JPH0416870A - Laser recording device - Google Patents

Abstract

PURPOSE:To prevent the device from breading by providing a detecting means which detects abnormality of a 1st control means for controlling a driving signal and a 2nd control means which cuts off the driving signal according to the abnormality signal from the detecting means. CONSTITUTION:The device is provided with the detecting means 27 which detects the abnormality of the 1st control means 6 for controlling the driving signal and the 2nd control means 27 which cuts off the driving signal according to the abnormality signal from the detecting means 7. Then, when a printer can not be controlled normally owing to abnormality of a control means 3 or 6, at least the light emission of a laser light emitting means 17 is stopped or the control means 3 and 6 are reset. Consequently, the device is prevented from breaking and there is no danger to an operator.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser recording apparatus that forms an image by irradiating a recording medium with a laser beam.

2. Description of the Related Art In recent years, a recording apparatus has been proposed which records a desired image by modulating a laser beam with an image signal and irradiating the modulated laser beam onto a recording medium.

This type of recording device generally has a light emitting means that emits a laser beam, an optical system such as a reflecting mirror or a lens, controlled elements such as a drive system, and a control means including a microcomputer, and is controlled by the control means. A desired image is obtained by causing the controlled element to perform a predetermined operation at a predetermined timing under the means.

Problems to be Solved by the Invention Incidentally, microcomputers sometimes malfunction due to noise such as electromagnetic waves. When an abnormality occurs in the control means of a recording apparatus having a laser emitting means, there is a risk that, for example, a photoreceptor may be damaged by the laser beam emitted from the out-of-control light emitting means.

Furthermore, in order to reset the malfunctioning microcomputer and return it to normal operation, the operator had to open the cover of the device and manually operate the microcomputer's reset switch. At this time, there is a risk that the laser beam emitted from the out-of-control light emitting means may pose a danger to the operator.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a laser recording device that can prevent damage to the device when an abnormality occurs in the control means. A further object of the present invention is to provide a laser recording device in which the control means can be reset without causing any harm to the operator.

Means for Solving the Problems In a laser recording device that records an image by irradiating a recording medium with a laser beam, the laser emitting means that emits the laser beam and the laser emitting means that can be driven when a drive signal is input, and the a laser driving means for driving the laser emitting means, a first control means for controlling the drive signal, a detection means for monitoring the first control means and detecting an abnormality in the first control means, and an abnormality from the detection means. It is characterized by having a second control means for cutting off the drive signal based on the signal.

Function According to the present invention, the detection for detecting an abnormality in the control means is turned off. At the same time, the control means is reset.

Embodiment FIG. 1 shows the overall configuration of a laser beam printer according to the present invention.

The printer main body 1 includes a paper feeding section, an image forming section, and an optical module.

The image forming section has a photoreceptor 11 in the center, and around the photoreceptor 11, a charging charger 12, a developing device 13, a transfer charger 14, a cleaning device 15, and an eraser 16 are arranged in this order.

The optical module 10 includes a laser diode 17 that emits laser light according to image information;
The photoreceptor includes a polygon mirror 21 that reflects the laser light emitted by the mirror and scans the photoreceptor.

The paper feed conveyance unit includes a paper feed cassette 22 in which a plurality of sheets of recording paper are stacked, and a paper feed roller 23 that sends out the stacked recording papers.
A pair of conveyance rollers 25 for conveying the paper sent out from the paper feed cassette 22, and a timing roller 24 for determining the timing for conveying the recording paper to the transfer nacarrier 14 are provided. Further, the paper feed conveyance section includes a heat fixing roller 18 that fixes the transferred image on the recording paper, and a paper discharge roller 19 that discharges the recording paper to the paper discharge tray 20.

In the above configuration, the laser emitted from the laser diode 17 scans the photoreceptor II by the polygon mirror 21 and forms an electrostatic latent image on the photoreceptor 11. The electrostatic latent image formed on the photoreceptor is developed by a developing device 13 . The formed image is transferred by the transfer unit 14 onto the recording paper sent out from the paper feed roller 21, and fixed onto the recording paper by the heat fixing roller 18. Then, the fixed recording paper is ejected, and the printing operation ends.

FIG. 2 shows a block diagram of the main control section of the laser beam printer.

The CPL 13 is a controlled element related to image formation in a laser beam printer, such as a laser diode 17.
, the paper feed roller 23, the photoreceptor 11, etc., via the address bus 4 and the data bus 5, and each of the controlled elements, the image signal controller 30, and the host computer 2.
and inputting information. In addition, CPU3 has a CPU
A reset means 26 for resetting the 3 is connected.

