JP3046038B2 - Lamp voltage correction method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp voltage correction method for preventing a color change in a color copying machine during zooming.

[Conventional technology]

In a color copier, the reading optical system includes color separation filters for green, blue, and red, and switches to a corresponding filter and developing device each time exposure, development, and transfer of one color are completed, and a plurality of color separation filters are provided. Is transferred so as to be superimposed on one recording sheet to form a color copy.

However, in such a color copy process, if there is uneven illuminance in the illuminance distribution in the width direction of the photoreceptor, it appears as a color difference on the copy and deteriorates image quality.

Conventionally, correction of uneven illuminance requires only one type of correction in black-and-white copying machines.However, in the case of color copying, uneven light emission due to differences in lamp colors, uneven reflectance due to differences in the color of the reflective mirror, and transmittance of filters There are various types of unevenness, such as unevenness in color and unevenness in color sensitivity of the photoreceptor, which appear as color unevenness on an actual copy.

Conventionally, in a black-and-white copying machine, the exposure energy on the photoconductor by changing the magnification is 4 m /
(1 + m) ² . For this reason, a notch shift occurs due to zooming, and the image density increases. Therefore,
The lamp voltage is corrected during zooming to prevent notch displacement. This correction amount is corrected according to the following formula, which is a general formula for a halogen lamp.

F / F ₀ = (V / V ₀ ) ^3.38 (However, F / F ₀ is the light amount ratio, V / V ₀ is the voltage ratio) [Problem to be Solved by the Invention] However, color separation is performed like color copying. In this case, since the light amount ratio with respect to the lamp voltage is not the same for each filter, if the same voltage correction is performed for all the color-separated lights, the respective energy balances change and appear as color changes during zooming. .

In order to correct unevenness in sensitivity and uneven illuminance of a color copying machine, for example, Japanese Unexamined Patent Publication No. Sho 62-3244 and
There is -99852. However, in each case, the configuration becomes complicated and the cost of the apparatus is unavoidable.

An object of the present invention is to provide a lamp voltage correction method capable of preventing a color change during zooming with a simple configuration.

[Means for solving the problem]

The above object is to expose a document a plurality of times, form an image on a photoconductor through a color separation filter selected for each exposure,
Perform color copying by toner development of a plurality of colors corresponding to each color separation light imaged on the photoreceptor through the color separation filter, and move an optical element that forms the image of each color separation light on the photoreceptor. The magnification is changed, and the voltage supplied to the lamp for exposing the original to correct the voltage supplied to the lamp for exposing the original to correct the exposure amount of each color separation light on the photoconductor at the time of the magnification is adjusted. In the method of correcting the lamp voltage of the color copying machine to be corrected, the correction light amount HE and the correction voltage HV are set so that the exposure amount and energy balance of each color separation light on the photoconductor are equal to the exposure amount and energy balance at the same magnification. HE = 4m / (1 + m) ² HV = (HE) ^{1 / a} · V ₀ −V ₀ (where m: variable magnification, a: count in each color separation light, V ₀ : operating center voltage) The lamp voltage is corrected based on this.

[Action]

According to the above-described means, when correcting the change in the exposure amount on the photoconductor in response to the color separation light, that is, the change in the energy balance with the lamp voltage, the correction light amount HE and the correction voltage HV
Is corrected based on the above equation, whereby the energy balance on the photoreceptor is not broken, and no color shift occurs due to the correction.

〔Example〕

FIG. 1 is a front view showing a color copying machine suitable for applying the present invention. FIG. 2 is a front view showing details of the reading system shown in FIG.

An ADF that automatically supplies originals is located at the top of the main unit 1
(Auto Document Feeder) 2 is provided. A contact glass 3 is provided on the upper surface of the device body 1.
Is provided, and an optical reading mechanism 4 is disposed in a lower space thereof. An electrophotographic color copying mechanism is provided below the optical reading mechanism 4.

