is possible to satisfactorily Naru printing that between the spots is uniform in each of the pitch P _x.

A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, the configuration of FIG. 8 used in the second embodiment, that is, the configuration including the image writing condition setting unit 16 functioning as a designating unit is used.
However, in the second embodiment the freely specify the pitch of the provisions as P _x, the pitch P of the provisions in this embodiment
Is fixed, the measurement conditions (imaging conditions) is freely designated by the image writing condition setting section 16 as C _y.
In correspondence with this, the correction data for light amount correction for correcting the spot diameter of the LED elements 3 to the correction data storage unit 15, the pitch P prescribed for each variety of measurement conditions (imaging conditions) C _y is It is stored in advance.

Here, in the image forming operation, when a desired image forming condition _Cy is designated by the image writing condition setting section 16, each LED element 3 is handled according to the designated image forming condition _Cy. It has a function of a correction data reading means for reading out the correction data to be performed from the correction data storage unit 15 and outputting the correction data to the multi-value conversion unit 12. Further, the multi-value conversion unit 12, the selector 13, and the LED array driving unit 5 use the read correction data to read each L of the LED array 4.
It functions as drive control means for controlling the lighting operation of the ED element 3.

Next, the correction Measurement Conditions (image forming condition) is previously written and stored in the data storage unit 15 for acquiring the correction data for each C _y will be described. The acquisition of these correction data is basically performed by using the optical writing device 1 and the dot pitch correction data generation device 21 as shown in FIG. The processing is performed in the same manner as in the embodiment. Figure 10 is a flow chart showing the processing for obtaining the correction data in this embodiment, representations of actual operations differs from Figure 6, the measurement condition C _y
Can be set. In step S2b, it is determined whether the first measurement condition C _y (y = 1 to Y: Y is arbitrary) is set. After being processed in the same manner as shown in FIG. 6 with respect to the measurement condition C _y, to determine whether the other measurement condition C _y there (S17), and repeats the type Y amount corresponding process measurement condition C _y .

Therefore, after all the measurements are completed, the data storage device 26 stores Each measurement condition _Cy is used as an address, and each LED is
This means that the correction data _{Mny for} each element 3 is stored. The correction data _Mny stored in the data storage device 26 is written into the correction data storage unit 15 in the optical writing device 1 using a ROM writer or the like, and is used at the time of actual image writing.

When optical writing is actually performed by the optical writing apparatus 1 using the correction data storage unit 15 in which the correction data M _{ny for} each of the various measurement conditions C _y is written, the image writing conditions by setting a desired image forming condition C _y by the setting unit 16, from the correction data storage unit 15 is outputted is read out corresponding compensation data M _ny is the multi-level conversion unit 12. Thereby, the lighting of each LED element 3 is controlled so as to be uniform at a desired pitch P.

Therefore, according to the present embodiment, it is assumed that various photoconductors having different characteristics are taken into consideration as measurement conditions C _y (therefore, image forming conditions), or conditions that can be changed during actual image formation are taken into consideration. Since the corrected light amount correction data for setting the pitch between dots for each of the various image forming conditions to the desired pitch P is stored in the correction data storage unit 15, the image forming conditions C are adjusted to match the characteristics of the photoconductor used. _{Even if y} is changed, the corresponding correction data M _ny is read from the correction data storage unit 15 in accordance with the image forming condition C _y ,
Since the lighting operation of each LED element 3 can be controlled using the correction data _Mny , it is possible to secure optical writing at a desired pitch P.

A fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, the configuration is a combination of the second and third embodiments. That is, the pitch of the provisions P _x in this embodiment, as the measurement conditions (imaging conditions) C _y, both the image writing condition setting section 1
6 can be specified freely. In correspondence with this, the correction data storage unit 15 various measurement conditions C _y every kind of provision light amount correction of the correction data is previously stored to correct the spot size of each LED element 3 to the pitch P _x of the Have been.

Here, in the image forming operation, when the desired image forming condition _Cy and the specified pitch _Px are designated by the image writing condition setting unit 16, the designated desired pitch _Px is set. and a function of the correction data reading means for outputting the multi-level conversion unit 12 reads out the corresponding correction data for each LED element 3 in accordance with the designated image forming condition C _y from in the correction data storage unit 15. In addition, the multi-level conversion unit 12, the selector 13, and the LED array driving unit 5 function as drive control means for controlling the lighting operation of each LED element 3 of the LED array 4 using the read correction data.

