JPH0990517A - Reciprocating driving device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize reciprocating movement at a constant speed regardless of the fluctuation of a load and backward movement for shortening a reciprocating cycle at a high speed without using a spring clutch mechanism in a conventional technique and to promote miniaturization. SOLUTION: This reciprocating driving device performing forward movement with a driving source rotating while giving driving force in only one direction, and a reduction means constituted of gear trains 3 and 5 reducing the driving force by the engagement of gear trains 3 and 5, and performing the backward movement by the returning force of the elastic force holding means holding the elastic force stored by the forward movement, is provided with an attenuating means 8 attenuating the speed of the movement, and the means 8 is provided with a forward and backward movement switching means 40 switching the attenuating means to be operating-condition in the case of the backward movement and to be non-operating condition in the case of the forward movement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive source that rotates only in one direction, a reciprocating drive device that reciprocates a load by using elastic force accumulated by the drive source, and an image using the same. The present invention relates to a forming device.

[0002]

2. Description of the Related Art Conventionally, as an example of reciprocating a load, there is an original moving table or a mirror table used as a reciprocating member in an electrophotographic copying machine as an image forming apparatus. The original table drive and the mirror table drive shorten the reciprocating cycle and the forward / backward movement at a constant speed irrespective of the load variation while synchronizing with the drive device of the apparatus main body such as the drum which is an image carrier and the conveying roller. Therefore, a reciprocating motion that realizes a backward motion at high speed is required.

As a structure of a reciprocating drive device for realizing this, in addition to a motor as a drive source that rotates only in one direction and a speed reducing device that is a speed reducing device composed of a plurality of gear trains, a forward and backward switching device is provided. There is one that reciprocates by using a combination of a spring clutch mechanism that transmits power and changes the rotation direction thereof, a solenoid that switches the spring clutch mechanism, and the like.

Further, as another reciprocating drive device, a forward movement is performed by a motor as a drive source that rotates only in one direction, and the forward movement holds an elastic force in a mainspring as an elastic force holding means. Some of them perform a backward movement by the stored elastic force.

[0005]

However, the reciprocating drive device using the spring clutch mechanism and the solenoid shown in the above-mentioned prior art has the following problems.

The first problem is that the spring clutch mechanism itself has a large number of parts, and when the accuracy of each part varies, phenomena such as noise, slippage, spring breakage, and whirling may occur. Therefore, it is important to control the accuracy of each individual part, and the phenomenon of clutch squealing particularly deteriorates the product image.

A second problem is that the spring clutch occupies a large volume due to the large number of parts, and the parts are composed of parts having a large specific gravity. The proportion of the entire reciprocating drive device has become large, which has hindered downsizing of the electrophotographic copying machine. Further, since a large number of highly accurate parts are required, it becomes an expensive reciprocating drive device, and it is difficult to achieve an inexpensive reciprocating drive device instead of downsizing.

As a third problem, a sudden sound is generated from the solenoid that operates each time the drive direction is switched. In particular, in a desktop type electrophotographic copying machine, which is often used in a quiet office, the sudden noise that is generated continuously increases the noise level and is a factor that deteriorates the product image. Furthermore, since the solenoid continues to be energized, power consumption increases and the temperature rises by itself, resulting in a product image that contradicts energy conservation.

Further, as another configuration, a reciprocating drive device that performs a forward movement by a motor and a backward movement by a mainspring or the like has the following problems.

As a first problem, since a backward movement is performed by a mainspring or the like, there is a possibility that the moving speed may differ depending on the fluctuation of the load. For example, when the load is very small, there is a risk of a sudden backward movement and damage to internal mechanical components at the stop position. Further, when the load is large, there is a problem that the moving speed of the reverse drive becomes slow and the reciprocating cycle becomes long.

Next, as a second problem, it is conceivable to apply a damping load such as a frictional resistance or a viscous resistance in order to control the reverse speed. However, the damping load acts even when moving forward, and since a motor that drives this load is required, a large output is required for the motor, which makes the motor large and downsizes the entire reciprocating drive device. Was difficult.

The present invention has been made to solve the above-mentioned problems of the prior art. The first object of the present invention is to reduce load fluctuations without using the spring clutch mechanism of the prior art. It is an object of the present invention to provide a reciprocating drive device which can realize a forward and backward motion at a constant speed and a backward motion at a high speed for shortening a reciprocating cycle, which can be made small, and an image forming apparatus using the same.

The second object of the present invention is to:
An object of the present invention is to provide a reciprocating drive device that can be inexpensive and small in size and an image forming apparatus using the same by a simple forward / reverse switching means having a small number of parts.

The third object of the present invention is to:
It is an object of the present invention to provide a reciprocating drive device capable of minimizing the sudden sound generated by a solenoid and realizing quietness and energy saving of a product, and an image forming apparatus using the reciprocating drive device.

[0015]

In order to achieve the above object, the first invention of the present application is directed to a drive source that rotates while applying a driving force only in one direction, and a deceleration composed of a gear train. In the reciprocating drive device, the gear train is decelerated by engaging with the gear train to perform forward movement, and the reciprocating drive device performs backward movement by the restoring force of the elastic force holding means that holds the elastic force accumulated by the forward movement. It is characterized in that it comprises damping means for damping, and the damping means has only forward / backward movement switching means for operating only the backward movement and switching the damping means inactive during the forward movement.

