JPS5934308B2 - Exposure device of color electrophotographic copying machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning speed variable type slit exposure device for a color electronic copying machine, and is intended to enable an operator to easily perform color correction.

FIG. 1 shows a typical example of the spectral characteristics of each element constituting the process in a color separation type color electrophotographic copying machine. First, the photoreceptor is required to be sensitive to all wavelengths of the light beam to be exposed, that is, to have full color matching, but in reality, as shown in Figure 1a, On the other hand, the sensitivity is low, so it cannot be uniform.

In addition, as for color separation filters, blue filters, green filters, and red filters with the characteristics shown in Figure 1 -d are commonly used, but although their color separation performance is fairly good, their transmittance is There are large variations between each color.

In addition, the spectral characteristics of a typical halogen lamp as a light source for illumination and the transmittance of the lens are shown in Figure 1e and f, and in a color separation type color electrophotographic copying machine, during exposure,
That is, it can be seen that the required exposure amount in each wavelength range is already different for each color at the time of forming an electrostatic latent image.

Furthermore, as shown in FIGS. 2a to 2d, the γ characteristics of toner vary among yellow toner, red toner, blue toner, and black toner, making it difficult to maintain an ideal state.

Furthermore, electrostatic transfer copying machines have the disadvantage that low potential areas, ie, low density areas, are difficult to transfer during transfer, and in combination with the above-mentioned gamma characteristic of toner, it is even more difficult to reproduce the low density areas of the original image. For these reasons, color electrophotographic copying machines have conventionally adopted a scanning speed variation method (Japanese Patent Application Laid-Open No. 104543/1989) in which color correction is performed by adjusting the exposure amount for each color by changing the scanning speed of the original image in each process. (see official bulletin).

However, since the original image is composed of a combination of a plurality of colors, it is difficult to perform color adjustment as a whole even if each color is monochromaticly corrected. This can also be seen from the relationship shown in FIG. 2, that is, the difference between standard exposure and underexposure. In other words, although it is possible to emphasize or suppress each color using only this scanning speed variation method, it is difficult to adjust the entire original image, especially the low-density portion, by keeping the balance of each color constant. Further, in general, in a slit exposure type electrophotographic copying machine, the exposure amount is controlled by the slit width and the aperture in the lens section. However, as shown in Figure 3, these are affected by variations in the mirror, light source lamp, lamp mounting position accuracy, mirror surface condition, mirror mounting precision, etc., and the illuminance varies widely within the slit width. It is difficult to keep constant. For this reason, during manufacturing of electrophotographic copying machines, it is necessary to turn on the lamp after assembly, measure the image plane illuminance distribution, and make detailed adjustments, which poses a major problem in terms of productivity. In particular, a color electrophotographic copying machine has three to four color processes, and it is very difficult to adjust the exposure amount in these processes. In addition, there are some devices in which the exposure amount is controlled by apertures inside and outside the lens, but this involves problems with the COs4θ law and aperture efficiency, and as a result, it is difficult to say that it is a good idea from an economic point of view. The present invention eliminates the above-mentioned drawbacks, makes it possible to easily correct the color reproduction of the original image by adjusting the overall tone while keeping the z balance of each color constant, and also makes it possible to easily correct the color reproduction of the original image. It is another object of the present invention to provide an exposure device for a color electrophotographic copying machine having a structure in which color correction can be easily performed by adjusting the number of light sources turned on.

An embodiment of the present invention will be explained below with reference to the drawings.

As shown in FIG. 4, the original placed on the original placing table 11 is illuminated by lamps 12 and 135 serving as illumination light sources.
The light beam from this original passes through a mirror 14, an in-prism lens 15, and a color separation filter 16, and is slit-exposed onto a photoreceptor film 17.

Lamps 12, 13, mirror 14, in-prism lens 1
5. The optical system 18 consisting of the color separation filter 16 is connected to the wire 1
It is driven by a motor via 9 and moves along a guide member 20 to scan the original. The color separation filter 16 is made up of a plurality of primary color or multicolor filters 21 to 24, and is replaced every time the original is scanned once to sequentially separate the light beam from the original into four-dimensional colors. The photoreceptor film 17 has one end fixed to the photoreceptor drum 25 and the other end fixed to the reel 26, and is reciprocated between the exposure position and the transfer position as the photoreceptor drum 25 and reel 26 rotate. When the photoreceptor film 17 is moved to the exposure position, it is charged in advance by the charger 27 in front of it, and then exposed at the exposure position as described above to form an electrostatic latent image.

Further, the photoreceptor film 17 moves to the transfer position and is brought into contact with the transfer paper 29 between the photoreceptor drum 25 and the transfer drum 28 to transfer the electrostatic latent image thereon, after which the static electricity is removed by the static eliminator 30. . The transfer paper 29 is pulled out from the roll 31 by a roller 32, cut into a suitable length by a cutter 33, conveyed by a roller 34 and a guide member 35, and clamped onto the transfer drum 28 by a clamper 36.

