JP3199864B2 - Laser optical system unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser optical system unit for emitting laser light, and more particularly, to a laser light receiving surface,
For example, it relates to a laser optical system unit for scanning (image exposure) the outer peripheral surface of a photoconductor.

[0002]

2. Description of the Related Art Conventionally, an electronic copying apparatus has been used for image exposure using a laser beam in order to form an electrostatic latent image corresponding to an image on a photosensitive layer disposed on the surface of a photosensitive drum. A laser scanning unit is provided. Further, in this electrophotographic apparatus, the electrostatic latent image formed on the photosensitive layer is developed by a developing device using toner, the developed visual image is transferred to a sheet, and the toner image transferred to the sheet is transferred. Is fixed by a fixing device so that a toner image (copy image) corresponding to the original image is formed on the sheet.

[0003]

Here, in a conventional laser scanning unit, in order to reduce the manufacturing cost, the fθ lens is manufactured from plastic. However, when a plastic fθ lens is used, it expands / contracts according to the temperature inside the unit. And this plastic f
The scanning width on the photosensitive layer as the light receiving surface becomes longer or shorter depending on the expansion / contraction of the θ lens. On the other hand, the effective scanning width on the photosensitive layer is kept constant. As a result, when the temperature inside the unit rises and the plastic fθ lens expands and the scanning width is lost, both ends are limited to the effective scanning width described above, and both ends of the image are substantially cut off. The phenomenon occurs, and improvement is demanded. Such a change in the scanning width depending on the temperature in the unit is not limited to that the fθ lens is made of plastic. It is.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser optical system unit capable of maintaining a constant scanning width regardless of a temperature change in the unit. Is the thing.

[0005]

In order to solve the above-mentioned problems and achieve the object, a laser optical system unit according to the present invention is provided in a unit housing, and is disposed in the unit housing, and converts laser light into image information. Laser output means that modulates and outputs the laser light according to the above, a rotating mirror for deflecting the laser light emitted from the output from the laser output means, and an fθ lens for scanning the laser light deflected by the rotating mirror Reflecting means for guiding a laser beam scanned by the fθ lens to a light receiving surface provided outside the unit housing via an opening formed in the unit housing; and a laser beam on the light receiving surface. And a scanning width holding means for keeping the scanning width constant with respect to a temperature change.

Further, in the laser optical system unit according to the present invention, the scanning width holding means is interposed between the unit housing and the apparatus main body provided with the light receiving surface, and the temperature in the unit housing is maintained. And a bimetal that adjusts the optical path length from the fθ lens to the light receiving surface in accordance with Further, in the laser optical system unit according to the present invention, the bimetal is, as the temperature inside the unit housing increases,
It is characterized in that the optical path length is changed so that the optical path length becomes shorter and the lower the temperature in the unit housing becomes, the longer the optical path length becomes. In the laser optical system unit according to the present invention,
The bimetal is attached to a mounting means for mounting the unit housing to the apparatus main body. Further, in the laser optical system unit according to the present invention, the bimetal is attached so as to be displaced along a direction parallel to a direction in which the laser light is incident on the light receiving surface.

Further, in the laser optical system unit according to the present invention, the scanning width holding means includes a temperature detecting means for detecting a temperature in the unit housing, and the fθ lens based on a detection result of the temperature detecting means. And an optical path length adjusting means for adjusting an optical path length to the light receiving surface. Further, in the laser optical system unit according to the present invention, the optical path length adjusting means is shortened when the temperature detecting means determines that the temperature inside the unit housing is high, and the optical path length adjusting means is provided inside the unit housing. When the temperature is determined to be low, the optical path length is adjusted so as to be longer. In the laser optical system unit according to the present invention,
The optical path length adjusting means moves the unit housing along a direction parallel to a direction in which the laser light is incident on the light receiving surface. Further, in the laser optical system unit according to the present invention, the fθ lens is made of plastic.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of an embodiment of a laser optical system unit according to the present invention applied to a facsimile machine.