The I10 circuit 6 is connected to the CPU 3 via an address bus 4 and a data bus 5. Further, it is connected to an LD drive circuit 27 via an AND circuit 8, and also connected to an abnormality detection means 7 and a reset means 26. I10
The circuit 6 outputs the output capacitor (LD) according to the command from the CPU 3.
outputs an LD drive signal S to the LD drive circuit 27, and also outputs + as a state signal of a predetermined period to the abnormality detection means 7 from the output port TIM.

Both the LD drive signal S1 generated from the output port LD of the I10 circuit 6 and the detection signal output from the output terminal of the abnormality detection means 7 are input to the AND circuit 8. The output terminal of the AND circuit 8 is connected to the LD drive circuit 27. The LD drive signal Sl is a binary signal, and when the LD drive circuit 27 enables the laser diode 17 to emit light, it is a High level signal (hereinafter referred to as Hi level). When the LD drive circuit 27 is deactivated so as to prevent the diode 17 from emitting light, the signal is at a low level (hereinafter referred to as Lo level).

FIG. 3 shows the oscillation command signal sent from the CPU 3 and the I
10 shows the relationship between the status signal outputted from the output port TIM of the circuit 6 to the abnormality detection means 7. When the CPU 3 is operating normally, in response to an oscillation command signal output at a constant period T, the I10 circuit 6 outputs a pulse with a constant width P from the output port T1M on the status signal Kt.

The abnormality detection means 7 outputs 2 as a Hi level detection signal when the CPU 3 is operating normally, that is, when the CPU 3 is sending out an oscillation command at a constant cycle T.

Therefore, if the CPU 3 is operating normally, the LD drive signal S1 output from the output port LD and the AND circuit 8
This is equivalent to the drive signal S output from the drive signal S. On the other hand, when the abnormality detection means 7 detects that the CPU 3 is not operating normally, the detection signal output from the abnormality detection means 7 becomes LO level. When a LO level signal is input to the AND circuit 8, a Hi level signal is not outputted from the AND circuit 8.

Further, the detection signal is input to the NOR circuit 9 constituting the reset means 26. N.

A signal from the RESET switch is input to the other input terminal of the R circuit 9. The signal R1 input from the RESET switch is normally a Hi level signal, and the RES
When the ET switch is operated, the signal becomes Lo level. The output terminal of the NOR circuit 9 is a RESET terminal of the CPU 3 and the I10 circuit 6, and the CPU 3 and the I10 circuit 6 are respectively reset. When at least one of the detection signal and the signal R1 from the RESET switch becomes Lo level, that is, when an abnormality in the CPU 3 is detected or when the RESET switch is turned on, the output from the NOR circuit 9 changes to Lo level, CPU3 and summer 1
Each of the 0 circuits 6 is reset.

The image signal control unit 30 has an address bus 4 and a data bus 5.
It is connected to the host computer 2 and the CPU 3 via the host computer 2, and sends an image signal to the LD drive circuit 27 based on the image information sent from the host computer 2.

The LD drive circuit 27 is enabled to be driven by the LD drive signal S, and changes the drive current of the laser diode 17 according to image information input from the image signal control section 30. Further, the LD drive circuit 27 includes the image signal control section 3
Even when no image signal is input from 0, if the LD drive signal Sl is at Hi level, a preliminary current is sent to the laser diode 17. This is to enable the laser diode to emit light and create an image immediately when an image signal is input. The preliminary current is sent out when the drive signal S output from the AND circuit 8 is at Hi level and the LD drive circuit 27 is in a drivable state.
When is at Lo level, the LD drive circuit 27 is inactive and no signal is sent out.

That is, the operation of the LD drive circuit 27 is controlled by switching the Hi/Lo level of the drive signal S, and furthermore, whether or not current is sent to the laser diode 17 is controlled. Therefore, t: Even if image information is input to the LD drive circuit 27 from the image signal control section, the drive signal S.

When is Lo, the laser diode 17 does not emit light.

FIG. 4 is a diagram showing the principle of the abnormality detection means 7. This circuit consists of a differentiating circuit made up of a capacitor 〇 and a resistor R, and a comparator circuit F.

FIGS. 5(a) and 5(b) show the IN of the abnormality detection circuit 7.
This is a time chart showing the relationship between the input to the PUT terminal, the output appearing at the output point a of the differentiating circuit (see FIG. 4), and the output from the 0UTPUT terminal.

