JP6464715B2 - Scanning optical apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a scanning optical device applied as an image forming unit to an image forming apparatus such as an electrophotographic copying machine, and an image forming apparatus including the scanning optical device.

  In recent years, image forming apparatuses using electrophotographic technology have also entered the light printing market. In the light printing market, since the book is used for the purpose of bookbinding, the required accuracy for the image forming position becomes severe.

  For this reason, a technique has been proposed in which a cross-line image called a register mark image is formed outside the image forming area and used as an image alignment when forming images on the front and back sides of a sheet and as a cutting reference after bookbinding. Yes.

  In an image forming apparatus, in order to generate an SOS (start of scan) signal used as a synchronization signal for taking a scanning timing of light for forming an image, a synchronization sensor is provided at a position where scanning light can enter, and the synchronization sensor A synchronization signal is generated using the scanning light incident on the.

  When the registration sensor image or the area where the image is formed is provided with a detection sensor in which the light for the synchronization signal is incident or a mirror that reflects the light toward the detection sensor, the registration mark There is a range where the image or the light scanned to form the image is blocked by the detection sensor or the mirror.

  For this reason, conventionally, a technique in which an optical path of light for synchronization signal incident on a detection sensor is provided outside of an optical path of light irradiated on a region where a registration mark image is formed (see, for example, Patent Document 1). ).

JP 2011-227279 A

  In a scanning optical device applied to an image forming apparatus, light is scanned using a rotary polygon mirror, and a synchronization signal is generated and a registration mark image and an image are formed. The light to be formed is imaged by the same optical system.

  Thereby, in the structure provided with the optical path of the light for the synchronization signal incident on the detection sensor outside the optical path of the light irradiated to the area where the registration mark image is formed, it is further than the area where the light forming the registration mark image passes. A lens having a size having a region through which light for synchronization signal can pass is required. For this reason, it led to the cost increase of the whole apparatus accompanying the enlargement of a lens and the enlargement of the components accompanying a lens.

  In order to solve such a problem, an object of the present invention is to provide a scanning optical device that can be reduced in size and an image forming apparatus including the scanning optical device.

In order to solve the above-described problem, an invention according to claim 1 is provided by a first light source that emits light that forms an image, a second light source that emits light that generates a synchronization signal, and a first light source. A deflector that deflects the emitted light and the light emitted from the second light source in the main scanning direction and the light emitted from the first light source and deflected by the deflector are imaged on the image plane, and 2 is provided with an imaging optical system that forms an image on the light detection means, and the light emitted from the first light source and the light emitted from the second light source are: Either the incident angle or the incident position in the sub-scanning direction orthogonal to the main scanning direction with respect to the deflector is made different, and the light path emitted from the second light source is emitted from the first light source. is maximum scanning beam path of the light, the scanning light outside in the main scanning direction It is a device.

The invention according to claim 2 is the scanning optical system according to claim 1, wherein the light emitted from the first light source and the light emitted from the second light source have different incident angles in the main scanning direction with respect to the deflector. Device.

In the invention according to claim 3 , the incident angle in the main scanning direction of the light emitted from the first light source is smaller than the incident angle in the main scanning direction of the light emitted from the second light source. The scanning optical device according to claim 2 .

According to a fourth aspect of the present invention, there is provided an image forming apparatus including an image forming unit that forms an image on a sheet, and the image forming unit includes the scanning optical device according to any one of the first to third aspects. is there.

  In the present invention, a light source that emits light for forming an image including a registration mark image and a light source that emits light for generating a synchronization signal are made independent, and the optical path is separated in the sub-scanning direction. It is not necessary to provide an optical path of light for generating a synchronization signal outside the optical path of light that forms an image including the image forming optical system, and the imaging optical system can be downsized. As a result, it is possible to suppress an increase in the size of the accompanying components accompanying an increase in the size of the imaging optical system and an increase in the cost of the entire apparatus.

