JP3233834B2 - Method and apparatus for correcting light emission intensity width of LED print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for correcting the emission intensity width of an LED print head used in an electrophotographic printing apparatus, and an apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic printing apparatus forms an electrostatic latent image by exposing the surface of a photosensitive drum uniformly charged by a charger, and develops the electrostatic latent image into a toner image. The toner image is transferred to a print medium and fixed. In such an electrophotographic printing apparatus, an optical print head is used in an exposure section for exposing the surface of a uniformly charged photosensitive drum. Among the optical print heads, an LED print head using an LED element as a light emitting element has been widely used because it can be operated at high speed and is small in size. The LED print head is composed of a number of LED elements, a driving circuit for driving the LED elements to emit the LED elements, and a cell hook for converging the light output from the LED elements to the surface of the uniformly charged photosensitive drum. It consists of a lens (trade name). (Hereinafter, the cell hoc lens is referred to as a “lens”.)

[0003]

However, the LED print head has a variation in the position of the optical system between each LED element and the lens and a variation in the shape of each LED element.
Even if a certain amount of driving energy is applied to each LED element, uneven exposure occurs on the electrostatic image formed on the surface of the photosensitive drum, so that the amount of adhered toner transferred to the print medium varies, resulting in uneven print density. Sometimes occurred. SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for correcting the emission intensity width of an LED print head which eliminates the unevenness of the print density by the LED print head as described above.

[0004]

For this purpose, the present invention provides:
Measure the emission intensity distribution of each LED element of the LED print head using a large number of LED elements for the light emitting element, slice the emission intensity distribution by the reference emission intensity, calculate the emission intensity width at the reference emission intensity, The correction value of the driving energy of each light emitting element is set so that the light emission intensity width becomes a constant value, and each LED element emits light with the correction value of the driving energy of each light emitting element. Further, the apparatus has a storage means for storing the correction value obtained by the above method.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, a first embodiment will be described. FIG. 1 is an explanatory diagram illustrating the structure of the LED print head of the present invention. In FIG. 1, L
The ED print head 1 includes an LED chip 2 in which a plurality of LED elements of light emitting elements are collected, and each LED of the LED chip 2.
A driving circuit 3 for driving the elements and a non-volatile storage means 4 for storing a correction value of the driving energy of each LED element in the driving circuit 3
A frame 5 for supporting the substrate 5,
It comprises a lens 7 and a housing 8. A large number of LED chips 2 are arranged on the substrate 5 at predetermined intervals with the light emitting surface 2a facing up and the electrode surface facing backward. The board 5 has a connection section 5a for connecting a signal line to the print control section 9 (FIG. 2) of the printing apparatus main body. Further, the housing 8 holds the substrate 5 and the lens 7 so as to keep the gap between the light emitting surface 2a of each LED chip 2 and the lens 7 constant.

Next, the operation of the LED print head 1 according to the present invention will be described with reference to FIG. FIG. 2 is a block diagram of the LED print head and the electrophotographic printing apparatus main body of the present invention. In FIG. 2, the LED print head 1 is a DA transmitted from the print control unit 9 of the electrophotographic printing apparatus main body.
It is controlled by signals TA, CLK, LOAD, and STB. DATA is an actual print data signal for transmitting print data from the print control unit 9 of the main body of the electrophotographic printing apparatus to the LED print head 1, CLK is a clock signal for timing of each operation, LOAD is a data latch signal, and STB.
Is a print drive signal for driving the driver. The actual print data signal DATA and the clock signal CLK are input to the LED print head 1 from the print control unit 9 of the electrophotographic printing apparatus main body. Input actual print data signal DAT
A sequentially inputs to the driver circuits DR1, DR2,... As data of the LED elements LD1, LD2,. The actual print data DATA of the LED elements LD1, LD2,.
, When one line is entirely input to the driver circuits DR1, DR2,..., At this timing, the latch signal LOAD is input from the print control unit 9 to the driver circuits DR1, DR2,. Latched. Then, the print drive signal STB is output to the driver circuits DR1, DR
, ..., the driver circuits DR1, DR
Actual print data DAT of logic meaning light emission in 2, ...
The driver circuit having A causes each LED element to emit light sequentially. The light emission exposes the uniformly charged surface of the photosensitive drum, and an electrostatic image is formed on the surface of the photosensitive drum.

