JPH0420186B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a printing apparatus using an electrophotographic method such as an electrophotographic copying machine, an electrophotographic printer, etc.
The present invention relates to an electrophotographic printing apparatus equipped with a safety mechanism that prevents laser light from a laser light source as a light source from being irradiated to the outside of the apparatus.

Printing devices using electrophotography are widely used as copiers and computer printers. For example, a printer using an electrophotographic method is configured as shown in the overall configuration diagram of FIG. 4.

That is, a charger 5 for uniformly charging the entire surface of the photosensitive drum 4, a developing device 6, a transfer device 7, a static eliminating unit 8, and a cleaner 9 are arranged around the photosensitive drum 4 having a photoconductor (photoreceptor) on its surface. constitutes an electrophotographic unit, and also includes a laser diode (laser light source) 12, a collimator lens 13, a polygon mirror (polygon mirror) 14, and an F-θ (imaging) lens 1.
6 constitutes an exposure optical unit, and further includes a paper hopper 1, a feeding tractor 2, an ejection tractor 3,
The fixing device 10 and the stacker 11 constitute a paper handling unit. In such an electrophotographic printer, a laser diode 1 as a laser source is used.
A laser beam modulated according to the written image from 2 is optically scanned by a polygon mirror 14 rotated by a spindle motor (servo motor) 15 via a collimator lens 13, and is scanned by a polygon mirror 14 rotated by a spindle motor (servo motor) 15. The photosensitive drum 4 charged by the charger 5 is exposed to light. As a result, an electrostatic latent image is formed on the photosensitive drum 4, which is developed by a developing device 6 that uses two-component magnetic toner as developer powder, and is then developed at the paper hopper 1.
A developing powder image is transferred by a transfer device 7 onto the continuous paper PP which is fed out by a feeding tractor 2 and discharged and fed by a discharge tractor 3. Later paper
The PP is fixed by the fixing device 10, and the PP is fixed by the fixing device 10.
On the other hand, the photosensitive drum 4 is neutralized by a static eliminating unit 8, cleaned by a cleaner 9, and used for the next latent image formation.

In such an electrophotographic printing apparatus, the area around the photosensitive drum 4 is kept in a dark state by blocking external light, and an internal door is provided for replacing the cleaner 9 or the like. We are trying to exchange 9 etc. At this time, if the laser light leaks from the laser light source 12 to the outside and irradiates the human eye, there is a risk of blindness, etc., so a safety mechanism is provided to cut off this laser light and prevent it from leaking to the outside.

[Conventional technology]

Conventionally, electrical control methods have been known in which the drive circuit of the laser light source 12 is stopped, but in the unlikely event that the drive circuit or the like fails, the drive of the laser light source 12 may not be stopped, so this method is not particularly recommended. 1971-
As seen in Publication No. 90826, etc., laser light source 1
A method is adopted in which the optical path from 2 is mechanically blocked.

For this reason, conventionally, as shown in FIG. 5, an internal door 19 (hereinafter referred to as a laser beam protection cover) that opens and closes around a support shaft 19a is installed on one frame 18 of a pair of frames 17 and 18 that support the photosensitive drum 4, etc. A protective cover 19 is provided between the frames 17 and 18 to enable manual replacement by a maintenance person or the like.
A micro switch 20 for detecting opening/closing of the laser light source 12 and a rotary shutter 21 provided between the collimator lens 13 and the polygon mirror 14 for blocking the optical path of the laser light source 12 are provided. When the protective cover 19 is opened by a maintenance person as shown by the dotted line, the micro switch 20 detects the opening of the cover 19 and drives the rotary shutter 21, which blocks the optical path as shown by the arrow. It was hot.

[Problem that the invention seeks to solve]

This conventional safety mechanism is an indirect control in which the switch 20 detects the opening of the cover 19 and electrically controls the rotary shutter 21.
If the drive circuit for the switch 20 or the shutter 21 were to fail, the optical path could no longer be interrupted, causing a problem in the reliability of the shutter against electrical failure. Moreover, it requires a switch, a rotary shutter, and a drive circuit, leading to the problem of increased costs.

