JPH07253552A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image forming device capable of easily detecting the state of the beam light path of laser beam optionally scanning a surface to be scanned and displaying detected information with a display means. CONSTITUTION:As for the image forming device forming an image by guiding the laser beam optically modulated from a light source means 1 on the surface 6 to be scanned through an image formation means 5 after polarizing by a deflecting means 4; a synchronization detecting means 7 detecting timing for the write of image information to the surface to be scanned, a comparing and calculating means comparing and calculating the output width of an output signal obtained from the synchronization detecting means 7 and the display means displaying information obtained by the comparing and calculating means are installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a photoconductor or a static image sensor through which light-modulated laser light (also referred to as a light beam) from a light source means is passed through an optical deflector including a rotating polygon mirror. For example, a copying machine or a laser beam printer (LBP) in which light is guided to the surface of an image carrier such as an electrographic recording medium and image information composed of, for example, an electrostatic latent image is formed on the surface.
The present invention relates to an image forming apparatus suitable for a facsimile or the like.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a laser beam printer, laser light from a laser light source is optically modulated according to an image signal. The light-modulated laser light is periodically deflected by an optical deflector composed of a rotating polygonal mirror, and spotted on the surface of a photosensitive recording medium (photosensitive drum) by an imaging optical system such as an f-θ lens. Image recording is performed by focusing and optical scanning.

In this type of image forming apparatus, as a means for detecting the timing of writing the image information on the surface of the photosensitive drum, a synchronous detecting means having an optical sensor or the like is provided in the vicinity of the photosensitive drum to perform optical scanning. The writing timing is synchronized by detecting a part of the laser light by the synchronization detecting means.

At this time, the output signal obtained from the optical sensor (hereinafter referred to as "BD sensor") is the laser beam emitted from the laser light source reaching (incident) the BD sensor.
It was used only to judge whether or not.

[0005]

In the conventional image forming apparatus, only when the laser light from the laser light source does not reach the BD sensor, or when the output image (printout) has an obvious abnormality, There is a problem that the abnormality of the beam optical path (laser optical path) in the scanning direction of the laser light is not detected. For this reason, it is impossible to prevent the printing of an image having a quality deteriorated due to, for example, an abnormality in the laser optical path.

The reason why the laser light does not reach the BD sensor may be, for example, a laser unit failure, an optical system abnormality, a BD sensor unit failure, or the like, and when an obvious abnormality is recognized in the output image. However, various causes including the photosensitive section and the fixing section are expected. Therefore, there is a problem that enormous effort is required to detect an abnormality in the laser optical path.

Therefore, in such an image forming apparatus,
For example, when an abnormality occurs in the laser optical path, it is desirable to instantly inform the user of the information.

The present invention utilizes the output signal from the synchronization detecting means for detecting the timing of writing the image information on the surface to be scanned, and the state of the beam optical path in the scanning direction of the laser light (for example, the deviation or inclination of the scanning line). Etc.) is detected by the comparison calculation means,
By displaying the detection information on the display means, it is possible to easily detect even a slight abnormality in the laser optical path, and it is possible to prevent the printing of an image of image quality deteriorated due to the abnormality in the laser optical path. An object is to provide a forming apparatus.

[0009]

In the image forming apparatus of the present invention, (1-1) after the light-modulated laser light from the light source means is polarized by the deflecting means, the surface to be scanned is passed through the image forming means. In an image forming apparatus that guides an image upward to form an image, a synchronization detection unit that detects the timing of writing image information on the surface to be scanned and an output width of an output signal obtained from the synchronization detection unit are compared and calculated. It is characterized by comprising a comparison calculation means and a display means for displaying the information obtained by the comparison calculation means.

In particular, the comparison calculation means detects the state of the beam optical path in the scanning direction of the laser light by comparing the output width of the output signal obtained from the synchronization detection means with a reference width which is a reference obtained in advance. In addition, the synchronization detecting means is provided at two locations near the surface to be scanned before the start of scanning and after the completion of scanning, and the output signals from these two synchronization detecting means are used. .