[0007] Here, the LED print head 1 of the present invention.
Is provided with a non-transitory storage means 4 composed of an EPROM or an EEPROM. Each of the LED elements LD1, LD2,
.. Are input. The driving energy correction value is not set so as to make the light emission intensity of each LED element constant, but to form a dot image of a uniform size on the surface of a uniformly charged photosensitive drum of an electrophotographic apparatus. Is set to In the present invention, the selector 10 is arranged to transmit the correction value of the driving energy of the nonvolatile storage means 4 to the call driver circuits DR1, DR2,. The selector 11 is used when writing a correction value of the driving energy, and its operation will be described separately.

Hereinafter, a method of transmitting the correction value of the driving energy will be described. In this embodiment, when the latch signal LOAD input to the selector 10 becomes high, the selector 10 is switched, and the clock signal CLK is output to the counter 12. Then, in response to the input of the clock signal CLK, the counter 12 outputs an address signal S2 indicating the address of the nonvolatile storage unit 4 to the nonvolatile storage unit 4. The non-volatile storage means 4 stores each of the LED elements LD1, LD
A correction value of the driving energy is stored for each of 2,.
Upon receiving the address signal S3, each LED element LD1,
The drive energy correction value for each LD2,.
Are sequentially transmitted to the driver circuits DR1, DR2,... As the drive energy correction value instruction signal S1. The driver circuits DR1, DR2,... Cause the LED elements LD1, LD2,. The light emission of each of the LED elements LD1, LD2,... Exposes the surface of the uniformly charged photosensitive drum to form an electrostatic image having a uniform dot diameter. The drive energy correction values stored in the non-volatile storage means 4 are used as drive energy correction value instruction signals S1 as driver circuit DR1, D2 prior to the start of printing based on the actual print DATA signal.
R2,... Are stored. This transfer is performed, for example, when the power is turned on, so that the actual print data signal DA
It is possible to prevent the transfer time from overlapping with the TA.

Next, a method of measuring the emission intensity of each LED element and a method of setting the correction value of the driving energy for setting the correction value of the driving energy of the LED print head 1 will be described. FIG. 3 is a schematic diagram of an apparatus for measuring the light emission intensity distribution of the LED elements of the LED print head 1 of the present invention and setting a drive energy correction value for correcting the light emission intensity. In FIG. 3, the emission intensity of the LED element of the LED print head 1 is
An XY table 14 comprising a lighting controller 13 for connecting each LED element to select and light each LED element, a surface plate 14a on which the LED print head 1 to be measured is mounted, and an arm part 14b moving in the XY directions; Arm 14b of XY table 14 attached to arm 14b of Y table 14
A camera 15 for measuring the light emission intensity of the LED elements of the LED print head 1 by moving to a predetermined position, measuring a light emission intensity distribution from an image captured by the camera 15 and processing the light emission intensity of the image to obtain a digital image. It is measured by the camera controller 16 which converts it into a signal.
Further, the correction value of the driving energy is obtained by inputting the light emission intensity distribution of each LED element and processing the data by the data processor 17.
And a correction R for writing the processed data to the storage means.
This is set by the OM writer 18.

Next, a measuring method using the above apparatus will be described. In FIG. 3, the LED print head 1 to be measured
Is fixed to the surface plate 14a of the XY table 14 while being connected to the lighting controller 13. Note that the correction value of the driving energy of the LED print head 1 to be measured is set to a constant value in advance for all the LED elements. The lighting controller 13 selects and turns on the LED elements of the LED print 1, and outputs information on which LED element is turned on to the data processor 17. XY table 1
Reference numeral 4 moves to a position where the camera 15 mounted on the arm portion 14b of the XY table 14 can capture all the light emitting portions of the LED elements that are turned on. Then, the camera 15 that has moved to the above position captures an image of the light emitting portion of the lit LED element.

