JPH02179660A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent light from leaking outside, to prevent dusting and to prevent image quality degradation by facing the light transmitting part of a shutter to a light exit window for exposure when the device is normally used, and interlocking the light shielding part of the shutter with a movable member and facing it to the light exit window when the device is maintained. CONSTITUTION:A shutter member 44 is provided outside the light exit window 42, the shutter 44 is supported by a guide 47 freely slidable on a housing 40. A cum 49 is pushed by a spring 48, and the light transmitting part 44a faces the window 42. A photosensitive body is irradiated by laser light through the light transmitting part 44a. At the time of maintaining the device, when the upper cover of a main body 10 is opened, the cum 49 is interlocked and moved upward, the shutter 44 is moved by the spring 48, and the light shielding part 44b faces the window 42. On this condition, the laser light does not leak outside the housing 40. Under this constitution, the image quality is improved due to dustproof.

Description

[Detailed Description of the Invention] Industrial Problems This invention forms an image on a recording sheet by repeating the electrophotographic process of charging, exposing, developing, transferring, and cleaning in printers, copiers, facsimile machines, etc. that use lasers. It relates to an electrophotographic device. More specifically, the present invention relates to an optical writing means for performing exposure in such an electrophotographic apparatus, and more particularly to its dust-proof structure.

Conventional technology Conventionally, this type of dustproof structure was disclosed in Japanese Patent Application Laid-Open No. 59-151.
There is one described in Publication No. 170. The dust-proof structure described in the publication is provided with a shutter plate that opens and closes the light emitting opening of the optical writing means.During normal use, the shutter plate is left open, and during maintenance, the process kit is removed from the main body of the device. It is moved in conjunction with the removal and opening/closing operations of the upper cover of the main body of the apparatus, and the shutter plate is kept in a closed state to prevent leakage of laser light to the outside.

Problem to be Solved by the Invention However, in this type of conventional dustproof structure, the light exit opening is open during normal use, so foreign substances such as dust, toner, and paper powder can enter through the opening. There is a problem in that the mirrors, lenses, etc. inside the optical writing means are contaminated, resulting in a reduction in image quality. In particular, in so-called top conveyance bottom writing type electrophotographic devices that form an image on the bottom surface of a recording sheet conveyed above a photoreceptor, such problems are a big problem because the light exit opening usually faces upward. It was a problem to be solved.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such problems in electrophotographic apparatuses, improve the dustproof structure of the optical writing means, prevent deterioration of image quality, and increase reliability.

Therefore, in the present invention, for example, as shown in the illustrated embodiment below, the surface of the photoreceptor 11 is charged and then exposed to light by the optical writing means 16 to form an electrostatic latent image on the surface. In an electrophotographic apparatus in which a latent image is developed into a visible image by a developing means 13, and the visible image is transferred by a transfer means 14 to form an image on a recording sheet 17, a light-transmitting part 44a and a light-shielding part 44b are provided. A shutter member 44 having a shutter member 44 that closes a light exit window 42 of the writing means 16, faces the light transmitting portion 44a in the light exit window 42 during normal use, and moves during maintenance with the maintenance operation. The apparatus is characterized in that the shutter member 44 is moved in conjunction with movable members such as the upper cover 50 of the main body 10 and the process kit 51 inside the apparatus main body 1o, so that the light shielding part 44b faces the light shielding part 44b.

Function: During normal use, the transparent portion 44 of the shutter member 44
a is opposed to the light exit window 42 of the optical writing means 16, and laser light is irradiated through the light exit window 42 to expose the surface of the photoreceptor 11. On the other hand, during maintenance, the shutter member 44 is moved in conjunction with the movable member, and its light blocking portion 44b is opposed to the light exit window 42 to block laser light and prevent its leakage to the outside.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 4 shows a general schematic configuration of the internal mechanism of a laser printer according to an embodiment, and reference numeral 1o in FIG. 1 indicates the main body of the apparatus. Inside the main body 10 of the apparatus, there is a drum-shaped photoreceptor 1 in the center.
1 will be provided. Around the photoreceptor 11, in order of rotation direction (counterclockwise in the figure), there is a charging means 12, a developing means 13, a transfer means 14, and a cleaning means 15.
Place. An optical writing means 16 is provided below the charging means 12, developing means 13, and cleaning means 15. By the way, below the optical writing means 16, there is further provided a paper feed cassette 18 for storing recording sheets 17. A paper feed section 21 including a paper feed roller 19 and a friction butt 20 that presses against the paper feed roller 19 is arranged on the right side of the paper feed cassette 18 in the drawing. The paper feed section 21 and paper feed path 2
2, and a resist roller pair 23 is disposed above the developing means 13. On the other hand, on the opposite side of the registration roller pair 23, sandwiching the transfer means 14 described above.

