JP2006337716A5 - - Google Patents

Description

Optical scanning device

The present invention relates to an optical scanning apparatus having a start point detection sensor substrate.

  Conventionally, an optical scanning device is generally used in the optical and electronic fields such as a laser printer.

The optical scanning apparatus includes a scanning optical system mainly including a laser light source, a collimating lens, a cylinder lens, an optical deflector (also referred to as a polygon mirror rotation control means or MPA), an fθ lens, and the like.
Laser light emitted from the laser light source is deflected and reflected by the polygon mirror of the optical deflector, and is condensed by the fθ lens to record an image on the photosensitive drum.

  In order to record an image on the photosensitive drum, it is necessary to rotate the photosensitive drum at the same timing as the image writing operation by the optical scanning device. For this reason, it is necessary for the rotation control device of the photosensitive drum to recognize the timing at which the optical scanning device starts writing an image on the photosensitive drum. As a means for this, it is generally employed to provide a start point detection sensor substrate for detecting laser light beside the writing start point on the photosensitive drum.

The start point detecting sensor substrate, the start point detecting sensor for photoelectrically converting the laser light received, made from a signal amplifier circuit for amplifying and outputting a photoelectrically converted signal (received signal) as the starting point detection signal by the start point detecting sensor The start point detection signal is transmitted as a signal to start writing an image of the optical scanning device to the rotation control device of the photosensitive drum. Generally, the signal amplification circuit amplifies the light reception signal of the start point detection sensor with a predetermined amplification factor.
JP-A-8-106062 JP-A-5-313087

However, the start point detection sensor substrate has a problem that it is easily affected by noise generated from irregular reflection by laser light when the start point detection sensor receives light emitted from the laser light source. That is, a direct current component such as noise affects the received light signal, and the received light signal that has received the direct current component is amplified together with the direct current component such as noise by the signal amplification circuit. There arises a problem that the detection signal fluctuates.

  Therefore, if the received light signal including noise or the like under the influence as described above is amplified as it is, the start point detection signal varies due to the noise or the like. In this case, since the writing start timing of the image by the optical scanning device varies, there is a problem that the position of the scanning line to be written varies, and the image cannot be written on the photosensitive drum with high accuracy.

Noise that affect the origin detection sensor (PD), as shown in Figure 8, generated by the laser beam hits the edge portion 16 mainly corresponding to the side end portion of the starting point detection sensor. Since the light receiving surface 15 of the start point detection sensor is formed at a position close to the edge portion 16 of the start point detection sensor, if the light reception surface 15 of the start point detection sensor is wide, noise is easily generated due to the influence of irregular reflection.

To solve such a problem, to narrow the light receiving surface 1 5 of the above start point detecting sensor, to develop and redesign the hard start detection sensor affected by noise due to elevation Ranhan by the edge portion 16 of the start point detection sensor it takes a lot of time and expense, there is a problem that the cost of the starting point detection sensor and start sensor substrate.

The present invention has been made in view of such conventional problems, to suppress the effect of noise or the like in the light-receiving signal of the start point detecting sensor, made it possible to output the start detection signal of the high-precision Providing the start point detection sensor substrate and providing the start point detection sensor substrate and the optical scanning device including the start point detection sensor substrate that can suppress variations in the start timing of image writing by the optical scanning device. Objective.

The optical scanning device according to claim 1, wherein a light source that emits laser light, a collimating lens that collimates the laser light emitted from the light source, and the laser light that is collimated by the collimating lens are sub-scanned. A cylinder lens that narrows in the direction, an optical deflector that deflects and reflects the laser light that is narrowed down in the sub-scanning direction by the cylinder lens, and forms an image on the recording medium the laser light that is deflected and reflected by the optical deflector An optical scanning device comprising: an imaging lens; and a starting point detection sensor substrate that detects a timing at which the laser beam deflected and reflected by the optical deflector scans the recording medium. Two or more start point detection sensors arranged closely along the direction, and the received light signals photoelectrically converted by the start point detection sensors are different from each other. Those having a 2 or more amplification device for amplifying an amplification factor.
The start point detection sensor substrate deflects light reflected from a light source by an optical deflector and scans the surface to be scanned, and transmits light passing through a leading end position in the main scanning direction when writing is started. In the start point detection sensor substrate of the optical scanning device that detects at the synchronization timing, two or more start point detection sensors are closely arranged along the scanning direction on the substrate, and the signal received by the sensor at each magnification from the substrate. Since the signal is amplified and converted and output, the start point detection sensor substrate can suppress the influence of a direct current component such as noise on the light reception signal of the start point detection sensor and can output a stable start point detection signal with little influence of noise.

