JPS627262A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To always correspond an exposure timing signal to the specified position of an image supporting body even when the rotational speed of the supporting body varies by providing plural signal exposing means, rotational phase detecting means, and delaying means. CONSTITUTION:An exposure controller 5 consists of rotary phase counters 7-10, delay counters 11-13, FFs 14 and 15, and gate circuits 16 and 17. The output rotary phase signal from the rotary phase detector 2 is first inputted to the counters 7 and 8. The said input signal then goes through the counter 11 and the FF 14 and is outputted from the gate circuit 16. The said signal is inputted to the circuit 16 together with the exposure data for the first exposing means 3 from an exposure data memory 18 so that the first exposure signal is obtained. Then, the output from the counter 2 is inputted to the counters 9 and 10, so that the second exposure signal is obtained from the circuit 17 via the counters 12 and 13, the FF 15, and the exposure data of the second exposing means 4 from the memory 18. By matching the starting and ending timings of exposure in such way as the above, the exposure timing signal can be corresponded to the specified position on the image supporting body.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic apparatus that exposes an image carrier such as a photoreceptor drum to light using a plurality of signal exposure means.

2. Description of the Related Art A conventional electrophotographic apparatus for setting the exposure start and end timings of a plurality of exposure means is disclosed in, for example, Japanese Patent Laid-Open No. 58-9763.

FIG. 4 is a block diagram of an exposure timing signal generation circuit of this conventional electrophotographic apparatus, and FIG. 5 is a signal waveform diagram of each part. A plurality of timing signals are generated based on FIGS. 4 and 6.

To explain in detail, the output of the beam detector 19 is transferred to the amplifier 2.
The output is amplified by a slicer 22 whose slice level is determined by a potentiometer 21.

When this output is used as the clear signal of the counter 23, the count operation is performed only during the period when the clear signal is "H level".The counter 23 counts the clock of the crystal oscillation circuit 24; The frequency is higher than the image recording clock of the recording device.

The timing signal 1 shown in FIG.
Made in 5. The output of the slicer 22 (Fig. 5b) is “H”.
"When the level is reached, the output of the flip-flop 26 becomes H"
At the same time, the counter 23 starts counting. The output of the counter 23 is a multi-bit parallel output, and the output is input to the comparators 26-32.

The comparison inputs of the comparators 26 to 32 are preset by the switch group 33. For example, the numerical value M is set to the comparator 2.
6, N1 is input to the comparator 27, N1+M is input to the comparator 28, and so on as shown in the figure. When such a preset value and the output of the counter 23 match, the comparator output becomes 1H'' level and inverts the shift flip-flop.

When the timing signal is 1 (FIG. 6a), the counter 23 counts the numerical value M, and when the comparator 26 outputs a matching output, the flip-flop 26 is reset, and as a result, the timing shown in FIG. 6C occurs. Signal 1 is output.

In the case of timing signal 2, the counter 23 has a value N1
By counting, a coincidence output is derived from the comparator 27 and the flip-flop 34 is set, and by the counter 24 counting the number N1+M, a coincidence output is derived from the comparator 28 and the flip-flop 34 is set. After resetting, an output as shown in FIG. 6d is derived.

Thereafter, timing signals 3 and 4 (FIG. 5e and f) are derived from the flip-flops 35 and 36 in the same manner. The exposure means is controlled by these timing signals 1 to 4.

Problems to be Solved by the Invention◆ However, in the above configuration, the beam detector 19
Since the exposure timing signal is generated by counting the time from this point based on the timing at which the beam is incident on the There was a problem with exposure.

In order to eliminate such problems, the present invention aims to maintain the exposure timing signal and the
The relationship with the rotational phase of the image carrier does not change, and the exposure timing signal always corresponds to a predetermined position on the image carrier.
The purpose is to provide an electrophotographic device.

Means for Solving the Problems The present invention provides an image carrier, a plurality of signal exposure means for exposing the image carrier, a detection means for detecting the rotational phase of the image carrier, and this detection means. and a time delay means for delaying the output of the signal exposure means, and the exposure start and end timings of the signal exposure means are set using the output of the rotational phase detection means and the output of the time delay means. It is a device.

According to the present invention, even when there is a variation in the rotational speed of the image carrier, the exposure timing signal can be generated corresponding to a predetermined position on the image carrier.