Next, each pitch P _x each be pre-written and stored in the correction data storage unit 15, and will be described acquisition of correction data for each measurement condition (image forming condition) C _y. The acquisition of these correction data is basically performed by using the optical writing device 1 and the dot pitch correction data generation device 21 as shown in FIG. It is executed in the same manner as in the case of the embodiment. FIG. 11 is a flowchart illustrating a process for acquiring correction data according to the present embodiment. First, the first pitch P _x (x
= 1 to X: X is arbitrary) is determined (S1c), and if it is set, the first measurement condition C _y (y
= 1 to Y: Y is arbitrary) is determined (S2c). The pitch P _x and the measurement conditions C _y are processed in the same manner as in the case shown in FIG.
it is determined whether _y is present (S17), and repeats the process only the type Y minutes of measurement conditions C _y in the pitch P _x if there. Upon completion of the processing for all measurement conditions C _y, it determines whether the pitch P _x other provisions there (S16), and repeats similar processing steps S1c~S17 if there.

Therefore, after all the measurements are completed, the data storage device 26 stores Of As, so that the corrected data M _NXY of each LED element every 3 in the form of an address to the pitch P _x and the measurement condition C _y of each defined is stored. The correction data M _nxy stored in the data storage device 26 is written into the correction data storage unit 15 in the optical writing device 1 by using a ROM writer or the like, and is used at the time of actual image writing.

The correction data M _NXY of such various provisions of pitch per P _x and for each various measurement conditions (imaging conditions) C _y
Desired pitch P _x and a desired image forming condition C _y when actually performing optical writing by the image writing condition setting section 16 by the optical writing device 1 by using the correction data storage unit 15 which is written Is designated, the corresponding correction data M _nxy is read from the correction data storage unit 15 and output to the multi-value conversion unit 12. Accordingly, each LED element 3 so as to be equalized is lighting control at a desired pitch P _x specified in the given image forming conditions C _y.

[0050] Therefore, according to this embodiment, it is possible to cope with any if you want to change the pitch P _x of the image forming condition C _y and regulations.

A fifth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, in obtaining the correction data _Mn for light quantity correction for correcting the dot diameter to obtain the desired pitch P (or _Px ) as described above,
After correcting the dot diameter of each LED element 3 to a desired dot diameter (spot diameter) D, as described above, each LED element 3
Is light amount correction data for correcting the dot diameter of each LED element 3 such that the pitch between the dots becomes the desired pitch P (or P _x ).

For this reason, in the dot pitch correction data generating device 21 used in this embodiment, the dot diameter & dot pitch measuring device 2 is used instead of the dot pitch measuring device 23.
7 is used. That is, a function of measuring the dot diameter when each LED element 3 is turned on is added, and the measured dot diameter is output to the controller 22. In addition to the correction data storage device 26, a correction data storage device 28 for temporarily storing correction data for setting the dot diameter of each LED element 3 to a specified dot diameter is also added.

The acquisition of the correction data _Mn written and stored in advance in the correction data storage unit 15 will be described.
The acquisition of these correction data is basically performed using the optical writing device 1 and the dot pitch correction data generation device 21 before shipment from the factory, as shown in FIG. FIG.
FIG. 3 is a flowchart illustrating a process for obtaining the correction data _{Mn according} to the present embodiment. Finally, the processing is performed according to the processing shown in FIG.
As a process prior to the process of (1), a process of obtaining correction data _Mn for setting the dot diameter of each LED element 3 to the specified dot diameter D is executed (S21 to S32).

This processing will be described sequentially. First,
It is checked whether the specified dot diameter D has been set (S2).
1). The specified dot diameter D means a target dot diameter (spot diameter) at the time of actual image writing. When the specified dot diameter D is set by the measurement condition setting unit 24 (S
It is checked whether or not the measurement condition C is set (Y of 21) (S22; corresponding to S2). This condition is set because the dot diameter changes depending on which light amount is used as the threshold value, and is set by the measurement condition setting unit 24 in accordance with one of the exposure conditions at the time of actual image writing. When the measurement condition C is set (Y in S22), n = 1 is set to target the dot 1 (S23). Next, the correction data M
_n (meaning correction data for light quantity correction for the n-th LED element 3) is temporarily assumed to be “128” (= “100,000”).
0 ") (S24). However, as in the case of step S4 in FIG. 6, there is no point in limiting to this numerical value" 128 ", and" 1 "to" 8 "indicated by 8-bit data are not significant.
Any numerical value within the range of "255" is arbitrary, but as in the present embodiment, it is set to an intermediate value "128" to facilitate increase / decrease adjustment, or a desired dot diameter based on existing experimental data and the like. It is preferable to use a value expected to be closest to D. The correction data _Mn is set in the correction data setting unit 25, and is provided to the multi-value conversion unit 12 side.