According to a second aspect of the present invention, there is provided the optical scanning device according to the first aspect, wherein a dimming means is provided in an optical path region from the optical deflector to the start point detection sensor.

By the light emitted from the light source before Symbol optical scanner to deflect reflected by the optical deflector start point detecting sensor comprises a light-reducing means in the optical path area to receive, in addition to the effect of claim 1, by power over Les chromatography the chromatography light is light reduced even stronger power over the outside light receiving detection range of the start point detection sensor, it is possible to within a photodetection range of above start point detecting sensor, Les chromatography the chromatography even if the setting change due to specification change of the light amount of the light source is required, Ru can respond universally.

Start detecting sensor substrate according to the present invention has an effect that it is possible to output a stable starting point detection signal is less affected by noise.

  The present invention will be described in detail with reference to FIGS.

1 to 4 show an embodiment of a starting point detection sensor substrate according to the present invention. The starting point detection sensor substrate according to the present invention will be described.

Figure 1 is a configuration diagram of the start point detecting sensor substrate arranged in an image forming apparatus according to the present invention. The start point detection sensor substrate 12 is disposed at a position where the laser beam deflected and reflected by the rotation of the optical deflector 4 in the optical scanning device 9 can be received, and the position where the light can be received is relative to the image recording area of the photosensitive drum 7. This corresponds to the scanning start position outside the image recording area for determining the writing start timing.

FIG. 2 is a block diagram of the starting point detection sensor substrate. Start detecting sensor board is disposed the PD1 and PD2 of the starting point detection sensor for receiving the laser beam 8 which is deflected and reflected by the rotation of the optical deflector 4, the start point detecting sensor which receives the laser beam 8 photoelectric converted electric signal (light-receiving signal) is amplified by a signal amplifier circuit wire to above start point detecting sensor substrate, you output as a start point detection signal.

As shown in FIG. 8, Le Za light to scan the starting point detection sensor PD is, diffused reflection at the moment striking the edge portion 16 mainly corresponding to the side end portion of the starting point detection sensor PD is generated, noise is generated. Due to the influence of this noise, there is a problem that the waveform of the received light signal is disturbed and a stable signal cannot be output.

  Therefore, as shown in FIG. 3, by arranging the start point detection sensors PD1 and PD2 closely along the scanning direction, there is no edge in the close portions, and no irregular reflection occurs. Therefore, noise generated at the edge portion can be suppressed.

In this way, by using the falling portion of the received light signal of PD1 and the rising portion of the received light signal of PD2 as the received light signal of the start point detection sensor, which eliminates the edge portion and suppresses the influence of noise, a direct current component such as noise It is possible to output the received light signal that can suppress the influence of the signal to the signal amplifier circuit.

Receiving signals that could suppress the effect of the DC component such as noise obtained from the start point detecting sensor, the signal amplifier circuit be disposed above start point detecting sensor in the substrate, Ru is amplified.

Receiving signals that could suppress the effect of the DC component of the noise or the like, although the noise or the like was suppressed, the influence of some noise remains. State in particular, since if power over the semiconductor laser 1 emitted from Les Za source is weak is output at low current, some of the light receiving signal effect remained the noise affected by noise by the signal amplifying circuit Therefore, since it is output as a start point detection signal in which the waveform of the amplified light reception signal is disturbed, it cannot be output as a stable start point detection signal.

