JP2000343745A - Quantity-of-light correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an accurate quantity-of-light correction value by providing an optical sensor having pixels each of which has a diameter smaller than that of each of the dots of a specific number of LED elements and operating the area of each LED element from the detection result of the optical sensor to correct the quantity of light of the LED element on the basis of the operation result. SOLUTION: A charge coupling element (CCD) 54 having a diameter smaller than that of one dot of an LED element is arranged to the image forming part of an optical system 52 to detect the quantity of the light emitted from the LED element. A quantity-of-light correction value is set on the basis of the measured data. Therefore, pixels exceeding a threshold value are counted to be subjected to cumulation processing to calculate the area of each dot. Next, the correction value based on the calculated value is formed in a correction data forming part. By this constitution, a quantity-of-light correction value can be accurately determined at every individual LED element and printing excellent in printing quality can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a printer device, and more particularly to a light amount correcting device for correcting the light amount of an LED head.

[0002]

2. Description of the Related Art Today, printer devices are used which optically write image data on a photoreceptor using an LED head and print on recording paper using an electrophotographic system. In such a printer device, it is important to suppress the variation in the amount of emitted light for each chip on which a plurality of LED elements are provided, and to make the amount of emitted light uniform for each chip.

Therefore, in order to suppress variations in the amount of light emitted from each conventional chip, the amount of light emitted from the LED element is determined in order to make the illuminance per unit area per dot uniform, and the value is used as the light amount of each LED chip. It is stored in the memory as a correction value. The memory and the LED head are paired and mounted on a printer device, and the LED elements emit light in accordance with the light amount correction values stored in the memory, so that the light emission amount of each LED chip is made uniform.

On the other hand, with respect to the variation of the light emission amount of each LED element, a light sensor larger than the size of a dot generated by the light emission of the LED element is conventionally used to measure the light emission amount of the LED element alone.

[0005]

In the above conventional method,
An optical sensor larger than the size of a dot generated by the light emission of the LED element is used to determine the light intensity correction value for one dot. For this reason, when determining the light intensity correction value, the light intensity distribution within one dot is not captured, and an accurate light intensity correction value cannot be obtained. Therefore, in this case, the density error between the LED elements is reflected in the print image, and the print quality is significantly deteriorated.

[0006] The present invention has been developed to solve the above-mentioned problems.
An object of the present invention is to provide a light quantity correction device that eliminates a density error between D elements and prevents deterioration of print quality.

[0007]

According to an aspect of the present invention, there is provided an optical sensor having a pixel having a diameter smaller than one dot of an LED element, and the LE sensor is obtained from a detection result of the optical sensor.
A light amount correcting apparatus comprising: a calculating means for calculating an area of one dot of a D element; and a correcting means for correcting a light emission amount of the LED element based on a calculation result of the calculating means.

Here, the optical sensor is, for example, a CCD sensor, and is composed of, for example, a line sensor or a plane sensor. Also, the pixels of this optical sensor are small, for example, LED
It is about 1/10 of one dot generated by light emission of the element.

The arithmetic means performs arithmetic processing based on the detection result detected by the optical sensor, and calculates the area of the dot emitted from one LED element. In this case, for example, a certain value is set as a threshold value, and only a detected value exceeding the threshold value is involved in the calculation of the area of one dot.

The correction means calculates, for example, an average value of the area of one dot set according to the calculation result of the calculation means, and compares the area of one dot of the target LED element with the average value. To determine the correction value. Then, the light emission amount of the target LED element is corrected according to the correction value.

With such a configuration, each L
The light amount correction value can be accurately determined for each ED element, and printing with excellent print quality can be performed. According to a second aspect of the present invention, in the first aspect of the present invention, the calculating means sets a constant threshold value to a detection value detected by the optical sensor, and sets a predetermined threshold value to a detection value exceeding the threshold value This is a configuration in which arithmetic processing is performed.

With this configuration, the arithmetic means performs arithmetic processing on the detection value detected by the optical sensor with respect to a detection value equal to or greater than a predetermined threshold value. The detected value becomes a target of the arithmetic processing, and a more accurate light amount correction value excluding optical noise can be obtained.

According to a third aspect of the present invention, in the second aspect, the calculating means sets a constant threshold value for a detection value detected by the optical sensor, for example. In this configuration, when a predetermined number of values are consecutive, arithmetic processing is performed.

In this embodiment, the arithmetic processing is performed when a predetermined number of detection values exceeding the threshold value continue for the second aspect of the present invention. Therefore, with such a configuration, it is possible to obtain a more accurate light amount correction value in which optical noise is further eliminated.

According to a fourth aspect of the present invention, in the first aspect, the optical sensor is, for example, a line sensor.
This is a configuration for specifying the optical sensor, and the optical sensor is configured by a line sensor. Further, in the present invention, the optical sensor may be constituted by a surface sensor.