FIG. 4 shows a lit L captured by the camera 15.
It shows an image of the ED element, and actually models what appears as a shadow image. The line shown in FIG. 4 connects points having the same light emission intensity, and the light emission intensity increases from the outside to the inside. In FIG. 4, two LEs
An example in which the D elements are simultaneously turned on is shown. The number of LED elements to be turned on may be any number as long as the entire image is captured by the lens of the camera 15, but it is assumed that the images of the turned on LED elements do not interfere with each other. The image of the LED element captured by the camera 15 is
And is quantified accordingly. When the image of the LED element captured by the camera 15 is cut along the X axis in FIG. 4, the image of the LED element can be displayed as a light emission intensity distribution curve as shown in FIG.

FIG. 5 is a graph in which the vertical axis represents X and the horizontal axis represents emission intensity. The camera controller 16 outputs the lit L
The emission intensity distribution of the ED element is output to the data processor 17. The above measurement is performed for all LEs of the LED print head 1.
This is performed for the D element. Then, the measurement results of all the LED elements of the LED print head 1 are input to the data processor 17.

FIGS. 6 and 7 show a certain L obtained by the above method.
FIG. 9 shows a light emission intensity distribution when an LED element having a different light emission intensity distribution of the ED print head 1 is present,
The horizontal axis represents X, and the vertical axis represents emission intensity. Such a difference in the emission intensity distribution is caused by the variation in the position of the optical system between the LED element and the lens and the variation in the shape of the LED element as described above. 6, 7, when the photosensitive drum of an electrophotographic printing machine equipped with a LED print head 1, a device having sensitivity so as to adhere the toner to the surface by the emission intensity E _T or more, the surface of the photosensitive drum Then, the emission intensity distributions Ea (x), Eb (x)
LED elements having different emission intensity widths Wa, with different emission intensity distributions even when the driving energy is equal.
Wb. That is, since the toner adheres to the light emission intensity width on the surface of the photosensitive drum, if the light emission intensity width is different, the amount of toner adhered is different, and density unevenness occurs. In addition, LEs having different emission intensity distributions as described above.
Even when the drive energy is corrected for the D element to correct the light emission intensity, the light emission intensity distribution Ea having large dispersion as shown in FIG.
In the first LED element having (x), even if the driving energy is corrected to be small, the emission intensity width is corrected to be large, so that the amount of adhered toner is corrected to be large. In the second light emitting element having the intensity distribution Eb (x), the emission intensity width is hard to be corrected even when the driving energy is largely corrected, so that the toner adhesion amount is also hard to be corrected.

Therefore, in the present invention, the difference between the emission intensity distributions is determined by the following method, and the correction value of the driving energy is set. This method will be described with reference to FIG. FIG. 8 is an explanatory diagram for explaining a method for determining a difference in emission intensity distribution according to the first embodiment of the present invention. It is to be noted that the data processor 17 (FIG. 3) determines the difference between the following light emission intensity distributions and sets a drive energy correction value. In FIG. 8, the minimum value min (max) of the maximum values max (i) (i = 1, 2,..., K, k + 1,...) For each light emission intensity distribution of each LED element, and the light emission intensity of each LED element The minimum value min (i) (i = 1, 2,...,
k, k + 1,...) is determined as the maximum value max (min). Then, the minimum value min (max) and the maximum value ma
A range between x (min) is set as a reference light emission intensity, and a large reference light emission intensity E1 and a small reference light emission intensity E2 are determined as two reference light emission intensities from this range. In the present embodiment, as shown in FIG. 8, the large reference light emission intensity E1 and the small reference light emission intensity E2 of these two reference light emission intensities are calculated as follows: E1 = 0.9 × min (max) E2 = 1.1 × max (min) And Then, the emission intensity width W2i of the portion where E (X)> E2 and the emission intensity width W1i of the portion where E (X)> E1 are calculated. This W2i and W
When the difference from 1i is large, it is understood that the variance of the emission intensity distribution is large. When the difference is small, it is understood that the variance of the emission intensity distribution is small. From this, in the present invention,
When the difference between the light emission intensity widths W2i and W1i is small, the variance of the light emission intensity distribution E (X) is small, so that the driving energy is largely corrected. When the difference between the light emission intensity widths W2i and W1i is large, Since the variance of the emission intensity distribution E (X) is large, the driving energy is corrected to be small.