It is a block diagram which shows an example of the scanning optical apparatus of 1st Embodiment. It is a block diagram which shows an example of the scanning optical apparatus of 1st Embodiment. It is a block diagram which shows the modification of the scanning optical apparatus of 1st Embodiment. It is a block diagram which shows the modification of the scanning optical apparatus of 1st Embodiment. It is a block diagram which shows the other modification of the scanning optical apparatus of 1st Embodiment. It is a block diagram which shows the other modification of the scanning optical apparatus of 1st Embodiment. It is explanatory drawing which showed typically the position of the light which passes an imaging optical system. 6 is a time chart showing control timings of a synchronization signal and an image forming signal. It is explanatory drawing which shows the relationship between light emission control and an image formation position. It is a block diagram which shows an example of the scanning optical apparatus of 2nd Embodiment. It is a block diagram which shows an example of the scanning optical apparatus of 2nd Embodiment. It is explanatory drawing which showed typically the position of the light which passes an imaging optical system. 6 is a time chart showing control timings of a synchronization signal and an image forming signal. It is explanatory drawing which shows the relationship between light emission control and an image formation position. 1 is a configuration diagram schematically illustrating an image forming apparatus according to an exemplary embodiment.

  Embodiments of a scanning optical device of the present invention and an image forming apparatus to which the scanning optical device is applied will be described below with reference to the drawings.

<Configuration Example of Scanning Optical Device of First Embodiment>
1 and 2 are configuration diagrams illustrating an example of a scanning optical device according to the first embodiment. FIG. 1 is a plan view of the scanning optical device 1A according to the first embodiment as viewed from the main scanning direction. 2 is a side view of the scanning optical apparatus 1A according to the first embodiment viewed from the sub-scanning direction. Here, the main scanning direction is a direction in which light is scanned in the scanning optical apparatus 1A, and is a direction along the axial direction of the photosensitive drum as the image plane. The sub-scanning direction is the main scanning direction. It is a direction orthogonal to.

  The scanning optical device 1A of the first embodiment includes a first light source 2a, a first light source optical system 20a that condenses the light L1 emitted from the first light source 2a, and a second light source 2b. The second light source optical system 20b that condenses the light L2 emitted from the second light source 2b is provided.

  Further, the scanning optical device 1A includes a rotating polygon mirror 3 that deflects the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b in a predetermined direction. Further, the scanning optical apparatus 1A forms an image of the light L1 deflected by the rotary polygon mirror 3 on the image plane 4, and forms an image of the light L2 deflected by the rotary polygon mirror 3 on the synchronization sensor 5. 6 is provided. The scanning optical device 1 </ b> A includes a mirror 7 that reflects the light L <b> 2 deflected by the rotary polygon mirror 3 to the synchronization sensor 5.

  As the first light source 2a, a semiconductor laser array called a multi-beam light source having a plurality of light emitting points is used in this example. The first light source optical system 20a includes a collimator lens 21a that collimates the light L1 emitted from the first light source 2a, and a cylindrical lens 22a that condenses in the sub-scanning direction indicated by the arrow Y of the parallel light.

  As the second light source 2b, a semiconductor laser (single beam) is used. The second light source optical system 20b includes a collimator lens 21b that collimates the light L2 emitted from the second light source 2b, and a cylindrical lens 22b that condenses light in the sub-scanning direction indicated by the parallel light arrow Y.

  In the first light source 2a and the second light source 2b, the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b differ in the sub-scanning direction indicated by the arrow Y. The arrangement of the first light source 2a and the second light source 2b and the optical path formed by the first light source optical system 20a and the second light source optical system 20b are set so as to enter the rotary polygon mirror 3 at an angle. Is done. Thereby, the optical path of the light L1 emitted from the first light source 2a and the optical path of the light L2 emitted from the second light source 2b are separated in the sub-scanning direction.

  The rotating polygon mirror 3 is an example of a deflector, which is called a polygon mirror, and scans the light incident on the rotating polygon mirror 3 in the main scanning direction by being rotated by a motor (not shown). The imaging optical system 6 includes a toroidal lens 60 and a cylindrical lens 61.

  The light L 1 emitted from the first light source 2 a is deflected in the direction of the image plane 4 by the incident angle to the rotary polygon mirror 3, and forms an image on the image plane 4 through the imaging optical system 6. The light L 2 emitted from the second light source 2 b is deflected in the direction of the synchronization sensor 5 by the incident angle to the rotary polygon mirror 3, and passes through the imaging optical system 6 and forms an image on the synchronization sensor 5.

  In this example, the image plane 4 is constituted by a photosensitive drum 40 on which an electrostatic latent image is formed, and the light L1 is scanned in the sub-scanning direction as the photosensitive drum 40 rotates. The synchronization sensor 5 outputs an electrical signal for generating a synchronization signal when the light L2 emitted from the second light source 2b is deflected by the rotary polygon mirror 3 and incident.

