JPS6048658A - Print control method - Google Patents

Abstract

PURPOSE:To decrease the fault of a printer by stopping printing when the turning speed of a rotary polygon mirror scanning light on a photosensitive drum exceeds a specified value, and restarting automatically the printing when the turning speed is restored to the prescribed value. CONSTITUTION:The rotary polygon mirror 3 scans a laser light beam from a laser light source 2 onto the photosensitive drum 1, a detector 8 supervises the turning speed of the polygon mirror 3 and gives its output signal to an amplifier 9. The amplifier 9 changes the output signal of the detector 8 to a logic signal and gives the signal to a timer 10 and a turning fault detection circuit 11. When the timer 10 receives a signal from the amplifier, the timer 10 feeds a reference synchronizing signal having a prescribed pulse width to the circuit 11. When the output period of the amplifier 9 exceeds a value set by the timer 10, the circuit 11 transmits a fault detection signal to a print control section 7. When the control section 7 receives the fault detection signal, the section 7 inhibits the paper feed of a print paper sheet 13 to which no transfer is started to prevent the transfer of printed matter where fluctuated character occurs. When the turning of the polygon mirror 3 is restored to a normal value, laser exposure is conducted from the head of the stopped page.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a printing apparatus having a polygon mirror that rotates at a constant speed, such as a laser beam printer using an electrophotographic method.

In a printing device that has a polygon mirror and a photosensitive drum that rotate at a constant speed, if the rotational speed of the polygon mirror deviates from synchronization, if the foreprinting operation is continued, the timing of the position at which light is irradiated onto the photosensitive drum may change. This may cause problems such as garbled characters or shaky characters.

Therefore, in order to prevent the print quality from deteriorating due to rotational fluctuations of the polygonal mirror, a printing control device has been devised that, when detecting rotational fluctuations of the polygonal mirror, treats it as an abnormal state and stops the printing device. There is.

However, in this conventional technique, when rotational fluctuations of the polygon mirror are detected and the printing apparatus is stopped, an operator's operation is required to restart the operation. Therefore, the printing apparatus is stopped even when the rotation of the polygon mirror is temporarily changed due to a momentary power interruption, noise, etc., which has the disadvantage of reducing the operating rate of the printing apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to reduce obstacles in a printing device.

In the present invention, most of the rotational fluctuations of the polygon mirror are due to temporary factors, and if these fluctuation factors disappear, the rotational speed will return to normal after a certain period of time, and the electrophotographic method is used. mark! In the 1:I device, we focused on the fact that there is a certain time delay between the exposure of the photosensitive drum and the actual printing on paper due to the development process, and detected the rotational fluctuation of the multi-sided boundary. In this case, printing is temporarily prohibited, the rotational speed of the polygon mirror is continuously detected, and when the rotational speed of the polygon mirror returns to normal, the printing operation is restarted.

An example in which the present invention is implemented in a cut paper printer will be described.

FIG. 1 shows a block diagram of an embodiment. In the figure, 1 is a photosensitive drum that rotates along the paper running direction, 2 is a laser light source for exposing the photosensitive drum 1, and 3 is a laser beam of the laser beam trace 2 that scans and stops on the photosensitive drum 1. a double polygon mirror; 4 a detector for detecting the instantaneous position of the laser beam reflected by the polygon mirror 3; 5 a mirror for reflecting the laser beam to the detector 4; 6;
8 is an amplifier that converts the output signal of the detector 4 into a logic signal; 7 is a print control unit that receives the signal from the amplifier 6 and controls the printing device; 8 is a detector that monitors the rotational speed of the polygon mirror 3; , 9 is an amplifier that converts the output signal of the detector 8 into a logic signal; 10 is a timer that receives the output signal of the amplifier 9 and generates a reference synchronization signal with a pulse width of 2t after a time (Tt); 11 is the amplifier 9 shows a rotational abnormality detection circuit that generates a rotational abnormality signal when the output cycle deviates from the value set by the timer 10.A laser beam is applied to a position on the photosensitive drum 1 where the multifaceted border 3 is located. If the laser beam is irradiated with the laser beam so as to be reflected, a latent image can be formed at any location on the photosensitive drum.

FIG. 2 shows a detailed view of the surroundings of the photosensitive drum 1.

In the figure, 12 is a developing device that applies toner to the latent image formed on the paper by the laser beam; 13 is printing paper;
14 is a paper feed roller that feeds the printing paper 13 at a speed equal to the circumferential speed of the photosensitive drum 1; 15 is the photosensitive drum 1;
A transfer device for transferring the toner adhered thereon to the printing paper 13 is shown. The latent image formed by the laser beam is developed and transferred by the developing device 12, and a certain printing operation is performed by the rotation of the photosensitive drum 10. FIG. 3 shows a timing chart showing the operation of the main side, and FIG. 4 shows a partially enlarged view.

Detection means 1, such as encoders, are provided at equal intervals on the multifaceted boundary 3 rotating at a constant speed.

Therefore, the output signal of the amplifier 9 is output by the timer 10 at a constant period T.
and is sent to the rotation abnormality detection circuit 11.