According to a fifth aspect of the present invention, in the first aspect of the invention, the calculating means can calculate, for example, the volume of one dot of the LED element. With such a configuration, the calculating means can perform one-time operation based on the light emission of the LED element.
By calculating the light quantity of the dot as a volume, a more accurate light quantity correction value of the LED element can be obtained.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> In recent years, a color printer using an LED head as an optical writing unit for image data has been put into practical use.
Excellent in terms of high printing quality and miniaturization. FIG. 1 is an overall sectional view of a color printer using the above-described tandem system.

In FIG. 1, a color printer device 1 comprises:
It comprises a paper supply / transport mechanism 2, an image forming unit 3, and a fixing device 4. The paper supply / transport mechanism 2 includes a paper feed cassette 5 in which paper P is loaded and stored, and a paper transport system 6. Further, the paper transport system 6 transfers the paper P
Roller 7, a paper transport path 8 for transporting the paper P carried out by the paper feed roller 7, a standby roll 9 for feeding the paper in a state where the paper position matches the toner image, and a motor (not shown) The driving rollers 10 and 11 are driven by the driving rollers 10 and 11, and the transport belt 12 is rotated by the driving rollers 10 and 11.

The paper P carried out from the paper supply cassette 5 to the paper transport path 8 by the rotation of the paper supply roller 7 is sent to the standby roll 9 by the rotation of the paper supply roller 7, and is formed on a photosensitive drum described later. It moves on the conveyor belt 12 at a timing coincident with the toner image to be formed.

While the paper P moves on the conveyor belt 12,
Each image forming unit 1 is placed on a sheet P on the conveyor belt 12.
The toner of each color is transferred by 5, 16, 17, and 18, and color transfer is performed on the paper P. After that, the fixing device 4
The paper P is carried out of the apparatus.

The fixing device 4 comprises a heat roll 4a and a pressure roll 4b. While the paper P is nipped and conveyed between the heat roll 4a and the pressure roll 4b, for example, a plurality of colors transferred to the paper P are transferred. The toner is melted and printed on the paper P.

On the other hand, the image forming section 3 includes the above-mentioned yellow (Y), magenta (M), cyan (C), and black (B
K) composed of four image forming units 15 to 18;
They are arranged in this order. Yellow (Y), magenta (M), and cyan (C) are image forming units 15 to 17 that perform color printing by subtractive color mixture, and black (B)
The image forming unit 18 of K) is an image forming unit used for monochrome printing.

Each of the image forming units 15 to 18 has the same configuration except for the developer (color) contained in the developing container, and has a charger, a print head, a developing device, a transfer device near the peripheral surface of the photosensitive drum. This is a configuration in which containers are sequentially arranged. Here, the configuration will be described by taking the image forming unit 17 for cyan as an example as a representative of the four image forming units 15 to 18. The peripheral surface of the photoconductor drum 20 is made of, for example, an organic photoconductive material.
a, print head 21b, developing roll (developing device 21c),
The transfer rolls 21d are sequentially arranged. The photoreceptor drum 20 rotates in the direction of the arrow, and first charges the peripheral surface of the photoreceptor drum 20 uniformly by applying a charge from the charger 21a. Next, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 20 by optical writing based on print information from the print head 21b, and a toner image is formed by a developing process by the developing roll 21c. At this time, the toner image formed on the peripheral surface of the photoconductor drum 20 is the cyan (C) image stored in the developing container 21c.
Depends on the color toner.

The toner image formed on the peripheral surface of the photosensitive drum 20 reaches the position of the transfer roll 21d with the rotation of the photosensitive drum 20 in the direction of the arrow, and is conveyed by the transfer roll 21d. Paper P conveyed above
Is transferred to

The toner image transferred onto the upper surface of the sheet P is transported in the direction of the arrow with the movement of the transport belt 12, and is sequentially transferred by another image forming unit 15, 16 having the same configuration as described above. Color printing based on subtractive color mixing is performed with the toners of (Y) and magenta (M).

For example, if the print image is blue, the magenta (M) toner is transferred from the image forming unit 16 to the paper P based on the principle of subtractive color mixture, and then the cyan (C) color is transferred from the image forming unit 17. The toner is transferred to the paper P to realize a blue image. For example, if the print image is red, the yellow (Y) toner is transferred from the developing unit 15 to the paper P, and then the magenta (M) toner is transferred from the image forming unit 16 to the paper P. Realize a red image.

The paper P on which the color printing has been performed as described above is guided to the paper discharge unit by the transport roll 22 and discharged to the paper discharge unit 24 by the paper discharge roll 23. A desired color printing can be performed by the printer device having the above-described mechanism and performing the above-described processing.