  The synchronization sensor 5 is an example of a light detection unit, and is provided at a position that does not block the optical path of the light L1 emitted from the first light source 2a, deflected by the rotary polygon mirror 3, and scanned in the main scanning direction. In this example, the synchronization sensor 5 has a maximum scanning optical path L10 in the main scanning direction and maximum scanning in the light L1 emitted from the first light source 2a, deflected by the rotary polygon mirror 3, and scanned in the main scanning direction. It is provided at a position that does not block the optical path of the light L1 scanned in the range inside the optical path L10.

  The mirror 7 is emitted from the second light source 2b and is deflected by the rotary polygon mirror 3 in the optical path of the light L2 that is deflected by the rotary polygon mirror 3, and is deflected by the rotary polygon mirror 3 in the main scanning direction. It is provided at a position that does not block the optical path of the light L1 to be scanned. Similarly to the synchronization sensor 5, the mirror 7 also emits the first light source 2 a, is deflected by the rotary polygon mirror 3, is scanned in the main scanning direction, and is scanned in the main scanning direction. It is provided at a position that does not block the optical path of the light L1 scanned in the range inside the maximum scanning optical path L10.

  The light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b are incident on the rotary polygon mirror 3 at different incident angles in the direction along the sub-scanning surface indicated by the arrow Y. Therefore, the light L1 deflected by the rotary polygon mirror 3 and scanned in the main scanning direction passes above or below the mirror 7, in this example, above the mirror 7.

  In the image forming apparatus including the scanning optical device 1A, as will be described later, toner is attached to the electrostatic latent image formed on the photosensitive drum 40, and the toner image is transferred and fixed on a sheet to form an image. .

  In the photosensitive drum 40 irradiated with light L1 emitted from the first light source 2a, deflected by the rotary polygon mirror 3 and scanned in the main scanning direction, outside the image forming area E1 along the main scanning direction, A register image area E2 is formed. In the scanning optical device 1A, the registration mark image area E2 is made to coincide with the maximum scanning optical path L10.

  On the other hand, the synchronization signal generation optical path L20 of the light L2 emitted from the second light source 2b, deflected by the rotary polygon mirror 3, and incident on the mirror 7 and the synchronization sensor 5 is emitted from the first light source 2a. It is arranged so as to overlap the maximum scanning optical path L10 of the light L1 in the direction along the main scanning plane indicated by the arrow X.

  However, the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b are incident on the rotary polygon mirror 3 at different incident angles in the direction along the sub-scanning surface indicated by the arrow Y. Since the light enters, the mirror 7 and the synchronization sensor 5 do not block the maximum scanning optical path L10.

  Thus, it is not necessary to provide an optical system for forming the synchronization signal generation optical path L20 further outside the maximum scanning optical path L10, and the imaging optical system 6 designed in accordance with the maximum scanning optical path L10 is used. The light L2 passing through the synchronization signal generation optical path L20 can be imaged on the synchronization sensor 5. Therefore, it is possible to reduce the size of the optical system.

<Modification of Scanning Optical Device of First Embodiment>
3 and 4 are configuration diagrams showing a modification of the scanning optical device according to the first embodiment, and FIG. 3 shows a scanning optical device 1B according to a modification of the first embodiment from the main scanning direction. FIG. 4 is a side view of a scanning optical device 1B according to a modification of the first embodiment viewed from the sub-scanning direction.

  The scanning optical device 1B according to the modification of the first embodiment has a configuration in which no mirror is provided in the synchronization signal generation optical path L20 by the light L2 emitted from the second light source 2b.

  The synchronization sensor 5 is provided at a position that does not block the optical path of the light L1 emitted from the first light source 2a, deflected by the rotary polygon mirror 3, and scanned in the main scanning direction. In this example, the synchronization sensor 5 is in the vicinity of the image plane 4 and is emitted from the first light source 2a, deflected by the rotary polygon mirror 3, and scanned in the main scanning direction. It is provided at a position that does not block the maximum scanning optical path L10 and the optical path of the light L1 scanned in the range inside the maximum scanning optical path L10.

  5 and 6 are configuration diagrams showing another modification of the scanning optical device according to the first embodiment. FIG. 5 shows a scanning optical device 1C according to another modification of the first embodiment. A side view seen from the sub-scanning direction, FIG. 6 is a side view seen from the sub-scanning direction of the scanning optical device 1C of another modification of the first embodiment.