The facsimile machine 10 of this embodiment is
As shown in FIG. 1, image information of a transmission original in which a plurality of sheets are set at one time is automatically read one by one, and the read image information is transmitted to a facsimile apparatus on the other party's receiving side using a telephone line. Then, the image information transmitted from the facsimile machine on the partner transmission side is transferred to a built-in paper (cut plain paper in this embodiment) via an electrophotographic method using a laser scanning method (image formation). ). On the other hand, the facsimile apparatus 10 is configured to have a so-called electronic copying function that can copy (image formation) image information read from a document onto a built-in sheet. Further, the facsimile apparatus 10 has a so-called printer function that can transfer (image formation) image information transmitted from, for example, an information processing apparatus to a built-in sheet via a connection line other than a telephone line. It is configured.

The facsimile apparatus 10 includes a main plate 1 disposed substantially parallel to a mounting surface thereof.
2, a print mechanism 14 mounted on the upper surface of the main plate 12 and performing the above-described image forming function, and pivotally supported by the rear end of the main plate 12 so as to swing with respect to the main plate 12. A possible swing frame 16,
An image reading mechanism 18 arranged on the upper surface of the swing frame 16 and having the above-described image reading function, and a rear end rotatably supported at an intermediate portion of the swing frame 16,
A control panel 20 that can swing with respect to the swing frame 16, a lower frame 22 that is fixed to the left and right sides of the lower surface of the main plate 12 described above, and that extends in the front-rear direction, respectively. The laser as a laser optical system unit according to the present invention, which is arranged in a space to be mounted and attached to the lower surface of the main plate 12 and has a function of forming a latent image on the outer peripheral surface of the photosensitive drum 24 in the printing mechanism 14 A scanning unit 26 and four legs 28 fixed to the front and rear ends of the lower surface of each lower frame 22 described above, respectively, and mounted on a mounting surface (not shown) are roughly provided.

As described above, in this embodiment,
The laser scanning unit 26 includes the main plate 1
2 is set to be attached to the lower surface. The laser scanning unit 26 is set so that a part thereof (specifically, a port for extracting a laser beam for image exposure to the photosensitive drum 24) projects toward the upper surface of the main plate 12. Here, if the leg 28 is attached to the lower surface of the lower housing 30 and the lower housing 30 is configured to receive a load via the leg 28, the laser scanning unit 26 will be mounted unless the lower housing 30 is assembled in advance. It becomes difficult to assemble, and a great restriction is imposed on the work order, resulting in extremely poor workability. However, in this embodiment, the legs 28 for receiving the load are connected to the lower frame 22 in a state independent of the lower housing 30.
The laser scanning unit 26
Can be assembled to the lower surface of the main plate 12 at any time after the lower frame 22 has been assembled to the main plate 12, so that the degree of freedom in workability can be increased and workability can be improved. .

Next, the structure of the laser scanning unit 26 of this embodiment will be described in detail with reference to FIGS. The laser scanning unit 26 is mounted on the main plate 1 of the facsimile machine 10 to which the laser scanning unit 26 is mounted.
2 has a unit housing 32 attached to the lower surface thereof. In the unit housing 32, as shown in FIG. 2, a collimator 34 provided with a semiconductor laser (to be described later) and a polygon mirror (rotating polygon mirror) 36 for deflecting the laser light oscillated from the collimator 34
And the laser light deflected by the polygon mirror 36,
An fθ lens 38 as an imaging lens for scanning at a constant linear velocity on a light receiving surface (that is, a photosensitive layer formed on the outer peripheral surface of the photosensitive drum 24), and a laser beam scanned by the fθ lens 38 A first reflecting mirror 40 for once reflecting downward, and a second reflecting mirror 42 for reflecting the laser light reflected by the first reflecting mirror 40 upward. Provided roughly. Note that this f
The θ lens 38 is formed of plastic in this embodiment.