FIG. 2 shows a color printer 1 having the above configuration.
Is shown. The control circuit of the color printer device 1 includes an interface controller (hereinafter, referred to as an I / F controller) 30 and the I / F controller 30.
And a printer controller 31 connected to the
A host computer 32 is connected to the F controller 30, and each mechanism in the color printer 1 is connected to the printer controller 31.

The I / F controller 30 creates bitmap data corresponding to the paper P on a one-to-one basis according to print data output from the host computer 32. still,
The display unit 33 is connected to the I / F controller 30, and various displays are performed. Also, the printer controller 31
Are the CPU 34, ROM 35, EEPROM 36, LE
It comprises a D head controller 37, a driver 38, and a buffer 39. The CPU 34 controls printing in accordance with a program stored in the ROM 35, and outputs, for example, bitmap data created by the I / F controller 30 to the LED head control unit 37. Further, the correction data of the LED element is written in the EEPROM 36. This correction data will be described later.

The LED head controller 37 is provided with the LED head 4 provided in each of the image forming units 15 to 18 described above.
0Y, 40M, 40C, and 40BK, and the bitmap data is transmitted to each LED via the LED head control unit 37.
It is supplied to the heads 40Y, 40M, 40C, 40BK. Here, the LED head 40Y is a print head disposed in the yellow (Y) image forming unit 15,
The LED head 40M is a print head disposed in the magenta (M) image forming unit 16, and the LED heads 40C and 40BK are similarly provided in the cyan (C) and black (BK) image forming units 17 and 18, respectively. The print head is disposed. In FIG. 1, for the above description, the print head 40C used for the cyan (C) image forming unit 17 is also shown as 21b.

On the other hand, the above-mentioned heat roll 4
a, a high-voltage power supply unit 41, a DC motor 42, a pulse motor 43, a developing clutch 44, a belt up / down motor 45,
The standby clutch 46, the fixing clutch 47, and the above-described paper feed roller 7 are connected. The heat roll 4a is disposed in the heat fixing unit 4 as described above, and heats the heat roll 4a to a predetermined temperature according to a control signal output from the driver 38.
The high-voltage power supply unit 41 is a circuit that applies a predetermined high voltage to the charger 21a and the transfer roll 21d, and is driven by a control signal output from the driver 38.

The DC motor 42 and the pulse motor 4
Reference numeral 3 denotes a motor for rotating the photosensitive drum 20 and various rolls, and is driven by a drive signal output from a driver 38. The belt up / down motor 45 is a motor that is driven when switching between monochrome printing and color printing.

Further, the developing clutch 44 is connected to the developing device 21c.
The rotational force of the DC motor 42 described above is transmitted to the developing roller provided in the inside, and the standby clutch 46
The fixing clutch 47 is a clutch for transmitting the torque of the DC motor 42 to the fixing roller 21d. Further, a drive signal for the above-described paper feed roller 7 is also output from the driver 38, and outputs a drive signal and a control signal to various other loads.

On the other hand, each sensor 48 is connected to the CPU 34 via a buffer 39. Each of the sensors 48 includes a position detection sensor for the sheet P, and LED heads 40Y to 4Y.
A 0BK temperature detection sensor and the like are included. Next, the acquisition of light amount correction information to be stored in the EEPROM 36 of the color printer device 1 having the above configuration will be described.

FIG. 3 shows an example of the configuration of a light quantity correction device used to acquire light quantity correction information. In the figure, reference numeral 40 denotes the aforementioned LED head, and the aforementioned LED head 40Y
40BK is represented as number 40. A plurality of LED element arrays (chips) are arranged in a line on the LED head 40, and each LED element array has a large number of LEs.
A D element is provided and has a resolution of, for example, 600 dpi.

An optical system 52 is provided with a lens and a lens holding device. The optical system 52 is a motor 5
3 to receive the light emitted from the LED element.

The CCD (Charge Coupled Device) 54 includes an optical system 5
2, and detects the amount of light emitted from the LED element. The CCD 54 outputs a signal according to the amount of received light to a CCD counter (CCDCNT) 55. CCD counter 5
Reference numeral 5 amplifies a signal output from the CCD 54 to a predetermined level and performs analog / digital (A / D) conversion. Data digitized by the analog / digital (A / D) conversion is transmitted to a PC interface (PCI).
/ F) 56.

The PCI / F 56 outputs the above data to a personal computer (hereinafter, referred to as PC) 59. Further, the PCI / F 59 determines a light quantity correction value based on the above-described data, and uses the determined data as a light quantity correction ROM.
36 '. The light amount correction ROM 36 'is the above-mentioned EEPROM 36, and the data of the light amount correction value set by the light amount correction device shown in FIG.
6 ′ and set as the EEPROM 36 in the color printer 1.