A conveying means 24 and a fixing means 25 are arranged in sequence.

On the left side of the fixing means 25 in the figure, there is a pair of paper ejection rollers 26.
Further, on the left side thereof, a part thereof projects upwardly from the apparatus main body 10 and is provided with a paper discharge receiver 27.

When an image is formed by an electrophotographic process using this laser printer, the paper feed roller 19 is driven to feed the recording sheet 17 from the paper feed cassette 18 in the direction indicated by the arrow in the figure. Then, the sheet is conveyed by a pair of conveying rollers 28 and passed through the paper feed path 22, and its leading end is passed through a pair of registration rollers 28.
Hit 3. On the other hand, while rotating counterclockwise in the figure, the surface of the photoreceptor 11 is first uniformly charged by the charging means 12, and then laser light is irradiated by the optical writing means 16 to form an electrostatic latent image on the surface. , and then the electrostatic latent image is successively visualized by the developing means 13 using toner. Then, aligning the timing with the image, register roller pair 2
The above-mentioned recording sheet 17 that had been pressed against the photoreceptor 11
send it towards. The image on the photoreceptor 11 is then transferred onto the recording sheet 17 by the transfer means 14 . After transcription,
The surface of the photoreceptor 11 is cleaned by a cleaning means 15.

The residual toner on the photoreceptor 11 is removed. On the other hand, the recording sheet 17 is sent to the fixing means 25 by the conveyance means 24, and the transferred image is fixed by the fixing means 25. Thereafter, the recording sheets 17 with images formed thereon are sent out in the direction of arrow B in the figure by a pair of paper discharge rollers 26, and stacked one after another on a paper discharge tray 27.

By the way, the optical writing means 16 has a structure as shown in FIG. 5 in principle. Reference numeral 30 in the figure is a semiconductor laser, and the semiconductor laser 30 emits laser light. Then, the laser beam is converted into a parallel light beam by a collimating lens 31, shaped by an aperture 32, and inputted into a deflector 34 via a cylindrical lens 33. Deflector 3
4 rotates clockwise in the figure, and its deflector 34 deflects and scans the transmitted laser beam. The light is then condensed by the fθ lens 35, passes through the surface tilt correction lens 36, and is transmitted to the photoconductor 1.
37 in the figure is a scanning line on the photoreceptor 11. Further, as shown in FIG. 5, a part of the laser beam that has passed through the fθ lens 35 is reflected by a mirror 38 and enters a synchronization detection device 39.

Such an optical writing means 16, as shown in FIG.
It is housed in an optical housing 40. Specifically, the laser beam that has passed through the above-mentioned surface tilt correction lens 36 is reflected by a reflecting mirror 41 provided within the housing 4o as shown in the figure. The laser beam reflected by the reflecting mirror 41 passes through the light exit window 42 of the housing 40 and scans the photoreceptor 11, thereby exposing the surface of the photoreceptor 11. In FIG. 6, reference numeral 34 denotes a deflector of the optical writing means 16 mentioned above, and 43 denotes a developing roller of the developing means 13 also mentioned above, which presses against the photoreceptor 11.

Now, as shown in FIG. 6, a shutter member 44 is provided outside the light exit window 42, and the light exit window 42 is closed with the shutter member 44. The shutter member 44 has a light-transmitting part 44a and a light-blocking part 44b, as shown in FIGS. 7(A) and 7(B). In the shutter member 44 shown in FIG. 7(A),
One side of the elongated inorganic glass is left as it is to form a light-transmitting part 44a there, and the other side is coated with black paint or paper, plastic, metal, etc. is attached to form a light-blocking part 4 there.
Form 4b. On the other hand, in the shutter member 44 shown in FIG. 7(B), one side of the elongated inorganic glass is left as it is to form a light-transmitting part 44a there, and the other side is wrapped with another light-shielding member and a light-shielding part 44b is formed there. It forms.

As shown in FIG.
7 to support it so that it can slide freely. Then, the compression coil springs 48, 48 are biased in the direction of the arrow in the figure to press against the cam members 49, 49, and the transparent portion 4 is pressed as shown in the figure.
4a faces the light exit window 42 of the optical housing 40.

Accordingly, in this state, laser light passes through the light-transmitting portion 44a and irradiates the surface of the photoreceptor 11.

However, in order to perform maintenance such as toner replenishment and replacement of consumables, for example, as shown in FIG.
When the upper cover 50 of 0 is opened, the cam members 49 shown in FIG. 1 move upward in conjunction with the upper cover 50. Then, along with the movement of the cam members 49, 49, the shutter member 44 is moved by the biasing force of the compression coil springs 48, 48, and this time the light shielding portion 44b is opposed to the light exit window 42. Accordingly, in this state, the light shielding portion 44b blocks light to prevent laser light from leaking to the outside of the optical housing 40.

Apart from this, for example, a third
As shown in the figure, when the process kit 51 is taken out from the apparatus main body 10, the cam members 49, 49 provided in the process kit 51 move horizontally in conjunction with the movement of the cam members 49, 49, and the shutter member 44 is moved. The light shielding portion 4 is moved by the biasing force of the compression coil springs 48, 48.
4b may be opposed to the light exit window 42 to prevent laser light from leaking to the outside.

In the above description, the cam members 49 are provided on the movable member 50 or the process kit 51 side, and the optical writing means 16 is provided by being fixed within the apparatus main body 1o. However, on the contrary, the optical writing means 16 may be provided on the movable member side, and the cam members 49 may be provided within the main body of the apparatus.

After the maintenance is completed, when the upper cover 50 is closed or the process kit 51 is inserted, the above-mentioned shutter member 44 is moved in conjunction with the movement of these movable members, and the light-transmitting part 44a of the shutter member 44 is reattached to the optical housing. 4o, so that the laser light from the optical writing means 16 can be irradiated onto the photoreceptor 11.

Note that, as in the illustrated embodiment, during use, the shutter member 44 is opened against the biasing force, and the light-transmitting portion 44a is opened to the light exit window 4.
2, when the optical writing means 16 is stored alone, the light shielding part 44b faces the light exit window 42 and can prevent the laser light from leaking to the outside, making it easier to handle. Moreover, a separate storage seal member or the like can be made unnecessary.

Further, in the above-described embodiment, since the shutter member 44 is made of inorganic glass, if toner or the like adheres to the upper surface of the shutter member 44, it can be wiped with a solvent or cleaner.

Unlike plastic, etc., it does not cloud or get scratched, which prevents deterioration in image quality.

Effects of the Invention Therefore, according to the present invention, since the light exit window of the optical writing means is closed by the shutter member both during normal use and during maintenance, foreign substances such as dust, toner, and paper powder are constantly removed from the light exit window. Intrusion can be prevented, the inside of the optical writing means will not be contaminated, image quality can be prevented from deteriorating, and reliability can be improved.

In addition, during maintenance, the light exit window is automatically blocked by the light shielding part of the shutter member, preventing laser light from leaking to the outside, so it is safe and can be used with confidence even with high output laser light sources. Can be done.

[Brief explanation of the drawing]

The drawings show a laser printer which is an embodiment of the present invention, FIG. 1 is an external perspective view of an optical writing means used in the printer, and FIG. 2 is a schematic diagram of the printer with the top cover of the main body of the device opened. FIG. 3 is a perspective view showing the process kit taken out from the main body of the apparatus, FIG. 4 is a general schematic diagram of the internal mechanism of the printer, and FIG. 5 is the principle of the optical writing means. A configuration explanatory diagram, FIG. 6 is a configuration diagram explanatory of the relationship between the optical writing means and the photoreceptor, and FIG. 7 (
A) and (B) are perspective views of shutter members used in the optical writing means, respectively. 10... Apparatus main body 11... Photoreceptor 13... Development means 14... Transfer means 16. ...... Optical writing means 17... Recording sheet 42... Light exit window 44... Shutter member 44a. ...Transparent part 44b... Light blocking part 5o... Upper cover (movable member) 51...
・・・・・・Process kit (movable parts) L・・・・
・・・・・・Laser light Figure 1 v43 Figure 2

Claims (1)

[Claims] After charging the surface of the photoreceptor, it is exposed to light by an optical writing means to form an electrostatic latent image on the surface, the latent image is developed by a developing means to make it visible, and the visible image is transferred to a transfer means. In an electrophotographic apparatus that forms an image on a recording sheet by transferring an image to the recording sheet, a shutter member having a light-transmitting part and a light-blocking part closes the light exit window of the writing means, and during normal use, the light exit window of the writing means is An electrophotographic apparatus, wherein the light-transmitting parts face each other, and during maintenance, the shutter member is moved in conjunction with a movable member that moves with the maintenance operation, and the light-blocking parts face each other.