JPS63300212A - Optical scanning type image forming device - Google Patents

Abstract

PURPOSE:To apply constitution for detecting the oscillation abnormality of a light beam to the detection of an illumination/nonillumination state by outputting an operation instruction for oscillation abnormality detection except in recording operation. CONSTITUTION:An oscillation abnormality detection control circuit 11 outputs the operation instruction for actuating an oscillation means OM forcibly for oscillation abnormality detection to a laser driving device 2 which constitutes an oscillation means OM until the rotating speed of a polygon mirror 5 reaches a stationary rotating speed for scanning according to an output pulse signal from an optical encoder 12 after a main switch is turned off. An abnormality detecting circuit 10 judges the oscillation abnormality of nonillumination and outputs a nonillumination abnormality detection signal LES to a host computer HC with the operation instruction unless another synchronizing signal SOS is inputted within a specific time after the input of a precedent synchronizing signal SOS.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is applicable to, for example, laser beam printers and laser C0
An optical scanning image forming apparatus such as the M system, more specifically, an oscillation device that modulates and oscillates a light beam, and a rotating optical deflector that reflects and deflects the incoming light beam for scanning. a scanning imaging optical system that forms an image on the photoreceptor; a light output control light receiving section that receives the light beam and outputs an electrical signal; and a light output control light receiving section that receives the light beam and outputs an electrical signal; The present invention relates to an optical scanning image forming apparatus including an abnormality detection means for detecting the presence or absence of abnormality in oscillation of a light beam.

[Conventional technology]

In the above-mentioned optical scanning image forming apparatus, conventionally, when recording by scanning a light beam, an electric signal from a light receiving section for controlling light output provided to align the recording start position on the photoreceptor for each scan is used. , by utilizing the fact that it is output at regular intervals in response to the rotation of the rotary optical deflector at a steady rotation speed for scanning, this electrical signal is output at a certain timing and then a predetermined period of time elapses. is configured to determine that an abnormality has occurred in the oscillation of the light beam from the oscillation means when the next electric signal is not output, and the detection of the abnormality in the oscillation of the light beam can be performed at low cost using the originally provided configuration. A method has been proposed that allows this to be carried out advantageously (for example, see Japanese Patent Laid-Open No. 51-93219).

[Problem that the invention seeks to solve]

However, the conventional configuration described above has the following problems.

In other words, the above-mentioned light output control light receiving section oscillates the modulated light beam from the oscillation means in order to start recording on the photoreceptor after a predetermined period of time from when the scanned light beam is received by the light receiving section. The light beam is normally configured to initiate the light beam whenever it is in a rotational phase in which the reflective surface of the rotary deflector reflects the light beam to the receiver for controlling the light output. Because it was in an oscillating state,
Oscillation abnormality in which the light beam does not oscillate when it should.
In other words, although it is possible to detect unlit lights, on the other hand,
It has not been possible to detect an oscillation abnormality in which the light beam is oscillating when it should not be oscillating, that is, an unextinguished light.

In view of the above circumstances, it is an object of the present invention to provide a configuration for detecting abnormal oscillation of a light beam that can detect not only unlit lights but also unlit lights.

[Means for solving problems]

A characteristic configuration of the optical scanning image forming apparatus according to the present invention is that an oscillation abnormality is outputted to the oscillation means for detecting an oscillation abnormality when the rotary optical deflector is rotating and other than during a recording operation based on image information. The reason is that a detection control means is provided.

[For production]

In other words, while the rotary optical deflector is rotating, recording using a light beam is not performed until the recording operation corresponding to, for example, one page of recording paper is completed and the next recording operation is started. Since there is no need to use the output signal from the light receiving section for controlling optical output to align the recording start position on the photoreceptor or to stabilize the output of the optical beam during recording, there is no need to use the rotary optical deflector. When the reflecting surface is in a rotational phase to reflect the light beam so as to reach the light receiving section for controlling light output, the light beam can be oscillated or not oscillated as desired.

