JPS6358356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying machine that can always form a desired margin at the leading edge of a sheet on which an image is copied.

In general, for electronic copying machines, for example, protection of the fixing device (heat roller), ease of paper separation from the photoreceptor drum, clarity of copied images, and elimination of shadows from the conveyance system when using an automatic document feeder, etc. In consideration of this point, many printers are designed so that a margin can be formed at the leading edge of the paper on which the image is copied. Conventionally, as a means to set this margin area, for example, white paint is applied to the area corresponding to the margin area at the leading edge of the paper on the surface of a transparent glass installed on the document table, and that area is exposed to light. There is also one that forcibly turns white. However, although such mechanical means are inexpensive, it takes time to adjust the margins accurately when installing the glass on the document table, and furthermore, it takes time for subsequent transportation and copying operations. It has the disadvantage that it is easily misaligned, and is not very practical.

The present invention has been made in view of the above circumstances, and an object of the present invention is to set the margin at the leading edge of the paper by electrically setting the margin. It is an object of the present invention to provide a copying machine that can perform the adjustment in a very short time, is easy to adjust, is less likely to be misaligned in the margin area, and can always form a desired margin area.

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

FIG. 1 schematically shows an electronic copying machine according to the present invention. That is, the document placed on the document table 1 is irradiated with light from the exposure lamp 3, which is reciprocated in the direction of the arrow shown by the camshaft 2, and the reflected light is reflected by the exposure lamp 3, which is reciprocated in the direction of the arrow shown in the figure. The light is guided through a lens 4 to a mirror 5, where it is reflected and reaches a photoreceptor drum 6, where an image of the document is formed on the surface of the photoreceptor drum 6 (slit exposure). The photosensitive drum 6 rotates in the direction of the arrow shown in the figure, and the surface is first uniformly charged by a charging device 7, and then the image of the document is exposed to slit light to form an electrostatic latent image. Ru. This electrostatic latent image is made visible by applying toner by the developing device 8.

On the other hand, the paper P is taken out from the paper feed cassette 9 by the paper feed roller 10 and is transferred to the aligning roller 1.
1 to the transfer section. The paper P sent to the transfer section comes into close contact with the photoreceptor drum 6 at the transfer charger 12, so that the toner image on the photoreceptor drum 6 is transferred by the action of the charger 12.
After the transfer, the paper P is peeled off from the surface of the photosensitive drum 6 by the peeling charger 13 and the peeling roller 14, and guided to the heat roller 15 as a fixing device, where the transferred image is fixed. be done. Then, the paper P after fixing is discharged to the paper discharge section 17 by the paper discharge roller 16. On the other hand, after the transfer, the photosensitive drum 6 is reversely charged by a charger 18 for neutralization, and then residual toner is removed by a cleaner 19 to return to the initial state. Note that the timing of these series of operations is controlled by a control circuit (not shown).

FIG. 2 shows a delay circuit according to the present invention, which is provided in the control signal system of the charger 7. That is, 21 is an input buffer amplifier for making the input signal resistant to noise and sharpening the rise characteristic, and the input terminal of this amplifier 21 receives a charger control signal (drive signal) output from a control circuit (not shown). Supplied. The output signal of the amplifier 21 is transmitted to a CR integrator circuit 2 consisting of a series circuit of a resistor 22 and a variable resistor 23 and a capacitor 24.
5. In this CR integration circuit 25,
A series circuit of the diode 26 and the resistor 27 constitutes a discharge circuit for the capacitor 24. The output signal of the CR integration circuit 25 is supplied to an output buffer amplifier 29 via a resistor 28. this amp 2
9 is for making the output signal resistant to noise and sharpening the rise characteristic. The output signal of the amplifier 29 is supplied to a drive circuit 30 that drives the charger 7.

When the charger drive signal is supplied to the amplifier 21, it is delayed for a predetermined time by the action of the CR integration circuit 25, and then outputted from the amplifier 29, and then supplied to the drive circuit 30, so that the charger 7 is activated. It will start working. Here, the above delay time is calculated by setting the resistance values of the resistor 22 and variable resistor 23 respectively
1, R2, and the capacitance of the capacitor 24 is C, it is determined by [(R1+R2)×C]. This delay time becomes the margin at the leading edge of the paper described above, and is set by varying the variable resistor 23 to change its resistance value R2. In other words, when there is little margin at the leading edge of the paper, the charger 7
Since the charging start time is too early, the charging start time is delayed by increasing the resistance value R2 and lengthening the delay time. Conversely, when there is a large margin at the leading edge of the paper, the charging start time by the charger 7 is delayed. Since the time is too slow, the charging start time can be made earlier by decreasing the resistance value R2 and shortening the delay time.

As described above, in this embodiment, a series of copying operations except for the operation of the charging device 7 are controlled as before, and a delay circuit that can change the delay time is newly provided in the control signal system of the charging device 7. A blank space at the leading edge of the paper is formed by electrically delaying the charging start time of the paper. With such a means, the margin to be formed at the leading edge of the paper can be set in a very short time and adjustment is also easy. Moreover, the margin adjuster (variable resistor 23) can be installed on the printed circuit board of the control circuit, etc. Since it can be incorporated, the desired margin area can always be formed without any displacement of the margin area during copying operations or during transportation of the machine.

In the above embodiment, a CR integrator circuit was used as the delay circuit due to its simple configuration and the ability to easily adjust the delay time, but similar effects can be obtained by using other delay circuits. Of course.

As detailed above, according to the present invention, a delay circuit capable of varying the delay time is provided in the control signal system of the charger that charges the photoreceptor, and the charging start time by the charger is arbitrarily delayed. By doing so,
Since the margins formed at the leading edge of the paper can be set electrically, the margins can be set in a very short time and can be easily adjusted, making it difficult for the margins to be misaligned and always ensuring the desired margins. It is possible to provide a copying machine that can form blank spaces.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view schematically showing the configuration of an electronic copying machine, and FIG.
The figure is a configuration diagram of a delay circuit. 1... Original table, 3... Exposure lamp, 6... Photoconductor drum (photoconductor), 7... Charger for charging, 8
...Developer, 9...Paper cassette, P...Paper,
15...Heat roller (fixing device).

Claims (1)

[Scope of Claims] 1. A moving photoreceptor is charged by a charger, and this charged portion is exposed to image light to form a latent image. This latent image is developed to make it visible, and this is transferred to a sheet of paper. In a copying machine configured to obtain a copy by transferring data to the charger, a delay circuit whose delay time can be arbitrarily set is provided in the control signal system of the charger, and by this delay circuit, the control signal system By delaying the drive signal of the charger supplied to the charger and controlling the start time of charging the photoconductor of the charger, a margin corresponding to the delay time of the delay circuit is formed at the leading edge of the paper. A copying machine characterized by forming.