JPH055092B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a recording machine, and particularly to an image forming apparatus with a fixed optical system and a movable document table.

2. Description of the Related Art In recent years, image forming apparatuses such as copying machines have been required to have multiple functions, color, and high speed, as well as miniaturization and weight reduction. For example, the optical path length of the optical system can be made extremely small by making the document table movable in order to save the optical system and scanning space within the main body of the device, and by using short focus lens arrays, which have become extremely popular in recent years. By doing this, efforts have been made to make the device smaller and lighter. In addition, the developing unit, cleaning unit,
Each process unit, such as the fixing unit, has also been improved, becoming smaller and lighter, and the situation has become such that the equipment itself can be further downsized. However, even if the document table is made movable, the actual situation is that it is not possible to downsize the document table and downsize the apparatus body due to various constraints described below.

FIG. 1 is a sectional view showing the overall configuration of an image forming apparatus of a movable document table type. 1 is a photosensitive drum, 2 is a short-focus lens array consisting of a large number of converging light transmitters (trade name: Self-Ox) and bar lens systems arranged in a direction substantially perpendicular to the optical axis, and 3 is a light source lamp for exposing originals, etc. The illumination system 4 is a document device table having a front end 4b and a rear end 4a and having a document pressure plate configured to hold a document and move back and forth. The position of the document mounting table 4 indicated by the dotted line in FIG.
That is, the position of the document table 4 located at the full width of the apparatus main body indicates the position taken at the end of the copying process, that is, the home position. At this time, when the copying operation start switch (not shown) is pressed, the document table 4 first moves from the home position to the position shown by the dashed line in FIG. 1 in the direction of arrow a. This position is called the start position, and the leading edge (not shown) of the original on the original placing table 4 is the illumination system 3.
The illumination light is arranged to be on the left side in the figure near the exposure aperture F through which the document passes, and the front end 4b of the document holder 4 is arranged near the aperture F without passing through it. ing. From this position of the document placement table 4, the document placement table 4 starts moving in the right direction as indicated by the arrow b in synchronization with the outer circumferential speed of the photosensitive drum 1 in order to scan the document. Then, the light from the illumination system 3 is reflected by a document (not shown) on the document table 4, and the reflected light passes through the aperture F and forms an image of the document on the photosensitive drum 1 by the short focus lens array 2. The electrophotographic process employed in such an apparatus is not directly related to the gist of the present invention and will therefore be omitted. Now, when the image forming apparatus is equipped with a paper feed cassette of the maximum size that can be copied, the document mounting table 4 is moved from the start position shown by the dashed line in the figure to the position shown by the dashed double dot line on the right side, that is, from the position shown by the chain double dot line in the figure. A position where the rear end of the document (not shown) on the placing table 4 is located on the right side in the figure near the exposure opening F, and the rear end 4a of the document placing table 4 is in the vicinity of the opening F without passing through the opening F. Then, it returns to the aforementioned home position and stops. The above is the image forming operation based on the schematic cross-sectional view of the image forming apparatus. FIG. 2 is a detailed sectional view of the illumination system and optical system of an image forming apparatus that performs the same operation. The illumination system 3 includes a light source lamp 3d, reflective mirrors with opposite slopes 3a and 3b, and an auxiliary reflective mirror 3c. The reflected light 3a', 3b' from the reflecting mirror reflection surfaces 3a, 3b and the reflected light 3'c from the auxiliary reflecting mirror 3c proceed in the directions of the respective arrows, reach the document table 4 through the opening F, and are reflected by the document P. The reflected light 3'e passes through the aperture F, and then passes through the short focus lens array 2,
As shown in 3'f, an original image is formed on the circumferential surface of the photosensitive drum 1. Reference numeral 5 designates an exterior cover fixed to the main body, which has an opening F so that these reflected lights 3a' to 3c' and 3'e can pass through without being blocked.