The motor counter (motor C) shown in FIG.
NT) 58 is a counter that counts a motor drive count signal output from the PCI / F 56, supplies a corresponding drive signal to the motor 53, and rotates the motor 53 by the specified angle.

FIG. 4 is a specific system configuration diagram of the PCI / F 56 described above. The PCI I / F 56 is a video I / F
61, a video data write control unit 62, line buffers 63 and 64, a video data read control unit 65, an I / F unit 66, a control circuit 67, a dot position search unit 68, a threshold counter 69, and a correction data generation unit 70 Have been.

The video I / F 61 is supplied with analog / digital (A / D) converted data in the aforementioned CCD counter 55. Also, a timing signal is supplied,
Synchronous control with a clock signal inside the PCI / F 56 is performed.

The video data write control unit 62 and the video data read control unit 65
Read and write control of video data is performed for 3, 64. For example, for the line buffers 63 and 64, processing such as setting of the head position of the writing pixel and the number of writing pixels, and setting of the head position of the reading pixel and the number of reading pixels are performed. The line buffers 63 and 64 are buffers having the same capacity, for example, and store the video data of the essential pixels in one line of the CCD 54 described above.

On the other hand, the dot position retrieving section 68
It is detected which of the plurality of images arranged above has focused on the focus surface of the LED element. Using the function of the dot position search unit 68, the LED is set so that all dots can be measured up to the left and right ends of the LED head 40.
The fixing position of the head 40 is adjusted.

The threshold counter 69 counts the set threshold value and the number of pixels exceeding the continuity for one line of video data. The correction data generation unit 70 sums up the values counted by the line of the CCD 54 by the above-described threshold counter 69 for each dot of the LED head 40, and
Calculate the dot area. In addition, a correction value (correction data) is generated by performing a calculation in dot units based on the calculated area. The correction value (correction data) generated by the correction data generation unit 70 is an HD counter (HDCNT) 57.
And writes it in the light intensity correction ROM 36 '.

The I / F section 66 is connected to the PC 59 from the PC 59 described above.
Used to set a register inside the I / F 56, for example, P
The profile is displayed based on the video data and the timing data received from the CI / F 56. Also,
According to the output from the dot position search unit 68, the adjustment of the head position is performed while monitoring.

On the other hand, FIG.
FIG. 4 is a diagram for explaining the positional relationship of the CD 54, and is a diagram illustrating the position of the CD 54;
0 ′ is a bottom view of the LED head 40. As shown in the figure, the CCD 54 is integrated with the optical system 52 described above,
The LED moves in the direction of the arrow (X direction) according to the driving of the motor 53, and the individual LEDs on the lower surface of the LED head 40 are formed.
The amount of light emitted from the element 60 is detected. The processing operation of the above-described light amount correction device having the configuration shown in FIGS. 3 to 5 will be described below.

FIG. 6 shows one of the LED elements by the CCD 54.
This is for explaining the process of extracting dots. CCD5
Reference numeral 4 denotes a line sensor including detection elements “0” to “13” having a pixel width and a pitch of 7 μm, for example, and moves in the X direction below the LED head 40 shown in FIG. 5 as described above. In this way, dot detection is performed.

For example, the example shown in FIG. 6 shows a result obtained by moving the CCD 54 in the X direction and detecting light emission of the LED element at a predetermined timing. In this example, the PCI
The detection process is executed by setting "2" as a threshold value in the internal register of / F56 and "3" as a continuous value of the threshold.

FIG. 7 is a time chart for explaining the processing operation of this embodiment. As shown in FIG. 6 described above, when the CCD 54 is moved in the X direction and the LED element 60 emits light,
Light emission from the element 60 is detected by the CCD 54 via the optical system 52. The CCD counter 55 converts the supplied data from analog to digital (A / D) and outputs it to the video I / F 61. The input of the data (VDATA) is performed in synchronization with the timing signal (/ TW).

The data (VD) input to the video I / F 61
ATA) are alternately input to the two line buffers 63 and 64 under the control of the video data write control unit 62. This switching is performed in synchronization with the video synchronization signal (/ ROG). For example, in the example shown in FIG. 7, one line data of "line N" is input to the line buffer 63 in synchronization with the first video synchronization signal (/ ROG) (at the timing shown in FIG. 7), and the next video synchronization signal One line data of “line N + 1” is input to the line buffer 64 in synchronization with (/ ROG) (the timing shown in FIG. 7).

Thereafter, every time the video synchronization signal (/ ROG) is input, the supplied data (VDATA) is alternately input to the line buffers 63 and 64. The data is read into the PC 59 while the data is alternately supplied to the line buffers 63 and 64 while the read signal (/ R) shown in FIG.
This is performed in synchronization with the output of D) (the timing shown in FIG. 7).

