JPS6156497B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying machine equipped with a document conveying device.

2. Description of the Related Art Conventionally, a method for conveying a sheet document on a fixed document table has been to rotate or rotate a roller or a belt, and to convey the sheet document by utilizing the frictional force thereof. Particularly, when the document mounting table is flat and has a length that is approximately equal to or longer than the length of the sheet document to be conveyed, various measures have been taken to ensure the reliable conveyance of the sheet document. In this case, sufficient care must be taken to transport the sheet original without damaging it, but increasing the frictional force to ensure reliable transport increases the risk of damaging the sheet original. Transporting the product without damaging it and transporting the product reliably are contradictory to each other, making it difficult. For example, Tokukai Akira
As described in No. 49-49640 and Japanese Patent Application Laid-open No. 114932/1984, a method has been proposed in which an air suction device is placed on the back side of an endless belt to reliably convey sheet documents without damaging them. It has the drawback of being large-scale and expensive.

In view of these points, the applicant proposed an air flow in the direction of sheet document conveyance between the moving sheet document and the document table on the front side of the stationary document table in the sheet document conveyance direction. We have already proposed a blowing airflow generator. (Special Application No. 157159/1984).
According to this method, since the sheet document is pressed against the conveyor belt by the air flow, the conveyance is ensured, and since an air layer is formed between the sheet document and the fixed document table, there is no risk of damaging the document. have.

By the way, in a copying machine equipped with such a device for transporting sheet originals, it is possible to copy not only sheet originals but also thick originals, so in the so-called book mode, the original transporting device is lifted upward and the original is placed on the original table. It is then exposed to light. This will be explained based on FIG. The document conveying device 1 is in an open state, and a sheet-like document 3 is placed on a document placing table 2. When air from an airflow generator (not shown) is blown out from the opening 4 as shown in the figure even in the book mode, the document 3 placed on the document table 2 may be blown away or its edges may vibrate, causing the document 3 to be exposed to light. The surface to be scanned is lifted from the document table 2, and a good image cannot be obtained at the raised portion A. Further, due to this air flow, there were problems such as not being able to correctly position the document 3, and the fact that the air was constantly blowing out even during copying, which caused discomfort.

Next, when the document transport device 1 is placed on the document table 2 in a so-called sheet mode, the illumination lamps 5,
When a moving sheet document is illuminated with the reflecting mirror 6 fixed, the temperature of the guide plate 7 and the document table 2 adjacent thereto gradually rises as copies are made continuously. The document mounting table 2 is cooled by the cooling fan 8.
Even if cooling air was sent to the lower part of the original plate 2, cooling of the upper surface of the original table 2 and the guide plate 7 was insufficient.
If the temperature rises locally, there is a risk that the original table 2 made of a glass plate may break or that the operator's hands may be injured.

The present invention has been made in order to eliminate all of the above-mentioned drawbacks, and its object is to provide an electrophotographic copying machine that prevents temperature rises in the original table and its surroundings.

Another object of the present invention is to prevent a document from floating when the document feeder is opened in the book mode.

Still another object of the present invention is to prevent a sheet document from lifting up when the document feeder is in a closed sheet mode.