  In the scanning optical device 1C according to another modification of the first embodiment, the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b are sub-scanned indicated by an arrow Y. The arrangement of the first light source 2a and the second light source 2b, and the first light source optical system 20a and the second light source optics so as to be incident on the rotary polygon mirror 3 at different heights in the direction along the surface. The optical path formed by the system 20b is set.

  Further, in the scanning optical device 1D of another modification of the first embodiment, the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b are indicated by arrows Y. The arrangement of the first light source 2a and the second light source 2b and the first light source optical system 20a so as to be incident on the rotary polygon mirror 3 at different incident angles and different heights in the direction along the sub-scanning plane. The optical path formed by the second light source optical system 20b is set. Note that both the scanning optical device 1C and the scanning optical device 1D may be configured not to include a mirror in the synchronization signal generation optical path L20 by the light L2 emitted from the second light source 2b.

<Operation Example of Scanning Optical Device of First Embodiment>
7 is an explanatory diagram schematically showing the position of light passing through the imaging optical system, FIG. 8 is a time chart showing the control timing of the synchronization signal and the image formation signal, and FIG. 9 is the light emission control and image formation. FIG. 3 is an explanatory diagram showing a positional relationship. Next, the operations of the scanning optical device 1A according to the first embodiment and the scanning optical devices 1B, 1C, and 1D according to the modified examples and the first embodiment. Differences between the scanning optical devices 1A, 1B, 1C, and 1D and the conventional scanning optical device will be described.

  In a conventional configuration in which a synchronization signal is generated, a registration mark image is formed, and an image is formed with a single light source, a registration mark image formation area E200 is formed outside the image formation area E100, and the maximum scanning optical path L100 of the registration mark image formation area E200. A synchronization signal generation optical path L200 is formed further outside.

  When the position of the light L passing through the imaging optical system 600 is schematically shown in FIG. 7B, the outer side of the imaging optical system 600 is further outside the passing position of the maximum scanning optical path L100 for forming a registration mark image. This is the passing position of the synchronization signal generation optical path L200. Thereby, it is necessary to extend the length of the lens constituting the imaging optical system 600 along the main scanning direction in accordance with the synchronization signal generation optical path.

  Further, when a multi-beam light source is used as a single light source, a light emission control pattern P100 at the time of generating a synchronization signal at the light emission points LD1 to LDn, a registration mark image, and a light emission control pattern P101 at the time of normal image formation are shown in FIG. 8 (b) shows a time chart.

  In a configuration in which a single light source generates a synchronization signal, forms a registration mark image, and forms an image, a synchronization signal generation optical path is provided outside the maximum scanning optical path constituting the registration mark image area. As a result, as shown in FIG. 8B, the synchronization signal generation optical path and the timing t20 until the light for forming the image is emitted from the timing t10 at which the light for generating the synchronization signal is emitted. A delay time t30 is generated due to the distance between the maximum scanning optical paths.

  Further, when a multi-beam light source is used as a single light source, the relationship between the light emission control pattern at the light emission points LD1 to LDn and the image forming position B100 is schematically shown in FIG. 9B. Here, in FIG. 9B, the light emission control pattern P100 at the time of generating the synchronization signal, the registration mark image, and the light emission control pattern P101 at the time of normal image formation are not time series but are positional relationships along the main scanning direction. Indicates.

  In the configuration in which the synchronization signal is generated, the registration mark image is formed, and the image formation is performed with a single light source, as shown in FIG. A synchronization signal generation optical path L200 is provided.

  In contrast, in the scanning optical devices 1A, 1B, 1C, and 1D of the first embodiment, the position of the light L1 emitted from the first light source 2a and passing through the imaging optical system 6, and the second light source The position of the light L2 emitted from 2b and passing through the imaging optical system 6 is schematically shown in FIG.

  In the scanning optical devices 1A, 1B, 1C, and 1D according to the first embodiment, in the imaging optical system 6, the synchronization signal generation optical path L20 is set with respect to the passing position of the maximum scanning optical path L10 for forming a registration mark image. The passing positions overlap in the main scanning direction indicated by the arrow X and are shifted in the sub-scanning direction indicated by the arrow Y. Thereby, the length along the main scanning direction of the lens constituting the imaging optical system 6 can be matched with the maximum scanning optical path L10 for forming the registration mark image.