Further, in the image forming apparatus of the present invention, (1-2) after the light-modulated laser light from the light source means is polarized by the deflecting means, it is guided onto the surface to be scanned through the image forming means. In an image forming apparatus for forming an image, a synchronization detecting means for detecting a timing of writing image information on the surface to be scanned is provided near the surface to be scanned, and an output width of an output signal obtained from the synchronization detecting means and a width in advance are provided. It is characterized in that the reference width obtained as a reference is compared and calculated by the comparison calculation means to detect the state of the beam optical path in the scanning direction of the laser light, and the detected information is displayed on the display means. I am trying.

Further, the synchronization detecting means is provided at two positions in the vicinity of the surface to be scanned before the start of scanning and after the completion of scanning, and the output signals from these two synchronization detecting means are used.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view (exposure control section) of the main part in the main scanning direction of the first embodiment of the present invention, and FIG. 2 is a schematic view of the main part of the entire apparatus when the present invention is applied to a copying machine. .

In FIG. 1, reference numeral 1 is a light source means, which is composed of, for example, a semiconductor laser. Reference numeral 2 denotes a collimator lens, which makes the laser light (light beam) emitted from the light source means 1 into a parallel light flux. An aperture stop 3 adjusts the diameter of the passing light beam.

Reference numeral 4 denotes an optical deflector as a deflecting means, which is composed of, for example, a rotary polygon mirror, and a driving means (not shown) such as a motor.
Due to this, it rotates at a constant speed in the direction of arrow A in the figure.

An image forming means (image forming optical system) 5 having an f-θ characteristic is composed of two lenses 5a and 5b, and is a laser beam based on image information deflected and reflected by the optical deflector 4. Is imaged on the surface of the photosensitive drum 6 as the surface to be scanned.

Reference numeral 7 is a synchronization detecting means, which is a slit plate 7a.
And a BD sensor (optical sensor) 7b, which are arranged at the scanning start side of the surface of the photosensitive drum 6. The synchronization detecting means 7 is reflected by each deflecting surface of the optical deflector 4 in order to detect (control) the timing of the scanning start position on the surface of the photosensitive drum 6 before optically scanning the surface of the photosensitive drum 6. A part of the laser beam is detected, and the timing of the scanning start position of image recording on the surface of the photosensitive drum 6 is controlled.

Further, in this embodiment, the BD sensor 7b is used.
The output width (time width) of the output signal is measured by the measuring unit using the output signal from the measurement unit, and the measured output width and the reference width (reference to the scanning line) which is a reference previously obtained. The time width when there is no deviation or inclination) is compared and calculated by the comparison calculation means to detect the state of the laser optical path (for example, the deviation or inclination of the scanning line in the sub-scanning direction), and the detection result is displayed on the display means. By displaying it, the state of the laser optical path is instantly notified to the user.

The slit plate 7a constituting one element of the synchronization detecting means 7 has a circular opening 7a1 in the sub-scanning direction, and is substantially equivalent to the surface of the photosensitive drum 6 in an optical manner. It is placed in the position.

First, the basic operation of the copying machine to which the present invention is applied will be described with reference to FIG.

In FIG. 2, the originals stacked on one original feeding device 11 are successively conveyed one by one onto the surface of the original glass 12. When the document is conveyed, the light source (lamp) 13 provided in the scanner unit 14 is turned on, and the scanner unit 14 moves in the horizontal direction with respect to the paper surface to illuminate the document. Then, the reflected light from the illuminated document passes through the imaging lens 18 via the reflection mirrors 15, 16 and 17, and is input (imaged) to the image sensor unit 19 as a reading unit.

The image signal based on the image information input to the image sensor section 19 is directly or once stored in an image memory (not shown), read out again, and then input to the exposure control section 20. The exposure control unit 20 has the configuration shown in FIG. 1, and guides the laser light optically modulated according to the image signal to the surface of the photosensitive drum 6 via an optical deflector or the like. Then, the latent image formed on the surface of the photosensitive drum 6 by the laser light is developed by the first developing device 22 or the second developing device 23.

The transfer sheet is conveyed by the first transfer sheet stacking section 24 or the second transfer sheet stacking section 25 at the same timing as the latent image, and the developed toner image is transferred at the transfer section 26. . Then, the transferred toner image is fixed on the transfer paper by the fixing unit 27, and then discharged by the paper discharge unit 28 to the outside of the apparatus.

Next, the optical operation of the exposure controller 20 shown in FIG. 2 will be described with reference to FIG.