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

FIG. 3 shows an embodiment of the present invention, with reference numeral 9.
1 shows the main body of the copying machine, on the upper surface of which a document mounting table 10 made of a transparent glass plate is provided. A slit exposure device 11 is arranged below the document table 10. As shown in FIG. This slit exposure device 11 includes an illumination lamp 12, a first movable reflecting mirror 13,
It is composed of a second movable reflecting mirror 14, a lens (not shown), and a fixed reflecting mirror. A sheet document conveying device 15 is mounted on the top of the copying machine so as to be rotatable around a shaft 16. In the sheet mode for conveying a sheet original, it is in the closed position shown, and in the book mode for copying an original, especially a thick original, the sheet original conveying device 15 is removed from the original table 10 and placed in the open position. This sheet document conveying device 15 includes an endless belt 19 that is divided into a plurality of parts and is stretched between a driving pulley 17 and a driven pulley 18. The driving pulley 17 and the driven pulley 18 are connected to the document mounting table 1.
It is placed slightly above 0.
Therefore, the lower part of the endless belt 19 (the slack side of the belt between the driving pulley 17 and the driven pulley 18) is pressed against the original table 1 by the pressing rollers 20 and 21.
It is being pushed to 0. The endless belt 19 near the left end of the document table 10 is stretched around two pressure rollers 22a, 22b and a guide roller 23 so as to bypass at least a guide plate 24 whose bottom surface is white. This portion is used for sheet mode copying, which will be described later. A stop member 25 for stopping the conveyed sheet original is disposed within the endless belt 19 near the right end of the original placing table 10.
A plurality of numerals 5 are provided along the axial direction of the driven pulley 18, and a divided endless belt 19 is provided.
It protrudes from between the holes and comes into direct contact with the glass. The operation and non-operation of this stop member 25 are controlled by a control device (not shown). A tension roller 26 is provided on the tension side of the endless belt 19. A semi-cylindrical guide plate 27 is arranged adjacent to the drive pulley 17 to form a sheet document path. A pinch roller 28 and an inlet stop member 29 are attached to the endless belt 19 through the holes in the guide plate 27 so as to move toward and away from the endless belt 19. Guide plate 2
A document guide plate 30 is attached to one end of the document plate 7 , and its free end is placed on the upper surface of the end of the document table 10 . The free end of this document guide plate 30 is cut out in a comb shape. There is a cooling fan 31 inside the copying machine 9, which sucks outside air from an outside air intake port 32 on the side wall of the copying machine and blows it into the wind guide plates 33, 3.
4 and 35 to guide it to a predetermined location within the copying machine. As shown in FIG. 4, an airflow passage consisting of an opening 33a is formed in the upper part of the wind guide plate 33, and an opening 36a is also formed in the support body 36 adjacent to the document mounting table 10.
is formed so that the air blown from the cooling fan 31 is blown toward the endless belt 19 at a certain angle. That is, the airflow flows in the direction in which the endless belt 19 travels.
A wire mesh 37 is attached to the lower part of the opening 36a. The wind guide plate 35 directs a portion of the air from the cooling fan 31 to the document table 10 corresponding to the guide plate 24.
It is shown at the bottom of the page. One end of a shutter plate 38 constituting an airflow passage opening/closing means is fixed to the end of the document mounting table 10 of the wind guide plate 33. The shutter plate 38 is composed of a leaf spring, is always urged upward, and has the habit of closing the opening 33a with the shutter plate 38. Of course, the shutter plate 38 can also be made of a normal stiffening plate and biased upward by an elastic member such as a spring. A pin 39 is attached to the top of this shutter plate 38.
is attached. The pins 39 are provided at both ends of the shutter plate and project upward from the support 36, as shown in FIG.
A portion of a side cover 40 is formed on the sheet document conveying device 15 so as to engage with this pin 39 . Figures 3 and 4 show the sheet document conveying device 1.
5 is in the closed position, and the pin 39 is pushed by the side cover 40 to push the shutter plate 38 downward. Therefore, part of the air from the cooling fan 31 is guided toward the endless belt 19 through the openings 33a and 36a, and the other part is guided toward the slit exposure device 11 through the lower part of the shutter plate 38. The wind guided to the endless belt 19 acts to press the fed sheet original against the endless belt 19, and also forms an air layer between the sheet original and the original placing table 10, so that the original sheet and the original placing table 10 are separated from each other. It acts to reduce the frictional force between. Furthermore, when the sheet original is not being conveyed through the exposure section, the endless belt 1
9 or endless belt 19 and document mounting table 1
Air is sent to the white guide plate 24 through the space between the guide plate 24 and the guide plate 24 to cool it. A sheet document carried out by the endless belt 19 is guided by a discharge guide plate 41 to a discharge roller 42 and discharged onto a document tray 43 at the upper part of the copying machine 9. The upper surface 44 of the sheet document conveying device 15 serves both as a sheet document insertion guide and a sheet document placement section.

Next, the copying apparatus of the present invention can perform three different copying modes. The first and second copy modes are called sheet mode, and the third copy mode is called book mode. The first copying mode is a method in which a sheet original is sent to a predetermined position on the original placing table 10 by the sheet original conveying device 15, kept stationary there, and the slit exposure device 11 performs exposure scanning to perform copying. This method is suitable for repeat copying in which multiple copies are obtained from one original. The second copying mode is a method in which a sheet original is transported by the sheet original conveying device 15, and the moving sheet original is exposed by the stationary slit exposure device 11, thereby making copies. It is suitable for efficiently making a single copy of an original. The third copy mode is similar to the first copy mode when copying a three-dimensional object such as a book, that is, a thick original, by opening the sheet document conveying device 15 upward and placing the document on the document table 10. In this method, a slit exposure device 11 is used to perform exposure scanning and copying.