Further, in the scanning optical devices 1A, 1B, 1C, and 1D of the first embodiment, the light emission control pattern P10 when the synchronization signal is generated in the second light source 2b (LD2), and the multi-beam light source as the first light source 2a In FIG. 8A, a registration mark image at the light emission points LD1 _{1 to} LD _1n and a light emission control pattern P11 during normal image formation are shown as a time chart in FIG.

  In the scanning optical devices 1A, 1B, 1C, and 1D of the first embodiment, the timing t1 at which the light for generating the synchronization signal is emitted by the second light source 2b and the light for forming the image are the first. The delay time t3 from the timing t2 until the light source 2a emits light may be arbitrary as long as it is a time necessary for generating the synchronization signal. Thereby, compared with the conventional apparatus using a single light source, the time until image formation can be shortened. Although the first light source 2a and the second light source 2b are separate light sources, there may be a timing shift due to an assembly error. However, due to the assembly error between the synchronization signal and the image signal. This can be done by adjusting the time difference.

Furthermore, in the scanning optical devices 1A, 1B, 1C, and 1D of the first embodiment, light emission control patterns in the light emission points LD1 _{1 to} LD _{1n of} the _first light source 2a and the second light source 2b (LD2). 9A schematically shows the relationship between the image forming position B10 and the image forming position B10. Here, in FIG. 9A, the light emission control pattern P10 at the time of generating the synchronization signal, the registration mark image, and the light emission control pattern P11 at the time of normal image formation are not time series but are positional relationships along the main scanning direction. Indicates.

  In the scanning optical devices 1A, 1B, 1C, and 1D of the first embodiment, as shown in FIG. 9A, the maximum scanning optical path L10 that can irradiate the image forming position B10 and the synchronization signal generation optical path L20. Can be at the same position in the main scanning direction indicated by arrow X.

<Configuration Example of Scanning Optical Device of Second Embodiment>
10 and 11 are configuration diagrams illustrating an example of the scanning optical device according to the second embodiment. FIG. 10 is a plan view of the scanning optical device 1E according to the second embodiment as viewed from the main scanning direction. FIG. 11 is a side view of the scanning optical apparatus 1E according to the second embodiment viewed from the sub-scanning direction. Here, in the scanning optical device 1E according to the second embodiment, members having the same configurations as those of the scanning optical devices 1A, 1B, 1C, and 1D according to the first embodiment will be described with the same numbers.

  In the scanning optical device 1E according to the second embodiment, the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b are along the main scanning plane indicated by the arrow X. And the arrangement of the first light source 2a and the second light source 2b and the first light source optics so as to be incident on the rotary polygon mirror 3 at different incident angles in the direction along the sub-scanning surface indicated by the arrow Y. An optical path formed by the system 20a and the second light source optical system 20b is set.

  In the direction along the main scanning plane indicated by the arrow X, the incident angle of the light L1 emitted from the first light source 2a with respect to the rotary polygonal mirror 3 is α1, and the rotational polygon of the light L2 emitted from the second light source 2b. When the incident angle with respect to the mirror 3 is α2, the arrangement of the first light source 2a and the second light source 2b and the first light source optical system 20a and the second light source optical system 20b are set so that α1 <α2. The optical path to be formed is set. Thereby, at an arbitrary deflection angle of the rotary polygon mirror 3, the light L1 emitted from the first light source 2a is imaged on the writing side from the light L2 emitted from the second light source 2b.

  In the direction along the sub-scanning plane indicated by the arrow Y, the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b are different in height from the rotating polygon mirror 3. The arrangement of the first light source 2a and the second light source 2b and the optical path formed by the first light source optical system 20a and the second light source optical system 20b may be set so as to be incident. .

  In the scanning optical device 1E, when the rotary polygon mirror 3 is set in the direction in which the light L2 emitted from the second light source 2 is incident on the synchronization sensor 5, the second light source 2b emits light L2 with respect to the light L2. The light L1 emitted from one light source 2a enters the rotary polygon mirror 3 at a shallow incident angle.

  Thereby, the light is emitted from the first light source 2a with respect to the synchronization signal generation optical path L20 of the light L2 emitted from the second light source 2b, deflected by the rotary polygon mirror 3, and incident on the mirror 7 and the synchronization sensor 5. The maximum scanning optical path L10 of the light L deflected by the rotary polygon mirror 3 and scanned on the photosensitive drum 40 is outside.