The color copying mechanism includes a drum-shaped photoconductor 5 to which light read from an optical reading mechanism 4 is exposed, a charger 6 for charging the surface of the photoconductor 5 prior to exposure, and a plurality of toners containing toners of different colors. , A recording paper winding drum 8, a transfer charger 9 installed in the drum 8 to transfer the toner image on the photoreceptor 5 to the recording paper surface, and a toner image on the recording paper after all the transfer is completed. Fixing device to fix
10, a paper discharge tray 11 for storing the recording paper discharged from the fixing device 10, and a plurality of paper feeders for setting recording paper of a frequently used size in advance and supplying a specified size paper at a predetermined timing. A paper cassette 12, a separation charger 13 for separating the recording paper after transfer from the surface of the drum 8
It is configured with such as.

Next, the configuration of the reading system shown in FIG. 2 will be described.

Exposure lamp 21 for illuminating the reading section of the supplied document, first mirror 2 for reflecting the reflected light from the reading section in the horizontal direction
2, a second mirror 23 for reflecting the light from the first mirror 22 downward, and a light for the first mirror 22 to reflect the light from the second mirror 23
A third mirror 24 for reflecting light emitted from the third mirror in the opposite direction,
A lens 25 movably disposed in the light exit path of the mirror 24 to focus an optical image on the surface of the photoconductor 5; a fourth mirror 26 for reflecting light from the lens 25 to the photoconductor 5; A color separation filter 27, which is disposed in the output optical path of the four mirrors 26 and inserts a filter color corresponding to a development color, separates a space between the reading system and the color copying mechanism so that dust does not enter the reading system. Each of the dustproof glasses 28 is provided.

Exposure lamp 21, first mirror 22, second mirror 23 and third
The mirror 24 reciprocates in the horizontal direction as shown in FIG. The lens 25 moves in the left and right direction according to the magnification.

In the above configuration, when the document is conveyed onto the contact glass 3 by the ADF 2, scanning starts from one end of the document to the other end, and the reading light is transmitted from the first mirror 22 to the second mirror 23 to the third mirror.
Mirror 24 → lens 25 → fourth mirror 26 → color separation filter 27
To the photoreceptor 5 along the path, and exposure is performed.

At this time, first, the first color filter is used as the color separation filter 27.
Is inserted into the optical path. The color of the color separation filter 27 is switched every time one exposure is performed.

By this exposure, an electrostatic latent image is formed on the photoreceptor 5, and development is performed with the first color (toner color corresponding to the filter color of the color separation filter 27) in the developing device 7. At a time when the toner image (visible image) resulting from the development reaches the transfer position, a recording sheet of a designated size is sent out from one of the sheet feeding cassettes 12 and the rotating drum 8 is rotated.
Wrapped around.

The drum 8 rotates in synchronization with the timing at which the first color toner image on the photoconductor 5 reaches the transfer position by the rotation of the photoconductor 5, and the leading end of the recording paper reaches the transfer position. Due to the electrostatic attraction of the transfer charger 9, the toner image on the photoreceptor 5 is transferred onto the recording paper, and is rotated while adsorbed on the drum 8 as it is.

On the other hand, the exposure corresponding to the second color is started, and an electrostatic latent image is formed on the photoconductor 5 through the second color filter of the color separation filter 27. The electrostatic latent image is developed with a second toner color by the developing device 7, and the drum 8 is adjusted in timing to reach the transfer position of the toner image.
Rotates while adsorbing the recording paper, and the second color toner image reaches the transfer position at the same time as the leading end reaches the transfer position, and the toner image has been transferred to the first color. It is transferred onto recording paper.

Thereafter, the transfer of the third color and the fourth color is performed in the same manner as described above, and the transfer of the full color is performed. When the transfer of all the colors is completed, the recording paper is separated from the surface of the drum 8 by driving the separation charger 13 and is conveyed to the fixing device 10. The fixing device 10 fixes the multi-transferred toner images of a plurality of colors on a sheet by heating and pressing means. The recording paper on which the fixing has been completed is discharged to the paper discharge tray 11.