First, the first copy mode will be explained. At this time, the illumination lamp 12, the first movable reflecting mirror 13, and the second movable reflecting mirror 14 of the slit exposure device 11 are
It is located at the home position on the right side of the document table 10, as shown by the imaginary line in the figure. on the other hand,
Endless belt 19 of sheet document transport device 15
The pressing rollers 20 and 21 that press the are only placed on the endless belt 19 by their own weight,
The pressure rollers 22a and 22b are lifted up by, for example, a solenoid and placed at a position away from the original table 10. Now, after a predetermined period of time has elapsed after the power is turned on, the machine becomes ready for copying. The sheet original is inserted with the side to be copied facing upward from the original insertion opening formed at the upper left of the sheet original transport device 15 in the direction shown by arrow B. Inlet stop member 29
The tip thereof is engaged with the drive pulley 17,
This prevents sheet originals from being further inserted beyond this point. Next, by pressing the print button, the entrance stop member 29 is separated from the drive pulley 17 to start conveying the sheet document.
A document detection device (not shown) may detect that a document has been inserted and automatically start the copying operation. When the copying operation is started in this manner, the endless belt begins to move, and the sheet document is conveyed by the pinch rollers 28 and the endless belt 19. When the trailing edge of the sheet document passes through the pinch rollers 28, the forced conveyance force decreases, but since the shutter plate 38 is pushed down as described above,
As shown in FIG. 4, the airflow from the cooling fan 31 is blown out from the openings 33a and 36a in front of the document mounting table 10, and the sheet document is transferred to the endless belt 19.
This acts to press against the endless belt 19, thereby ensuring that the sheet document is conveyed by the endless belt 19. Moreover, since this air flow is arranged to flow obliquely in the direction in which the endless belt 19 travels, it is also effective in assisting the conveyance. The air flow sent between the sheet document and the document table 10 forms an air layer to reduce friction and electrostatic attraction between the two. The sheet original is placed on the original placing table 10 by an endless belt 19.
At a predetermined position (original leading edge reference position) on the right side of the document table 10, there is a stop member 25 whose elastic member at the tip presses the document table 10 by the action of a spring (not shown). is located. In this mode, the drive pulley 17 drives the endless belt 19 at a faster speed _V1 than in the second copy mode, which will be described later. When the leading edge of the original sheet engages with the stop member 25, or slightly earlier, the driving force from the drive motor is cut off by the drive pulley 17 in response to a signal from a pulse control device (not shown). As a result, the endless belt 19 moves slightly. The leading edge of the sheet document abuts against the stop member 25 and is automatically corrected to the correct alignment. Preferable conditions for this are that the sheet original is being transported at a faster speed and that the endless belt 19 is not pressing the sheet original strongly against the original placing table 10. In this way, the sheet originals are correctly aligned and stopped at a predetermined position on the original placing table 10. Then, the illumination lamp 12' is turned on, and the illumination lamp 12' and the first movable reflecting mirror 1 are turned on.
3' and the second movable reflecting mirror 14' move leftward from the home position at the same speed V as the circumferential speed of the photosensitive drum to expose and scan the sheet original. By the way, the first
The movable reflecting mirror 13 and the second movable reflecting mirror 14 move parallel to the original table 10 and in the same direction, and their moving speeds or distances are at a ratio of 2:1. Now this one
If a preset counter is input in advance to copy N copies from a sheet original, exposure scanning by the slit exposure device 11 is performed N times, during which the sheet original remains stationary. When a predetermined exposure scan is completed, the stop member 25 is lifted upward by the solenoid, and at the same time the pressing rollers 20, 21 are pushed downward. The endless belt 19 starts moving again, and this time the sheet original and the endless belt 1
9 are strongly frictionally engaged with each other to convey the sheet original, and the sheet original is ejected by a guide plate 41 and an ejection roller 42 with the exposed surface facing downward. If the next sheet original is inserted through the original insertion slot during the above-mentioned exposure, it can be fed into the exposure section at the same time as this sheet original is ejected. The subsequent operations are exactly the same as in the case described above.

