JPS60122964A - Erasing device of copying machine - Google Patents

Abstract

PURPOSE:To erase exactly an unnecessary image by providing a variable and adjustable means of an erasing light source, and irradiating light for erasion without excess and shortage to a part of a picture area on a photosensitive body even in case of reduction copying. CONSTITUTION:One end of lamps LP1-LP4 is connected to a common power source VIN whose voltage is constant, and the other end is connected to a control part which is not shown in the figure, through A-1-A-3, respectively. In case of unmagnification copying, A-1-A-3 all become an H level,and the lamps LP1-LP4 are not turned on. In case of reduction copying of 92%, only the terminal A-3 becomes an L level and only the LP4 is turned on. In case of reduction copying of 87%, the terminals A-2, A-3 become L and the LPs 3-4 are turned on. In case of reduction copying of 71%, all the terminals become L, and LP1-LP4 are all turned on. In this way, even in case of reduction copying, light for erasion is irradiated without excess and shortage to a part except a picture area on the photosensitive body, and an unnecessary image can be erased exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an erase device for a copying machine that has a reduction/magnification function.

Erasing unnecessary images on the photoreceptor (image carrier) is performed by irradiating light from an erase light source onto areas other than the image area. Therefore, such an erase function has conventionally been provided in copying machines having a reduction/magnification function.

The prior art will be described below with reference to FIGS. 1 to 3 of the accompanying drawings. FIG. 1 is a diagram showing the configuration around a photoreceptor of a conventional copying machine. In addition, in the following description of the drawings, the same elements are indicated by the same reference numerals. The charging charger 2 installed close to the photoreceptor 1 rotating in the direction of arrow ^1,
Photoreceptor 1 is uniformly charged. A document image is exposed on the charged drum-shaped photoreceptor 1 by an exposure section 3, and a portion other than the document image area is irradiated with light from an erase lamp 4 to be erased. Note that erasing may be performed after charging by the 41F electric charger 2. Next, the document latent image is developed in a developing section 5 provided below and close to the photoreceptor 1, and transferred to a sheet of paper through processing by a transfer charger 6. After the transfer, the image is processed by a charge removal charger 7, cleaned by a cleaning section 8, and uniformly removed by a charge removal lamp 9. The neutralized photoreceptor 1 is uniformly charged again by the charging charger 2, and the next copying process is started.

By the way, when a document is uniformly charged by the charging charger 2 and then exposed by the exposure section 3 to form a latent image of the document,
In the case of reduction copying, an unnecessary latent image is formed on the photoreceptor 1. Therefore, in order to erase this unnecessary image, each light source constituting the erase lamp 4 blinks in accordance with the reduction ratio.

FIG. 2 is an explanatory diagram of the relationship between the photoreceptor l and the erase lamp 4 of a conventional copying machine having a variable magnification function.

The erase lamp 4 is in the direction of the axial lO force of the drum-shaped photoreceptor 1;
It is composed of four lamps 1.111 to LP4 arranged in a row. Then, none of the lamps LP1 to LP4 are lit during the same-size copying indicated by the width Q1 in the figure, and only the lamp LP4 is lit during the 92% reduction copying indicated by the width Q2; % reduction copy, only the lamp LP3.4 is turned on, and when the width Q4 is 71% reduction copy, all the lamps L111-4 are turned on.

FIG. 3 is a circuit diagram of a conventional lighting circuit for the erase lamp 4 shown in FIG. One end of the lamp LPI-LP/I is connected to a common power source vIN with a constant voltage, and the other end is connected to a control unit (not shown) via terminals A-1, A-2, and Δ-3, respectively. For same-size copy, use terminal ＾-1, A
-2 and ^-3 are both high level (hereinafter rr Hjl
), and the lamps LPI to LP4 do not light up. At the time of 92% reduction copying, only terminal A-3 becomes low level (hereinafter referred to as rz L It), and lamp L
Only P4' lights up. When 87% reduction copy is made, terminals A-2 and A-3 become "[, IH," so lamps LI'3 and LI'4 are lit, and when 71% reduction copy is made, all terminals become 'L. Therefore, both lamps LPI to LP4 are lit.

In this way, the light source for erasure used in copying machines with variable magnification/reduction functions has traditionally been switched on or off according to the variable magnification ratio, but even if the light source is a lamp, it is not a LIED. However, since the voltage applied to it is constant, the amount of light emitted from it is also constant. Moreover, within the range of variations in the sensitivity of the photoreceptor (image carrier), the distance between the light source and the photoreceptor, the amount of light from the light source, etc., the sensitivity of the photoreceptor may be poor,
If the light source and photoconductor are far apart, or if the amount of light from the light source is low, unnecessary images (images other than the original image on the photoconductor) may not be erased enough, resulting in afterimages on the copy. .

In order to eliminate the above-mentioned problems, there is a method of designing the light source to have a large amount of light in advance so that unnecessary flame can be completely eliminated even in the copying machine under the worst conditions. but,
If this is done, in a copying machine with the opposite quality condition, the amount of light that is applied to the photoreceptor becomes too large, resulting in fatigue of the photoreceptor.