Therefore, during that time, the oscillation abnormality detection control means outputs an operation command to the oscillation means to oscillate a light beam, so that the oscillation abnormality of the unlit light is detected by not outputting the electric signal from the light receiving section for controlling the light output. can be detected,
Meanwhile, the oscillation abnormality detection control means outputs an operation command to the oscillation means to stop the oscillation of the light beam, thereby outputting an electric signal from the light receiving section for controlling the light output, thereby causing the unlit light to be turned off. oscillation abnormalities can be detected.

〔Example〕

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic configuration of a laser beam printer which is an example of an optical scanning image forming apparatus according to the present invention.

The image information to be recorded is stored in the host computer (IIc).
is read out from the image memory (1a) in the image control circuit (1) and input to the laser driving device (2). The laser drive device (2) applies an excitation current [1e] based on this image information to the laser head (
Output to the semiconductor laser (3a) in 3). A laser beam (B) directly modulated by this excitation current [1e] is oscillated from the semiconductor laser (3a).

That is, a laser head (3) having a semiconductor laser (3a)
) and a laser drive device (2), an oscillation means (O
M).

The laser beam (B) from this oscillation means (OM) is made into parallel light by a collimator lens (4), and is reflected by a reflective surface (5a) with a polygon mirror (5) rotating at high speed. The laser beam (B) after reflection is passed through an fθ lens (
6), the image is formed on a photoreceptor drum (7) whose surface is uniformly charged, and the charged potential at the imaging position is attenuated according to the intensity.

By rotating this polygon mirror (5), which is an example of a rotating optical polarizer, the inclination of each reflecting surface (5a) with respect to the laser beam (B) that enters as parallel light changes.

Thereby, the traveling direction of the reflected laser beam (B) is deflected and scanned in the longitudinal direction of the photoreceptor drum (7) (this direction is the main scanning direction).

Namely, collimator lens (4), polygon mirror 5)
, an fθ lens (6), and the like constitute a scanning imaging optical system (IF).

On the other hand, the photoconductor drum (7), which is a cylindrical photoconductor, is configured to rotate at a constant speed in synchronization with the rotation of the polygon mirror (5) (this direction of rotation is the sub-scanning direction). .

Then, as the photoreceptor drum (7) rotates, the scanning of the laser beam (B) described above is repeated, thereby forming an electrostatic latent image on the photoreceptor drum (7) according to the image information. It is.

Thereafter, although not shown, toner, which is a colored pigment, is selectively attached to this electrostatic latent image and developed. Then, the output paper is brought into close contact with the toner adhesion surface to transfer the toner onto the paper surface. Furthermore, this toner is melted and fixed on the output paper by heating to obtain an output image.

Further, a photosensor (3) is provided on the upper scanning side than the photosensitive drum (7). This photosensor (8) outputs a photocurrent when scanned by the laser beam (B) after being reflected by the polygon mirror (5). This photocurrent is shaped by the waveform shaping circuit (9) and sent to the image control circuit (9) as a synchronization signal [SOS].
1) is input.

In response to this synchronization signal [SO2F, in the image control circuit (1), after a certain period of time counted by the built-in timer (lb), the scanned laser beam (B) moves to the position of the photosensor (8). From the photoreceptor drum (
After the time corresponding to reaching the recording start position in 7),
Reading of image information for one line from the built-in image memory (1a) is started. Then, the laser drive circuit (2) receives the image information read out from the image memory (1a), and starts outputting an excitation current [Ie] to the semiconductor laser (3a) based on the image information.

This synchronization signal [SO5F is used to align the starting position of the electrostatic latent image formed by repeated scanning of the laser beam (B) with respect to the rotational direction of the photoreceptor drum (7), that is, the sub-scanning direction. It is something.

In other words, there is some manufacturing error in the angle division accuracy of each reflective surface (5a) of the polygon mirror (5). Furthermore, there are uneven rotations of the polygon mirror (5) and vibrations associated with the rotation. Therefore, the scanning area of the laser beam (B) is not necessarily aligned in the sub-scanning direction, which causes a shift in recording.

