JPS5913632Y2 - Exposure lamp control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exposure lamp control device, and in particular provides an exposure lamp control device that allows accurate exposure control and is effective for color exposure.

2. Description of the Related Art Conventionally, an exposure lamp of an electronic copying machine or the like is provided with control means for adjusting exposure time, brightness, etc. according to the amount of exposure.

Particularly in color reproduction, the amount of exposure differs for each separated color, and the sensitivity of the photoreceptor also usually differs depending on the color.
Control measures are essential.

Such an exposure control device for color reproduction requires two types of adjustment: adjusting the color balance of each separated color to obtain the optimum color balance, and obtaining the optimum exposure amount of the reproduced image.

In general, once the color balance has been adjusted in the separation optical system, there is no need to make adjustments for each individual separated color; it is sufficient to maintain that color balance and make adjustments to obtain the optimum exposure for the reproduced image. be.

However, when the original and the photoreceptor are left still and reproduction is performed with a single exposure, color balance can be adjusted by adjusting the exposure time, but when scanning the original, the exposure amount itself must be adjusted.

To configure the exposure lamp control device as described above, a conventional sliding transformer is used to control the exposure lamp voltage, or a sliding transformer and semiconductor switching elements (SCR, TR) are used.
There are methods of controlling an exposure lamp using a phase control circuit including an IAC (IAC, etc.), but all of them have drawbacks such as large and complicated devices and high power consumption.

An object of the present invention is to provide an exposure lamp control device that can also be applied to a slit scanning type exposure system.

A further object of the present invention is to provide a compact device that is suitable for color reproduction, allows easy adjustment, accurate control, and consumes little power.

The device of the present invention includes an exposure lamp operated by an AC power source,
a first input means for making the light amount of the exposure lamp variable for each color; a second human power means for making the light amount of the exposure lamp variable for each color; and inputs from both the first human power means and the second human power means. control means for controlling energization of the exposure lamp based on a signal; further, the control means includes a pulse oscillation means; and a switching device that performs a switching operation based on an output pulse from the pulse oscillation means to control energization of the exposure lamp. The frequency and pulse width of the output pulse from the pulse oscillation means are variable, and the first input means and second human power means adjust the exposure amount for each color and the common exposure amount for each color. This is done by controlling the pulse frequency and pulse width.

Hereinafter, details of the present invention will be explained using specific examples with reference to the drawings.

FIG. 1 shows an embodiment of the device circuit based on the present invention.

A pulse oscillation circuit section A consisting of a unijunction transistor (hereinafter referred to as UJT) Ql, a variable resistor VR1, and a capacitor C1, a transistor Q3. Q4
Monostable multi-vibrator circuit section B consisting of
, and a lamp lighting control circuit section C including a switching transistor Q6.

The pulse period is set by the variable resistor VR of the pulse oscillation circuit section A.
Furthermore, the output pulse width is made variable by the monostable vibrator circuit sections ①R2, VR3, and ⑥R4.

FIG. 2 is an explanatory diagram of a slit exposure type electrophotographic copying machine to which an embodiment of the present invention is applied.

A document 2 placed on a document table 1 is subjected to slit exposure by an exposure source 3 as the document table 1 moves.

The slit-exposed image is formed on the photosensitive drum 6 by the lens system 5 via the filter 41 of the color separation device 4 .

The surface of the photosensitive drum 6 is already charged by a charger 7 prior to exposure, and an electrostatic latent image is formed by the exposure.

This electrostatic latent image is developed by a developing brush 101 of a developing device 10 having a developer of a predetermined color.

Of course, the selection of the developing brush may be linked to the filter selection of the color separation device 4, or may be controlled manually.

The microscopic image is post-charged by the post-charger 11 and transferred to the transfer member P.

After the transfer, residual developer on the surface of the photosensitive drum 6 is cleaned by a cleaning device 12 and used for the next image formation.

On the other hand, the transfer member P is sent out from the supply cassette 3 to the transfer roller 15 by the delivery roller 14 .

The transfer member P is electrostatically fixed to the surface of the transfer roller by a charger 16 or mechanically fixed by a clip 17.

After a reproduced image of a predetermined number of colors is obtained on the transfer member P, the transfer member P is separated from the transfer roller by a separation claw 18, fixed by a fixing device 19, and provided to a paper feed tray 20.