Next, dot n, here dot 1 is L
It is turned on by the ED array drive unit 5 (S25). The lighting timing at this time is the same as that shown in FIG.
The dot diameter (spot diameter) D _d of the dot n at this time was measured by the dot diameter and the dot pitch measurement device 27 (S2
6) Send the measurement result to the controller 22. Measurement results in the controller 22 has received its dot diameter D _d checks almost equal or not to the provision dot diameter D (S2
7). If it is still not almost equal (N in S27),
In accordance with the magnitude relationship between the two, the value of the correction data _Mn is increased or decreased (for example, _Mn is changed to "129" or _Mn is changed to "127" ... varying width is not limited to one by 1) (S28), re-measure the dot diameter D _d of the dot n to be turned in accordance with the correction data (S26), which until the dot diameter D _d is almost equal to the specified dot diameter D repeat. Here, step S
For even 27 determines, as in the judgment in step S10 in FIG. 6, the inherent, although both should be exactly equal to determination of whether the number of bits of the correction data M _n, dot diameter since conceivable that not necessarily equal in relation to the measurement errors of D _d, so that it is determined that the normal state when it becomes the data in the approximate range acceptable. This approximation range, the correction number of bits of the data M _n, the measurement error of the dot diameter D _d, is determined by actually considering variation range of the dot diameter may be acceptable quality aim when forming an image.

The measured dot diameter _Dd is _equal to the specified dot diameter D.
When it becomes approximately equal to (S27 of Y), the temporarily storing correction data M _n in the data storage device 28 for dot n (S29). The correction data _Mn at this time is a numerical value set in the correction data setting unit 25 at that time. Thereafter, the dot n, here, the dot 1 is turned off (S3
0), n is incremented by +1 to target the next dot n, here, dot 2 (S31).
At this time, it is checked whether or not the number of new dots n exceeds the total number N (S32), and if not, the processes of steps S24 to S31 are repeated for the dot n. Thereby, all the dots n (n = 1 to N)
The correction data _Mn for setting the dot diameter _Dd to the specified dot diameter D is temporarily stored in the data storage device.

After obtaining the correction data _Mn for setting the specified dot diameter D for each of the LED elements 3, a process according to FIG. 6 is performed. However, the difference from the process shown in FIG. 6 is that first, the measurement condition C of this time has already been set in step S22, so that the determination process in step S2 is omitted. In the processing shown in FIG. 6, in steps S4 and S7, the original correction data M _n
Is temporarily set to "128", but in the present embodiment, the correction data _Mn obtained and stored in the data storage device 28 to obtain the above-mentioned specified dot diameter D is read out (S4d, S7d), This is the initial value of the correction data. The subsequent processing is the same as in the case of FIG.

Therefore, after all the measurements are completed, the data storage device 26 stores No. of each LED element 3 as shown in FIG. Is used as an address, and the correction data _Mn for each LED element 3 is stored. The correction data _Mn stored in the data storage device 26 is written into the correction data storage unit 15 in the optical writing device 1 using a ROM writer or the like, and is used at the time of actual image writing.

Therefore, according to the present embodiment, as a result, the same correction data _Mn as in the first embodiment is used, but the correction of the dot diameter D is prioritized, and Since the data is obtained so that the pitch becomes a desired pitch, it is possible to correct the pitch between dots to a desired pitch P in a state where the dot diameter D of each LED element 3 is as small as possible. .

Although the present embodiment has been described as an example applied to the first embodiment, it can be similarly applied to the second to fourth embodiments.

A sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, in addition to the fifth embodiment, in order to obtain a desired pitch P, not only a fixed desired dot diameter D but also various dot diameters D _z (z
= 1 to Z: Z is as similarly corrected data M _nz are obtained for optional).

The acquisition of the correction data _Mn written and stored in advance in the correction data storage unit 15 will be described.
The acquisition of these correction data is basically performed using the optical writing device 1 and the dot pitch correction data generation device 21 before shipment from the factory, as shown in FIG. The processing is basically performed as shown in FIG. 14 according to FIG.