In the figure, the laser light (light beam) emitted from the semiconductor laser 1 is made into substantially parallel light by the collimator lens 2 and the diaphragm 3, and is incident on the deflection surface 4a of the light deflector 4 with a predetermined beam diameter. The optical deflector 4 is indicated by an arrow A in the figure.
Is rotated at a constant angular velocity in the direction of, and the incident laser light is reflected as a deflected beam whose angle is continuously changed with this rotation, and is received by the f-θ lens 5.

Since the f-θ lens 5 simultaneously corrects the distortion aberration for compensating the temporal linearity of the optical scanning, the laser light is directed onto the surface of the photosensitive drum 6 in the direction of arrow B (in the figure). Scanning is performed at a constant speed in the main scanning direction). The writing of data on the surface of the photosensitive drum 6 is performed by controlling the light amount of the semiconductor laser 1.

At this time, in this embodiment, before the optical scanning on the surface of the photosensitive drum 6, the deflecting reflection is performed by each deflecting surface of the optical deflector 4 in order to adjust the scanning start position on the surface of the photosensitive drum 6. A part of the generated laser light is guided to the BD sensor 7b through the slit 7a. Then, after a predetermined time t seconds from the time when it is detected by the BD sensor 7b, a writing signal is transmitted to record an image on the surface of the photosensitive drum 6.

Further, by using the output signal from the BD sensor 7b, the output width (time width) of the output signal is measured by the measuring unit as described later, and the measured output width and the output width are obtained in advance. The reference width (time width) serving as a reference is compared and calculated by the comparison calculation means to detect the state of the laser optical path (for example, the deviation or inclination of the scanning line in the sub-scanning direction), and the detection result is displayed on the display means. This notifies the user of the state of the laser optical path.

Here, the principle of this embodiment will be described with reference to FIGS. 3, 4, and 5.

FIG. 3 is a block diagram of the essential parts of this embodiment.
4 and 5 are explanatory diagrams showing output waveforms from the BD sensor when the laser light passes through the opening of the slit plate. In FIG. 4, when the laser light path is normal (scanning in the sub-scanning direction) FIG. 5 shows the case where the laser optical path is abnormal (the scanning line in the sub-scanning direction is displaced).
Is shown.

In FIG. 3, a BD sensor output signal measuring unit 35 measures the output width (time width) of the output signal from the BD sensor 7b. Reference numeral 36 denotes a comparison calculation unit as a comparison calculation unit, which calculates the output width of the output signal using the signal from the measurement unit 35 and compares it with a reference width (time width) which is a reference to be obtained in advance and which will be described later. To detect the state of the laser optical path. Reference numeral 37 denotes a display unit as a display unit, which displays information (the state of the laser optical path) calculated by the comparison calculation unit 36 to inform the user.

In FIGS. 4 and 5, 7a1 is an opening of the slit plate, which is circular in the sub-scanning direction. 41 and 51 are beam optical paths (laser optical paths) of laser light, and 42 and 52 are output waveforms (output signals) from the BD sensor 7b.

Normally, if there is no abnormality in the laser light path, the laser light passes through a certain portion of the slit plate 7a having the opening 7a1 (for example, the central portion of the opening 7a1) and the surface of the BD sensor 7b as shown in FIG. Incident on. At this time, the output width t ₀ of the output signal from the BD sensor 7b is always constant. This output width t ₀ is used as a reference width.

Here, for example, when a slight tilt that affects the output image occurs on the deflecting surface of the optical deflector, the laser light passes through the upper portion of the opening 7a1 as shown in FIG. 5, for example. Then, the laser optical path (scanning line) changes in the sub-scanning direction, and the output width t ₁ of the output signal from the BD sensor 7b fluctuates from the reference width t ₀ .

In this embodiment, the BD sensor 7b at this time is
The abnormality of the laser optical path is notified to the user by monitoring the variation of the output width of the output signal from the display unit. As a result, for example, it is possible to prevent the printing of an image deteriorated due to an abnormality in the laser optical path.

Explaining with a concrete example, for example, the output width of the output signal from the BD sensor 7b at the time of shipping is stored in advance in the memory as the reference width t ₀ . Then, the output width t ₁ of the output signal from the BD sensor after shipment is compared with the reference width t _0, and when it is determined that a predetermined value considering the intersection of the laser optical paths is exceeded, the laser optical path is abnormal. The occurrence is displayed on the display unit to notify the user. Then, based on the information obtained by the comparison calculation means, the deviation of the laser optical path is adjusted by, for example, an optical means.