By the way, as shown in FIG.
/ (1 + m) ⁴ This reduction rate is the same for all of the color separation lights. However, the light amount ratio when the lamp voltage is changed is not the same for each color separation light.
As shown in the figure, the exponent coefficients (rates of change) differ in the order of blue>green> red (FIG. 4 is obtained from experimental values).

When the amount of reduction due to the above-described zooming is corrected with the same lamp voltage (increased lamp voltage), the energy balance on the photoconductor 5 changes, causing color shift. In the example of FIG. 4, since the exposure amount of blue is the largest and the exposure amount of red is smaller, yellow is less, cyan is more developed, and the image is bluish, but an image is obtained.

Therefore, in the present invention, in order to prevent color misregistration, the correction amount calculated for each color separation light is calculated according to a preset coefficient. That is, the correction is performed such that the exposure amount on the photoconductor at the time of zooming is equal to the exposure amount at the same magnification, and the energy balance of each color separation light is equal to the energy balance at the same magnification. As a result, the energy balance on the photoconductor 5 does not collapse,
There is no color shift due to correction.

Here, the correction amount HE and the correction voltage HV are set as follows, and the correction is performed based on these.

HE = 4 m / (1 + m) ² HV = (HE) ^{1 / a} · V ₀ −V ₀ (where V _{0 is the} center voltage used, m is the magnification, a is a coefficient for each exposure, and is blue exposure. in a ≒ 4.0 a ≒ 3.54) using the center voltage V ₀ at a ≒ 3.83 Red exposure green exposure may be an average value of the variation of the lamp lighting voltage due to variation of the photoconductor sensitivity, also just before zooming etc. It may be calculated from the lamp voltage in double. By performing correction using the lamp voltage immediately before zooming in this manner, deterioration of the photoconductor 5 and dirt on the mirror are hardly affected, and good correction can be obtained, and color misregistration can be prevented.

〔The invention's effect〕

As is clear from the above, according to the present invention, the correction light amount
HE = 4m / (1 + m) ² and HV = (HE)
Set to _{^{1 / a · V 0 -V 0}} , since correction is performed based on this, it is possible to perform exposure by proper lamp voltage for each color separation, eliminate color shift due to zooming, stable Images can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view showing a color copying machine suitable for applying the present invention, FIG. 2 is a front view showing details of a reading system shown in FIG. 1, and FIG. FIG. 4 is a characteristic diagram showing a relationship between a lamp voltage ratio and a light amount ratio. 2 ... ADF, 3 ... Contact glass, 4 ... Optical reading mechanism, 5 ... Photoconductor, 7 ... Developer, 8 ... Drum, 9
... Transfer charger, 10 ... Fixer, 21 ... Exposure lamp, 22,23,24,26 ... Mirror, 25 ... Lens, 27 ... Color separation filter.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/01-15/01 117 G03G 15/04-15/04 120

Claims (1)

(57) [Claims] 1. An original is exposed a plurality of times, an image is formed on a photoreceptor through a color separation filter selected for each exposure, and each color is formed on the photoreceptor through the color separation filter. A color copy is performed by developing a plurality of colors of toner corresponding to the separation light, and the optical element that forms each of the color separation lights on the photoconductor is moved to change the magnification. In the method of correcting the voltage supplied to the lamp for exposing the original in order to correct the voltage supplied to the lamp for exposing the original to correct the amount of exposure described above, the lamp voltage correction method of the color copier, The correction light amount HE and the correction voltage HV are set to HE = 4 m / (1 + m) ² HV = (HE) ^{1 / a} so that the exposure amount and the energy balance on the photoreceptor become equal to the exposure amount and the energy balance at the same magnification.・ V ₀ −V ₀ (m: magnification, a: for each color A lamp voltage correction method for a color copying machine, wherein the lamp voltage is corrected based on the count in photolysis, V ₀ : used center voltage).