In this embodiment, the laser beam scanned by the polygon mirror 36 passes through the opening 32a formed in the upper part of the unit housing 32 in the thickness direction as shown in FIG. The photosensitive drum 20 having a photosensitive layer as a light receiving surface on the outer peripheral surface is set to be image-exposed. This opening 32
“a” is formed over substantially the entire width of the upper surface of the unit housing 32 along the scanning direction of the laser beam, and the toner as the developer dropped from the photosensitive drum 24 is supplied to the unit housing 32 through the opening 32a. In order to prevent intrusion into the inside 26, it is entirely covered with a cover glass 44.

Further, as shown in FIG.
The third reflection mirror 4 is provided on the bottom surface of the unit housing 32 in a state where the laser light scanned in the step 6 is located on one side outside the scanning range corresponding to the image forming range on the light receiving surface.
6 is mounted. On the other hand, in a state positioned on the other side outside the scanning range, the light receiving element 48 receiving the laser beam reflected by the third reflecting mirror 46 is connected to the unit housing 32.
It is fixed on the bottom surface. In this embodiment, the light receiving element 48 is set so as to function as a beam detector for detecting a horizontal synchronizing signal.

Here, as shown in FIG. 1, the laser scanning unit 26 is mounted on the lower surface of the main plate 12. Specifically, as shown in FIG. 4, the unit housing 32 of the laser scanning unit 26
The upper surface of the main plate 12
It is attached to the lower surface of. The mounting mechanism 50 includes a mounting piece 52 fixed to each of three points on the upper surface of the unit housing 32, a bimetal 54 mounted on each mounting piece 52 in a cantilevered manner, and a tip of each bimetal 54 attached to the main plate 12. And a fixing screw (not shown) for fixing to the lower surface of the device.

Further, each bimetal 54 has an inclination angle (similar to an incident angle α (specifically, an angle between the incident direction and the vertical axis) of the laser beam to the photosensitive layer of the photosensitive drum 24 as a light receiving surface. Specifically, it is set so as to be displaced in accordance with a temperature change at an angle formed by a vertical axis. In other words, each bimetal 54 is set to be displaceable along the direction of incidence of the laser beam on the photosensitive layer. Each bimetal 54 is set so as to be affected by the temperature inside the unit housing 32.
It is made to be displaced by the temperature inside. Therefore,
When the temperature inside the unit housing 32 changes, the length of the optical path length between the plastic fθ lens 38 and the light receiving surface changes with the change in the temperature.

More specifically, each bimetal 54 is displaced so that the length of the above-mentioned optical path length becomes shorter as the temperature inside the unit housing 32 becomes higher, so that the unit housing 32 serves as a light receiving surface. As the temperature near the photosensitive layer of the photosensitive drum 24 and the temperature inside the unit housing 32 decrease, the above-described optical path length is displaced so that the length of the optical path becomes longer, and accordingly, the unit housing 32 is separated from the photosensitive layer. It is set as follows.

On the other hand, the above-mentioned plastic fθ lens 38 expands as the temperature inside the unit housing 32 rises and is heated, so that the scanning width on the photosensitive layer is increased and the unit housing 32 is expanded. As the temperature in the inside 32 is lowered and cooled, the size is reduced and the scanning width on the photosensitive layer is reduced. However, in this embodiment, as described above, the distance between the unit housing 32 and the photosensitive drum 24 changes in accordance with the temperature change in the unit housing 32, and therefore, as shown in FIG.
The effective print width W is kept constant irrespective of the temperature change in the unit housing 32.

As described above, in this embodiment, the temperature inside the unit housing 32 rises with the driving of the laser scanning unit 26.
The printing width on the photosensitive layer is kept substantially constant by the action of the bimetal 54 which is displaced by the influence of the temperature. Even if the fθ lens 38 is formed of plastic, the printing state is maintained well. You can do it.

It is needless to say that the present invention is not limited to the configuration of the above-described embodiment, but can be variously modified without departing from the gist of the present invention. For example, in the above-described embodiment, the fθ lens is described as being made of plastic. However, the present invention is not limited to such a configuration, and may be applied to, for example, an fθ lens made of glass. It goes without saying that you can do it. Also,
In the above-described embodiment, the bimetal 54 is used as a means for keeping the printing width on the photosensitive layer as the light receiving surface constant regardless of the temperature inside the unit housing 32. The present invention is not limited to such a configuration, and as shown in FIG.
You may comprise.