FIG. 6 is a block diagram of the essential parts of the second embodiment of the present invention. 7 and 8 are explanatory diagrams showing output waveforms from the BD sensor when the laser light passes through the opening of the slit plate in FIG. 6, respectively. 7 shows the case where the laser optical path is normal, and FIG. 8 shows the case where the laser optical path is abnormal.
6, 7 and 8, the same elements as those shown in FIGS. 3, 4 and 5 are designated by the same reference numerals.

This embodiment is different from the first embodiment described above in that the slit plate has a triangular opening, and the same synchronization detecting means is provided at the scanning start side and the scanning end side of the photosensitive drum 6, respectively. And the respective synchronization detecting means 67,
The output signal obtained from 68 is used to detect the state of the laser optical path (for example, the deviation or inclination of the scanning line in the sub-scanning direction), and from the detection result, for example, the inclination direction or inclination angle of the deflection surface of the optical deflector is determined. That is, the detection information is detected and displayed on the display unit. Other configurations and optical functions are substantially the same as those in the first embodiment.

That is, in FIG. 6, FIG. 7 and FIG.
8) is a synchronization detecting means, which is a slit plate 67a (68).
a) and each element of the BD sensor 67b (68b). In this embodiment, the synchronization detecting means 67 is arranged at the scanning start side position on the surface of the photosensitive drum 6, the synchronization detecting means 68 is arranged at the scanning end side position, and the slit plate 67a (68a) is exposed. It is arranged so as to be in a position substantially equivalent to the surface of the body drum 6. 67a1 (68a
1) is an opening of the slit plate 67a (68a), which has a triangular shape in the sub-scanning direction.

Normally, as shown in FIG. 7, if there is no abnormality in the laser beam path 71, the laser beam passes through a certain portion of the slit plates 67a and 68a having openings 67a1 and 68a1.
It is incident on the BD sensor 67b / 68b surface. At this time, the output width t of the output signals from the BD sensors 67b and 68b
₁₀ · t ₂₀ is always constant. The output width t ₁₀ · t ₂₀ is used as the reference width.

Here, for example, when a slight tilt that affects the output image occurs on the deflection surface of the optical deflector, the laser optical path 81 changes as shown in FIG. 8, and the BD sensor 67b.
The output width t ₁₁ and t ₂₁ of the output signal from 68b is the reference width t _10.
・ Varies from t ₂₀ .

In this embodiment, each BD sensor 6 at this time is
The variation of the output widths t ₁₁ and t ₂₁ of the output signals from 7b and 68b is monitored on the display unit in the same manner as in the first embodiment described above to notify the user of the abnormality of the laser optical path.

[0043] Also, the output width of the output signals from the two BD sensors when the laser beam path 71 is normal _{(67b · 68b) (t 10} · t 20) In this embodiment, the two BD when the abnormality
Sensor (67b · 68b) output width of the output signal from the (t ₁₁ · t ₂₁₎ comparison operation unit values of the four output width of 36
For example, the tilt direction and tilt angle θ ₁ of the deflecting surface of the optical deflector are detected by making a comparison.

A specific example will be described below. For example, two BD sensors (67b and 68b) at the time of shipment are used.
The output width (t ₁₀ · t ₂₀ ) of the output signal from (b) is stored in the memory in advance as the reference width, and the output width (t ₁₁ · t) of the output signals of the two BD sensors (67b, 68b) after shipment is set.
t ₂₁ ) and the reference width (t ₁₀ · t ₂₀ ) are compared, and when the compared value exceeds a predetermined value in consideration of the intersection of the beam optical paths, it is determined that an abnormality of the beam optical path has occurred, and the output width The relationship between (t ₁₁ · t ₂₁ ) and the reference width (t ₁₀ · t ₂₀ ) is t ₁₁
> Direction of inclination of the scan line if t ₁₀ and t _20> t ₂₁ it can be seen that has a drawing on the left edge direction as shown in FIG.

The reference width t ₁₀ , the output width t ₁₁ and the reference width t
The tilt angle θ ₁ of the deflection surface of the optical deflector is calculated by comparing the respective values of ₂₀ and the output width t ₂₁ by the comparison calculation unit.
Can be asked. As a result, it is possible to display the abnormality of the laser optical path on the display unit and also display the tilt direction and tilt angle θ ₁ of the deflection surface of the optical deflector.

