JP2723743B2 - Document platen drive of image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used in copying machines and the like,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a document table driving device that reciprocates a document table during a copying operation.

[0002]

2. Description of the Related Art Conventionally, in a copier as an image forming apparatus for forming an image by moving a platen, when a document on the platen is scanned by an optical system, the platen first returns from a standby position. After moving to the scanning start position in the direction and then moving in the feed direction to the scanning end position to scan the original, the scanning device moves from the scanning end position to the original standby position in the return direction.

As shown in FIG. 10, a platen driving device 51 for moving the platen as described above has a platen 52
And has a structure as shown in FIG.
Then, the document table 52 is fed (F) from the scanning start position.
In the case of moving in the direction, the feed solenoid 53 is turned ON, whereby the latch 54 is engaged with the clutch brake 56 of the feed spring clutch 55,
The feed spring clutch 55 is brought into a connected state.
Accordingly, the driving force input to the input gear 57 is transmitted to the output gear 58 and further transmitted to the platen drive gear 59, and the platen 52 provided with the rack that meshes with the platen drive gear 59 is fed (F) ) Direction.

After that, when the document table 52 reaches the scanning end position, this state is detected by the detection switch 60 shown in FIG. 10, and the feed solenoid 53 is turned off and the return solenoid 61 is turned on. As a result, the latch 62 is engaged with the clutch brake 63 of the return spring clutch 67, and the return spring clutch 67 is engaged. Therefore, the driving force input to the input gear 57 is transmitted to the platen drive gear 59 via the gear 64, the input gear 65, the output gear 66, and the output gear 58, and the platen 52 is moved in the return (R) direction. It moves to the standby position.

In the above structure, however, the feed spring clutch 5 is used to reciprocate the original table 52.
5, a device such as a return spring clutch 67, a feed solenoid 53, and a return solenoid 61 is required. There is a problem that the ratio of the occupied cost is increased and the cost of the apparatus is increased.

In order to solve the above problems, the applicant has
A document table driving device using an endless gear has been previously proposed (see Japanese Patent Application No. 3-118860).

More specifically, as shown in FIG. 3 which is an explanatory view of the present invention, a platen driving device using an endless gear has two upper rack portions 3a and lower portions provided in parallel with their tooth surfaces facing each other. The rack part 3b and these two rack parts 3a and 3
b, two left half-circle internal gears 3 connecting the respective ends of
c, an annular endless gear 3 d which is connected to the document table 2 and is linearly movable integrally with the document table 2, and both rack portions 3 a. The sun gear 5, which is provided at a fixed position at an intermediate portion between the sun gears 3b and to which the driving force of the motor is input, and the sun gear 5 and the endless gear 3 are rotatably provided by meshing with these gears. Large diameter planetary gear 6
And a small-diameter planetary gear 10 and an input shaft 7 as a rotation shaft of the sun gear 5 are rotatably connected to a gear shaft 9 as a gear shaft of the large-diameter planetary gear 6 and the small-diameter planetary gear 10. A supporting plate 11 is provided.

When the driving force from the motor is transmitted to the input shaft 7, the sun gear 5 rotates in the direction of arrow A as shown in FIG. Rotates in the direction of arrow B to move the endless gear 3 in the return (R) direction. When the large-diameter planetary gear 6 comes to the left semicircular internal gear 3c of the endless gear 3, the endless gear 3 stops horizontal movement,
The connecting plate 11 starts to rotate clockwise around the input shaft 7, and accordingly, the large-diameter planetary gear 6 moves to the left semicircle internal gear 3c.
Revolve clockwise while meshing with the left half-circle internal gear 3c
To the end point of. When this position is reached, the small diameter planetary gear 10 meshes with the upper rack portion 3a of the endless gear 3,
The endless gear 3 moves in the feed (F) direction opposite to the above, and at this time, the document table 2 also moves horizontally in the feed (F) direction to start copying. As described above, the rotation of the sun gear 5 in a certain direction allows the endless gear 3,
That is, the document table 2 repeats the reciprocating movement to return and feed. As a result, the structure of the platen driving device is simplified, and the size can be reduced.