To explain the device of the present invention in the above configuration device, first,
The color balance for each color separation is optimally set according to the characteristics of the exposure source 3, color separation filter 4, or photoreceptor.

This ratio is the variable resistor VR2, vR3, vR of the first illustrated circuit.
It is affected by setting 4.

On the other hand, the overall exposure amount is also set to a standard value using the variable resistor VR1.

The oscillation frequency of the pulse oscillation circuit section set in this way is 1
/T1 is schematically shown in FIG. 3A1.

On the other hand, depending on the color balance setting, for example, in the case of a red filter, the pulse width is tl at the S□ contact of switch SW1.
, in the case of a green filter, the pulse width is t2 at the S2 contact, and in the case of a blue filter, the pulse width is t3 at the B3 contact.

When the copying machine starts exposure to reproduce an image of the first color (for example, using a red filter) with these settings, the output pulse of the pulse oscillation circuit A is as shown in Figure 3 A1, and the multi-color signal corresponding to this output pulse is - The output of the vibrator circuit B is as shown in Figure 3 0□2.

Since this output turns on the transistor Q6 only during the pulse width 11, the current for driving the light source lamp becomes a pulsed current as shown in FIG. 3 C11.

At the end of the image exposure, the switch SW2 is turned off, the light source lamp is turned off, and the power of the pulse circuit is also turned off.

When the second color (for example, using a green filter) image reproduction starts, the light source starts to be driven, but since the contact of the changeover switch SW1 has already been switched to B2, the multi-vibrator circuit B The output has a pulse width of 0□2<t2 in FIG.

According to this output pulse, the light source driving current also becomes as shown in FIG. 3, 0□2.

When the third color (using blue filter) image reproduction starts, the contact point of the changeover switch SW1 becomes B3, so the output of the multi-vibrator is as shown in FIG. 3 813.

Therefore, the light source driving current is also C1. As above,
This enables optimal exposure according to the color separation.

Also, sometimes the original document may be too light or too dark.

At this time, by adjusting the oscillation frequency 1/T of the pulse oscillation circuit section A, an appropriate reproduced image can be obtained.

That is, if the reference frequency is made larger than 1/T1, a darker image can be obtained by making it thinner or smaller.

FIG. 4 shows control waveforms corresponding to each color when adjusted according to a thin original.

In the apparatus of the above embodiment, the pulse width is changed according to the color separation, but those skilled in the art who have read the specification of the present application in detail will understand that the purpose of the present application can be achieved even if the pulse period is changed according to the color separation. That would be easy to understand.

As detailed above, the present invention is applicable not only to the full-surface exposure type but also to the slit I type.
- It enables an exposure lamp control device that can be optimally used for exposure-type color reproduction copying machines and the like.

Furthermore, if the pulse frequency and pulse width for controlling the switching elements are configured to be variable and applied to a color copying machine, color balance adjustment and exposure amount adjustment can be easily and accurately performed. It is also extremely effective in reducing power consumption.

[Brief explanation of the drawing]

The figures are for explaining the present invention, and Figure 1 is based on the present invention.
FIG. 2 is an explanatory diagram of a copying machine to which the apparatus of the present invention is applied, and FIGS. 3 and 4 are diagrams illustrating output pulses of each part of the embodiment apparatus. In the figure, 1 is a document table, 2 is a document, 3 is a light source, 4 is a color separation device, 5 is a lens system, and 6 is a photosensitive drum.

Claims (1)

[Scope of utility model registration request] an exposure lamp operated by an AC power supply; a first manual means for making the light amount of the exposure lamp variable for each color; and a second manual means for making the light amount of the exposure lamp variable for each color;
control means for controlling the energization of the exposure lamp based on input signals from both the first human power means and the second human power means; further, the control means includes a pulse oscillation means and an output pulse from the pulse oscillation means; and a switching element that performs a switching operation to control energization of the exposure lamp, and the frequency and pulse width of the output pulse from the pulse oscillation means are variable, and the exposure amount for each color can be adjusted and the common An exposure lamp control device characterized in that the exposure amount is adjusted by controlling the pulse frequency and pulse width by the first manual means and the second manual means.