Next, the second copy mode will be explained. Insertion of a sheet original into the sheet original transport device 15 is performed in exactly the same manner. When this second copying mode is selected, the pressing rollers 20, 21 and the pressing rollers 22a, 22b are in a pressurized state, and the stop member 25 is raised and is in an inactive state. Then, the slit exposure device 11 is also displaced. That is, the illumination lamp 12, the first movable reflecting mirror 13, and the second movable reflecting mirror 14 are moved to a predetermined position on the exposure end side, as shown by the solid line position, and are fixed stationary there. This allows the document placement table 10 to correspond to the white guide plate 24.
The portion will form another exposed area. Now, when the print button is pressed, the endless belt 19 is moved at the same speed V as the circumferential speed of the photoreceptor. It is ensured that the sheet document is reliably conveyed at the speed V in the exposure section by the pressing action of the pressure rollers 22a and 22b. Of course, at this time, the air flow from the cooling fan 29 described above does not contribute much to the conveyance of the sheet document;
This has the effect of cooling the original table 10. That is, since the illumination lamp 12 of the slit exposure device 11 remains stationary and remains lit for a long time, the vicinity of the white guide plate 24 of the document table 10 and the white guide plate 24 are locally overheated, and the temperature rises. Cooled by Now, the sheet original that has been exposed is directly ejected through the ejection roller 42 without stopping on the way. When the next sheet original is inserted, copying operations are performed in the same manner. By the way, in the exposure section, the white guide plate 2
4 is arranged and the endless belt 19 is detoured to pass behind this back side because the endless belt 19 is divided into a plurality of elongated stops as described above. This is to prevent the effects of areas that are not printed from appearing as black streaks on the copy.

Next, the third copy mode will be explained. When this mode is selected, the slit exposure device 11 is placed at the home position. In order to place a thick original (of course, a thin sheet original can also be used) on the original placing table 10, the sheet original conveying device 15 is moved in the direction of arrow C around the shaft 16 (see FIGS. 3 and 6). It is rotated and lifted upward. A suitable spring device is employed in the sheet document conveying device 15 so that it can be stopped at any opening angle. When the sheet document conveying device 15 is lifted upward, the shutter plate 38 rises as described above and closes the opening 33a of the wind guide plate 33 with the shutter plate 38, as shown in FIG. Therefore, the cooling air from the cooling fan 31 flows through the wind guide plate 3.
3 and 35 toward the slit exposure device 11 and the document mounting table 10 to cool them. Although the shutter plate 38 is moved using the force of a leaf spring, it is also possible to use a coil spring, and the movement command is given by a side cover 40 that moves integrally with the sheet original table 15. The upward movement of the sheet document conveying device 15 is detected by an appropriate detection device, and the shutter plate 38 is
It can also be configured to issue a command to operate a solenoid that raises the . Various other mechanisms are conceivable for operating the shutter plate 38. Now, the sheet document conveying device 15 is lifted, the document to be copied is placed on the document placing table 10, and the sheet document conveying device 15 or another commonly used document pressure plate is placed over the document.
Press the print button to start copying. The exposure method of the slit exposure device 15 is exactly the same as in the first copy mode.

Now, the cooling fan 3 is blown out from the opening 36a of the supporter 36 at the left end of the document table 10.
The airflow from 1 forces the sheet document against the endless belt 19, as explained many times.
However, since the endless belt 19 is divided into a plurality of parts, the sheet original is deformed between the belts as shown in FIG. In FIG. 7, an endless belt 1 is provided on the lower peripheral surface of the pressure roller 22a.
9 are in contact with each other, and the pressure roller 22a is in contact with the shaft 44.
Many are attached to. The width of one endless belt 19 is only 12 mm. A guide plate 45 is provided between the plurality of belts at a position a little apart from the document table 10, but the sheet document O is deformed by the airflow and moves away from the document table 10 between the endless belts 19. . Guide plate 4
If 5 is not present, a noticeable waving phenomenon will occur. FIG. 8 is a sectional view taken along the line X--X in FIG. 7. When such undulation occurs in the sheet original, the undulation phenomenon also occurs below the white guide plate 24 in the sheet original that has passed the pressure roller 22a. This results in a curved horizontal line, which is part of the image of the sheet original, on the copy. This can be explained as follows. In FIG. 9, the optical axis of the light beam from the illumination lamp 12 is inclined by Θ (approximately 12 degrees) with respect to the perpendicular to the original table 10. In FIG. Therefore, if the distance of the sheet document from the document table 10 changes by about 1 mm from point P to point Q, the horizontal line will change by 0.2 mm.
This results in a curvature l of about mm, resulting in a curvature of the copied image. Therefore, as shown in FIG. 10, a roller 46 for preventing the document from floating is attached to the shaft 44 either integrally or so as to be freely rotatable with respect to the shaft 44. The roller 46 is slightly larger than the outer diameter of the pressure roller 22a and is located inside the outer surface of the endless belt, and the distance between the document mounting table 10 and the outer peripheral surface of the roller 46 is set to 0.15 mm. The rollers 46 are arranged between the pressure rollers 22a as shown in the figure, and have an H-shaped cross section. Furthermore, a guide plate 47 is attached between the roller 46 and the pressure roller 22a, as in the case of FIG. 7. Now, the sheet original O is placed on the endless belt 19.
An air stream is blown to press the
In this way, the original lifting prevention rollers 46 prevent the sheet original from lifting up more than a predetermined amount, and since the sheet original is also conveyed and guided by the rollers 46, bending of the copied image is completely prevented.