Now, the document mounting table 4 is at the position where scanning of the document is started, that is, at the start position located on the left side in the figure. At this time, if the opening F is not covered, that is, if the document mounting table 4 is movable further to the left as indicated by arrow a than shown in FIG. When the placing table 4 moves to the right as indicated by the arrow b and starts scanning the document P, there is a risk that your fingers or the like may be caught between the document placing table 4 and the outer cover 5. This is an unacceptable problem. In addition, fingers can come into contact with parts that are extremely heated by the illumination light, that is, the light source lamp 3d, the reflecting mirror reflection surfaces 3a and 3b, the auxiliary reflecting mirror 3c, and the short focus lens array 2, which also poses a safety problem. Become. Moreover, the reflected light 3'a,
3'b and 3'c leak to the outside, causing extreme discomfort to the operator. Therefore, in order to prevent these problems from occurring, the portion indicated by the width A in the figure at the end of the document mounting table 4 contributes. In addition, in general, in order to prevent synchronization between the original P and the photosensitive drum 1 from entering the copy image area due to the start-up of the motor or impact when the original platen 4 is reversed, from the start of scanning to the leading edge of the image of the original P. To some extent (30mm to 60mm)
must maintain a certain distance. This distance is called a run-up and is indicated by the width B of the end of the document table 4. Similarly, the width C indicates the maximum document size that can be copied, and the width D of the edge of the document platform 4 when the document platform 4 is located on the right side in the figure, that is, at the end of document scanning.
The part indicated by is an overrun part to prevent image loss due to an error in the scanning amount, and the width E at one end of the document mounting table 4 closes the opening F at the end of scanning, similar to the width A. This is a necessary part. Generally, the total width dimension of the document mounting table 4 is defined as A+B+C+D+E from these. Therefore, the overall width of the entire apparatus is also defined in the same way as the dimension of the original platen 4, but even if the width of the apparatus body is made smaller than the width of the original platen 4 in order to downsize the apparatus, If the end portion of the document placing table 4 cannot be supported by the apparatus main body and force is applied to this portion, there is a high risk that this portion of the document placing table 4 will be damaged. Not only that, but a dead space is formed under the edge of the document table 4 when it is located at the home position, which is a very serious configuration from the standpoint of space saving. Also,
Separately, the above-mentioned safety problem can also be solved by blocking the opening F with a transparent material such as glass, but such a configuration may cause illumination light to leak to the outside and the transparent material. Problems such as a decrease in the amount of light due to reflection and absorption and excessive temperature rise due to blockage of the cooling air path occur.

The present invention has been made in view of the above-mentioned points and in order to eliminate the above-mentioned drawbacks.Based on the market demand for further downsizing and weight reduction, the present invention reduces the overall width dimension of the document mounting table and also provides an image forming apparatus. It is a small and lightweight image forming apparatus that enables the overall width to be made smaller and also solves the aforementioned problems such as the safety problem of the opening and the leakage of illumination light to the outside, and It is an object of the present invention to provide a device that allows easy cleaning of an optical system.

Embodiments of the present invention will be described in detail below with reference to the drawings.