Therefore, a light receiving signal affected by noise is input to a signal amplifying circuit disposed in the starting point detection sensor substrate, noise components are removed compared to a predetermined threshold, and a plurality of amplification factors are different. It is to the amplified received light signal by amplifying elements, and the like can output a light reception signal as a starting point detection signal can be further suppressed the influence of the DC component such as noise.

  By arranging the signal amplifying circuit, it is possible to output the start point detection signals as circles 1 to 4 with the amplification factors set for each as shown in FIG.

  In this case, since the waveform of the circle 1 is amplified in a state affected by noise or the like, it is not suitable as the start point detection signal, and the waveform of the circle 3 circle 4 is saturated and therefore suitable as the start point detection signal. Absent. By selecting the waveform of circle 2 as the start point detection signal, it is possible to output it as a stable start point detection signal.

  By doing so, it is possible to generate a highly accurate start point detection signal that is less affected by direct current components such as noise, and it is possible to suppress variations in image writing start timing by the optical scanning device. It can be done.

  FIG. 5 shows another embodiment according to the present invention. Note that the same parts as those of the starting point detection sensor substrate according to the first embodiment are denoted by the same reference numerals and description thereof will be omitted, and only differences from the first embodiment will be described in detail.

FIG. 5 is a plan view showing a basic configuration of an optical scanning device on which the start point detection sensor substrate according to the present invention is mounted. Here, the basic configuration of the optical scanning device will be described before describing the invention.

Laser beam 8 emitted from the semiconductor laser 1 to the record over The over light source and the light emitting portion is narrowed in the sub-scanning direction in the vicinity of the reflecting surface of the optical deflector 4 by a cylinder lens 3 after converting into a parallel beam by a collimator lens 2 The light is deflected and reflected by the rotation of the optical deflector 4 .

The deflected reflected laser beam 8 is narrowed down to a pitch corresponding to the recording density on a recording medium by the imaging lens called fθ lens 5, the reflection-mirror 6, which is further disposed on the downstream side, An image is formed in a predetermined scanning range (hereinafter referred to as “scanning region”). The above is the basic configuration of the optical scanning device 9.

Wherein the scanning region is disposed a photosensitive drum 7 as a record medium, the laser beam 8 emitted from the optical scanning device 9 is imaged.

Further, the optical scanning device 9 is provided with a writing start point detecting means 10 for determining a scanning start position on the image recording area. As the configuration of the writing start point detecting means 10, the optical deflector 4 includes: the fixed reflection mirror 11 reflects to allow receiving a laser beam 8 which is deflected and scanned by a rotating start point detecting sensor be disposed portion corresponding scanning start position outside the image recording area, it is reflected by the fixed reflecting mirror 11 was as a scanning bi chromatography beam L synchronization signal by receiving the start point detection sensor substrate 12 mounted with the starting point sensor for determining the write start timing it is in the construction of arranging for an image recording area of the photosensitive drum.

Suppressing the influence of noise or the like in the light-receiving signal of the start point detection sensor by a constitution or, to provide a starting point detection sensor substrate made it possible to output the start detection signal of high accuracy, the image by the optical scanning device It is possible to provide an optical scanning device that can suppress variations in writing start timing.

  FIG. 6 shows another embodiment according to the present invention. Note that the same portions as those of the start point detection sensor substrate according to the second embodiment are denoted by the same reference numerals and description thereof is omitted, and only differences from the second embodiment will be described in detail.

As shown in FIG. 6, differs from the second embodiment in that the laser beam 8 which is deflected and reflected by the rotation of the optical deflector 4 is the starting point detection sensor having a light reduction unit 13 in the optical path area to receive It is.

By providing the dimming means 13 before Symbol optical path region, by power over the semiconductor laser 1 Les Za light source light reduction even stronger power over the outer light receiving detection tolerable range of the start point detection sensor, the start point detecting sensor It can be within the permissible detection range.