Embodiment FIG. 1 shows a configuration diagram of an electrophotographic apparatus in an embodiment of the present invention. In FIG. 1, 1 is a photoreceptor drum, 2 is a rotational phase detector of the photoreceptor drum, 3 is a first signal exposure means located at the position where exposure should first be started, and 4 is a second signal exposure means. , 5 is a control device for driving the signal exposure means. FIG. 2 shows a block diagram of the control device 5, and FIG. 3 shows a timing diagram, and the operation of this embodiment will be described below.

First rotational phase counter 7, second rotational phase counter 8
, third rotational phase counter 9, fourth rotational phase counter 10, first delay counter 11, second delay counter 1
The second and third delay counters 13 receive clock inputs No, N1 . N2. N3°Ml, N2. It is assumed that the setting is such that the output changes after counting M3 times (N□<N1 tN2 - N3).

First, the first rotational phase counter 7 is connected to the rotational phase detector 2.
When the output (Q2) is counted N0 times, the output changes and the output of the first 7 lip-flop 14 is preset (Q3). Next, the output of the second rotational phase detector 8 changes when the output (Q2) of the rotational phase detector 2 is counted N1 times. At this point, the first delay counter 11 is cleared and starts counting the reference delay clock (Ql). The output of the first delay counter 11 changes when the reference delay clock is counted N1 times (Q7), and the output of the first 7-lip-flop 14 is cleared. As a result, the output of the first flip-flop 14 changes at the timing shown in Q3. By inputting this output and the exposure data of the q-first exposure means 3 from the data memory 18 to the gate circuit 16, the first exposure signal can be obtained.

Similarly, the output of the third rotational phase counter 9 changes when the output (Q2) of the rotational phase detector 2 is counted N2 times. From this point on, the second delay counter 12 counts the delayed reference clock (Ql), and when it counts N2 times, the output changes (Q6) and presets the output of the second 7-lip-flop 15 (Q4). ). Furthermore, the output of the fourth rotational phase counter 10 and the rotational phase detector 2 (
The output changes when Q2) is counted N3 times. From this point on, the third delay counter 13 counts the delayed reference clock (Ql), and when it counts N3 times, the output changes (Q8) and clears the output of the second flip-flop 15. As a result, the output of the second 7-lip-flop 15 changes at the timing indicated by Q4. By inputting this output and the exposure data of the second exposure means 4 from the data memory 18 to the gate circuit 17, a second exposure signal can be obtained.

As described above, according to this embodiment, since the rotational phase counter roughly matches the exposure start and end timings, even if there is a fluctuation in the rotational speed of the photoreceptor drum, one cycle of the rotational phase signal It is impossible for the timing to be more than that. Also, by counting the reference delay signal,
Since the timing is finely adjusted, the higher the frequency of the delayed reference signal is, the more precisely the predetermined exposure timing can be set while the photosensitive drum is rotating at a predetermined rotational speed.

In this embodiment, a delay counter for counting the delayed reference signal is used as the time delay means, but it goes without saying that other signal delay means such as one-shimmit multi can also be used.

Furthermore, considering the case where there is no delay time as a special case of this embodiment, since the exposure timing signal matches the rotational phase signal, it is possible to generate the exposure timing signal by completely following the rotational fluctuation.

As described in detail, according to the present invention, even if the rotational speed of the image carrier varies, the start and end timings of exposure for the image on the image carrier can be determined by one rotational phase detection means. It never deviates by more than a cycle. Additionally, when rotating at a predetermined speed, the predetermined exposure start and end timings can be set with extremely high precision.
Its practical effects are great.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an electrophotographic apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram for explaining a part of the embodiment, and FIG. 3 is a waveform diagram showing the timing of each part in FIG. 2. , FIG. 4 is a block diagram of a conventional timing signal generation circuit, and FIG. 5 is a waveform diagram of each part of FIG. 4. 1... Photosensitive drum, 2... Rotation phase detector, 3.4... Signal exposure means, 5...
...Exposure control device, 6...Delay reference clock. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
--Kankyo Drum 2- [Phase] - Biting Headgear 3--One Rod + Biting Figure 2 Figure 30 1'lJ Figure 4 Figure 5

Claims (1)

[Claims] An image carrier, a plurality of signal exposure means for exposing the image carrier, a detection means for detecting the rotational phase of the image carrier, and a time delay means for delaying the output of the detection means, An electrophotographic apparatus characterized in that exposure start timing and exposure end timing of the signal exposure means are set using an output of the detection means and an output of the time delay means.