Further, during the above-described processing, the dot position search section 68 simultaneously performs the detection processing of the position of the corresponding dot,
The threshold counter 69 performs a corresponding counting process. This counting process is a process of counting light amount data (data (VDATA)) exceeding the above-described threshold value when input. As described above, in the present example, "2" is set as the threshold value in the internal register of the PCI / F 56, and therefore, when there is input data exceeding "2", the count process is performed. That is, when the data (VDATA) detected by the CCD 54 exceeds the threshold value “2”, counting is performed.

For example, in the example shown in FIG. 8, the data (luminance data / VDATA) of a certain line is "01014200".
24684200.... In such a case, the threshold counter 69 analyzes the supplied data (VDATA) and counts data exceeding the threshold value “2”. In this case, the threshold is used. The count result of the counter (TH counter) 69 is as shown in FIG.

That is, the threshold counter (TH counter) 69 temporarily changes from 1 to 2, but does not reach “3” registered as the above-mentioned continuous value, and returns to “0”. However, the threshold counter (TH counter) 69 changes again from 1 → 2 → 3 → 4 → 5 → 6. Since “3” is set as the continuous value as described above, the data (three times) When VDATA) is input, for example, it is determined that it is not noise or the like, and is detected as dot position data.

On the other hand, the time chart shown in FIG.
It shows a data structure read into the PC 59,
The first data (DO) is “0B” h, indicating that the above-described dot position is the count value “11” of the VA counter. “06” h of the data (DO) indicates that the continuous value exceeding the threshold value “2” is “6”.

On the other hand, the example shown in FIG.
It shows the initial position of the data to be written to Nos. 3 and 64, and its continuous value. The VA counter shown in FIG.
When data up to 4999 is targeted, the data corresponding to the dot position in the data is stored in the line buffer 6.
3 and 64 show data to be written. For example, when detecting the light amount data shown in FIG. 7, data according to the data shown in FIG.

That is, in the case of the detection data described above, the initial value of the data to be written into the line buffers 63 and 64 is the pixel at the initial position at the second pixel (“0002” h) of the CCD 54, and the subsequent length is 13 pixels (“00
C "h).

The data output to the PC 59 is the data shown in FIG.
004 "h) is the pixel at the initial position, and the length thereafter is 7
This corresponds to a pixel (“007” h).

As described above, by setting the range of data to be written to the line buffers 63 and 64 in advance, the data actually written to the line buffers 63 and 64 is as shown in FIG. The data supplied to the PC 59 is as shown in FIG.

On the other hand, the data (VDATA) input to the line buffers 63 and 64 is alternately read under the control of the video data read control unit 65, and output to the PC 59 via the I / F 66. The data read timing at this time is the read signal (/ RD) shown in the time chart of FIG. 7 described above, and data is read from the line buffer 63 or 64 alternately.

Further, a light quantity correction value is set based on the data (VDATA) measured as described above. FIG.
FIGS. 0 to 12 are diagrams for explaining the setting process of the light amount correction value. FIG. 10 is a time chart of, for example, data (VDATA) for 10 pixels in line units and a threshold count value. Since the threshold value is set to “2” as described above, the threshold value is set to “2” or more. Detect video data. Then, as described above, the count value of the pixel exceeding the threshold value "2" is set as the TH count value, and the TH count value is accumulated in the CCD line direction (X direction).

More specifically, in FIG. 10, for line N + 1..., All data are data equal to or smaller than the threshold set value, so that the counting process is not performed.

Line N + 2: video data of dot m of the third pixel 3, video data of dot m of the fourth pixel 3, video data 3 of dot m of the fifth pixel, video of dot m of the sixth pixel Data 3 is detected, and the TH count value is set to “4” and the TH accumulated value is set to “4”.

Thereafter, similarly, for line N + 3, the value of the TH count is "6".
And the TH accumulated value is “10”.

Line N + 4: The TH count value is "6" and the TH accumulated value is "16".・ ・ ・ Line N + 7: TH count value is “4”
And the TH accumulated value becomes “32”.

Then, in the next line N + 8, since no video data having a threshold value of “2” or more is detected (TH count value “0”),
+1 is determined as a dot boundary line, and the counting process is temporarily terminated.

FIG. 11 shows a case where the above-mentioned data (VDATA) is input. In FIG. 11, the area surrounded by a thick line indicates the focus plane of, for example, dot m and dot m + 1 when the threshold value "2" is set. Area. FIG.
2 is a diagram summarizing each dot area from the description shown in FIG. In this case, for example, the area of the dot m is “3”.
2 ", and the area of the dot m + 1 is" 12 ".

The light intensity distribution of one dot obtained as a result of the above processing can be represented as shown in FIG.
In FIG. 16, for example, the range is the portion where the detection level of the optical sensor is “2”, and the range is the portion where the detection level of the optical sensor is “3”. Similarly, as shown in FIG. It is.