Therefore, the laser beam (B
) is received as a reference, and by controlling the start of modulation of the laser beam (B) scanned on the photosensitive drum (7), occurrence of recording jitter is avoided.

On the other hand, inside the laser head (3), a laser drive device (2
) by the excitation current [1e] from the laser beam (
B) At the same time, a photodiode (3b) receives a laser beam (B) oscillated backward from a semiconductor laser (3a).
) is provided. The output signal from this photodiode (3b) is input to the laser driving device (2).

Using the output signal from this photodiode (3b), the power of the laser beam (B) oscillated forward from the semiconductor laser (3a) is adjusted to the output signal from the semiconductor laser (3a).
The structure is such that the excitation current [1e] to the semiconductor laser (3a) is controlled so that it is always constant regardless of temperature fluctuations or the like.

In this laser beam printer, the laser beam (B) to be scanned is connected to the above-mentioned photosensor (8).
The structure is such that an abnormality in oscillation of the laser beam (B) can be detected using a synchronization signal [SOS] that is output when the laser beam (B) is received.

Next, to explain its configuration, the above-mentioned synchronization signal [SO
S] is configured to be input to an abnormality detection circuit (10) which is an abnormality detection means, and on the other hand, an oscillation means (OM
oscillation abnormality detection control that outputs a signal for forcibly exciting the semiconductor laser (3a) for detecting oscillation abnormality, that is, an operation command for oscillation abnormality detection, to the laser driving device (2) constituting the oscillation abnormality, in addition to image information. A circuit (11) is provided.

This oscillation abnormality detection control circuit (11), which is an oscillation abnormality detection control means, receives an output signal from an optical encoder (12) that is attached to the polygon mirror (5) and outputs a pulse signal according to its rotation speed. is configured to be This oscillation abnormality detection control circuit (11
), after the main switch turns on, the rotation speed of the polygon mirror (5) reaches the steady rotation speed for scanning based on the output pulse signal from the optical encoder (12). , is configured to output the above-mentioned operation command.

This operation command includes a quantity rate conductor laser (3
The laser beam (B) is generated by forcibly exciting the semiconductor laser (3a), and the laser beam (B) is generated by stopping the excitation for a predetermined period of time from a state in which the semiconductor laser (3a) is continuously and forcibly excited. There is a method that stops the oscillation of the oscillation.

Then, when the former operation command is being output, the abnormality detection circuit (10) detects the synchronization signal [S] at a certain timing.
If another synchronization signal [SOS] is not input manually within a predetermined time after the [OS] is input, it is determined that an oscillation abnormality of the unlit light has occurred, and a non-lit abnormality detection signal is sent to the host computer (IIC). On the other hand, to output [LES],
When the latter operation command is being output, if the synchronization signal [SO3] is still being input even after a predetermined period of time has elapsed after the operation command was output, it is determined that an oscillation abnormality of the unlit light has occurred, and the host computer (IIc) is the unlit abnormality detection signal [
DBS].

Next, the operation of the laser beam printer including the operation of detecting abnormal oscillation described above will be explained using the flowcharts of FIGS. 2 and 3.

FIG. 2 shows the main routine that controls the overall recording operation.

The main routine starts, and if the main switch is closed <11>, then the (error detection) subroutine is called <112>. This subroutine will be described later. After that, call the (initial setting) subroutine (T3).

In this subroutine, the image forming elements around the photoreceptor drum (7) are activated and set to the optimal initial state, so that a stable high-quality image can be obtained from the beginning of the printing operation. , check the operation of each of these elements.

After that, when the print request signal [PRS] from the host computer (IIc) is input, the (print processing) subroutine is called and the recording operation is performed.<T15
〉, to determine whether the main switch is opened or not16
>, if it is determined that it is open, the process returns to step <11>; on the other hand, if it is determined that it remains closed, (T
The process returns to step 4> and waits for the print request signal [PR3].

FIG. 3 shows the subroutine (error detection) called in step <112>.