Further, when there is an LED element having a light emission intensity distribution with a large dispersion and an LED element having a light emission intensity distribution with a small dispersion due to this difference in distribution, an LED element having a light emission intensity distribution with a large dispersion that can be easily corrected. Is corrected. That is, there is a first LED element having a light emission intensity distribution Ea (x) having a large dispersion as shown in FIG. 6 and a second LED element having a light emission intensity distribution Eb (x) having a small dispersion as shown in FIG. In this case, the driving energy of the first LED element is changed. Then, the second L in FIG.
The drive current for driving the LED element is changed so that the emission intensity width Wb of the ED element and the emission intensity width Waa of the first LED element in FIG.
Alternatively, the driving energy for driving the LED element is corrected by changing the driving time for driving the LED element.

FIG. 9 shows the emission intensity distribution Eaa after correcting the emission intensity distribution Ea (x) (indicated by a solid line) of the first LED element.
(X) (indicated by a broken line), the emission intensity width Waa is adjusted to the emission intensity width Wb of the second LED element. The drive energy correction value set by the above method is written from the correction ROM writer 18 (FIG. 3) to the nonvolatile storage means 4 (FIG. 2) of the LED print head 1. Before the writing, the ROM for correction
The writer 18 (FIG. 3) and the LED print head 1 are connected. The correction ROM writer 18 (FIG. 3) has a latch signal output terminal for outputting a latch signal LOAD, a correction data output terminal for outputting a drive energy correction value, and a clock signal output terminal for outputting a clock signal CLK. ing. The actual print data signal DATA is also supplied to the LED print head correction ROM writer 18 (FIG. 3) 1.
, An input terminal for the latch signal LOAD, and an input terminal for the clock signal CLK. Then, each output terminal of the correction ROM writer 18 and each input terminal of the LED print head 1 disconnected from the electrophotographic apparatus main body are connected as follows.
8 and the input terminal of the actual print data signal DATA of the LED print head 1
The latch signal output terminal of the OM writer 20 is connected to the input terminal of the latch signal LOAD of the LED print head 1, and the clock signal output terminal of the correction ROM writer 20 is connected to the clock signal CLK input terminal of the LED print head 1. I do.

Next, a method of inputting the correction value of the driving energy of each LED element to the nonvolatile storage means 4 of the LED print head 1 in this state will be described. In FIG. 2, the correction ROM writer 18 inputted to the selector 11
When the latch signal LOAD output from FIG. 3 becomes high level, the selector 11 is switched, and the correction RO
The correction value data signal DATA output from the M writer 18 (FIG. 3) is input to the nonvolatile storage unit 4. Similarly, when the latch signal LOAD output from the correction ROM writer 18 (FIG. 3) becomes high level, the selector 10 is switched, and the correction ROM writer 18 is switched.
The clock signal CLK output from FIG. 3 is output to the counter 12. In response to the input of the clock signal CLK, the counter 12 outputs an address signal S2 indicating the address of the nonvolatile storage means 4 to the nonvolatile storage means 4,
According to the address, the correction value of the driving energy for each of the LED elements LD1, LD2,... Is stored. Further, the correction value of each LED element of the present invention is stored in the storage unit 9a of the print control unit 9 of the electrophotographic printing apparatus main body, and the S value of the print drive signal is stored.
The drive energy may be set by the TB signal.

Next, a second embodiment of the present invention will be described. Note that the second embodiment differs from the first embodiment only in the method of setting the correction value of the driving energy, and the structure of the LED print head and the method of measuring the emission intensity are the same as those in the first embodiment. Only the method of setting the correction value of the driving energy will be described.