Next, the correction data generator 70 generates a correction value based on each value. In order to set the light amount correction value, an arithmetic process is performed using the following equation. Assuming that the correction levels are 16 levels from 0 to 15, the average value is “6”, and the transition of the correction 1 level and the area ratio are 1.5, the arithmetic expression is: 6level + {100% − (of one dot) Area ÷ Average of total dot area × 100)｝ ÷ 1.5% Example 1) Area of one dot = 101.5 Average of total dot area = 100 6+ ｛100− (101.5 ÷ 100 × 100) )｝ ÷ 1.5 = 6-1 = 5level Example 2) Area of a certain dot = 98.5 Average of total dot area = 100 6+ ｛100− (98.5 ÷ 100 × 100)｝ ÷ 1.5 = 6 + 1 = 7level 103.0% ・ ・ ・ 4Level 101.5% ・ ・ ・ 5Level 100.0% ・ ・ ・ 6Level (Average value) 98.5% ・ ・ ・ 7Level 97% ・ ・ ・ 8Level And like this The data of the light amount correction value obtained by the above is written in the light amount correction ROM 36 '. That. The light amount correction ROM 36 ′ in which the data is written is stored in the EEPROM 36.
Is incorporated in the color printer device 1.

In the above description of the embodiment, the optical system is described as 1: 1. However, by enlarging the aerial image on the focus surface using the magnifying optical system and taking in the CCD linear sensor, Detailed measurement is possible.

Further, according to the correction data described above, the motor CN
The operating speed is set to T, and the moving speed of the CCD linear sensor is adjusted. In the above embodiment, the CCD
Although a linear sensor is used as 54, the invention is not limited to the linear sensor, and may be configured to use, for example, an area (surface) sensor. <Second Embodiment> Next, a second embodiment of the present invention will be described.

In the above description of the first embodiment, the correction data is generated by calculating the two-dimensional area.
In this configuration, a volume is obtained as a dimension and correction data is generated. In this embodiment, the color printer to be used is a tandem-type color printer similar to the above-described embodiment, and has the configuration shown in FIG. The system configuration of the color printer is also the same as that of FIG. 2 described above, and the same circuits are denoted by the same reference numerals and description of the configuration will be omitted.

FIGS. 13 to 15 are diagrams for explaining the setting processing of the light quantity correction value of the present embodiment. FIG. 13 is a time chart of, for example, data (VDATA) for ten pixels in line units and a threshold count value, and the threshold value is set to “2” as described above. Therefore, the count value of the pixel exceeding the threshold value “2” is set as the TH count value, and the TH count value is accumulated in the CCD line direction (motor moving direction). More specifically, for the line N + 1, the data is not counted because the data is equal to or less than the threshold value “2”.

Line N + 2: video data of dot m at the third pixel, video data of dot m at the fourth pixel, video data of dot m at the fifth pixel, video of dot m at the sixth pixel Data 3 is detected, and becomes the X direction count value “12” and the Y direction count value “12”.

Thereafter, similarly, for line N + 3,..., X direction count value “22”
Y direction count value “34” For line N + 4: X direction count value “30”
Y direction count value "64" · · · Line N + 7: X direction count value "12"
The count value in the Y direction becomes “128”.

Then, when no video data equal to or larger than the threshold value is detected at the time of the line N + 8 (the count value in the X direction is "0"), it is determined that the boundary line is a dot boundary line, and the counting is completed.

FIG. 14 shows the focus plane of dots m and m + 1 when the data (VDATA) as shown in FIG. 13 is input and the range surrounded by the thick line is set to the threshold value “2”. Range.

FIG. 15 is a diagram summarizing the time chart shown in FIG. 13 described above.
8 ”and the volume of the dot m + 1 are“ 44 ”, and correction data is generated based on the respective values.

The generation of the correction data is calculated by the following equation. Assuming that the correction levels are 16 levels from 0 to 15, the average value is “6”, and the transition of the correction 1 level and the volume ratio are 1.5, the same as described above. The volume is calculated, and the correction data of each dot is calculated based on the value. Then, the data of the light amount correction value obtained in this manner is written into the light amount correction ROM 36 ', and is stored in the EEPROM 36 of the corresponding color printer.
Is set to <Third Embodiment> Next, a third embodiment of the present invention will be described.

In this embodiment, the variation in the light emission of the LED elements is corrected by correcting the waveform. In this embodiment, the color printer to be used is a tandem-type color printer similar to the above-described embodiment, and has the configuration shown in FIG. The system configuration of the color printer is also the same as that of FIG. 2 described above, and the same circuits are denoted by the same reference numerals and description of the configuration will be omitted.