[0009]

However, the above-mentioned platen driving device may stop in a state where the platen 2 is meshed with the semicircular internal gears 3c and 3d of the endless gear 3 due to a failure or the like. At this time, the motor for driving the platen driving device is immediately stopped by the failure detecting means of the copying machine. In this state, the main power of the copying machine 1 may be turned off. in this way,
When the large-diameter planetary gear 6 stops at the positions of the semicircular internal gears 3c and 3d in the endless gear 3, there is a problem that it is impossible to manually move the endless gear 3 due to the structure. I have.

In order to stop the document table 2 at the above-described position, the input shaft 7 of the sun gear 5 is extended, a knob is provided at the tip thereof, and the planetary gear 6 is rotated by rotating the knob. Semicircular internal gear 3c in endless gear 3
d, it has been proposed to move the platen 2 back to the home position after that, but this has a problem that the apparatus becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to avoid the complexity of the platen driving device and to reduce the planetary gear to a semicircular internal gear of an endless gear. An object of the present invention is to provide a platen driving device of an image forming apparatus that can move a platen and return to a home position even when stopped at a position.

[0012]

According to a first aspect of the present invention, there is provided a platen driving device for an image forming apparatus, which is provided in the image forming apparatus and has a tooth surface opposed to and parallel to the original plate driving device. It is provided with two provided rack portions and two semi-circular internal gears respectively connecting the ends of the two rack portions, and is connected to the document table and provided so as to be linearly movable integrally with the document table. A ring-shaped endless gear, a sun gear provided with a fixed position at an intermediate portion between the two rack portions in the endless gear, and a driving force of a motor input thereto, and a sun gear and an endless gear. A planetary gear rotatably provided by meshing with both gears, and a connecting plate rotatably connected to the rotation shaft of the sun gear and moving along an endless gear supporting the gear shaft of the planetary gear; Having A document table driving device for the image forming apparatus, wherein a position detecting means for detecting whether or not the planetary gear is located on the semicircular internal gear is provided, and when the power of the image forming apparatus is turned on, In the position detecting means,
Based on the output signal indicating that the planetary gear is located at the semicircular internal gear, the motor is turned on until there is an output signal at the position detecting means indicating that the planetary gear is not located at the semicircular internal gear. It is characterized in that start-up control means is provided.

According to a second aspect of the present invention, there is provided an original platen driving device for an image forming apparatus, comprising: a failure detecting means for detecting a failure and turning off a motor when the failure occurs; It is provided with two rack portions provided in the forming device and provided in parallel with the tooth surfaces facing each other, and two semicircular internal gears respectively connecting each end of these rack portions, and is connected to the document table. A ring-shaped endless gear provided linearly movable integrally with the document table; and a sun fixed to a position intermediate between the two rack portions of the endless gear, to which the driving force of the motor is input. A planetary gear that is rotatably provided between the gear, the sun gear, and the endless gear so as to mesh with the two gears; and a gear of the planetary gear, which is rotatably connected to a rotation shaft of the sun gear. axis A platen driving device for an image forming apparatus, comprising: a connecting plate that moves along an endless gear to be supported; and a position detecting unit that detects whether the planetary gear is located at the semicircular internal gear. On the other hand, before the motor is turned off after the failure is detected by the failure detection means, based on the output signal indicating that the planetary gear is located at the semicircular internal gear, It is characterized in that there is provided a failure control means which keeps the motor on until there is an output signal indicating that the planetary gear is not located at the semicircle internal gear.

[0014]

According to the first aspect of the present invention, when the power supply of the image forming apparatus is turned on, the start-up control means outputs from the position detection means that the planetary gear is located at the semicircular internal gear. Based on the signal, the motor is turned on until there is an output signal from the position detecting means that the planetary gear is not located at the semicircular internal gear. For this reason, when the power of the image forming apparatus is turned on, if the planetary gear is located at the semicircular internal gear, the motor operates until the planetary gear passes through the semicircular internal gear and reaches the rack. Drive. Therefore, since the traveling direction of the planetary gear is the rack portion, it is possible to manually move the document table horizontally and return it to the home position. In addition, in terms of the structure, only the detection means is added, so that the apparatus can be prevented from becoming complicated.

According to the second aspect of the present invention, after the failure is detected by the failure detection means and before the motor is turned off,
The failure-time control means determines that the planetary gear in the position detecting means is not located in the semicircular internal gear based on the output signal indicating that the planetary gear is located in the semicircular internal gear in the position detecting means. The motor is kept ON until there is an output signal. Therefore, when the planetary gear is located at the semicircular internal gear at the time of failure of the image forming apparatus, the motor is driven until the planetary gear passes through the semicircular internal gear and reaches the rack. Therefore, since the traveling direction of the planetary gear is the rack portion, it is possible to manually move the document table horizontally and return it to the home position. In addition, in terms of the structure, only the detection means is added, so that the apparatus can be prevented from becoming complicated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The platen driving device of the present embodiment is installed in a copying machine or the like as an image forming apparatus, and as shown in FIG. 2, is movably mounted on an upper portion of a substantially rectangular parallelepiped box-shaped copying machine body 1. A substantially rectangular plate-shaped document table 2 is provided. The central portion of the platen 2 has a transparent member such as a glass plate, and the platen 2 is driven by a platen driving device 31 described later. The copying machine body 1 has an irradiation lamp 1
5 and a rod lens array 24. A photoconductor 13 is provided below the optical system. A charger 14 for charging the photoconductor 13 is provided around the photoconductor 13, and an electrostatic latent image formed on the photoconductor 13 by an exposure operation of the optical system. A developing device 20 for developing the toner image with toner, a transfer device 12 for transferring a toner image formed by the developing operation onto transfer paper, a cleaning device 17 for collecting residual toner on the surface of the photoconductor 13 and the like are provided.

On the supply side of the transfer paper to the photosensitive member 13,
Conveyance roller 22 for conveying transfer paper from manual paper feed unit 21
A fixing device 19 for fixing the transfer paper on which the toner image has been transferred by the transfer unit 12 is provided on the transfer paper output side with respect to the photoreceptor 13.
Is provided.

At the time of the copying operation, the document table 2 is moved from the position where the end in the return direction (R) substantially coincides with the end of the copying machine main body 1, ie, from the standby position P1, first in the return direction. (R) to the scanning start position P2, and then
In order to scan the original by the optical system, the original moves to the scanning end position P3 in the feed direction (F), and then returns to the original standby position P
Move to 1.

In order to detect the respective positions on the document table 2, the standby position detecting switch 26 is provided at the end of the copying machine main body 1 on the side of the manual paper feed section 21, and the start and end are provided near the rod lens array 24. A position detection switch 27 is provided. These position detection switches 26 and 27
The contact plates 36 protruding from the lower ends of both ends of the endless gear 3 are provided with position detecting switches 26.
ON while in contact with brushes provided on each of 27
It is supposed to.

In order to drive the above-mentioned platen 2, the copying machine is provided with a platen driving device 31 shown in FIGS. As shown in FIGS. 3 and 4, the platen driving device 31 includes a main support 4 on which the endless gear 3 is provided.
have. The main support 4 has a vertical wall shape, is vertically connected to the document table 2, and moves along with the document table 2 along the side surface of the copying machine main body 1. An oval concave portion is formed at the center of the main support 4, and the annular endless gear 3 having internal teeth is provided in the concave portion.

The endless gear 3 has an upper rack portion 3a and a lower rack portion 3 which are provided in parallel with their tooth surfaces facing each other.
b, and a left semi-circular internal gear 3c and a right semi-circular internal gear 3d having respective ends connected to each other of the rack portions 3a and 3b and having semi-circular internal teeth. The upper rack 3a has a smaller gear pitch than the lower rack 3b, and has a gear width substantially half that of the upper rack 3b. The step is provided toward the inside of.