Further, by using the output signal from each BD sensor, the scanning time for each scanning line can also be obtained, whereby the scanning unevenness can be detected.

As described above, in the present embodiment, the synchronization detecting means is provided at each of the start side and the end side of the surface to be scanned as described above, and the output signal from the synchronization detecting means is used to make the state of the laser optical path. Is detected and the user is notified by monitoring the detection result on the display unit. Further, at this time, when the abnormality of the laser optical path is detected, the laser optical path is adjusted by the optical means or the like based on the information from the comparison calculation means. This allows easy adjustment without using a tool for adjusting the laser optical path.

In the present embodiment, the shape of the opening of the slit plate may be any shape as long as it can detect the state of the laser optical path.

[0049]

According to the present invention, as described above, the output width of the output signal obtained by the synchronization detecting means and the reference width which is the reference obtained in advance are compared and calculated by the comparison calculating means or the like, and By detecting the state of the beam optical path in the scanning direction (for example, the deviation or inclination of the scanning line) and displaying the detected information on the display means, even a slight abnormality of the laser optical path can be easily detected. Therefore, it is possible to achieve an image forming apparatus capable of preventing the printing of an image having the image quality deteriorated due to the abnormality of the laser optical path.

Further, as described above, by providing the synchronization detecting means at the scanning start side and the scanning end side of the surface to be scanned, the state of the laser optical path can be detected in more detail, thereby detecting the abnormality of the laser optical path. At this time, it is possible to achieve an image forming apparatus that can easily adjust the laser light path by, for example, optical means without using a tool or the like for adjusting the laser light path.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part in a main scanning direction according to a first embodiment of the present invention.

FIG. 2 is a schematic view of main parts when the present invention is applied to a copying machine.

FIG. 3 is a block diagram of a main part of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an output waveform from the BD sensor when the laser light according to the first embodiment of the present invention passes through a normal optical path.

FIG. 5 is an explanatory diagram showing an output waveform from the BD sensor when the laser light according to the first embodiment of the present invention passes through an abnormal optical path.

FIG. 6 is a block diagram of a main part of a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an output waveform from the BD sensor when the laser light according to the second embodiment of the present invention passes through a normal optical path.

FIG. 8 is an explanatory diagram showing an output waveform from the BD sensor when the laser light according to the second embodiment of the present invention passes through an abnormal optical path.

[Explanation of symbols]

 1 Light Source Means 2 Collimator Lens 3 Aperture 4 Deflection Means 5 Image Forming Means 6 Photosensitive Drum 7 Synchronous Detection Means 7a Slit Plate 7b BD Sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical indication H04N 1/113

Claims (4)

[Claims] 1. An image forming apparatus for forming an image by guiding light-modulated laser light from a light source means by a deflecting means and then guiding it onto a surface to be scanned through an image forming means to form an image. A synchronization detection unit that detects the timing of writing image information on the surface, a comparison calculation unit that performs a comparison calculation of the output width of the output signal obtained from the synchronization detection unit, and the information obtained by the comparison calculation unit are displayed. An image forming apparatus comprising: a display unit. 2. The state of the beam optical path in the scanning direction of the laser beam is compared by comparing the output width of the output signal obtained from the synchronization detecting means with a reference width which is a reference obtained in advance. It has detected, Claim 1 characterized by the above-mentioned.
Image forming device. 3. An image forming apparatus for forming an image by guiding light-modulated laser light from a light source means by a deflecting means and then guiding it onto a surface to be scanned through an image forming means to form an image. A synchronization detecting means for detecting the timing of writing image information on the surface is provided in the vicinity of the surface to be scanned, and the output width of the output signal obtained from the synchronization detecting means is compared with a reference width which is a reference obtained in advance. An image forming apparatus characterized in that a state of a beam optical path in the scanning direction of the laser light is detected by a comparison means by a calculation means, and the detected information is displayed on a display means. 4. The synchronization detecting means is provided at two locations in the vicinity of the surface to be scanned, before the start of scanning and after the completion of scanning, and the output signals from these two synchronization detecting means are used. The image forming apparatus according to item 1 or 3.