Additionally, there is a method to adjust the amount of light irradiated onto the photoconductor (1) for each copying machine, but conventionally the light intensity is adjusted by changing the distance between the photoconductor and the light source, which is time-consuming and practical. It is said that it is lacking in sex]) It has a drawback.

Furthermore, if the amount of light irradiated to the photoconductor is set in advance, developer deterioration or photoconductor sensitivity fatigue may occur over time after the copying machine is put into operation, and this may cause changes in the required erase frequency. However, this method has the disadvantage of causing erase defects.

This invention has been made to overcome the drawbacks of the above-mentioned prior art, and is capable of reliably erasing unnecessary images in areas other than the reduced image area on the photoreceptor (image carrier), and It is an object of the present invention to provide an erase device for a copying machine that can easily adjust the amount of light for erasing according to changes in machine characteristics over time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 4 is a circuit diagram of an erase lamp lighting circuit according to an embodiment of the present invention.

The voltage Vout applied to the lamps LPI to LP4 is varied and adjusted by a light source voltage variable circuit 11 that manually maintains a constant voltage V iN. 3 terminal regulator
A voltage V iN is applied to the input terminal of the ICI, and its output Vout is ramped and sent to 131-LP4. The output terminal of the three-terminal regulator IC1 is grounded via the variable resistor VRz and the resistor R1 connected in series, and the voltage determined by the variable resistor VRz is applied to the non-inverting input terminal of the operational amplifier IC2. The output of the operational amplifier IC2 is applied to the common terminal of the three-terminal regulator ICz, and is also applied to its own inverting input terminal (Iit).

will be returned. Furthermore, the input terminal of the three-terminal regulator lc1 is grounded via the capacitor C1, and the output terminal is connected to the resistor R.
1. It is grounded to the variable resistor VR1 via a capacitor Cj in Mε series, and a diode lJ1 is connected between the input terminal and the output terminal.
It has been bino(s)ed in the opposite direction by

Here, the resistance values divided by the variable resistor VItx and the resistor 1 (1) are defined as (rx, rz) as shown in the figure, and the difference between the output of the operational amplifier IC2 (common input of the 3-terminal regulator ICz) and the output VouL of the 3-terminal regulator ICt is V
When x, Vout=(1+r2/r1)Vx. Therefore, by adjusting the variable resistor VRI, the output voltage %1out of the light source voltage variable circuit 11 can be adjusted.

Terminal ^-3 ゛L'? (92% reduction) Lamp L
['4 lights up and terminals A-2 and ^-3 are connected. 1. T.I.
(87% reduction) Lamp LP3.4 lights up, and when terminals ^-1, A-2, A-3 are set to 11 L I+ (
71% reduction) All lamps LPI to LP4 are lit. Incidentally, since VouL is constant regardless of the number of lamps lit, the amount of light does not change due to a change in the reduction ratio, which does not cause erase defects.

FIG. 5 is a circuit diagram of an erase lamp lighting circuit according to another embodiment of the present invention. Light emitting diodes L[ED1 to LIEl14 are used in place of the lamps LPI to LP4 in FIG. 4. The output voltage Vout of the light source voltage variable circuit 11 is applied to the anode of LIEDI-LHo4 through resistors no1 to +104, respectively, and the cathode is grounded through transistors TRIZ, TR3, and TR4, respectively. Note that the transistor Tll+2
'.

The ON/OFF switching of Tll:l-TR4 is performed by signals from a control circuit (not shown) provided through terminals n-1, B-2, and B-3, respectively. That is, when terminal It-3 is at I''' (92% reduction), LHo4 lights up, and terminals +3-2 and low 3 are at 'II'.
'' (87% reduction), LHo3, 4 lights up, and when terminals B-1, l5-2.B-3 are 1'' (71%
% reduction), LHo 1 to 4 all light up.

Note that the variable resistance for electrical adjustment is preferably provided as a volume with a knob at a location where it can be easily adjusted for convenience during manufacturing adjustment and service inspection.

As described in Section 2, this invention is equipped with means that can vary and adjust the light intensity of the erase light source, so even when making a reduced copy, the erase area on the photoconductor other than the image area can be erased without excess or deficiency. Unwanted images can be reliably erased by irradiating light. In addition, it is easy to adjust the amount of erase light during manufacturing adjustment (especially easy compared to the prior art, which adjusts by adjusting the distance between the light source and the photoreceptor).

Furthermore, even if the required amount of erase light changes over time in the market, it can be easily adjusted at the time of service or the like.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of the area around the photoconductor of a conventional copying machine, Figure 2 is an explanatory diagram of the relationship between the photoconductor and erase lamp of a conventional copying machine with a reduction/magnification function, and Figure 3 is similar to that of Figure 2. FIG. 4 is a circuit diagram of an erase lamp lighting circuit according to one embodiment of the present invention, and FIG. 5 is a circuit diagram of an erase lamp lighting circuit according to another embodiment. 1... Photoreceptor (image carrier), 4... Erase lamp (light source), 11... Light source voltage variable circuit (variable/adjustable means).

Claims (1)

[Scope of Claims] An erase device for a copying machine having a reduction/magnification function configured to irradiate light emitted from a light source onto a portion outside the reduced image area on an image carrier to erase unnecessary images, comprising: 1. An erase device for a copying machine, characterized in that the light source has variable light intensity/iiJ control means.