[0063] First, it is checked whether the dot diameter D _z of the first defined is set (S21a). Specified dot diameter D
_{When z} is set by the measurement condition setting unit 24 (Y in S21a) and the measurement condition C is set (Y in S22), n = 1 is set to target the dot 1 (S23). Next, the correction data M _nz (meaning the correction data for the dot diameter D _z for the n-th LED element 3) is temporarily set to “128” (= “100000”) (S
24a). Next, the dot n, in this case, the dot 1 is LE
It is turned on by the D array drive unit 5 (S25). At this time, the dot diameter Dd of the dot n is measured by the dot diameter / dot pitch measuring device 27 (S26), and the measurement result is sent to the controller 22. Measurement results in the controller 22 has received its dot diameter D _d checks almost equal or not to the provision dot diameter D _z (S27a). Yet, if not most equal (N in S27a), in response to both the magnitude relation, the correction data M to the value largely or or small _nz (S28a), the dot of the dot n to be turned in accordance with the correction data again measuring the diameter D _d (S26), and repeats this until the dot diameter D _d is almost equal to the specified dot diameter D _z. The measured dot diameter D _d is _equal to the specified dot diameter D _z
When it becomes approximately equal to (Y in S27a), for temporarily storing the corrected data M _nz in the data storage device 28 for dot n (S29a). The correction data _Mnz at this time is a numerical value set in the correction data setting unit 25 at that time.
Thereafter, the dot n, here, the dot 1 is turned off (S3
0), n is incremented by +1 to target the next dot n, here, dot 2 (S31).
At this point, it is checked whether or not the number of new dots n exceeds the total number N (S32), and if not, the processes of steps S24a to S31 are repeated for dot n in the same manner. As a result, all the dots n (n = 1 to
For N), the correction data _Mn for setting the dot diameter _Dd to the specified dot diameter _Dz is temporarily stored in the data storage device 28.

[0064] After obtaining the correction data M _nz for a dot diameter D _z defined for each such LED elements 3,
The processing according to FIG. 6 is performed to sequentially obtain the correction data M _nz
Are stored in the data storage device 26 (S1 to S1).
5).

[0065] After all of the correction data M _nz for dot diameter D _z is obtained, it is checked whether or not the dot diameter D _z of the other provisions there (S18), if any, step S21a
To S32 and S1 to S15 are similarly repeated.

Therefore, after all the measurements are completed, the data storage device 26 stores Thus, the correction data _Mnz for each LED element 3 is stored in such a manner that each prescribed dot diameter _Dz is used as an address. The correction data _Mnz stored in the data storage device 26 is written into the correction data storage unit 15 in the optical writing device 1 using a ROM writer or the like, and is used at the time of actual image writing.

[0067] When actually performing optical writing by the optical writing device 1 by using the correction data storage unit 15 for correction data M _nz of such various every dot diameter D _z is written, the image writing condition By setting the desired dot diameter D _z by the setting unit 16, the corresponding correction data M _nz is read from the correction data storage unit 15 and output to the multi-value conversion unit 12. Thereby, the lighting of each LED element 3 is controlled so as to be uniform at a desired pitch P at a desired dot diameter _Dz .

In each of these embodiments, each LE
In order to make the pitch between the spots of the D element 3 uniform, the light amount correction for correcting the spot diameter is performed by controlling the light emission time. However, the drive current for each LED element 3 is variable according to the correction data. May be used.

[0069]

According to the first aspect of the present invention, in order to set the pitch between the spots of each LED element in the LED array to a predetermined desired pitch under a predetermined desired image forming condition. A storage unit that stores correction data for correcting the spot diameter of each LED element, a correction data reading unit that reads correction data corresponding to each LED element from the storage unit during image formation, and an LED using the read correction data. Drive control means for controlling the lighting operation of each LED element of the array, so that even if the pitch between the spots of the LED elements on the LED array to be used varies, the distance between the spots of the LED elements on the photosensitive member The pitch can be corrected so as to be uniform at the desired pitch, and white and black streaks can be prevented from occurring in the print result. In addition, each of the LED arrays L
This means that even if the pitch accuracy between the ED elements is low, it can be dealt with by correction, and the manufacturing cost can be reduced.

According to the second aspect of the invention, basically,
The same effect as that of the invention described in claim 1 can be obtained, but in addition, since the correction data is stored in the storage unit for each pitch, when a desired pitch between spots is changed, that pitch is changed. The lighting operation of each LED element can be performed so as to be uniform, thereby increasing flexibility with respect to a desired pitch.

According to the third aspect of the invention, basically,
The same effect as that of the invention described in claim 1 can be obtained, but in addition, since the correction data for obtaining the desired pitch is stored in the storage unit for each of various image forming conditions, the image forming conditions are changed. In this case, each LED element can be operated to be turned on so as to be uniform at a desired pitch, and it is possible to flexibly cope with various image forming conditions.

According to the fourth aspect of the invention, the correction data for setting the pitch for each of various image forming conditions and each of the various pitches is also stored in the storage unit. Each LED element can be turned on so as to have an effect and to make the LED elements uniform at the desired pitch even when the image forming conditions and the desired pitch are changed.