When this subroutine is called, it first outputs a forced oscillation signal [FO3] for forcibly exciting the semiconductor laser (3a) to oscillate the laser beam (B).
1101>. After that, the first timer (T1) is set <11102>. The time-up time [1+] of this first timer (TI) is set to the time until the synchronization signal [SO5] is input several times.

Then wait for the synchronization signal [SO2F to be input <1
1103>. Synchronization signal [If there is no SO2F input, decrement the first timer (T1) 11104>
Then, it is determined whether or not the first timer (T1) has time-amplified <11105>.

If the first timer (TI) has not timed up,
Return to step <111.03> and send the synchronization signal [SOS
] Waits for input. Also, if the first timer (T1) times up, it indicates that the laser beam (B) is not oscillating, and since it is an oscillation abnormality of the unlit light, (unlit error processing) is performed. Call a subroutine
11106>.

Although not shown in this subroutine (unlighted error processing), all operations of devices related to recording are stopped, and the fact that there is an oscillation abnormality due to the unlit light is indicated on a display or the like.

On the other hand, the sync signal [SOS] is sent to the Ste knob of <1103>.
If it is determined that there is an input, it is determined whether this is the second input <1110>, and the synchronization signal [SO
If it is determined that the 5F input is the first, it may be caused by a malfunction due to noise, etc., so the process proceeds to step <1104> and the synchronization signal is input again [SO2F input]. wait.

Also, in step (#110), the synchronization signal [SO2F
If it is determined that the input is the second time, the laser beam (B) is oscillating normally, so <1
Proceed to step 111>.

In step <1111>, the forced oscillation signal (FO3)
Stop outputting. After that, a second timer (T2) is set <1112>. The time-up time [11] of this second timer (T2) is set to the time until the synchronization signal [SO3] is input several times.

However, taking into consideration that the number of rotations of the polygon mirror (5) gradually increases, it is possible to make the time-up time [ of the first timer (Tl) shorter than -].

Then wait for the synchronization signal [SO2F to be input <1
113>. If the synchronization signal [50S] is not input, the second
Decrement the timer (T2) of 11114>,
Subsequently, it is determined whether the second timer (T2) has timed up (11115>).

If the second timer (T2) does not time amplify,
(Return to step 11113> and use the synchronization signal [SOS]
wait for input. Furthermore, if the second timer (T2) times up, this indicates that the laser beam (B) is not oscillating, and this is a normal operation, so the process returns to the main routine.

On the other hand, in step <1113>, the synchronization signal [SOS]
If it is determined that there has been an input, it is determined whether or not this is the second input <1120>.

If it is determined that the synchronization signal [SOS] has been input for the first time, it may be caused by a malfunction due to noise, etc., so please proceed to step <111.14> and try again. Wait for input of synchronization signal [SO2F.

Also, in step <11120>, the synchronization signal [SOS
] If it is determined that this is the second input, it indicates that the laser beam (B) is still oscillating, and it is an oscillation abnormality with the unextinguished light. Processing) subroutine <$1121>.

Although not shown in the diagram, this (unlit light error processing) subroutine stops all operations of recording devices and indicates on a display, etc. that there is an oscillation abnormality due to the unlit light. .

Time charts of the above operations are shown in FIGS. 4 to 6. FIG. 4 shows normal oscillation, FIG. 5 shows abnormal oscillation when the light is not on, and FIG. 6 shows abnormal oscillation when the light is not turned off.

Note that in an optical scanning image forming apparatus configured to reduce the number of rotations of the polygon mirror (5) except during printing operations, the above-mentioned (error detection) subroutine is performed using the print request signal [PR5] for each printing operation. ] You can do this after entering.

Each operation is the same as the previous one, so the explanation will be omitted.

The flowchart for this is shown in Figure 7.2. Flowcharts associated with this process are shown in FIGS. 8 to 10.

Further, the rotation speed of the polygon mirror (5) at the time of error detection described above may be the same as the rotation speed during the printing operation. In this case, in FIGS. 8 to 10, the output timings of the synchronization signal [SO3] are at equal intervals.