When this transfer paper 29 passes between the transfer drum 28 and the photoreceptor drum 25, the electrostatic latent image is transferred to the photoreceptor film 1.
Developing tanks 37 to 40 at the developing position after being transferred from 7.
The image is developed with a developer from the printer, unnecessary developer is absorbed by a plotter roller 41, and dried by heaters 42 and 48. Furthermore, each electrostatic latent image corresponding to each color separation of the color separation filter 16 is transferred to the transfer paper 29 in a superimposed manner every rotation of the transfer drum 28, and the developing tanks 37 to 40 are also transferred to the transfer drum 28.
The electrostatic latent image on the transfer paper 29 is sequentially moved to the transfer position every rotation, and the electrostatic latent image on the transfer paper 29 is developed with a developer of each color corresponding to the color separation, thereby reproducing a color image. When development is completed and a color image is reproduced from the transfer paper 29, the clamper 36 is removed by the clamp cam 43, and the transfer paper 29 is peeled off from the transfer drum 28 by the peeling claw 44.
It is transported by a heater 48 and a fan 49, and is dried by a cutter 50.
The paper is cut off and conveyed to a copy receiver 55 by rollers 52, 53 and a guide member 54. For example, as shown in FIG. 5, a DC motor is used as the above-mentioned motor and is controlled by a voltage control method. In other words, the output of the AC power supply is
The DC voltage from the rectifier circuit REC is applied to the rectifier circuit REC via the triac T and the switch SW2.
-, , is applied to the motor M via SW2-2.
The switch SWl is a switch that is closed when the optical system 18 is operated, and the switches SW2l and SW2-2 work together with the switches SW2-3 and SW2-4 to operate the optical system 18.
This is a switch that is turned on when changing the direction of movement.
Therefore, motor M has switches SW2-1 and SW2-2.
The power supply terminal is switched, the rotation direction is switched, and the direction in which the optical system 18 is moved is reversed. Also, Switch S
W3-1 is sequentially switched for each process in conjunction with switch SW3-2, and selects each series circuit of variable resistors VRl to VR4, VR, to VR8, which are linearly tracked to the reproduced image density, in order for each process. . The switch SW2-3 selects variable resistors VRl to VR8 when moving the optical system 18 forward, and selects the resistor R1 when returning the optical system 18. Capacitor C has the output of AC power supply as switch SWl,
It is applied via selected resistances of the rectifier circuit RECl switches SW2-3 and SW31. The charging voltage of the capacitor C is applied to the triac T via the diode B as an ignition voltage. Therefore, the firing phase of the triac T is determined according to the time constant of the resistor and capacitor C selected by switches SW2-3 and SW3-1, and the output voltage of the rectifier circuit REC changes according to the firing phase. Motor M
The rotation speed changes. That is, when the optical system 18 moves forward and performs exposure, the speed of the motor M is controlled by the variable resistors R1 to
By switching each series circuit of R4, R5 to R8 in the order of each process with switches SW, -1, the speed is changed to an appropriate speed for each process, and when the optical system 18 returns, resistor R1 is selected with switch SW2-3. This results in a constant speed.

The density of each color can be adjusted by varying the tracking variable resistors R1 to VR4, changing the moving speed of the optical system 18 in each step, and changing the exposure amount. Also, the variable resistors R5 to R8 are interlocked, and the overall color density can be changed by varying the variable resistors R5 to VR8 and changing the moving speed of each step of the optical system 18 overall while keeping the ratio constant. It can be adjusted by

Further, the lamp 12 is supplied with power through switches SW, , SW2-4, and is turned on when the optical system 18 is moved forward to perform exposure. Lamp 13 is switch SWl, SW2-4, S
It is supplied with power via W3-2 and lights up during a specific process, for example, a blue process. That is, the number of lamps 12 and 13 lit is changed according to each process, and the amount of exposure is greatly changed. Therefore, the exposure amount may be adjusted within a small range by varying the speed of the motor M within an appropriate operating range. In addition, as shown in FIG. 6, a fixed resistor R2 is commonly used in place of the variable resistors VR, ~R8, and a variable capacitor VC is used as the capacitor C, and the overall color density can be adjusted by this variable capacitor VC. .

As described above, according to the exposure device of the color electrophotographic copying machine according to the present invention, since the speed of the optical system drive motor in each process can be changed overall while keeping the ratio constant, color correction is possible. This makes it easier to carry out the entire process, which has great effects in terms of productivity, etc.

In addition, if the number of illumination light sources to be lit can be selected according to each process, the operation of the optical system drive motor can be easily kept within the appropriate operating range, and adjustments during manufacturing can be made to turn on the illumination light sources. It is very economical and easy to adjust. Since the amount of exposure changes greatly by changing the number of lighting light sources, it is no longer necessary to adjust the scanning speed to the one that requires the most exposure of each color, as was the case in the past, and the number of lighting light sources can be changed. By changing the amount of light and increasing the exposure amount, the operating speed can be increased and power consumption can be saved.

[Brief explanation of the drawing]

Figures 1a-f are spectral characteristic diagrams of each element of a conventional color electrophotographic copying machine, Figures 2a-d are characteristic diagrams showing the gradation reproducibility of each color toner, and Figure 3 is a conventional slit exposure device. Figure 4 shows the variation in image plane illuminance distribution within the effective slit width of
The figure is a schematic model diagram showing an example of a color electrophotographic copying machine to which the present invention is applied, and FIGS. 5 and 6 are circuit diagrams each showing an example of an electrical system used in the present invention. 12, 13...Lamp, 18...Optical system, M...
Motor, REC... Rectifier circuit, C, VC... Capacitor, R1 to VR8, Rl, R2... Resistor, T...
Triack, B...Diac, SWl, SW2-
1 to SW2-4, SW3-1, SW3-2...Switch.

Claims (1)

[Scope of Claims] 1. In a scanning speed changing type slit exposure device for a color electrophotographic copying machine, which can change the exposure amount by changing the speed of the optical system drive motor and changing the scanning speed of the original image, A color electrophotographic copying machine characterized by having an adjustment device that can change the overall speed of the optical system and drive motor during exposure for each color while keeping the speed ratio constant for each color. Exposure equipment. 2. A device that operates the optical system drive motor within an appropriate operating range during exposure for each color, has a plurality of illumination light sources, and can select the number of illumination light sources to be lit according to the exposure process for each color. An exposure device for a color electrophotographic copying machine according to claim 1.