[Means for Solving the Problems] An object of the present invention is to provide an electrophotographic printing apparatus having a safety mechanism that has a highly reliable shutter and can be constructed at low cost.

Therefore, the present invention provides an electrophotographic printing apparatus in which an optical scanning means optically scans a photosensitive drum with laser light from a laser light source to form an electrostatic latent image and prints, the optical scanning means and the photosensitive drum. Between,
A shutter member for blocking the optical path of the laser beam is provided to be rotatable around a spindle, and a door that opens and closes the interior is provided with an operating member with a pointed tip that engages with and operates the shutter member. According to the opening/closing operation of the door, the operating member rotates the shutter member so that the shutter member blocks and releases the optical path.

[Effect]

The present invention uses a mechanical shutter that mechanically operates the shutter in conjunction with a cover (door) without using any electrical means, thereby improving reliability against electrical failure and making it possible to have an inexpensive configuration. It is something.

In addition, since the shutter member is provided near the photosensitive drum near the door, the movement of the door is directly transmitted by the operating member provided on the door, and the shutter member opens and closes, eliminating the need for a transmission mechanism and simplifying the configuration. At the same time, the shutter can be operated reliably without transmission errors.

Furthermore, by making the shutter member rotatable and sharpening the tip of the door operating member, even if the door is directly transmitted,
The shutter member can be smoothly rotated by the engaging operation.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a configuration diagram of one embodiment of the present invention.
Figure A is a top view thereof, Figures 1B and C are sectional views thereof, and Figure 2 is a perspective view of essential parts of the configuration shown in Figure 1.

In the figure, the same parts as those shown in FIGS. 4 and 5 are indicated by the same symbols, and 22 is a shutter that rotates around a support shaft 22a and connects the imaging lens 16 and photosensitive drum. 4, and 2
Reference numeral 3 indicates a shutter operating member, which is formed into a projection shape and is attached to the cover 19. Reference numeral 24 indicates a spring, which is attached to the shutter 22 and is attached to the shutter 22.
25.
is a stopper, which regulates the lower limit position of rotation of the shutter 22. Note that 26 is an outer casing.

Next, the operation of the embodiment configuration will be explained using FIGS. 1B and 1C.

As shown in FIG. 1B, when the cover 19 is closed, the shutter operating member 23 provided on the cover 19 engages with the shutter 22 and rotates upward against the spring 24 about the support shaft 22a. I'm forcing you,
The shutter 22 is located above the optical path LP of the laser beam, opens the optical path LP, secures the optical path LP from the laser light source 12 to the photosensitive drum 4 via the collimator lens 13, the polygon mirror 14, and the imaging lens 16, and The drum 4 can be exposed to light.

Meanwhile, a door (not shown) of the outer casing 26 is opened,
Further, when the protective cover 19 is opened around the support shaft 19a, the shutter operating member 23 attached to the protective cover 19 also rotates together with the protective cover 19 as shown in FIG. 1A, and disengages from the shutter 22. . Therefore, as shown in FIG. 1C, the shutter 22 rotates around the support shaft 22a by the tensile force of the spring 24, and stops when its tip hits the stopper 25. At this time, the shutter 22 is tilted about the support shaft 22a and blocks the optical path LP.
Therefore, even if laser light is emitted, the optical path LP (light scanning range) is covered by the shutter 22 and will not leak to the outside, allowing maintenance personnel to clean the photosensitive drum 4 and cleaner 9 with confidence. , replacement, etc. can be performed.

As shown in the figure, since the tip of the shutter operating member 23 is formed into a conical shape, the shutter operating member 23
3, when the engagement with the shutter 22 is released as the cover 19 is opened, the shutter 22 is gradually moved downward, and the impact force of the shutter 22 hitting the stopper 25 by the spring 24 is alleviated; Conversely, when the shutter operating member 23 engages with the shutter 22 by closing the cover 19, the shutter 22 is gradually raised and the cover 19 can be closed smoothly without requiring any extra force. Closing operation and shutter 2
2 upward movement is possible. FIG. 3 is a block diagram of another embodiment of the present invention, in which the same parts as shown in FIG. 1 are indicated by the same symbols.
27 is a mirror. In the embodiment shown in FIG. 1, the shutter 22 was provided between the imaging lens 16 and the photosensitive drum 4, but in this embodiment, the shutter 22, the spring 24, and the stopper 25 are connected to the polygon mirror 14 and the imaging lens. 16.