FIG. 10 is an explanatory diagram for explaining a method of setting a correction value of drive energy according to the second embodiment of the present invention. A method of setting a correction value of drive energy according to the second embodiment will be described below with reference to FIG. The emission intensity distribution of each LED element of the LED print 1 obtained by the same measuring method as in the first embodiment is input to the data processor 17. The data processor 17 stores each L of the input LED print 1.
The reference light emission intensity h (i), which is the light emission intensity of each LED element that obtains a predetermined reference light emission intensity width W in which the light emission intensity distribution of the ED element is set in advance, is calculated. This reference emission intensity h (i) (i = 1, 2,..., K, k + 1,.
Calculated for each ED element. Next, an average value h.ave of the reference light emission intensity h (i) is calculated. Then, this value is set as a target value of each LED element, and a correction value of the driving energy of each LED element is set.
Set Hosei (i) as follows. Hosei (i) = h.ave / h (i) When the following correction is performed for each LED element using this correction value, the reference light emission intensity of each LED element after correction is obtained.
h.after (i) is h.after (i) = h (i) × Hosei (i) = h (i) × h.ave / h (i) = ha
ve, the reference light emission intensity of each LED element becomes the same value, and the light emission intensity width of each LED element becomes a constant value W. In other words, in this correction, the driving energy is corrected so that the emission intensity width of each LED element becomes the predetermined emission intensity width W at the average value h.ave of the reference emission intensity. Then, since the toner adheres to the predetermined light emission intensity width W, the toner having the same area adheres to the photosensitive drum in all the LED elements, and a uniform image is obtained.

The correction value obtained by the above method is transmitted to a correction ROM writer. Then, similarly to the first embodiment, the writer 18 controls the LED.
The data is written to the non-volatile storage unit 4 (FIG. 2) in the print 1 and the storage unit 9a (FIG. 2) of the print control unit 9 of the electrophotographic printing apparatus main body. According to the second drive energy correction value setting method, since the reference light emission intensity is first corrected so as to have a predetermined light emission intensity width, accurate correction can be performed for each LED element.

As described above, in the second embodiment, since a correction value with which the width after correction is constant can be directly obtained from the first embodiment, more accurate correction can be performed, and the density can be made more uniform. Print results can be obtained.

Next, a third embodiment of the present invention will be described. Continuous printing of adjacent dots, such as when two adjacent LED elements emit light at the same time, or when one LED element emits light for more than one dot travel in the paper transport direction. There is. At this time, the image formed on the photosensitive drum has a shape in which the light emission intensity distributions of the respective dots overlap each other, depending on the resolution of the LED print head and the resolution of the electrophotographic apparatus in the paper transport direction. Therefore, a portion where the light emission intensity distributions of the respective dots overlap, that is, a foot portion of the light emission intensity distribution of each LED element greatly affects the formation of the light emission intensity distribution when the adjacent dots are continuously printed. Therefore, the first embodiment and the second embodiment are different from the respective LEs.
In contrast to the method of individually correcting the light emission intensity width for each of the D elements, in the third embodiment, the LED element itself is replaced with another L element.
The present invention proposes a method of correcting the light emission intensity width in consideration of the light emission of the ED element and its influence on the LED element.

In the third embodiment, as in the first embodiment, the measurement is performed by using the apparatus for measuring the total light emission intensity of each light emitting unit and setting the correction value of the driving energy in FIG. With the LED print head 1 connected to the lighting control device 13,
The LED is fixed to the surface plate 14a of the XY table 14, and is lit so that the light emission of each LED element of the LED print head 1 is not affected by the light emission of other LED elements. For example, the LED print head 1 has a resolution of 600 DPI (6 per inch).
(A resolution of 00 dots)
When the dot is turned on and the next three consecutive dots are turned off, the emission intensity distribution of one dot can be measured by the camera 15 and the camera controller 16 without being affected by the emission of the other LED elements. The data processor 17 temporarily stores emission intensity distribution data from the measurement result. Next, the data processor 17
Is obtained by superimposing the stored emission intensity distribution data and the emission intensity distribution data obtained by shifting the stored emission intensity distribution data by one dot (1 × 1/600 inch) in the X direction, and obtaining a new superimposed emission intensity distribution. Create data. This corresponds to showing the light emission intensity distribution when two adjacent dots are printed. The correction method of the superimposed emission intensity distribution data thereafter sets the correction value by performing the same correction method as the correction method of the second embodiment.
However, when the predetermined reference light emission intensity width set in advance is 2 dots (2/600 inch), it has been found by experiments that the best correction is performed. It is assumed to be the width of a dot.