Inside the endless gear 3, a sun gear 5 is fixedly provided at an intermediate portion between the upper and lower racks 3a and 3b, and between the sun gear 5 and the endless gear 3, A small-diameter planetary gear 10 and a large-diameter planetary gear 6 that mesh with both are provided. This small-diameter planetary gear 10
Is formed on the copier body 1 side of the large-diameter planetary gear 6 and has a smaller number of teeth than the large-diameter planetary gear 6, and meshes with the upper rack portion 3a. I have. The large-diameter planetary gear 6 is bonded to the small-diameter planetary gear 10 so as to rotate integrally therewith. The lower rack portion 3b, the left semicircle internal gear 3c, and the right semicircle internal gear 3d and the gears. Are adapted.

The main support 4 has an endless gear 3
Is moved, the groove 8 through which the input shaft 7 which is the rotation shaft of the sun gear 5 passes is formed in parallel with the upper and lower rack portions 3a and 3b. A drive force from a motor (not shown) is transmitted to the input shaft 7.

The large-diameter planetary gear 6 and the small-diameter planetary gear 10
The gear shaft 9 as a gear shaft of (1) is rotatably connected near the center of the connecting plate 11.

The input shaft 7 of the sun gear 5 is rotatably connected near one end of the connection plate 11. And
The sliding member 30 connected to the outside of the connecting plate 11 slides in a sliding guide groove 29 provided on the back side of the protective cover 28 of the main support 4, so that the connecting plate 11 is connected to the endless gear 3. It rotates along.

As shown in FIG. 6, the control section for operating the platen driving device 31 has a control device 32. The control device 32 includes a main power switch 33 of the copier main body 1; While output signals such as ON / OFF from a standby position detection switch 26 for detecting that the document table 2 is at the standby position P1, a start / end position detection switch 27 as position detection means, and various device sensors 34 are input, The control device 32 turns on the motor 35 by these output signals.
-A signal for turning off is output.

When the main power switch 33 of the copying machine main body 1 is turned on, the control device 32 starts and ends while the large-diameter planetary gear 6 is located at the semicircular internal gears 3c and 3d. Based on the ON signal of the position detection switch 27, it has a function as start-up control means for turning on the motor 35 until there is an OFF signal of the start / end position detection switch 27.

Further, the control device 32 includes various device sensors 3
4 has a function as failure detection means for detecting the operation state of each device, detecting a failure and turning off the motor.

Further, after the failure is detected by the failure detecting means, the control device 32 operates while the large-diameter planetary gear 6 is located at the semicircular internal gears 3c and 3d before the motor 35 is turned off. Of the start / end position detection switch 27 based on the ON signal of the start / end position detection switch 27
It has a function as a failure control means that keeps the motor 35 turned on until there is an FF signal.

In the above configuration, the copying operation of the copying machine will be described first.

In the copying operation, as shown in FIG. 3, first, the original 25 is scanned by the optical system. That is, the original 25 placed on the transparent member on the original platen 2
Is irradiated by the irradiation lamp 15, and the reflected light is
The photosensitive member 13 rotatably arranged is exposed through a rod lens array 24. And this photoconductor 13
Is exposed to the reflected light from the original 25 in a state where the surface of the photoreceptor 13 is uniformly charged by the charger 14 disposed to be opposed to and close to the photoconductor 13, thereby forming an electrostatic latent image on the photoconductor 13. Is formed.

This electrostatic latent image is developed with toner supplied from the developing device 20 to form a toner image corresponding to the original 25 on the photoconductor 13. Next, transfer paper is supplied to the photoconductor 13 from the manual paper feed unit 21 via the transport roller 22 and the registration roller 16, and the toner image is transferred by the transfer unit 12 that is disposed in close proximity to the photoconductor 13. The image is transferred to paper, and the transfer paper is conveyed to the fixing device 19.

The residual toner adhering to the transfer unit 12 after the transfer of the toner image onto the transfer paper is moved onto the photosensitive member 13 by applying a voltage having a polarity opposite to that of the toner to the transfer unit 12. The toner transferred from the transfer unit 12 is
The toner is removed by the cleaning device 17 together with the toner remaining on the toner cartridge 3, and is collected in the toner storage unit 18. further,
After the transfer, the surface of the photoconductor 13 is evenly discharged by the direct light of the irradiation lamp 15 to be in a standby state. On the other hand, when the transfer paper is conveyed to the fixing device 19, the toner image on the transfer paper is heated and pressed by the fixing device 19 to be fixed on the transfer paper, and then the transfer paper is carried out.

Next, the operation of the platen driving device 31 will be described.

First, as shown in FIG. 4, when the driving force of a motor 35 (not shown) is transmitted to the input shaft 7, the sun gear 5 rotates in the direction A as shown in FIG. 6
Rotates in the direction B while meshing with the lower rack portion 3b of the endless gear 3. As a result, the main support 4, that is, the document table 2 moves in the return (R) direction. Then, as shown in FIGS. 7A and 7B, the left semicircle internal gear 3c of the endless gear 3 is connected to the large-diameter planetary gear 6.
, The endless gear 3 stops horizontal movement, and the large-diameter planetary gear 6 moves along the left semicircle internal gear 3c to the sun gear 5.
Revolves around and moves upward. While the large-diameter planetary gear 6 is revolving around the left semicircle internal gear 3c, the start / end position detection switch 27 is in the ON state, whereby the control device 32 determines that the original table 2 has moved to the scanning start position. It is detected that it is located at P3.

Thereafter, as shown in FIG. 3, the small-diameter planetary gear 10 meshes with the upper rack portion 3a, whereby the document table 2 is moved in the feed (F) direction, and the document scanning is started. Then, as shown in FIGS. 8A and 8B, when the right semicircle internal gear 3d of the endless gear 3 reaches the small-diameter planetary gear 10, the endless gear 3 stops horizontal movement and the large-diameter As the planetary gear 6 revolves around the sun gear 5 along the right semicircle internal gear 3d and moves downward, FIG.
The state shown in FIG. 9A and FIG. While the large-diameter planetary gear 6 is revolving around the right half-circle internal gear 3d, the start / end position detection switch 27 is in the ON state, whereby the control device 32 causes the document table 2 to scan the document table 2. It is detected that it is located at the end position P2.

When copying is completed, the motor 35 is further driven, the endless gear 3 moves, and the document table 2 moves to the standby position P1. When the platen 2 moves to the standby position P1, the standby position detection switch 26 is turned on, and the control device 32
Is located at the standby position P1.

In this embodiment, the small-diameter planetary gear 10 has fewer teeth than the large-diameter planetary gear 6, and the upper rack 3a has a finer pitch than the lower rack 3b. The moving speed in the (R) direction is higher than the moving speed in the feed (F) direction.

As described above, as long as the sun gear 5 is rotating, the document table 2 alternately repeats the movement in the return (R) direction and the feed (F) direction. Therefore, by appropriately setting the lengths of the upper and lower rack portions 3a and 3b in the endless gear 3 and the position of the sun gear 5 between the scan end position P3 and the standby position P1, the document table 2 is moved to the scan start position P2. Can be moved. The large-diameter planetary gear 6 and the small-diameter planetary gear 10 in the endless gear 3 revolve only clockwise.
Further, in this copying machine, since the operation of the document table 2 is controlled only by turning on and off the motor, the document image is not copied until the document table 2 returns to the standby position P1 in one copy operation. The transferred transfer paper passes through the fixing device 19 and is discharged from the copying machine main body 1.

Here, the main power switch 3 of the copying machine body 1
Control of the platen driving device when the switch 3 is turned on or when a failure occurs due to various device sensors will be described with reference to the flowchart of FIG.

First, the main power switch 33 of the copying machine body 1
Is turned on, an initial operation is performed (S1), and then it is determined whether or not the start / end position detection switch 27 is ON (S2). Start and end position detection switch 27 in S2
Is OFF, a warm-up process for copying is performed, and operations such as heating to a set temperature by a heater are performed (S3). If the start / end position detection switch 27 is ON in S2, it indicates that the document table 2 is at the scan end position P2 or the scan start position P3, and therefore it is necessary to move the document table 2 to the standby position P1. At this time, as shown in FIG. 7B, when the large-diameter planetary gear 6 is positioned above the lower end of the left semicircular internal gear 3c, or in FIG.
As shown in (b), when the large-diameter planetary gear 6 is located below the upper end of the right semicircular internal gear 3d, the traveling direction of the large-diameter planetary gear 6 becomes the upper rack portion 3a. Therefore, the document table 2 cannot be moved manually. At this time, in the document table driving device 31 of the present embodiment, the control device 32 as the start-time control means turns on the motor 35 until the start / end position detection switch 27 is turned off (S10). Next, it is determined whether or not the start / end position detection switch 27 is OFF (S11). When the start / end position detection switch 27 is turned OFF, the large-diameter planetary gear 6 rotates the left semicircle internal gear 3c or FIG. As shown in ()), it means that the meshing with the right semicircle internal gear 3d has been disengaged, so the motor 35 is turned off (S12), and the process proceeds to S3. As a result, the document table 2 is manually moved to the standby position P.
You can move to 1.

After the warm-up process of S3, it is determined whether or not copying is ready, that is, whether or not the photoconductor 13 has reached the set temperature (S4). It becomes possible state. This state is maintained until the copy switch is turned on.

Next, it is determined whether or not the copy switch has been turned on (S5). When the copy switch is turned on in S5, the operation state of various devices is detected by the various device sensors 34 and output to the control device 32. Control device 32
Judge whether or not there is a failure (S6), and if it is not a failure, the above-mentioned series of copying operations is started (S7). Next, it is determined whether the copying operation has been completed (S8). If the copying operation has not been completed, the process returns to S6. As described above, various equipment failures such as abnormal high temperature and abnormal low temperature of the photoconductor 13, irradiation lamp 15 burnout, and jam (Jam) while performing the copying operation are performed.
Alternatively, a diagnosis is made as to whether a failure such as another abnormality has occurred. If there is no failure, the copying operation of S7 is continued.

When the copying operation is completed in S8, the process returns to S5 to be in a standby state, and it is determined whether or not the copy switch is turned on (S5). If the copy switch is turned on, the copy process from S6 is started. .

On the other hand, if it is determined in step S6 that the motor is faulty, the motor 35 is immediately turned off in the related art. However, in the original platen driving device 31 of the present embodiment, the motor 35 is turned off before the motor 35 is turned off. , Start / end position detection switch 2
It is determined whether or not 7 is OFF (S13). If the start / end position detection switch 27 is OFF in S13, the original table 2 can be moved manually.
5 is turned off (S14), a failure is displayed (S15),
Stop. Start / end position detection switch 27 in S13
Is not OFF, it indicates that the document table 2 is at the scanning end position P2 or the scanning start position P3. Therefore, the control device 32 as a failure-time control unit operates until the start / end position detection switch 27 is turned OFF. That is, the motor 35 is kept ON until the large-diameter planetary gear 6 finishes rotating the left semicircle internal gear 3c or the right semicircle internal gear 3d (S16).
It returns to S13.