The timer 10 receives the output of the 4-amplifier 9 and outputs a pulse of 2 hours after T-.

Here, T is the output period of the amplifier 9 when the rotational speed of the multifaceted boundary 3 is normal, and t is the output period of the amplifier 9 when the rotation speed of the multifaceted boundary 3 is normal, and t is the output period of the amplifier 9 when the rotation speed of the multifaceted boundary 3 is normal, and t is the output period of the amplifier 9 to ensure that even if the period T fluctuates within the range of ±t, problems such as character shaking do not occur. This is the permissible variation time that is set in advance. That is, the output of the timer 10 becomes a reference synchronization signal.

After time T after the output of the amplifier 11WM unit 9 is generated, the next output of the amplifier 9 and the reference synchronization signal from the timer 10 are input to the rotation abnormality detection circuit 11. If the output of the amplifier 9 is HIGH when the output of the timer 10 is LOW, the rotational abnormality detection circuit 1 detects the rotational fluctuation of the multi-sided boundary 3 and makes the rotational abnormality signal HIGH. By the way, in the photosensitive drum 1, since the developing device 12 is interposed between the exposure position where the laser beam is irradiated and the transfer position, the circumferential length of the photosensitive drum in this period is longer than the assembly length. Therefore, when the rotational variation of the multifaceted border 3 occurs, the groove transfer has not started for the page that is being exposed at the time.

The print control unit 7 prohibits paper feeding of the printing paper 13 when the rotation abnormality signal reaches 1-1 i g even though the transfer has not yet started. That is, in FIG. 2, the KJ- (feeding) of the right-hand printing paper 13 in front of the paper feed roller 14 is prohibited. This prevents the transfer of print data that has caused shaky characters.

On the other hand, in the figure 81￥2, for the printing paper 13 on the left, which is already being transferred, the print data at the P end 1 of the page has finished exposure and is at l- before the rotation abnormality signal becomes HI g h. Subsequently, paper feed transfer is performed.

When the rotation returns to normal after that, the output of the rotation abnormality signal becomes LOW, and laser exposure is performed again from the top of the page where the rotation abnormality occurred. Also, printing paper 1. Paper feeding was prohibited. - Well, the print data newly exposed on the photosensitive drum 1 is picked up by IIl and paper feeding is resumed.

z) In the embodiment shown in FIG. 11, when the rotational fluctuation of the polygon mirror returns to normal and the blur occurs, the printing prefecture f horse continues at any time [-1]. Therefore, the following application example can be considered to improve this point. In addition to f710 in FIG. 1, a timer is provided to send out an output with a pulse width t'=axt (a'>l). The value of the pulse width at of this timer is set as the output fluctuation width of the detector 8 when the rotational force of the polygon mirror fluctuates to such an extent that it cannot return to normal.

The output of this timer and the output of the detector 8 are monitored, and if the rotational variation of the polygon mirror exceeds the range of T11, an error display can be made to notify the operator of an abnormality in the printing apparatus.

According to the present invention, since printing can be prohibited only while the rotational speed of the polygon mirror is changing, it is possible to set a strict range of rotation 1-11, and to improve the quality of marks 1-1. I can do it. Further, since no operator operation is required to restart printing, the profit i%;i'< is improved.

[Brief explanation of drawings]

Fig. 1 is a conversion diagram showing one embodiment of the present invention, and Fig. 2 is a conversion diagram showing an embodiment of the present invention.
It is a partially detailed schematic diagram of the figure. Third I? 4 is a timing chart showing the operation of an embodiment of the present invention. -), Figure 4 shows the 3rd
This is a partially enlarged version of the timing cheat tote. In the figure, 1 is a photosensitive drum, 2 is a laser light source, and 3 is a photosensitive drum.
is a polygon mirror, 4 is a detector, 5 is a mirror, 6 is an amplifier, 7 is a print control unit, 81 is a detector, 9 is an amplifier;), 10 is a timer, 11 is a rotation abnormality detection circuit, and J2 is a developing machine. , 13 is mark 1
．． i: t1 paper, 14 is a paper feed roller, and 15 is a transfer device. Name of patent applicant: Hitachi Koki Co., Ltd. 'A' 3 Round 4m 1 rμ−□□□□□□□□ −

Claims (1)

[Claims] The present invention includes a photosensitive drum that rotates in a paper running direction, a light source that exposes the photosensitive drum, and a rotating polygon mirror that scans the light from the light source on the photosensitive drum at a constant cycle, and the instantaneous position of the rotating polygon mirror is determined by the rotation polygon mirror. In a printing apparatus using an electrophotographic method that detects and forms an image on the photosensitive drum by appropriately irradiating the photosensitive drum with light from the light source, means for monitoring the rotational speed of the polygon mirror is provided. If the monitoring means detects that the rotation speed of the polygon mirror deviates from a specified value, printing is temporarily prohibited, and when the rotation speed of the polygon mirror returns to the specified value, printing is prohibited. A printing control method characterized by automatically restarting.