According to the fifth aspect of the present invention, in the invention of the first, second, third or fourth aspect, the correction of the spot diameter is prioritized so that the pitch between the spots has a desired pitch. Since the correction data obtained in step (1) is used, it is possible to correct the distance between the spots to a desired pitch in a state where the spot diameter of each LED element does not vary as much as possible, thereby further improving the printing quality. it can.

According to the invention described in claim 6, in the invention described in claim 5, the desired spot diameters are plural types.
Since correction data is obtained for each spot diameter, not only one kind of spot diameter, but also the pitch between spots is uniform at various desired spot diameters without any variation in spot diameter. Such printing can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical writing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a basic configuration of an LED drive circuit.

FIG. 3 is a time chart showing the basic LED array drive timing.

FIG. 4 is a block diagram showing an optical writing device and a dot diameter data measuring device.

FIG. 5 is a time chart showing a light amount control method based on variable light emission time.

FIG. 6 is a flowchart illustrating a process for acquiring correction data.

FIG. 7 is a time chart illustrating an example of lighting timing of each dot according to correction data.

FIG. 8 is a block diagram of an optical writing device according to a second embodiment of the present invention.

FIG. 9 is a flowchart showing a process for obtaining the correction data.

FIG. 10 is a flowchart illustrating a process for acquiring correction data according to the third embodiment of the present invention.

FIG. 11 is a flowchart illustrating a process for acquiring correction data according to a fourth embodiment of the present invention.

FIG. 12 is a block diagram showing an optical writing device and a dot diameter data measuring device according to a fifth embodiment of the present invention.

FIG. 13 is a flowchart showing a process for acquiring the correction data.

FIG. 14 is a flowchart illustrating a process for acquiring correction data according to a sixth embodiment of the present invention.

[Explanation of symbols]

 3 LED element 4 LED array 15 Storage unit 16 Designation means

Claims (6)

[Claims] 1. An LED array printer which forms an image by electrophotography using an LED array in which a large number of LED elements whose lighting is controlled in accordance with image data is arranged in a line, comprises: A storage unit storing correction data for correcting a spot diameter of each LED element in order to set a pitch between spots of each LED element in the LED array to a predetermined desired pitch, Correction data reading means for reading the corresponding correction data for the LED elements from the storage unit; and drive control means for controlling the lighting operation of each LED element of the LED array using the read correction data. LED array printer characterized by the above-mentioned. 2. An LED array printer which forms an image by electrophotography using an LED array in which a large number of LED elements whose lighting is controlled in accordance with image data is arranged in a line, comprises: Under the conditions, a storage unit that stores correction data for correcting the spot diameter of each LED element in order to set the pitch between the spots of each LED element in the LED array to various pitches, and specifies a desired pitch between the spots A correction data reading means for reading out, from the storage unit, correction data corresponding to each LED element in accordance with a specified pitch; and using the read correction data to read out each LED element of the LED array. An LED array printer comprising: a driving control unit that controls a lighting operation. 3. An LED array printer that forms an image by electrophotography using an LED array in which a large number of LED elements whose lighting is controlled in accordance with image data is arranged in a line. , Each LED in the LED array
A storage unit that stores correction data for correcting the spot diameter of each LED element in order to set a pitch between element spots to a predetermined desired pitch; and a designation unit for designating desired image forming conditions. Correction data reading means for reading correction data corresponding to each LED element from the storage unit in accordance with a designated image forming condition; and controlling the lighting operation of each LED element of the LED array using the read correction data. An LED array printer comprising: 4. An LED array printer that forms an image by electrophotography using an LED array in which a large number of LED elements whose lighting is controlled in accordance with image data is arranged in a line. , Each LED in the LED array
A storage unit for storing correction data for correcting the spot diameter of each LED element so that the pitch between the element spots can be various pitches; a designation unit for designating desired image forming conditions and a pitch; Correction data reading means for reading correction data corresponding to each LED element from the storage unit in accordance with an image forming condition and a pitch; and controlling a lighting operation of each LED element of the LED array using the read correction data. An LED array printer comprising: a drive control unit. 5. The correction data stored in the storage unit is each L
The value obtained by correcting the spot diameter of each LED element so that the pitch between the spots of each LED element becomes the desired pitch after correcting the spot diameter of the ED element to the desired spot diameter. Claim 1, characterized in that
The LED array printer according to 2, 3, or 4. 6. The LED array printer according to claim 5, wherein there are a plurality of desired spot diameters, and correction data is provided for each spot diameter.