Hereinafter, the configuration of another embodiment of the present invention will be described.
This will be schematically described with reference to FIG. That is, as shown in FIG. 6, the unit housing 32 and the main plate 12 are attached to each other via a movable attachment mechanism 56 as an optical path length adjusting means. This movable mounting mechanism 56
Are fixed to the unit housing 32, three drive motors 58, a pinion 60 fixed coaxially to the motor shaft 58 b of each drive motor 58, and fixed to the main plate 12 and meshed with each pinion 60. A rack 62 is provided. Here, the moving direction of each rack 62 is set to be parallel to the direction of incidence of the laser beam on the photosensitive layer.

On the other hand, inside the unit housing 32, a temperature sensor 64 for measuring the temperature inside the unit housing 32 is provided. The temperature sensor 64 is connected to a control unit 66, and the control unit 66 is connected to the drive motor 58 described above. Here, the control unit 66 is configured to control the driving direction and the driving amount of the driving motor 58 based on the detection result from the temperature sensor 64. Specifically, the control unit 66 controls the drive motor 58 so as to shorten the above-described optical path length as the detected temperature in the unit housing 32 increases, and accordingly, the unit housing 32 The drive motor 58 is controlled so that the above-described optical path length becomes longer as the detected temperature in the unit housing 32 becomes lower as the photosensitive layer becomes closer to the photosensitive layer of the photosensitive drum 24. Reference numeral 32 is configured to be separated from the photosensitive layer.

As described above, by constructing the embodiment shown in FIG. 6, the same effect as that of the above-described embodiment can be obtained. That is, even if the plastic fθ lens 38 is used, the temperature change in the unit housing 32 can be prevented. Irrespective of this, the effect that the printing width on the photosensitive layer can be kept constant can be achieved.

[0024]

As described in detail above, the laser optical system unit according to the present invention is provided with a unit housing and a laser output which is disposed in the unit housing and modulates and outputs laser light according to image information. Means, a rotating mirror for deflecting the laser light emitted from the output from the laser output means, an fθ lens for scanning the laser light deflected by the rotating mirror, and a laser scanned by the fθ lens. Reflecting means for guiding light to a light receiving surface provided outside the unit housing through an opening formed in the unit housing, and a scanning width of the laser light on the light receiving surface with respect to a temperature change. And a scanning width holding means for holding the scanning width constant.

Further, in the laser optical system unit according to the present invention, the scanning width holding means is interposed between the unit housing and the apparatus main body provided with the light receiving surface, and the temperature within the unit housing is maintained. And a bimetal that adjusts the optical path length from the fθ lens to the light receiving surface in accordance with Further, in the laser optical system unit according to the present invention, the bimetal is, as the temperature inside the unit housing increases,
It is characterized in that the optical path length is changed so that the optical path length becomes shorter and the lower the temperature in the unit housing becomes, the longer the optical path length becomes. In the laser optical system unit according to the present invention,
The bimetal is attached to a mounting means for mounting the unit housing to the apparatus main body. Further, in the laser optical system unit according to the present invention, the bimetal is attached so as to be displaced along a direction parallel to a direction in which the laser light is incident on the light receiving surface.

Further, in the laser optical system unit according to the present invention, the scanning width holding means includes a temperature detecting means for detecting a temperature in the unit housing, and a fuzzy lens based on a detection result of the temperature detecting means. And an optical path length adjusting means for adjusting an optical path length to the light receiving surface. Further, in the laser optical system unit according to the present invention, the optical path length adjusting means is shortened when the temperature detecting means determines that the temperature inside the unit housing is high, and the optical path length adjusting means is provided inside the unit housing. When the temperature is determined to be low, the optical path length is adjusted so as to be longer. In the laser optical system unit according to the present invention,
The optical path length adjusting means moves the unit housing along a direction parallel to a direction in which the laser light is incident on the light receiving surface. Also. In the laser optical system unit according to the present invention, the fθ lens is made of plastic.