As described above, the platen driving device 3 of the present embodiment
1, when the power of the copying machine main body 1 is turned on, the control device 32 as a start-up control means causes the large-diameter planetary gear 6 of the start / end position detecting switch 27 to change to the semicircular internal gear 3c.
Motor based on the output signal indicating that the large-diameter planetary gear 6 is not positioned on the semicircle internal gear 3c or 3d based on the output signal indicating that the large-diameter planetary gear 6 is positioned on the 3d. 35 is turned ON. For this reason, if the large-diameter planetary gear 6 is located at the semicircular internal gears 3c and 3d when the power of the copying machine body 1 is turned on, the large-diameter planetary gear 6
The motor 35 is driven until the gear passes through the semicircular internal gears 3c and 3d and reaches the upper rack 3a or the lower rack 3b. Therefore, the large-diameter planetary gear 6 or the small-diameter planetary gear 10
Is in the upper rack section 3a or the lower rack section 3b, the document table 2 can be manually moved horizontally to return to the home position. In addition, since only the start / end position detection switch 27 is added in terms of structure, the apparatus can be prevented from becoming complicated.

The control device 32 as a failure detecting means
After the failure is detected by the motor 35 and before the motor is turned off, the control device 32 as the failure time control means determines that the large-diameter planetary gear 6 in the start / end position detection switch 27 is positioned at the semicircle internal gears 3c and 3d. The motor 35 is turned on based on the output signal indicating that the large-diameter planetary gear 6 is not located at the semicircle internal gears 3c and 3d. continue. Therefore, when the power of the copying machine body 1 is turned on,
If the large-diameter planetary gear 6 is located at the semicircular internal gears 3c and 3d, the large-diameter planetary gear 6 passes through the semicircular internal gears 3c and 3d and reaches the upper rack portion 3a or the lower rack portion 3b. Until the operation, the motor 35 is driven. Therefore, since the traveling direction of the large-diameter planetary gear 6 or the small-diameter planetary gear 10 is the upper rack portion 3a or the lower rack portion 3b, the original table 2 can be manually moved horizontally to return to the home position. Become. In addition, since only the start / end position detection switch 27 is added in terms of structure, the apparatus can be prevented from becoming complicated.

[0048]

According to the first aspect of the present invention, there is provided an original platen driving device for an image forming apparatus, as described above, provided with position detecting means for detecting whether or not the planetary gear is located on the semicircular internal gear. On the other hand, when the power supply of the image forming apparatus is turned on, the planetary gear in the position detecting means is turned into a semicircle based on an output signal indicating that the planetary gear is located in the semicircular internal gear in the position detecting means. In this configuration, start-up control means for turning on the motor until an output signal indicating that the internal gear is not located is provided.

Thus, when the power of the image forming apparatus is turned on, if the planetary gear is located in the semicircular gear, the motor is driven until the planetary gear passes through the semicircular gear and reaches the rack. Drives. Therefore, since the traveling direction of the planetary gear is the rack portion, it is possible to manually move the document table horizontally and return it to the home position. In addition, in terms of the structure, only the detection means is added, so that the apparatus can be prevented from becoming complicated.

Further, the platen driving device of the image forming apparatus according to the second aspect of the present invention is provided with the position detecting means for detecting whether the planetary gear is located at the semicircular internal gear as described above. On the other hand, before the motor is turned off after the failure is detected by the failure detection means, based on the output signal indicating that the planetary gear is located at the semicircular internal gear, Until there is an output signal that the planetary gear is not located on the semicircle internal gear,
This is a configuration in which a failure-time control unit that continues N is provided.

If the planetary gear is located at the semicircular internal gear at the time of failure of the image forming apparatus, the motor is driven until the planetary gear passes through the semicircular internal gear and reaches the rack. I do. Therefore, since the traveling direction of the planetary gears is the rack portion, the document table can be manually moved horizontally and returned to the home position. In addition, in terms of the structure, only the detection means is added, so that the device can be prevented from becoming complicated.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating drive control of a platen driving device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a copying machine including the document table driving device.

FIG. 3 is a perspective view of a main part of the platen driving device.

FIG. 4 is an enlarged sectional view of a main part showing the structure of the platen driving device.

FIG. 5 is a block diagram showing a control unit in the platen driving device.