In order to prevent the document from lifting up, instead of the rollers 46, a sheet of material such as Mylar that does not damage the document is placed between the pressure rollers 22a, and the sheet document O is pressed from above the document. It is also possible to prevent it from rising too much from the mounting table 10. The pressing force with the sheet-like object is sufficient to prevent the sheet document from being lifted up by the air current; if it exceeds this force, the resistance between the sheet document and the document mounting table 10 becomes large and the conveyance becomes difficult. This is not very desirable as it may worsen the condition. If it has a certain width like a sheet-like material, it is effective in preventing the edges of the sheet document from lifting up.

As described above, according to the present invention, a sheet document can be effectively transported and exposed by the document transport device in the sheet mode. Furthermore, when the document transport device is opened in the book mode, the flow of air blown out from the vicinity of the document placement table is blocked, so the document is not blown away and the document can be placed correctly. Further, it is also possible to prevent the temperature of the document placing table and the sheet document guide plate above it from rising. Furthermore, although an air stream is blown onto the sheet original to assist in conveyance, it is possible to prevent the sheet original from lifting off the original placement surface, making it possible to make good copies without image distortion.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams of an electrophotographic copying machine equipped with a conventional sheet document conveying device,
FIG. 3 is a sectional view of an electrophotographic copying machine equipped with a sheet document conveying device showing an embodiment of the present invention, FIG. 4 is an enlarged sectional view of only the main parts of FIG. 3, and FIG. 5 is a sheet FIG. 6 is a cross-sectional view showing only the main parts of the electrophotographic copying machine when the document conveyance device is lifted upward; FIG. 6 is a perspective view of the electrophotographic copying machine of the present invention with the sheet document conveyance device lifted upward; The figure is a partial front sectional view of a conventional sheet document conveying device, and FIG.
FIG. 9 is a diagram for explaining the bending of an image due to lifting of a sheet original; FIG. 10 is a partial normal cross-section of a sheet original conveying device showing an embodiment of the present invention. It is a diagram. 1, 15... Sheet original conveyance device, 2, 10...
...Original table, 5, 12...Illumination lamp, 7, 2
4... White guide plate, 8, 31... Cooling fan,
19... Endless belt, 22a, 22b...
Pressure roller, 33, 34, 35... Wind guide plate, 3
3a, 36a...opening, 38...shutter plate,
39...pin, 40...side cover, 46...
Roller to prevent document from lifting, O... Sheet document.

Claims (1)

[Scope of Claims] 1. A document feeder that transports a sheet original by a rotating belt is mounted on a document tray so as to be openable and closable, and when the document feeder is opened, the document is placed on the document tray. In an electrophotographic copying machine that can be set to a book mode in which exposure is performed using the sheet document transport path, and a sheet mode in which the sheet document is transported on the document tray and exposed when the document transport device is closed, From the front side of the stand,
an airflow generator that blows air through an airflow passage toward the bottom surface of the sheet document being transported by the belt; An electrophotographic copying machine comprising an air flow passage opening/closing means for closing the air flow passage. 2. A document transport device that transports sheet originals by rotating belts divided into a plurality of parts is mounted on the document placement table so as to be openable and closable, and when the document transfer device is opened, the document is placed on the document placement table and exposed. In an electrophotographic copying machine that can be set to a book mode in which the document transport device is closed, the sheet mode is set in a sheet mode in which the sheet document is transported on the document table and exposed when the document conveyance device is closed. an airflow generator that blows air toward the lower surface of the sheet document being transported by the belt from the side; and a document lifting prevention member that is provided between the belt and prevents the sheet document from lifting up from the document mounting table. . An electrophotographic copying machine, comprising an air flow passage opening/closing means for closing the air flow passage in conjunction with the opening operation when the document conveying device is opened with respect to the document mounting table.