Therefore, according to the present invention, an optical system unit capable of maintaining a constant scanning width regardless of a temperature change in the unit is provided.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing an internal configuration of a facsimile apparatus to which a configuration of an embodiment of a laser optical system unit according to the present invention is applied.

FIG. 2 is a plan sectional view showing the configuration of a laser scanning unit as one embodiment of a laser optical system unit according to the present invention;

FIG. 3 is a longitudinal sectional view showing a configuration of a laser scanning unit as an embodiment of a laser optical system unit according to the present invention.

FIG. 4 is a side view schematically showing a mounting state of a bimetal.

FIG. 5 is a top view schematically showing a state where a printing width is kept constant on a light receiving surface.

FIG. 6 is a side sectional view schematically showing a configuration of another embodiment of the laser optical system unit according to the present invention.

[Explanation of symbols]

 Reference Signs List 24 photosensitive drum 26 laser scanning unit 32 unit housing 34 collimator 36 polygon mirror 38 fθ lens 38a; 38b first and second lenses 46 third reflecting lens 48 light receiving element (beam detector) 50 mounting mechanism 52 mounting piece 54 bimetal 56 Moving mounting mechanism 58 Drive motor 58a Motor shaft 60 Pinion 62 Rack 64 Temperature sensor 66 Control unit.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 26/10 B41J 2/44

Claims (8)

(57) [Claims] 1. A unit housing, a laser output means disposed in the unit housing, for modulating laser light in accordance with image information and outputting the same, and for deflecting the laser light emitted from the laser output means. Rotating mirror, and fθ for scanning the laser beam deflected by the rotating mirror.
A lens; a reflecting means for guiding the laser beam scanned by the fθ lens to a light receiving surface provided outside the unit housing via an opening formed in the unit housing; A laser optical system unit comprising: a scanning width holding unit that holds a scanning width of a laser beam corresponding to a scanning width constant with respect to a temperature change; wherein the scanning width holding unit includes the unit housing and the light receiving unit. Laser optics, comprising a bimetal interposed between the apparatus main body having a surface disposed thereon and adjusting an optical path length from the fθ lens to the light receiving surface according to a temperature in the unit housing. System unit. 2. The bimetal according to claim 1, wherein the higher the temperature in the unit housing, the shorter the optical path length, and the lower the temperature in the unit housing, the longer the optical path length. 2. The laser optical system unit according to claim 1, wherein the laser optical system unit is formed so as to change. 3. The laser optical system unit according to claim 1, wherein the bimetal is mounted on mounting means for mounting the unit housing to the apparatus main body. 4. The laser optical system unit according to claim 3, wherein the bimetal is attached so as to be displaced along a direction parallel to a direction in which the laser light is incident on the light receiving surface. . 5. A unit housing, a laser output means disposed in the unit housing, for modulating laser light in accordance with image information and outputting the same, and for deflecting the laser light emitted from the laser output means. Rotating mirror, and fθ for scanning the laser beam deflected by the rotating mirror.
A lens; a reflecting means for guiding the laser beam scanned by the fθ lens to a light receiving surface provided outside the unit housing via an opening formed in the unit housing; A scanning width holding unit for holding a scanning width of the laser beam corresponding to the scanning width constant with respect to a temperature change, wherein the scanning width holding unit is provided with a temperature in the unit housing. A laser optical system unit, comprising: a temperature detecting means for detecting the temperature of the light; 6. The optical path length adjusting means, when the temperature detecting means determines that the temperature inside the unit housing is high, shortens the temperature, and when the temperature detecting means determines that the temperature inside the unit housing is low, The laser optical system unit according to claim 5, wherein the optical path length is adjusted so as to be longer. 7. The laser optical system unit according to claim 5, wherein the optical path length adjusting means moves the unit housing along a direction parallel to a direction in which the laser light is incident on the light receiving surface. . 8. The laser optical system unit according to claim 1, wherein the fθ lens is made of plastic.