3 and 4 are a partial perspective view and a schematic partial cross-sectional view of an image forming apparatus showing an embodiment of the present invention, in which 1 to 5 are the same as the configuration shown in FIG. 2, and 7 is a document mounting table. 4 is a hook fixed to the lower side of the front end 4b, and 6 is a guide rail that guides the reciprocating movement of the document table 4, and a part of the guide rail 6 is provided on the side along this guide rail 6. Grooves 6a and 6b are provided. P is a document placed on the document table 4; 8 is a shutter plate which is the main element of the present invention; the shutter plate 8 has guide grooves 6a, 6;
It is constructed so that it can reciprocate in the directions of arrows a and b along arrow b. 8a and 8b are guide grooves 6
This is a pin that fits into holes a and 6b and is fixed to the shutter plate 8. A spring 9 has one end fixed to the main body of the apparatus and the other end fixed to the shutter plate 8, and pulls the shutter plate 8 in the direction of arrow b in the figure (the direction in which the opening F opens). Further, 10 is a hook obtained by bending one end of the shutter plate 8. Note that the guide grooves 6a, 6b and the guide rail 6 are omitted in FIG. Now, as described above, when the operator presses the copy operation start button (not shown), the document device table 4 moves to the start position in the direction of arrow a in the figure, which is opposite to the scanning direction. As the document device table 4 approaches the start position, the hook 7 fixed to the document table 4 engages with the hook 10 fixed to the shutter plate 8, and the shutter plate is moved in synchronization with the movement of the document table 4. 8 and move in the direction of arrow a in the figure as shown in the figure. FIG. 4 is a diagram showing the document placement table 4 having completed its movement to the start position. In this state, the opening F is closed by the shutter plate 8.
Now, when the document placing table 4 moves in the direction of arrow b from this position and document scanning is started, the shutter plate 8 again releases the spring 9 in synchronization with the scanning movement of the document placing table 4 in the direction of arrow b in the figure. The shutter plate 8 is moved in the direction of arrow b in the figure due to the tensile force, and when the leading edge of the original P reaches the exposure section, the shutter plate 8 moves under the outer cover 5 and opens the opening F so as not to interfere with image exposure. . By configuring as above,
In the conventional example, the portions having widths A and B at the end of the original document mounting table 4 explained in FIG. 2 are almost no longer needed. In FIG. 4, only the width B' of the positioning plate for the leading edge of the document (the plate on which the leading edge of the original is placed when placed on the document table) shown at 4c is added.

In this way, by providing the shutter plate 8 that covers the opening F in synchronization with the end of the document table 4, the part of the document table 4 that covers the opening F in FIG. The width A and the width B of the run-up part can be configured only in the positioning plate 4c, and it is difficult for fingers etc. to get into the opening F or to come into contact with heating parts such as the lighting system 3. A smaller and more compact document table 4 that solves the safety problems such as light leakage and leakage of illumination light from the illumination system 3 to the outside, and also meets modern needs for smaller and lighter weight. This made it possible to provide copying equipment, etc.

FIG. 5 shows another embodiment of the present invention.
In addition to the configuration shown in FIGS. and 4, another shutter plate is provided, and 7' is a hook provided near the rear end 4a of the original table 4, and 11 is the same as the shutter plate 8 mentioned above. This shutter plate 11 is similarly constructed, and is pulled to the left in the figure by a spring 12 (in the direction of arrow a, that is, in the direction of opening the opening F), and has a hook 7' at the tip.
A hook 13 is fixed thereto, and pins 11a and 11b are provided at both ends of the shutter plate 11 to fit into guide grooves (not shown). As mentioned above, immediately after the original plate 4 finishes scanning the original P, the shutter plate 11 covers the opening F in synchronization with the rear end of the original plate 4 (while the original is being scanned, the shutter plate 11 closes the opening F). By providing the opening (open), the width D of the Oban run part and the width E for blocking the opening F of the original table 4 shown in Fig. 2 are unnecessary, and the width D' is shown as D'. It is obvious that it is sufficient to add only the stopper plate 4d for the original document P. Therefore, instead of the total width A+B+C+D+E of the document placement table 4 shown in FIG. 2, in this embodiment, in addition to the maximum document size C, the width of the positioning plate shown in FIG.
Width B′ + C, which is the sum of B′ and the width D′ of the stop plate in Figure 5.
A small width of +D′ is sufficient.

Now, in a general copying apparatus, a cooling fan (not shown) is used to forcefully blow air to cool the light source lamp 3d and its surroundings. As a result, the scattered tray and dust inside the device adhere to and accumulate on the top surface 2a of the short focus lens array 2 and the reflective surfaces 3a and 3b of the reflector, resulting in direct image quality deterioration and 3a and 3b cause background fogging due to a decrease in the reflectance of the reflecting mirror. Therefore, in order to maintain good image quality, periodically
a and the reflecting mirror reflection surfaces 3a and 3b must be cleaned. However, as explained above, in the configurations of the two embodiments shown in FIGS. 3 to 5, contrary to the effect of the shutter plate on shielding the illumination light and the contribution to safety problems, No matter how you move the document table 4, the short focus lens array top surface 2a and the reflector reflection surfaces 3a, 3b will not be exposed to the outside of the apparatus, and the short focus lens array top surface 2a and the reflection mirror reflection surfaces 3a, 3b will not be exposed to the outside of the apparatus. This causes the inconvenience that cleaning becomes difficult. The above-mentioned disadvantages can be solved by configuring the short focus lens array 2 and the illumination system 3 so that they can be easily attached to and removed from the device body (for example, by pulling them out toward the front of the device body). Lens array 2 and illumination system 3
The mounting method on the main body of the device is complicated, which not only causes the device to become larger, but also causes the problem of complicating the cleaning work.