FIG. 17 shows the image forming units 15 to 15 described above.
LED head (optical writing head) 4 disposed at 18
It is sectional drawing of 0 (40Y-40BK). FIG.
FIG. 4 is a diagram showing a surface configuration of the LED array substrate 82. L
The ED head 40 (40Y to 40BK) is configured by arranging a plurality of LED array chips 83 on an LED array substrate 82, and has a drive IC for LED drive in an adjacent part.
84a and 84b are provided. Each LED light emitting section (LED array chip 83) is provided with a drive IC 84
A drive signal is sent from a and 84b via bonding wires 85a and 85b, and light is emitted according to the drive signal. In the figure, reference numeral 86 denotes a SELFOC lens which forms the light emitted from the LED light emitting unit on the photosensitive drum 20 and is supported by the lens support unit 87.

The LED array substrate 82 is mounted on a substrate support 81 formed integrally with the lens support 87, and the substrate support 81 (lens support 87) is mounted on a housing 88 of the image forming unit. I have.

FIG. 19 shows drive ICs 84a and 84a.
FIG. 4 is a diagram showing a circuit configuration in b. Video data (DATA) is supplied to a shift register 90 shown in FIG. 2 in synchronization with a clock signal (CLK), and video data for one line is input serially. The video data input to the shift register 90 is supplied to the latch circuit 91 in synchronization with the latch signal (LAT), and is held in the latch circuit 91. While the video data for one line is latched in the latch circuit 91, the strobe signal (ST
AND gate 92, buffer 93 in synchronization with the input of B)
, Video data is output to the LED element 60.
The processing operation of this example in the above configuration will be described below.

A latent image is formed on the peripheral surface of the photosensitive drum 20 by the light intensity due to the light emission of the LED element 60 formed in the LED head 40. FIG. 20 shows the distribution state of the light intensity. In the figure, the solid line shows the distribution state of even-numbered dots, and the dotted line shows the distribution state of odd-numbered dots. Also,
The S line indicates a threshold value at which the latent image can be visualized.

Conventionally, the illuminance was measured per unit area. Therefore, even if the illuminance values are the same, the light intensity distribution state within one dot has a different MTF.
In some cases, the characteristics as shown in FIG. That is,
In this case, even if the illuminance values are the same, the light intensity distribution within one dot is different, and a density difference appears between the dots.

Therefore, as shown in FIG. 22, by measuring the light intensity distribution within one dot, even when the state shown in FIG. The state is changed to the state shown in FIG.

Further, as shown in FIGS. 23A and 23B, the light emission amount of the LED element 60 is determined so that the light intensity distribution line is aligned with the intersection of the dot pitch P and the S line.
The light amount correction value is stored in the EEPROM 36.

The EE storing the light amount correction value in this manner
The PROM 36 is incorporated in the color printer 1 described with reference to FIGS. 1 and 2 together with the LED head 40. That is, yellow (Y), magenta (M),
Image forming unit 1 for cyan (C) and black (BK)
It is incorporated into 5 to 18 LED heads.

FIG. 24 is a circuit diagram for explaining the actual light emitting operation of the LED element 60. The light amount correction value stored in the EEPROM 36 is controlled by the CPU
The (voltage) data VB output to the digital / analog (D / A) converter 95 and converted into analog data is input to the LED circuit 60 ′ including the LED element 60 via the.

On the other hand, serial data is supplied to the shift register 90 from the LED head controller 37, latched by the latch circuit 91, and then supplied to the LED circuit 60 'in synchronization with the output of the strobe signal (STB). The LED circuit 60 ′ includes three transistors Q1 to Q3, a resistor R, and an LED element 60, and turns on / off the transistor Q1 according to video data supplied from the latch circuit 91.
The LED element 60 corresponding to the transistor Q1 which is turned off and turned on emits light.

At this time, the above-described analog data (voltage data) VB is supplied to the transistors Q2 and Q3 via the above-described resistor R, and the base current (IB) of the transistor Q2 is adjusted to provide the LED element 60 with the same. It controls the flowing current (IC). Therefore, by adjusting the analog data (voltage data) VB, the LED element 6
The current (IC) flowing to 0 can be changed, and the light emission amount of the LED element 60 can be changed.

[0092]

As described above, according to the present invention, the area of the focus surface of each dot is measured, correction data for each dot is generated, and correction of the light amount of each dot is performed according to the correction data. This is a configuration for performing printing without light amount unevenness.

Further, by measuring the volume of the focus surface of each dot, correction data considering luminance is generated.
More detailed adjustment is possible. Further, by adjusting the analog data (voltage data) VB, the current flowing through the LED element is varied, and the light emission amount of the LED element is adjusted.
Printing with excellent print quality can also be performed.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a color printer using a tandem system.

FIG. 2 is a diagram illustrating a control circuit of the color printer device.

FIG. 3 is a configuration example of a light amount correction device used to acquire light amount correction information.

FIG. 4 is a specific system configuration diagram of a PCI / F.

FIG. 5 is a diagram illustrating a positional relationship of a CCD with respect to an LED head.

FIG. 6 is a diagram illustrating a process of extracting one dot of an LED element by a CCD.

FIG. 7 is a time chart illustrating a processing operation of the first embodiment.

FIG. 8 is a diagram showing data write information when data is written into a line buffer.

FIG. 9 is a diagram showing data write information when data is written into a line buffer.

FIG. 10 shows data (VDAT) for 10 pixels in line units.
6A is a time chart for explaining a threshold count value.

FIG. 11 is a diagram illustrating the area of the focus surface of dots m and m + 1.

FIG. 12 is a diagram showing a table summarizing the time chart shown in FIG. 10;

FIG. 13 is a diagram illustrating a line unit 10 for explaining the second embodiment;
6 is a time chart illustrating pixel data (VDATA) and a threshold count value.

FIG. 14 is a diagram illustrating an area of a focus surface of a dot m and a dot m + 1 according to the second embodiment.

FIG. 15 is a diagram summarizing the time chart shown in FIG. 13;

FIG. 16 is a diagram showing a light intensity distribution of one dot.

FIG. 17 is a cross-sectional view of an LED head (optical writing head) provided in each image forming unit.

FIG. 18 is a diagram showing a surface configuration of an LED array substrate.

FIG. 19 is a diagram showing a circuit configuration in a drive IC.

FIG. 20 is a diagram illustrating a distribution state of light intensity.

FIGS. 21A and 21B are diagrams showing a difference in light intensity distribution state within one dot.

FIGS. 22A and 22B are diagrams showing a difference in light intensity distribution state within one dot.

FIGS. 23A and 23B are diagrams illustrating an example in which a light emission value of an LED element is determined such that a light intensity distribution line is aligned with an intersection of a dot pitch P and an S line.

FIG. 24 is a circuit example illustrating an actual light emitting operation of an LED element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 printer device 2 paper supply / transport mechanism 3 image forming unit 4 fixing device 5 paper feed cassette 6 paper transport system 7 paper feed roller 8 paper transport path 9 standby roll 10, 11 drive roll 12 transport belt 13 auxiliary roll 15-18 images Forming unit 20 Photoreceptor drum 21a Charger 21b Print head 21c Developing device 21d Transfer roll 22 Transport roll 23 Discharge roll 24 Discharge unit 30 I / F controller 31 Printer controller 32 Host computer 33 Display unit 34 CPU 35 ROM 36 EEPROM 37 LED head control unit 38 Driver 39 Buffer 40Y, 40M, 40C, 40BK LED head 41 High voltage power supply unit 42 DC motor 43 Pulse motor 44 Developing clutch 45 Belt up / down motor 46 Standby clutch 47 Fixed Clutch 48 Each sensor 51 LED head 52 Optical system 53 Motor 54 CCD (Charge-coupled device) 55 CCD counter (CCDCNT) 56 PC interface (PCI / F) 57 ROM 58 Motor counter (Motor CNT) 59 Personal computer (PC) 60 LED Element 61 Video I / F 62 Video data write control section 63, 64 Line buffer 65 Video data read control section 66 I / F 67 Control circuit 68 Dot position search section 69 Threshold counter 70 Correction data generation section 82 LED array board 83 LED Array chip 84a, 84b Drive IC 85a, 85b Bonding wire 86 LED light emitting part 87 Lens support part 88 Housing 90 Shift register 91 Latch circuit 92 AND gate 9 Buffer Q1~Q3 transistor R resistance

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yukio Akita 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. Tokyo Office (72) Inventor Makoto Asako 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Inside the Tokyo office (72) Kenji Takano Inventor 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Computer Co., Ltd. Tokyo office F-term (reference) 2C162 AE12 AE21 AE28 AE47 AE87 AF13 AF23 AF70 AF84 AF89 AF94 AH74 AH79 AH84 FA04 FA17 FA45

Claims (5)

[Claims] An optical sensor having a pixel having a diameter smaller than one dot of the LED element; an arithmetic unit for calculating an area of one dot of the LED element from a detection result of the optical sensor; Correction means for correcting the amount of light emitted from the LED element based on the correction value. 2. The method according to claim 1, wherein the calculating means sets a constant threshold value for the detection value detected by the optical sensor, and performs a calculation process on the detection value exceeding the threshold value. The light amount correction device according to claim 1. 3. The arithmetic means sets a constant threshold value for a detection value detected by the optical sensor, and performs an arithmetic process when a predetermined number of detection values exceeding the threshold value are consecutive. The light amount correction device according to claim 1 or 2, wherein: 4. The light quantity correction device according to claim 1, wherein said optical sensor is a line sensor. 5. The light quantity correction device according to claim 1, wherein the calculation means also calculates the volume of one dot of the LED element.