In the embodiment shown in FIG. 3, the distance between the polygon mirror 14 and the photosensitive drum 4 is increased by reflection from the mirror 27, thereby making it possible to downsize the polygon mirror 14.
A shutter 22 is installed between the photosensitive drum 4 and the photosensitive drum 4. The shutter operation member 23 for operating the shutter 22 may be provided at a position on the protective cover 19 corresponding to the position of the shutter 22, and the optical path blocking operation is the same as that in the embodiment shown in FIG. 1, so a description thereof will be omitted.

In the embodiment described above, when the cover 19 is opened, the shutter operating member 23 is disengaged from the shutter 22 and the shutter 22 is rotated downward to block the optical path. Therefore, the cover 19 is configured to engage the shutter operating member 23 and the shutter 22 to block the optical path, and close the cover 19 to release the engagement between the shutter operating member 23 and the shutter 22 and open the optical path. The shutter operating member 23 may be connected to the shutter operating member 23 using mechanical connecting means. Further, the laser light source 12 is the first
In the case where the shutter 22 is provided on the opposite side of FIG. A, that is, closer to the frame 18 than the polygon mirror 14, the shutter 22 may be provided between the laser light source 12 and the polygon mirror 14.

Further, the shutter 22 is not limited to one on a plate, but may be arc-shaped, and may be one that slides up and down instead of rotating around the support shaft 22a. In this case, the shutter 22 is shaped like an L. It should be configured as follows. Moreover, in the case where the protective cover 19 is not provided, the shutter operating member 23 is attached to the door of the outer casing 26.
may be provided.

Although the present invention has been described above with reference to examples, the present invention can be modified in various ways according to the gist of the present invention.
These are not excluded from the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, the following effects are achieved.

Since a mechanical shutter is used in which the shutter member is mechanically operated in conjunction with the cover, it can operate accurately even in the event of an electrical failure, and is highly reliable.

Since a shutter member is provided between the photosensitive drum near the door and the optical scanning means, the operation of the door is directly transmitted and the shutter member is opened and closed, so there is no transmission error and the shutter is reliably executed. In addition to eliminating the need for a transmission mechanism, the configuration is simplified and downsized.

By making the shutter member rotatable and by making the tip of the operating member of the door sharp, the shutter member can be smoothly rotated by the engagement operation even when direct transmission is performed.

Since a shutter member is provided between the optical scanning means and the photosensitive drum, the shutter member is sufficient for the optical scanning width, which not only eliminates the need to increase the width of the device, but also suffices the height for the optical scanning, making it possible to realize a compact device. .

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention, FIG. 2 is a perspective view of essential parts of the configuration shown in FIG. 1, FIG. 3 is a configuration diagram of another embodiment of the present invention, and FIG. 4 is an electrophotographic printing apparatus. An example configuration diagram, FIG. 5, is an explanatory diagram of a conventional configuration. In the figure, 4...photosensitive drum (photosensitive member), 12...
Laser light source, 14... Polygon mirror, 19...
Internal door, 22...shutter, 23...shutter operating member.

Claims (1)

[Scope of Claims] 1. In an electrophotographic printing apparatus that performs printing by optically scanning a photosensitive drum with a laser beam from a laser light source using a light scanning means to form an electrostatic latent image, the light scanning means and the photosensitive drum are provided. A shutter member for blocking the optical path of the laser beam is provided between the shutter member and the shutter member so as to be rotatable around a support shaft, and the shutter member is engaged with the door that opens and closes the interior. Electrophotographic printing characterized in that an operating member with a pointed tip is provided, and when the door is opened and closed, the operating member rotates the shutter member, thereby blocking and releasing the optical path by the shutter member. Device.