FIG. 11 is a first diagram illustrating a correction method according to the third embodiment of the present invention, and FIG. 12 is a second diagram illustrating a correction method according to the third embodiment of the present invention. FIG. The effects of the correction method according to the third embodiment described above will be described with reference to FIGS. In FIG. 11, the solid line shows the light emission intensity distribution when the light emission of each LED element is turned on so that the light emission of other LED elements is not affected by the light emission as described above. In FIG.
(K) and Ec (k + 4). This Ec
The emission intensity distributions of (k) and Ec (k + 4) do not require the correction of the second embodiment, and the average value h. It is assumed that the predetermined light emission intensity width at ave is equal to W. The light emission intensity distributions Ec (k) and Ec (k + 4) are Ecc (k) and Ecc (k + 4), each of which is even one dot in the X direction, and are indicated by dotted lines. FIG. 12 shows that the data processor 17 converts Ec (k) and Ecc (k) into Ec (k + 4) and Ec as described above.
Emission intensity distribution Ed obtained by combining cc (k + 4)
(K) and Ed (k + 4). In FIG. 12, the luminous intensity at which the luminous intensity width for two dots of the reference luminous intensity width is obtained is represented by the luminous intensity distribution E, as in the second embodiment.
By calculating d (k) and Ed (k + 4), emission intensities H (k) and H (k + 4) are obtained. This H (k),
H (k + 4H)> H (k + 4H)> as shown in FIG.
H (k). This means that Ec (k) and Ec (k +
Although the emission intensities at which the emission intensity distribution width W of 4) is obtained are equal, the emission intensity distributions Ed (k) and Ed (k +
In 4), the light emission intensity H (k) and H (k + 4) for obtaining the reference light emission intensity width of 2 dots are H (k + 4H)> H.
(K), the emission intensity Ec (k + 4)
However, since the bottom of the emission intensity distribution is wider than the emission intensity distribution Ec (k), when two adjacent dots are printed, the emission of one's own light tends to affect other dots. I understand.

As described above, in the correction method according to the third embodiment of the present invention, the influence of each LED element on other LED elements and its own light emission is taken into account by correcting the combined light emission intensity distribution. This is a method of correcting the light emission intensity width, which is more effective as the print pattern to be actually printed becomes denser.
Note that the shift distance and the reference light emission intensity width in the third embodiment change depending on the resolution of the print head. In the third embodiment, adjacent dots are influenced by the bottom of the emission intensity distribution.
It is believed that using a D print head also increases the number of interacting dots. In this case, the same correction may be performed by increasing the number of light emission intensity distributions to be superimposed and widening the reference light emission intensity width.

[0026]

As described in detail above, the L of the present invention
Method and apparatus for correcting emission intensity width of ED print head
Is applied to an LED print head having a large number of light-emitting elements, the luminescence intensity distribution of the LED print head is measured, the luminescence intensity distribution is sliced by the reference luminescence intensity, and the luminescence intensity width at the reference luminescence intensity is calculated. Calculation is performed, and a correction value of the driving energy of each light emitting element is set so that each light emission intensity width becomes a constant value.

Then, the driving energy correction value of each light emitting element is stored in the storage means, and at the time of printing, the correction value of the driving energy of each light emitting element is called from the storage means, and the driving energy is changed, so that the print density of the image is changed. Unevenness is eliminated and dots with uniform print density are output.

Further, by detecting and correcting the print density unevenness of each light emitting element itself and the influence on the print density applied to the light emitting element near each light emitting element, it is possible to further eliminate the print density unevenness in the actual print pattern. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view of an LED print head of the present invention.

FIG. 2 is a block diagram of an LED print head and a main body of an electrophotographic printing apparatus according to the present invention.

FIG. 3 is a schematic diagram of an apparatus for measuring a total light emission intensity of each light emitting unit and setting a drive energy correction value in the embodiment of the present invention.

FIG. 4 is a diagram modeling a captured image of a camera when a light emitter is turned on in the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the emission intensity distribution of FIG. 4;

FIG. 6 shows a first dispersion having a large dispersion on the surface of the photosensitive drum.
FIG. 5 is a diagram showing a light emission intensity distribution of the LED element of FIG.

FIG. 7 shows a second dispersion having a small dispersion on the surface of the photosensitive drum.
FIG. 5 is a diagram showing a light emission intensity distribution of the LED element of FIG.