Starting point detection signal output by the start point detecting sensor substrate can be output as a start point detection signal with an amplification factor set in each. Then, to suppress the effect of noise or the like in the light-receiving signal of the start point detecting sensor, it is possible to the child outputs a start point detection signal with high accuracy.

Therefore, in addition to the effect of Embodiment 2 With such a configuration, power over the laser beam even receiving and detecting unacceptable strong power over the start point detecting sensor, the light receiving detection tolerable range of above start point detection sensor by dimming it is possible to, even when the necessary configuration changes due to specification change of the record over the chromatography amount of source light, it can provide an optical scanning device that can respond generic.

  The above-described embodiments are illustrated for explanation, and the present invention is not limited thereto, and those skilled in the art will recognize from the claims, the detailed description of the invention, and the description of the drawings. Modifications and additions are possible without departing from the technical idea of the present invention.

  For example, in the start point detection sensor substrate of the present invention, two start point detection sensors PD are arranged, but the number is not limited to this.

  The signal amplification circuit wired to the starting point detection sensor substrate may be arbitrarily set with an amplification factor, or may be used with an additional circuit and amplification element.

The extinction device 13 Oite described in Example 3, ND filter over, although mentioned as illustrative sheet glass or the like, low-reflection Mirror and bi having a spectral means 14 that splits the laser beam 8 as shown in FIG. 7 no problem using means for dimming by placing the over beam splitter or the like.

In the first embodiment, the start point is provided by providing the light reducing means 13 or the spectroscopic means 14 in the optical path region until the laser beam 8 deflected and scanned by the rotation of the optical deflector 4 is received by the start point detection sensor for photoelectric conversion. photodetection allowable range corresponding to a strong power over the sensor may be used means for dimming the.

  Provided is a start point detection sensor substrate that can suppress the influence of a direct current component such as noise on the light reception signal of the start point detection sensor and can output a stable start point detection signal that is less affected by noise, and an optical scanning device including the start point detection sensor substrate To do.

1 is a configuration diagram of an image forming apparatus according to the present invention. Example 1 It is a block diagram of a starting point detection sensor substrate according to the present invention. Example 1 It is a figure showing the relationship between the light reception signal of the start point detection sensor which concerns on this invention, and a start point detection sensor. Example 1 It is an output waveform diagram of the start point detection sensor substrate according to the present invention. Example 1 It is a block diagram of the optical scanning device which concerns on this invention. (Example 2) It is a block diagram of the optical scanning device which concerns on this invention. (Example 3) It is a block diagram of the optical scanning device which concerns on this invention. It is a figure showing the relationship between the light reception signal of the conventional start point detection sensor and a start point detection sensor.

Explanation of symbols

1 semiconductor laser over The 2 collimating Trends 3 cylinder lens 4 optical deflector (MPA)
5 f [theta] lens 6 reflected Mirror 7 photoconductive drum 8 Les chromatography The chromatography beam 9 an optical scanning device 10 writing start point detection means 11 fixed reflective-mirror 12 starting detection sensor substrate 13 darkening means 14 spectroscopic means PD start detecting sensor 15 receiving surface 16 edge portion L scanning bi chromatography beam

Claims (2)

A light source that emits laser light;
A collimating lens that collimates the laser light emitted from the light source;
A cylinder lens that narrows down the laser light parallel to the collimating lens in the sub-scanning direction;
An optical deflector for deflecting and reflecting the laser beam narrowed down in the sub-scanning direction by the cylinder lens;
An imaging lens for imaging the laser beam deflected and reflected by the optical deflector on a recording medium;
In the optical scanning device, comprising: a start point detection sensor substrate that detects timing when the laser beam deflected and reflected by the optical deflector scans the recording medium,
The start point detection sensor substrate includes two or more start point detection sensors arranged closely along the main scanning direction;
An optical scanning device having two or more amplifying elements for amplifying light reception signals photoelectrically converted by the respective start point detection sensors at different amplification factors The optical scanning device according to claim 1, wherein a light reducing unit is provided in an optical path region from the optical deflector to the start point detection sensor.