FIG. 5(a) shows the case where one pulse is input to the INPUT terminal. The output voltage at the output point a of the differentiating circuit undergoes a predetermined attenuation change due to the time constant of the capacitor C and the resistor R.

The voltage Vs indicated by the broken line in the figure is the threshold of the comparator circuit F, and the voltage at the output point a of the differentiator circuit is the threshold Vs.
When it is higher, a Hi level signal is output from the 0UTPUT terminal.

As mentioned above, FIG. 5(b) shows that an oscillation command is sent from the CPU 3 to the 110 circuit 6 at a constant period T, and the INPU
This is a time chart when a pulse with a constant period T is input to the T terminal. The period T4+ means that the voltage at the output point a of the differentiator circuit is equal to the threshold value V of the comparator circuit F.
It is a value that does not cut s. INP at the period T mentioned above.
Since pulses are input one after another from the UT terminal, 0UTP
The output from the UT terminal will remain at Hi level.

The attenuation time at the output point a of the differentiating circuit is determined by the values of the capacitor C and the resistor R.

As described above, the abnormality detection means 7 outputs a Hi-level detection signal while the CPU 3 sends a pulse oscillation command to the 110 circuit 6 at a constant period T. On the other hand, C.P.
When an abnormality occurs in U3, a constant period T is applied to the 110 circuit 6.
, the oscillation command signal cannot be sent, and the abnormality detection means 7 becomes 0.
The output of the UTPUT terminal changes to Lo level. Therefore, when the output from the abnormality detection means 7 changes to the LO level, the CPU 3, which is the control means for the laser diode 17, determines that an abnormality has occurred.

In the above configuration, when the CPU 3 is operating normally, the drive signal S input to the LD drive circuit 27 is
2 is a Hi level. At this time, the LD drive circuit 27 becomes operational, sends out a preliminary current even when no image signal is present, and immediately responds when an image signal is input from the image signal control section 30 to drive the laser diode 17.
to emit light.

On the other hand, when an abnormality occurs in CPLJ3, the drive signal S,
changes to Lo level, the LD drive circuit 27 becomes inactive, and even if an image signal is input, the laser diode 17 stops emitting light, and the preliminary current sent to the laser diode is stopped. Sending is also stopped. Furthermore, when an abnormality is detected, the CPU 3 is also reset at the same time.

Therefore, in the present invention, when an abnormality occurs in the control means, the image signal is not stopped, but the current of the laser die is flowing, and it is not enough to stop the image signal, but the driving means of the laser diode is stopped, This is to ensure that the laser diode 17 stops emitting light.

Effects of the Invention According to the present invention, when the printer cannot be controlled normally due to an abnormality in the control means, damage to the apparatus can be prevented by at least preventing the laser emission means from emitting light or resetting the control means. In addition to preventing
It poses no danger to the operator and is extremely useful in practice.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view showing the configuration of the laser beam printer, Figure 2 is a block diagram of the main parts centering on the control means, and Figure 3 is the relationship between the output of the control means and the output from the 1/ and 0 ports. FIG. 4 is a circuit diagram showing the principle of the abnormality detection means, and FIGS. 5(a) and 5(b) are time charts showing the relationship between the pulse input to the abnormality detection means and its output. 1: Printer body, 3: CPU. 6: 110 circuit, 7: Abnormality detection means. 10: Optical module. Applicant: Minolta Camera Co., Ltd. No. 2 Draft amendment 1, Indication of the case 1990 Patent M No. 121798 2, Name of the invention Laser recording i device 3, Person making the amendment Relationship to the case Applicant address Osaka 2-3-13 Azuchi-cho, Chuo-ku, Osaka Kokusai Building Name (607) Minolta Camera Co., Ltd. 5. Insert the column for the statement subject to amendment.

Claims (2)

[Claims] (1) In a laser recording device that forms an image by irradiating a recording medium with a laser beam, there is provided a laser emitting means that emits the laser beam, and a laser emitting means that can be driven when a drive signal is input, and that operates the laser emitting means in accordance with image information. a laser drive means for driving; a first control means for controlling the drive signal; a detection means for monitoring the first control means and detecting an abnormality in the first control means; and based on an abnormality signal from the detection means. A laser recording apparatus comprising: second control means for cutting off the drive signal. (2) Based on the abnormality detection signal from the detection means, the first
A laser recording device characterized by having a third control means for resetting the control means.