FIGS. 6, 7, and 8 are sectional and perspective views showing an embodiment of the present invention that also solves the above-mentioned disadvantages. 6a is the aforementioned guide groove, and the right end of this guide groove 6a is provided with a vertical guide groove 6c continuing therefrom. Usually pin 8 as shown
The elastic member 1 prevents a from falling into the vertical guide groove 6c.
4, it is pressed upward.

The pin 8a is a guide rail 6 provided with a guide groove 6a.
through the outside of the image forming device (user-accessible part)
It stands out. When cleaning the top surface 2a of the short focus lens array and the reflection surfaces 3a and 3b of the mirrors, when the knob 8c provided at the tip of the pin 8a is manually pushed down against the elastic force of the elastic member 14, the pin 8a is removed. falls into the vertical guide groove 6c, and this pin 8
Together with a, the hook 10 is also pushed down and the engagement between the hooks 7 and 10 is released. After this, when the original table 4 is further moved in the direction of the arrow a in FIG. The reflective surfaces 3a, 3b are exposed from the opening F, and are connected to the short focus lens array upper surface 2a and the reflective mirror reflective surfaces 3a, 3b.
cleaning becomes easier. Also, after these cleanings are completed,
When the original table 4 moves in the direction of arrow b due to manual operation or the next copying operation, the hook 7 moves as shown in the figure.
The hook 10 is constructed so that the engagement occurs naturally. That is, the hook 10 is pushed down by the hook 7 against the spring 14, and the hook 7 is pushed down by the hook 1.
After passing through 0, the hook 10 is pushed up by the spring 14 and can be engaged with the hook 7. FIG. 7 is a partial perspective view of the embodiment, and FIG. 8 shows the document table 4 moved in the direction of the arrow a with the knob 8c pressed down as described above, and the opening F is It is shown in an open state in which the top surface 2a of the short focus lens array and the reflective surfaces 3a and 3b of the mirror can be cleaned from the outside.

As explained above, the present invention has a simple structure in which a shutter plate is provided to cover the opening in synchronization with the movement of the document table, and the size of the document table can be reduced to substantially the size of a transparent plate. To provide an extremely compact image forming device that not only allows the document table to be reduced to a desired copying size but also makes it possible to clean the short focal length lens array and the reflecting surface of the reflecting mirror. It is something.

In this specification, an image forming apparatus using a short focal length lens array has been described, but it goes without saying that the present invention can also be applied to an image forming apparatus using a normal through lens or an in-mirror lens.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of a conventional document table moving type image forming apparatus, FIG. 2 is a detailed diagram of its optical system, and FIGS. 3 to 5 show embodiments of the present invention. Each detailed view, FIG. 6 is a sectional view showing another embodiment, and FIGS. 7 and 8 are perspective views thereof. 1; Photosensitive drum, 2; Short focus lens array,
3; Illumination system, 4; Original table, 8, 11; Shutter plate, 6a, 6b; Guide groove, 8a; Pin, 8
c; knob; 14; elastic member.

Claims (1)

[Scope of Claims] 1. In an image forming apparatus having a document table on which a document is placed and an exposure opening for exposing and scanning the document, when an end of the document table passes through the exposure opening. ,
A light-shielding plate provided to engage and move with a portion of the document table to close the exposure opening; and a release member for releasing the engagement between the portion of the document table and the light-shielding plate. An image forming apparatus characterized by: