JP2004177512A - Optical write-in device and image forming device equipped with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently radiate the heat generated in an optical deflector to the outside of an optical housing with a structure having a small number of components. <P>SOLUTION: The optical deflector 62 which deflects and scans a light beam emitted from a light source with polygon mirrors 62a and 62b is housed together with four optical systems 41, 42 and 43 which guide and focus respective light beams L1, L2, L3 and L4 onto respective photoreceptors 5 in the optical housing 50. An opening 31 is formed on an upper side housing 50a of the optical housing 50, an upper cover 32 is removably fitted to the opening 31, the optical deflector 62 is fitted on the cover 32. Thus, the heat generated in the optical deflector 62 is efficiently radiated from the upper cover 32. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical writing device that forms a light beam emitted from a light source and deflected and scanned by an optical deflector on a surface to be scanned by an optical system, and an image forming apparatus including the same.
[0002]
[Prior art]
As a conventional optical writing apparatus for forming an image of a light beam emitted from a light source and deflected and scanned by an optical deflector on a surface to be scanned by an optical system, for example, there is one described in Patent Document 1. .
[0003]
[Patent Document 1]
JP-A-2001-208997 (page 4, FIG. 6)
[0004]
In the above document, an optical deflector (polygon scanner) is provided in an optical housing, and a cover member made of an iron plate is provided at a position spaced from the optical deflector so that its outer surface is exposed outside the optical housing. By fitting one end of a heat transfer member made of an iron plate into the bearing portion of the light deflector and fixing the other end of the heat transfer member to the cover member with a screw, the heat generated by the light deflector is generated. There is described an optical writing device in which the generated heat is radiated from the cover member to the outside of the optical housing via the heat transfer member.
As a result, the optical deflector usually has a driving motor having a coil and a heat source such as a driver IC, a capacitor, and a resistor for driving the motor. While the heat is generated, an airflow is generated by the rotation of the polygon mirror of the optical deflector while the polygon mirror is rotating, so that the temperature around the optical deflector tends to rise. The heat can be efficiently dissipated.
Therefore, it is possible to prevent the Fθ lens, the long lens, and the like, which constitute the optical system normally arranged around the optical deflector, from being affected by heat. Changes in the writing position (beam spot position and beam diameter) can be prevented, and image degradation can be suppressed.
[0005]
[Problems to be solved by the invention]
However, the optical writing device described in Patent Document 1 has a configuration in which heat generated by the optical deflector serving as a heat source is radiated to the outside of the optical housing using a heat transfer member made of an iron plate. However, there is a disadvantage that the cost is increased by the amount required for the heat transfer member. Further, since the heat transfer member is accommodated in the optical housing, the optical housing may be enlarged accordingly.
The present invention has been made in view of the above problems, and has as its object to efficiently radiate heat generated by an optical deflector to the outside of an optical housing with a small number of components. I do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a light source, an optical deflector for deflecting and scanning a light beam from the light source, and a light beam deflected and scanned by the optical deflector on a surface to be scanned to form an image. An optical system, wherein the light source, the optical deflector, and the optical system are housed in one optical housing, a working opening is formed in the optical housing, and a lid member is detachably provided in the opening. In the optical writing device, the optical deflector is attached to the lid member.
It is preferable that a lens constituting the optical system is also attached to the lid member. Further, a handle having a lower thermal conductivity than the lid member may be attached to the outside of the lid member. Further, when the optical deflector has a substrate, the substrate may also serve as a lid member.
Further, the present invention also provides an image forming apparatus provided with any one of the above optical writing devices.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing an embodiment of an optical writing device according to the present invention, and FIG. 2 is an overall configuration diagram showing an example of a small color printer which is an image forming apparatus using the optical writing device. .
The color small printer shown in FIG. 2 is a four-drum full-color electrophotographic image forming apparatus. In the apparatus main body 1, four photoconductor units 2A, 2B, 2C, and 2D as image carrier units are provided. Are detachably attached to the apparatus main body 1.
In this small-sized printer, a transfer belt 3 is installed at a substantially center in the apparatus main body 1 so as to be rotatable in a direction indicated by an arrow A between a plurality of rollers.
The photoreceptor units 2A to 2D are provided such that the photoreceptor drums 5 provided for the four photoreceptor units 2A, 2B, 2C, and 2D contact the upper surface of the transfer belt 3 in FIG. 2D is provided. The photoreceptor units 2A to 2D are, from right to left in FIG. 2, a photoreceptor unit 2A for yellow, a photoreceptor unit 2B for magenta, a photoreceptor unit 2C for cyan, and a photoreceptor unit for black. Although they are arranged in the order of the body units 2D, the arrangement order may be other than that.
The photoconductor units 2A to 2D are provided with developing devices 10A to 10D that use different toner colors, respectively. An optical writing device 6 is provided above the photoreceptor units 2A to 2D, and a double-sided unit 7 is provided below.
[0008]
Downstream of the transfer belt 3 in the transfer paper transport direction, a fixing device 9 for fixing the image of the transfer paper on which the image has been transferred is provided.
On the downstream side of the fixing device 9 in the transfer paper transport direction, a reverse transport path 20 is formed by branching, and the transfer paper P transported there is allowed to be discharged onto a discharge tray 26 by a pair of discharge rollers 25. .
In the lower part of the apparatus main body 1, paper feed cassettes 11 and 12 capable of storing transfer paper P having different sizes in two upper and lower tiers are provided, respectively.
Further, a manual tray 13 is provided on the right side of the apparatus main body 1 so as to be openable and closable in a direction indicated by an arrow B, and the manual tray 13 is opened so that manual paper can be fed therefrom.
The photoconductor units 2A to 2D are units having the same configuration. The photoconductor unit 2A forms an image corresponding to yellow, the photoconductor unit 2B forms an image corresponding to magenta, and 2C forms an image corresponding to cyan, and the photoconductor unit 2D forms an image corresponding to black. Each of the photoconductor units 2A to 2D is provided with a charging roller 14 for charging the charged surface of each photoconductor drum 5.
[0009]
In this small printer, when an image forming operation is started, each photosensitive drum 5 rotates clockwise in FIG. Then, the surface of each photosensitive drum 5 is uniformly charged by applying a voltage between the photosensitive drum 5 and the charging roller 14 of each charging device.
Then, the charged surface of the photosensitive drum 5 of the photosensitive unit 2A is irradiated with laser light corresponding to a yellow image by the optical writing device 6.
A laser beam corresponding to a magenta image is applied to the charged surface of the photoconductor drum 5 of the photoconductor unit 2B by the optical writing device 6, and a cyan color is applied to the charged surface of the photoconductor drum 5 of the photoconductor unit 2C. The laser beam corresponding to the black image is applied to the charged surface of the photosensitive drum 5 of the photosensitive unit 2D, and a latent image corresponding to each color is formed thereon. You.
Each of the latent images reaches the positions of the developing devices 10A, 10B, 10C, and 10D by rotating the photosensitive drum 5, where the latent images are developed by the yellow, magenta, cyan, and black toners, thereby forming four colors. Of the toner image.
[0010]
On the other hand, the transfer paper P is fed from the selected paper feed tray in the paper feed cassette 11 or 12 by the separation paper feed unit 55 or 56, and is transferred to the registration roller pair provided immediately before the photoconductor unit 2A. Due to 59, the toner image is conveyed between the photoconductive drum 5 of the photoconductive unit 2A and the transfer belt 3 at an accurate timing coincident with the toner image formed on each photoconductive drum 5.
At this time, the transfer paper P is charged to a positive polarity by the paper suction roller 58 disposed near the entrance of the transfer belt 3, and thereby electrostatically attracted to the surface of the transfer belt 3.
Then, while the transfer paper P is attracted to the transfer belt 3 and is conveyed in the same direction by the rotation of the transfer belt 3 in the direction of arrow A, yellow, magenta, cyan, and cyan The black toner images are sequentially transferred, and when passing through the photoreceptor unit 2D, a full-color toner image of four colors is formed.
The transfer paper P is melted and fixed by applying heat and pressure to the transfer paper P in the fixing device 9, and then passes through a paper discharge system according to a designated mode, and is passed through a paper discharge tray 26 at the top of the apparatus main body. , Or straight out of the fixing device 9 and straight out.
Thereafter, when an instruction to form two or more images is given, the above-described image forming process is repeated.
[0011]
The optical writing device 6 includes four light source units 51, 52, 53, and 54 each of which emits a light beam toward two polygon mirrors 62a and 62b arranged vertically as shown in FIG. An optical deflector 62 having the above-described polygon mirrors 62a and 62b that deflects and scans by rotating a light beam from each light source, and a light beam L ₁ shown in FIG. There are provided four optical systems 41, 42, 43, and 44 for guiding L ₂ , L ₃ , and L ₄ onto the respective photosensitive drums 5 serving as surfaces to be scanned and forming images.
The four light source units 51, 52, 53, and 54, the optical deflector 62, and the four optical systems 41, 42, 43, and 44 are housed in one optical housing 50. The optical housing 50 includes an upper housing 50a and a lower housing 50b. An opening 31 for work is formed in the upper housing 50a, and an upper cover 32 serving as a lid member can be detached from the opening 31. Attached. The optical deflector 62 is attached to the upper cover 32.
[0012]
The optical system 41 includes optical members such as an Fθ lens 63, a long lens 69, and mirrors 67, 73, and 74 for turning back the optical path.
Similarly, the optical system 42 includes optical members such as an Fθ lens 63, a long lens 70, and mirrors 65, 75, and 76 for turning back the optical path, which are common to the optical system 41.
Further, the optical system 43 includes optical members such as an Fθ lens 64, a long lens 71, and mirrors 66, 77, and 78 for turning back the optical path.
The optical system 44 includes optical members such as an Fθ lens 64, a long lens 72, and mirrors 68, 79, and 80 for turning back the optical path, which are common to the optical system 43.
The optical writing device 6 is provided with the polygon mirror 62a of the optical deflector 62 at a predetermined timing from each of the four light source units 51, 52, 53, and 54 (the arrangement positions thereof can be changed as appropriate). , 62b, the light beams L ₁ , L ₂ , L ₃ , L ₄ are deflected and scanned in two symmetric directions (left and right directions in FIG. 1) as shown in FIG. .
The optical deflector 62 includes a driver IC, a capacitor, a resistor, and the like, and further includes electrical components for controlling the rotation of a polygon motor that rotates the polygon mirrors 62a and 62b.
The optical deflector 62 is attached to the upper cover 32 as described above, and the upper cover 32 with the optical deflector 62 fixed to the inner surface side is used as a cover for covering the upper part of the optical writing device 6. It is attached to substantially the center of the upper housing 50a that functions.
The upper cover 32 is formed of a metal such as aluminum in consideration of heat radiation.
[0013]
The optical writing device 6 shown in FIG. 1 converts the color-separated image data input from the control system into a signal for driving a light source, and accordingly converts each of the light source units 51, 52, 53, and 53 shown in FIG. The light source (semiconductor laser) 54 is driven to emit a light beam. The light beams L ₁ , L ₂ , L ₃ , L ₄ emitted from the respective light source units 51, 52, 53, 54 pass through a cylindrical lens for surface tilt correction to reach the optical deflector 62, and are shown in FIG. The upper and lower polygon mirrors 62a and 62b, which are rotated at a constant speed by the polygon motor of the optical deflector 62, deflect and scan in two symmetric directions.
The light beam is irradiated by the four optical systems 41, 42, 43 and 44 onto the respective photosensitive drums 5 corresponding to the respective color images, and the electrostatic latent images are written there.
Incidentally, the optical deflector 62 has a driving polygon motor having a coil as described above, a driver IC and a capacitor for driving the motor, and a heat source such as a resistor. Therefore, during driving, heat is generated from these heat sources. Further, when the polygon mirrors 62a and 62b are rotating, air flows are generated around the polygon mirrors 62a and 62b, so that the temperature around the optical deflector 62 tends to rise.
[0014]
However, in the small printer including the optical writing device 6 according to this embodiment, the optical deflector 62 is directly attached to the upper cover 32 made of a metal such as aluminum in consideration of heat dissipation as described above. (For example, the metal yoke portion covering the coil portion of the motor is directly fixed).
Thus, the heat generated from the heat source is efficiently radiated to the outside of the upper housing 50a through the upper cover 32 having excellent heat radiation.
Therefore, the Fθ lenses 63, 64 and the long lenses 69 to 72, which constitute the optical systems 41, 42, 43, 44 disposed around the optical deflector 62, are adversely affected by the temperature rise. Since there is no change, it is possible to prevent a change in the writing magnification and a change in the writing position (beam spot position and beam diameter), and suppress deterioration of the image.
Furthermore, since the heat generated by the optical deflector is not radiated to the outside of the optical housing by using a heat transfer member made of an iron plate as seen in a conventional optical writing device, The number of parts can be reduced by the amount that a dedicated heat transfer member is not required, and the cost can be reduced. In addition, the optical housing can be reduced in size because the heat transfer member does not need to be provided in the optical housing.
[0015]
FIG. 4 is a configuration diagram similar to FIG. 1 showing an embodiment of an optical writing device in which an upper cover to which an optical deflector is fixed is fixed to a positioning projection formed on an optical housing by screws. The same reference numerals are given to the portions to be performed.
The optical writer according to this embodiment is different from the optical writer described with reference to FIGS. 1 to 3 in that the fixing of the upper cover 32 ′ as the cover member to the optical housing 50 ′ is performed by projecting the lower housing 50 b ′. The difference is that screws 29 are fixed to respective screw holes formed in the plurality of positioning projections 28 provided.
The upper cover 32 'is also made of a metal such as aluminum in consideration of heat dissipation. An elastic member 34, for example, a sponge, is provided over the entire periphery between the upper periphery of the upper cover 32 'and the upper surface of the upper housing 50a' in order to increase the degree of sealing.
As described above, in this optical writing device, the upper cover 32 ′ integrally fixing the optical deflector 62 is fixed to the plurality of positioning projections 28, 28 integrally formed on the lower housing 50 b ′ with the screws 29. Since each of the optical deflectors 62 is tightened and fixed, the optical deflector 62 can be positioned with high mounting position accuracy with respect to the lower housing 50b '. Accordingly, a stacking error relating to the positional relationship between the optical deflector 62 and each of the optical systems 41 to 44 is reduced, so that a more accurate writing magnification and writing position (beam spot position and beam diameter) can be obtained. it can.
[0016]
FIG. 5 is a configuration diagram similar to FIG. 4 showing an embodiment of an optical writing device in which a lens constituting an optical system is integrally fixed to an upper cover, and portions corresponding to FIG. Is attached.
The optical writer according to this embodiment is different from the optical writer described with reference to FIG. 4 in that an Fθ lens 63 constituting the optical systems 41 and 42 and an Fθ lens 64 constituting the optical systems 43 and 44 are provided. Are fixed to the lower surface side of an upper cover 32 ″ which is a lid member.
Also in this optical writing device, the optical deflector 62 is fixed to the upper cover 32 ", and the upper cover 32" closes the opening 31 of the upper housing 50a ". A plurality of positioning projections 28, 28 integrally formed by molding with a resin at 50b ″ are tightened and fixed by respective screws 29.
The upper cover 32 "is also formed of a metal such as aluminum in consideration of heat radiation. The Fθ lenses 63 and 64 are fixed (for example, bonded) to the upper cover 32" as described above. Lenses 63 and 64 are more effectively cooled than when the Fθ lenses 63 and 64 are fixed (for example, bonded) to the lower housing 50b ″ made of resin.
Therefore, it is possible to prevent a change in the writing magnification and a change in the writing position (beam spot position and beam diameter) caused by a thermal effect due to an increase in the temperature of the Fθ lenses 63 and 64, which are the optical elements, to prevent the image from being changed. Deterioration can be suppressed.
[0017]
FIG. 6 is a perspective view showing an example of an upper cover with a handle attached to the outside.
The upper cover 82 is provided with handles 83, 83 having a lower thermal conductivity than the cover portion 82a serving as a lid member on the outer surface of the upper cover 32, 32 ', 32 "of each embodiment described above by screwing. It is attached by caulking or the like.
That is, the cover 82a is formed of a metal such as aluminum in order to improve heat dissipation, and the two substantially U-shaped handles 83, 83 attached thereto are formed by, for example, resin molding. The handle 83 has a lower thermal conductivity than the cover 82a.
With this configuration, for example, the aluminum cover portion 82a has a heat conductivity of 100 W / m · K, and thus has high heat dissipation. On the other hand, the thermal conductivity of the handle 83 formed by resin molding is generally about 0.2 to 5 W / m · K, so that the thermal conductivity is considerably lower than that of aluminum. Thus, even when the cover portion 82a is hot, the handle 83 is not so hot, so that the handle 83 is not hot.
Therefore, if the upper cover 82 is formed and used in a size corresponding to each of the above-described upper covers 32, 32 ', and 32 ", for example, after the device has been continuously used for a long time, for example, the inside of the optical housing can be removed. When it becomes necessary to replace parts (optical elements) or the like that constitute the optical system, even if the user lifts the upper cover 82 by holding the handle 83, the handle 83 is not hot and cannot be held.
[0018]
FIG. 7 is a configuration diagram similar to FIG. 1 showing an embodiment of an optical writing device in which a substrate of an optical deflector also serves as an upper cover, and portions corresponding to FIG. 1 are denoted by the same reference numerals. .
The optical writing device according to this embodiment is different from the optical writing device described with reference to FIG. 1 in that an optical deflector 92 has a large substrate 94, and the substrate 94 also serves as an upper cover serving as a lid member. The difference is that the substrate 94 is fixed to the plurality of positioning projections 28 projecting from the lower housing 100b of the optical housing 100 with screws 29, respectively.
In the fixed state, the opening edge 31a of the upper housing 100a has a positional relationship corresponding to the peripheral edge of the substrate 94, and the degree of sealing is increased between the opening edge 31a and the peripheral edge. For example, an elastic member 34 such as a sponge is provided over the entire circumference.
[0019]
According to this optical writing device, a dedicated upper cover serving as a cover member is not required, and the heat generated by the polygon motor and other heating elements of the optical deflector 92 provided in the optical housing 100 is transferred to the substrate 94. Since heat can be directly radiated from the optical housing 100 to itself, the heat radiation effect is further enhanced.
Therefore, a change in the writing magnification and a change in the writing position (beam spot position and beam diameter) caused by the thermal displacement of the Fθ lenses 63 and 64 and the long lenses 69 to 72 due to the temperature rise in the optical housing 100. This can prevent deterioration of the image. Further, the cost can be reduced by the amount that the exclusive upper cover made of aluminum or the like is not required.
Although FIG. 7 shows an example of the optical writing device in which the substrate 94 also serves as the upper cover, it is needless to say that the Fθ lenses 63 and 64 are provided on the lower surface side of the substrate 94 or the upper surface side (external (Exposed side) may be provided with the handle 83 as described in FIG.
In each of the above-described embodiments, an example of the optical writing device in which there are four light source units serving as light sources has been described. However, the present invention is similarly applicable to a device having only one light source. Can be.
2 can be replaced with the optical writer described in FIGS. 4, 5, and 7 instead of the optical writer 6. The same operation and effect are obtained.
[0020]
【The invention's effect】
As described above, according to the present invention, since the optical deflector serving as a heat source in the optical housing is attached to the lid member detachably provided at the opening of the optical housing, the heat generated by the optical deflector is provided. Can efficiently radiate heat to the outside of the optical housing while having a configuration with a small number of components. As a result, when the temperature of the optical system in the optical housing rises, it is possible to suppress the deterioration of the image due to the change in the writing magnification and the writing position due to the thermal influence.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of an optical writing device according to the present invention.
FIG. 2 is an overall configuration diagram showing an example of a small color printer which is an image forming apparatus using the optical writing device.
FIG. 3 is a perspective view illustrating four light source units provided in the optical writing device of FIG. 1;
FIG. 4 is a configuration diagram similar to FIG. 1 showing an embodiment of an optical writing device in which an upper cover to which an optical deflector is fixed is fixed to a positioning projection formed on an optical housing by screws.
5 is a configuration diagram similar to FIG. 4 showing an embodiment of an optical writing device in which a lens constituting an optical system is integrally fixed to an upper cover.
FIG. 6 is a perspective view showing an example of an upper cover having a handle attached to the outside.
FIG. 7 is a configuration diagram similar to FIG. 1, showing an embodiment of an optical writing device in which a substrate of an optical deflector also serves as an upper cover.
[Explanation of symbols]
6: Optical writing device 31: Openings 32, 32 ', 32 ": Upper cover (lid member)
41, 42, 43, 44: optical systems 50, 50 ', 50 ", 100: optical housings 51, 52, 53, 54: light source unit (light source)
62, 92: optical deflector 82: upper cover 82a: cover (cover member) 83: handle 94: substrate

Claims (5)

A light source, an optical deflector that deflects and scans a light beam from the light source, and an optical system that guides and forms an image of the light beam deflected and scanned by the optical deflector on a surface to be scanned. An optical writing device in which a container and an optical system are housed in one optical housing, a working opening is formed in the optical housing, and a lid member is detachably provided in the opening.
An optical writing device, wherein the optical deflector is attached to the lid member. The optical writing device according to claim 1, wherein a lens constituting the optical system is also attached to the lid member. 3. The optical writing apparatus according to claim 1, wherein a handle having a lower thermal conductivity than the lid member is attached to an outer side of the lid member. 4. The optical writing device according to claim 1, wherein the optical deflector has a substrate, and the substrate also serves as the lid member. 5. An image forming apparatus comprising the optical writing device according to claim 1.

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