FIG. 8 is an explanatory diagram illustrating a method of setting a correction value of drive energy.

FIG. 9 is an explanatory diagram illustrating a method of correcting a light emission intensity width according to the first embodiment of the present invention.

FIG. 10 is an explanatory diagram illustrating a light emission intensity width correction method according to a second embodiment of the present invention.

FIG. 11 is a first diagram illustrating a correction method according to a third embodiment of the present invention.

FIG. 12 is a second diagram illustrating a correction method according to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LED print head 2 LED chip 2a LED chip light emitting surface 3 Drive circuit 4 Non-volatile storage means 5 Substrate 5a Connection part 6 Frame 7 Lens 8 Housing 9 Print control part

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihisa Aiko 1-7-12 Toranomon, Minato-ku, Tokyo Inside Oki Electric Industry Co., Ltd. (56) References JP-A-4-77274 (JP, A) JP-A 62-25071 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/44 B41J 2/45 B41J 2/455 H01L 33/00 G01M 11/00

Claims (8)

(57) [Claims] 1. A method for correcting an emission intensity of an optical print head having a plurality of light emitting elements, comprising the following steps:
(A) measuring the luminous intensity distribution in each light emitting element of the optical print head; (b) slicing the luminous intensity distribution by the reference luminous intensity to calculate the luminous intensity width at the reference luminous intensity; A light emission intensity correction method for an optical print head, wherein a correction value of drive energy of each light emitting element is set so that the light emission intensity width becomes a constant value. 2. An electrophotographic recording apparatus having an optical print head provided with a large number of light emitting elements, wherein a light emission intensity distribution of the optical print head is measured, and the light emission intensity distribution is sliced according to a reference light emission intensity. An electrophotographic recording apparatus comprising: storage means for setting a correction value of a driving energy of each light emitting element so that a light emission intensity width for each intensity becomes a constant value, and storing the correction value of the driving energy. 3. A method for correcting a light emission intensity of an optical print head having a plurality of light emitting elements, comprising the following steps:
(A) measuring the emission intensity distribution in each light emitting element of the optical print head; (b) slicing the emission intensity distribution by at least two reference emission intensities; calculating the emission intensity width at the reference emission intensity; c) A method for correcting the light emission intensity of the optical print head, wherein a correction value of the driving energy of each light emitting element is set based on each light emission intensity width. 4. The light emission intensity correction method according to claim 3, wherein the reference light emission intensity is smaller than the minimum value of each maximum value of the light emission intensity of each light emitting element and larger than the maximum value of each minimum value. 5. A driving energy correction value is increased when a difference in light emission intensity width for each reference light emission intensity obtained by slicing the correction value of the driving energy by the at least two reference light emission intensities is increased. 4. The light emission intensity correction method according to claim 3, wherein the correction value of the driving energy is set to be smaller when the difference between the widths is larger. 6. An electrophotographic recording apparatus having an optical print head having a plurality of light emitting elements, wherein an emission intensity distribution of the optical print head is measured, and the emission intensity distribution is sliced by at least two reference emission intensities. There is provided storage means for calculating a light emission intensity width for each of the reference light emission intensities, setting a drive energy correction value for each light emitting element calculated based on each light emission intensity width, and storing the drive energy correction value. Electrophotographic recording device. 7. A method for correcting a light emission intensity of an optical print head having a large number of light emitting elements, comprising the following steps:
(A) measuring the emission intensity distribution of the optical print head,
(B) calculating a reference light emission intensity which is a light emission intensity of each light emitting element from which a reference light emission intensity width of the light emission intensity distribution is obtained;
(C) calculating an average value of the reference light emission intensity, and (d) setting a correction value of the driving energy so that the light emission intensity of each light emitting element becomes the average value of the reference light emission intensity. Emission intensity correction method. 8. An electrophotographic recording apparatus having an optical print head provided with a large number of light emitting elements, wherein an emission intensity distribution of the optical print head is measured, and a reference emission intensity width of the emission intensity distribution is obtained for each light emitting element. An electrophotographic recording apparatus, comprising: storage means for calculating a light emission intensity, setting a drive energy correction value for each light emitting element based on each light emission intensity width, and storing the drive energy correction value.