FIG. 6 is an explanatory diagram showing a positional relationship between an endless gear and a planetary gear in the platen driving device.

FIGS. 7A and 7B show a state in which the platen returns to the scanning start position in the platen driving device, where FIG. 7A is a front view showing the positional relationship between the platen and the copying machine main body, and FIG.
FIG. 3 is a schematic view of a main part showing a positional relationship between a large-diameter planetary gear and an endless gear.

8A and 8B show a state in which the platen in the platen driving device is fed to a scanning end position, and FIG.
Is a front view showing the positional relationship between the platen and the copying machine main body,
(B) is a principal part schematic diagram showing a positional relationship between the large-diameter planetary gear and the endless gear.

FIG. 9 shows a state in which the large-diameter planetary gear rotates the right semicircular internal gear in the endless gear, and FIG. 9A is a front view showing a positional relationship between the document table and the copying machine main body. FIG. 1B is a schematic view of a main part showing a positional relationship between a large-diameter planetary gear and an endless gear.

FIG. 10 is a front view showing a structure near a document table of a copying machine having a conventional document table driving device.

FIG. 11 is a front view of an essential part showing a platen driving device in the copying machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Copier main body 2 Original table 3 Endless gear 3a Upper rack part (rack part) 3b Lower rack part (rack part) 3c Left semicircular gear part (semicircular gear part) 3d Right semicircular gear part (semicircular gear part) Reference Signs List 4 Main support 5 Sun gear 6 Planetary gear 7 Input shaft 11 Connecting plate 26 Standby position detection switch 27 Start / end position detection switch (position detection means) 31 Platen drive 32 Control device (startup control device, failure control device) ,
Failure detection means) 35 Motor

Claims (2)

(57) [Claims] 1. An image forming apparatus comprising: two rack portions provided in parallel with their tooth surfaces facing each other; and two semicircular internal gears respectively connecting respective ends of the two rack portions. An annular endless gear connected to the platen and linearly movable integrally with the platen; and a fixed position provided at an intermediate portion between the two rack portions of the endless gear, the motor being driven. A sun gear into which power is input,
A planetary gear, which is rotatably provided between the sun gear and the endless gear so as to mesh with the two gears, is rotatably connected to a rotation shaft of the sun gear, and supports a gear shaft of the planetary gear. A platen driving device for an image forming apparatus having a connecting plate that moves along an endless gear, wherein position detecting means is provided for detecting whether the planetary gear is located on the semicircular internal gear. On the other hand, when the power supply of the image forming apparatus is turned on, the planetary gears in the position detecting means are set in the semicircle on the basis of an output signal indicating that the planetary gears are located in the semicircular internal gears. Turn the motor off until there is an output signal indicating that it is not
N. A document table driving device for an image forming apparatus, comprising: a start-up control unit for causing the document table to be driven. 2. An image forming apparatus having a failure detecting means for detecting a failure and turning off a motor when a failure occurs, comprising two rack portions provided in parallel with tooth surfaces opposed to each other, and An annular endless gear comprising two semicircular internal gears for connecting respective ends of both rack portions, connected to a document table and provided so as to be linearly movable integrally with the document table; A fixed position is provided at an intermediate portion between the two rack portions, and a sun gear to which the driving force of the motor is input, and the sun gear and the endless gear are rotatably provided by meshing with the two gears. A platen drive of an image forming apparatus having a planetary gear and a connecting plate rotatably connected to a rotating shaft of the sun gear and moving along an endless gear supporting the gear shaft of the planetary gear; Position detecting means for detecting whether or not the planetary gear is located on the semicircular internal gear, and detecting the position of the motor after turning off the motor after detecting the failure by the failure detecting means. In the means, based on the output signal that the planetary gear is located in the semicircular internal gear, in the position detecting means,
A document table driving device for an image forming apparatus, comprising: a failure control unit that keeps the motor on until an output signal indicates that the planetary gear is not located at the semicircular internal gear.