  However, the light L1 emitted from the first light source 2a and the light L2 emitted from the second light source 2b rotate at different incident angles or different heights in the direction along the sub-scanning surface indicated by the arrow Y. Since the light enters the polyhedral mirror 3, the mirror 7 and the synchronization sensor 5 do not block the maximum scanning optical path L10.

  Thus, it is not necessary to provide an optical system for forming the synchronization signal generation optical path L20 further outside the maximum scanning optical path L10, and the imaging optical system 6 designed in accordance with the maximum scanning optical path L10 is used. The light L2 passing through the synchronization signal generation optical path L20 can be imaged on the synchronization sensor 5. Therefore, it is possible to reduce the size of the optical system.

  Also in the scanning optical device 1E, as shown in FIGS. 3 and 4, the mirror may not be provided in the synchronization signal generation optical path L20 by the light L2 emitted from the second light source 2b.

<Operation Example of Scanning Optical Device of Second Embodiment>
12 is an explanatory diagram schematically showing the position of light passing through the imaging optical system, FIG. 13 is a time chart showing the control timing of the synchronization signal and the image formation signal, and FIG. 14 is the light emission control and image formation. It is explanatory drawing which shows the relationship of a position, Next, operation | movement of the scanning optical apparatus 1E of 2nd Embodiment is demonstrated.

  In the scanning optical apparatus 1E of the second embodiment, the position of the light L1 emitted from the first light source 2a and passing through the imaging optical system 6, and the imaging optical system 6 emitted from the second light source 2b. The position of the light L2 passing through is schematically shown in FIG.

  In the scanning optical device 1E of the second embodiment, in the imaging optical system 6, the passage position of the synchronization signal generation optical path L20 is the arrow X with respect to the passage position of the maximum scanning optical path L10 for forming a registration mark image. The position is shifted inward in the main scanning direction indicated by, and shifted in the sub-scanning direction indicated by arrow Y. Thereby, the length along the main scanning direction of the lens constituting the imaging optical system 6 can be matched with the maximum scanning optical path L10 for forming the registration mark image.

Further, in the scanning optical device 1E of the second embodiment, when the light emission control pattern P10 when the synchronization signal is generated in the second light source 2b (LD2) and a multi-beam light source is used as the first light source 2a, A registration mark image at the light emission points LD1 _{1 to} LD _1n and a light emission control pattern P11 at the time of normal image formation are shown as a time chart in FIG.

  In the scanning optical device 1E according to the second embodiment, the delay time t6 is set between the timing t4 when the light for generating the synchronization signal is emitted and the timing t5 until the light for forming the image is emitted. The The delay time t6 is a time necessary for generating the synchronization signal.

Furthermore, in the scanning optical device 1E of the second embodiment, the light emission points LD1 _{1 to} LD _{1n of} the _first light source 2a and the light emission control pattern in the second light source 2b (LD2) and the image forming position B10 This relationship is schematically shown in FIG. Here, in FIG. 14, the light emission control pattern P <b> 10 at the time of generating the synchronization signal, the registration mark image, and the light emission control pattern P <b> 11 at the time of normal image formation indicate not a time series but a positional relationship along the main scanning direction.

  In the scanning optical device 1E of the second embodiment, the rotating polygon mirror 3 has a shallow incident angle with respect to the light L2 emitted from the first light source 2a with respect to the light L2 emitted from the second light source 2b. Therefore, when the rotary polygon mirror 3 has the same deflection angle, the writing position by the light L1 emitted from the first light source 2a is located outside the light L2 emitted from the second light source 2b. Therefore, as shown in FIG. 14, the synchronization signal generation optical path L20 can be set inward in the main scanning direction indicated by the arrow X with respect to the maximum scanning optical path L10 that can irradiate the image forming position B10 with light. Thereby, in the imaging optical system 6, the width direction of the lens can be utilized to the maximum extent.

<Example of Configuration of Image Forming Apparatus of Embodiment>
FIG. 15 is a configuration diagram schematically showing the image forming apparatus according to the present embodiment. Next, the image forming apparatus S including any one of the scanning optical devices 1A to 1E according to the above-described embodiments will be described. To do.

  The image forming apparatus S is an electrophotographic image forming apparatus such as a copying machine. In this example, a plurality of photoconductors face a single intermediate transfer belt and are arranged in a vertical direction to form a full color image. This is a so-called tandem color image forming apparatus.

  The image forming apparatus S includes a document reading device SC, an image forming unit 100, a paper transport unit 200, and a fixing unit 300.

  The document reader SC scans and exposes an image of the document with the optical system of the scanning exposure device, reads the reflected light with a line image sensor, and obtains an image signal. The image forming apparatus S may have a configuration in which an automatic document feeder (not shown) that feeds a document is provided on the top.

  The image forming unit 100 includes an image forming unit 100Y that forms a yellow (Y) image, an image forming unit 100M that forms a magenta (M) image, and an image forming unit 100C that forms a cyan (C) image. The image forming unit 100BK forms a black (BK) image.

  The image forming unit 100Y includes a photosensitive drum Ye constituting the image surface 4 described with reference to FIG. 1 and the like, a charging unit 12Y disposed in the periphery thereof, and an optical writing unit 13Y that is one of the scanning optical devices 1A to 1E. A developing device 14Y and a drum cleaner 15Y are provided. Similarly, the image forming units 100M, 100C, and 100BK are any of the photosensitive drums M, C, and BK that form the image surface 4 and the charging units 12M, 12C, and 12BK, and the scanning optical devices 1A to 1E that are arranged in the periphery thereof. And optical writing units 13M, 13C, 13BK, developing devices 14M, 14C, 14BK and drum cleaners 15M, 15C, 15BK.

  The surface of the photosensitive drum Ye is uniformly charged by the charging unit 12Y, and a latent image is formed on the photosensitive drum Ye by scanning exposure by the optical writing unit 13Y. Further, the developing device 14Y develops the latent image on the photosensitive drum Ye by developing with toner. Thereby, an image (toner image) of a predetermined color corresponding to yellow is formed on the photosensitive drum Ye.

  Similarly, the surface of the photosensitive drum M is uniformly charged by the charging unit 12M, and a latent image is formed on the photosensitive drum M by scanning exposure by the optical writing unit 13M. Further, the developing device 14M develops the latent image on the photosensitive drum M by developing with toner. As a result, a toner image of a predetermined color corresponding to magenta is formed on the photosensitive drum M.

  The surface of the photosensitive drum C is uniformly charged by the charging unit 12C, and a latent image is formed on the photosensitive drum C by scanning exposure by the optical writing unit 13C. Further, the developing device 14C develops the latent image on the photosensitive drum C by developing with toner. As a result, a toner image of a predetermined color corresponding to cyan is formed on the photosensitive drum C.

  The surface of the photosensitive drum BK is uniformly charged by the charging unit 12BK, and a latent image is formed on the photosensitive drum BK by scanning exposure by the optical writing unit 13BK. Further, the developing device 14BK develops the latent image on the photosensitive drum BK by developing with toner. As a result, a toner image of a predetermined color corresponding to black is formed on the photosensitive drum BK.

  Images formed on the photoconductive drums Ye, M, C, and BK are sequentially transferred to predetermined positions on the intermediate transfer belt 16 that is a belt-like intermediate transfer member by primary transfer rollers 17Y, 17M, 17C, and 17BK. Transcribed.

  The image composed of each color transferred onto the intermediate transfer belt 16 is transferred by the secondary transfer roller 18 to the paper P transported at a predetermined timing by the paper transport unit 200. The secondary transfer roller 18 is disposed in pressure contact with the intermediate transfer belt 16 to form a transfer nip portion 19, and transfers the image onto the paper P while transporting the paper P.

  In this example, the paper transport unit 200 includes a plurality of paper feed trays 201 and a paper feed unit 202 that feeds the paper P from the paper feed tray 201. The paper transport unit 200 also reverses the front and back of the paper P from the main transport path 204 through which the paper P fed out by the paper feed unit 202 or the paper P fed from the external paper feed unit 203 is transported. A reverse conveyance path 205 is provided.

  The main transport path 204 constitutes a transport path from the paper feed unit 202 that feeds the paper P from the paper feed tray 201 to the paper discharge port 207 from which the paper P is discharged by the paper discharge roller 206. Note that the conveyance path from the external sheet feeding unit 203 merges with the main conveyance path 204 on the upstream side of the merge point between the main conveyance path 204 and the reverse conveyance path 205.

  The reverse conveyance path 205 branches from the main conveyance path 204 on the downstream side of the fixing unit 300, and includes a switching gate 208 at a branch point between the main conveyance path 204 and the reverse conveyance path 205. The reverse conveyance path 205 includes a first reverse conveyance path 209 that branches from the main conveyance path 204 and extends in a substantially horizontal direction below the main conveyance path 204. In the first reverse conveyance path 209, the conveyance direction of the paper P is reversed from the arrow D1 direction to the arrow D2 direction.

  The reverse transfer path 205 branches from the first reverse transfer path 209 upward in the transfer direction indicated by the arrow D2, and is bent from the second reverse transfer path 210 and the second reverse transfer path 210 that bend into a substantially U shape. And a third reverse conveyance path 211 extending along the first reverse conveyance path 209. Further, the reverse conveyance path 205 includes a fourth reverse conveyance path 212 that bends in a substantially U shape from the third reverse conveyance path 211 and joins the main conveyance path 204.

  In the image forming apparatus S, an image is formed on the surface of the paper P that has been transported through the main transport path 204 and passed through the transfer nip portion 19 and the fixing portion 300 and directed upward. When images are formed on both sides of the paper P, the paper P on which an image is formed on one side facing upward is conveyed from the main conveyance path 204 to the first reverse conveyance path 209 of the reverse conveyance path 205. The image forming surface faces downward.

  The sheet P transported to the first reverse transport path 209 is transported from the second reverse transport path 210 to the third reverse transport path 211, so that the image forming surface faces upward. Then, the sheet P transported to the third reverse transport path 211 is transported from the fourth reverse transport path 212 to the main transport path 204, so that the image forming surface faces downward. As a result, the paper P is turned upside down, and an image can be formed on the other side facing upward.

  The fixing unit 300 performs a fixing process for fixing the image on the paper P to which the image has been transferred. The fixing unit 300 includes a fixing roller 301 and a fixing roller 302 as a pair of fixing members arranged in pressure contact with each other, and a fixing nip portion 303 is formed by the fixing roller 301 and the fixing roller 302 being pressed against each other.

  In addition, the fixing unit 300 includes a fixing heater 304 that heats the fixing roller 301 as a heating unit that heats the fixing member. The fixing heater 304 is turned on by energization, and for example, a halogen lamp can be used. The fixing unit 300 conveys the paper P and fixes the image on the paper P by performing pressure fixing with the pair of fixing rollers 301 and 302 and heat fixing with the fixing heater 304.

  In the image forming apparatus S, the optical writing units 13Y, 13M, 13C, and 13BK are provided with any of the above-described scanning optical devices 1A to 1E, so that a registration mark image is formed outside the image forming area. It is not necessary to provide an optical system in which a synchronization signal generation optical path is formed further outside the maximum scanning optical path for forming an image. Thereby, the light passing through the synchronization signal generation optical path can be imaged on the synchronization sensor using the imaging optical system designed in accordance with the maximum scanning optical path. Therefore, it is possible to reduce the size of the optical system.

  The present invention is applied to a scanning optical device of an image forming apparatus used for a purpose such as bookbinding.

  DESCRIPTION OF SYMBOLS 1A, 1B, 1C, 1D, 1E ... Image forming apparatus, 2a ... 1st light source, 2b ... 2nd light source, 3 ... Rotary polygon mirror, 4 ... Image surface, 5 ... Synchronous sensor, 6 ... Image-forming optical system, 7 ... Mirror

Claims (4)

A first light source that emits light forming an image;
A second light source that emits light that generates a synchronization signal;
A deflector for deflecting light emitted from the first light source and light emitted from the second light source in a main scanning direction;
The light emitted from the first light source and deflected by the deflector is imaged on the image plane, and the light emitted from the second light source and deflected by the deflector is imaged on a light detection means. An imaging optical system
The light emitted from the first light source and the light emitted from the second light source are either the incident angle in the sub-scanning direction orthogonal to the main scanning direction with respect to the deflector, the incident position, or both. It was different,
2. A scanning optical apparatus according to claim 1, wherein a maximum scanning optical path of the light emitted from the first light source is outside in the main scanning direction with respect to the optical path of the light emitted from the second light source . 2. The scanning optical system according to claim 1, wherein the light emitted from the first light source and the light emitted from the second light source have different incidence angles in the main scanning direction with respect to the deflector. apparatus. An incident angle of light emitted from the first light source with respect to the deflector in a main scanning direction is smaller than an incident angle of light emitted from the second light source with respect to the deflector in the main scanning direction. The scanning optical apparatus according to claim 2 . An image forming unit for forming an image on paper;
The image forming unit includes the scanning optical device according to any one of claims 1 to 3.
An image forming apparatus.

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