Note that this error detection may be performed between a series of print operations during a multi-print operation.

In the previous embodiment, in order to detect abnormal oscillation of the laser beam, a photosensor (8) for generating a synchronization signal [SO3] is used.
Although the configuration using the photodiode (3b) provided in the laser head (3) may be used instead of this, it is also possible to use the photosensor (8) and the photodiode (3b) to output light. It is called a control light receiving section (I2).

In addition, as the laser beam (B), a semiconductor laser (3
Instead of the one oscillated from a), one oscillated from a gas laser or a solid-state laser may be used. In this case, an oscillation means (OM) is constituted by the gas laser or solid-state laser and a modulator such as an AO modulator or an EO modulator. The operation command for oscillation abnormality detection from the oscillation abnormality detection control means (11) may be output as a forced modulation signal of the above-mentioned modulator.

In the previous embodiments, the present invention was applied to a photoreceptor drum (7).
An explanation has been given of an application to an indirect type laser beam printer in which an electrostatic latent image is formed by scanning a laser beam (B) on a target, and then this electrostatic latent image is developed and transferred onto an output sheet. The present invention can also be applied to a direct type laser beam printer that directly records on photosensitive paper by imaging and scanning a laser beam (B). Furthermore, in addition to these laser beam printers, the present invention also applies to a laser COM system that imprints microimages on microfilm, a laser imager that imprints both CT and CT images on silver halide film, and furthermore, It can also be applied to optical printers that use light.

[Effects of the Invention] As described above, in the optical scanning image forming apparatus according to the present invention, when the rotary optical deflector is in a rotating state in which recording is not performed using a light beam, the light beam is not used for recording. By oscillating and stopping oscillation, the light receiving section provided for controlling the optical output during recording can be used to detect oscillation abnormalities, and oscillation abnormalities such as unlit and unextinguished lights can be detected. Therefore, by using the light receiving section for the optical output control 1111 that is originally provided in this type of optical scanning image forming apparatus, it is possible to reduce the cost and detect abnormal oscillations of unextinguished lights, which could not be detected conventionally. It is now possible to detect abnormal oscillations in light beams.

[Brief explanation of drawings]

1 to 6 show an embodiment of the optical scanning image forming apparatus according to the present invention, FIG. 1 is a schematic configuration diagram of a laser beam printer, and FIGS. 2 and 3 show the operation of the laser beam printer. The flowcharts shown in FIGS. 4 to 6 are time charts 1 showing the operation of the laser beam printer. FIG. 7 is a flowchart corresponding to FIG. 2 showing another embodiment, and FIGS. 8 to 10 are the flowcharts shown in FIGS. It is a time chart corresponding to the figure. (5)... Rotating optical deflector, (7)...
・Photoreceptor, (10)... Abnormality detection means, (11
)...Oscillation abnormality detection control means, (B)...
...Light beam, (R)...Light receiving section for controlling light output, (It?)...Scanning and imaging optical system, (Oh)...
...Oscillation means.

Claims (1)

[Claims] 1. An oscillation means that modulates and oscillates a light beam, and a scanning beam that scans and forms an image on a photoreceptor by reflecting and deflecting the light beam from a rotating optical deflector. an imaging optical system, a light output control light receiving section that receives the light beam and outputs an electrical signal, and detects whether or not there is an oscillation abnormality in the light beam using the output electrical signal from the light output control light receiving section. an optical scanning image forming apparatus comprising an abnormality detection means, outputting an operation command for detecting an oscillation abnormality to the oscillation means when the rotary optical deflector is rotating and is not performing a recording operation based on image information. An optical scanning image forming apparatus is provided with an oscillation abnormality detection control means. 2. The output of an operation command for detecting oscillation abnormality from the oscillation abnormality detection means to the oscillation means is performed until the rotational speed of the rotary optical deflector reaches a steady rotational speed for scanning. An optical scanning image forming apparatus according to claim 1.