In a second invention according to the present application, the forward / reverse switching means has a holding member that holds the deceleration means and the damping means and is swingably supported, and the holding member is the damping means. The switching is performed by an urging means for urging the urging means in an activating direction and a solenoid for moving the holding member against the urging means in a direction in which the damping means becomes inoperative.

A third invention according to the present application is characterized in that the solenoid operates only when the forward movement is started, and the switching operation to the reverse movement is performed depending on whether the gear train is engaged or not. To do. A fourth invention according to the present application is characterized in that the reciprocating driving device having each of the above-described configurations is used as a driving portion of a member that reciprocates in an image forming apparatus.

In the first aspect of the present invention described above, the damping means operates only in the backward movement, and the damping means is set so as not to operate in the forward movement. Therefore, the damping means is set in the backward movement. (Velocity control) is performed, and the damping resistance does not load during forward movement.

In the above-described second invention of the present application, the forward / backward movement switching operation can be performed only by moving the holding member holding the deceleration means and the damping means.

In the third aspect of the present invention described above, since the operating time of the solenoid is reduced and the meshing of the gear train is eliminated, the forward and reverse movements are automatically switched. Therefore, the switching timing is changed. It is not necessary to separately provide a detection means for controlling the control circuit and its control circuit.

In the fourth invention of the present application, the reciprocating driving device is used for the driving portion of the reciprocating member of the image forming apparatus, so that the product is small and the product is quiet and energy saving. Can be realized.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Hereinafter, a reciprocating drive device according to Embodiment 1 of the present invention will be described in detail with reference to the drawings.
The reciprocating drive device of the present embodiment will be described with reference to a document table moving mechanism adopted in an electrophotographic copying machine or the like.

FIG. 1 shows the forward / backward movement switching means of the reciprocating drive device in the initial state. FIG. 2 is a schematic diagram of an electrophotographic copying machine as an image forming apparatus that employs a reciprocating drive device, and FIGS. 3 to 5 are diagrams for explaining an operation of repeating forward and backward movements.

As shown in FIG. 2, the electrophotographic copying machine according to the present embodiment has a document table 2 installed on the upper part of an apparatus body 1 having a substantially rectangular parallelepiped shape, and a document to be read is placed in the central portion. It has a platen glass 20. The manuscript table 2 is provided with a slide guide rail (not shown) so that arrows x1-x2 in the figure are provided.
It is supported so that it can be scanned in any direction, and is reciprocally driven by a reciprocating drive device described later. An optical system including a light source 21 for irradiating a document and a lens array 22 as an exposure unit is provided on the upper part of the apparatus main body 1.

A process cartridge 23 for forming an image includes a photosensitive drum 24 which is an electrophotographic photosensitive member, a primary charging roller 25 which is a charging means around the photosensitive drum 24, and a developing device 2.
6. The cleaner 27 and the like are integrally incorporated.

The original document placed on the original table glass 20 is irradiated by the light source 21, and the reflected light image is exposed through the range array 22 on the photosensitive drum 24 which is uniformly charged in advance by the primary charging roller 25. An electrostatic latent image is formed, and a developing device 26 forms a toner image corresponding to the electrostatic latent image to form a visible image.

Then, by applying a voltage to a transfer roller 28 provided opposite to the photosensitive drum 24, the toner image is transferred onto a sheet as a recording medium, and the cleaner 27 removes the toner remaining on the photosensitive drum 24. Is configured.

Reference numeral 29 denotes a pair of sheet feeding rollers for feeding a sheet, and a sheet inserted from a cassette (not shown) or from a manual feed port is skewed by a pair of registration rollers 30 that are temporarily stopped. Is corrected and is conveyed in synchronization with the toner image formed on the photosensitive drum 24.

Reference numeral 31 is a conveying device for conveying the sheet after the image transfer, and 32 is a fixing device for fixing the transferred image, which is composed of a fixing belt containing a heater and a pressure roller in pressure contact with the fixing belt. ing. Reference numeral 33 is a pair of discharge rollers for conveying the sheet after image fixing to the outside of the apparatus main body 1, and 34 is a fan for forcibly exhausting the warmed air in the apparatus main body 1 to the outside.

Further, as shown in FIG. 2, as a power source for driving the document table 2 in the backward direction, a mainspring 41 as elastic force holding means is wound around the apparatus main body 1, and one end of the mainspring 41 is wound around the document table 2.
It is locked to the locking portion 2b provided on the. When the document table 2 moves in the direction of arrow x1 (hereinafter referred to as the forward direction), the mainspring 41 is stretched and retains its elastic force. As a result, the original table 2 is biased in the direction of arrow x2 (hereinafter referred to as the backward direction) by the return force of the mainspring 41 as the document table 2 moves in the forward direction. However, the spring constant is set so that the original table 2 is always biased in the backward direction even when the original table 2 is in the initial position (the position shown by the solid line in FIG. 2).

The elastic force holding means is not limited to the spring, and may be a spring member such as a coil spring.

Further, the apparatus main body 1 is provided with the forward / backward movement switching means 40 of the reciprocating drive device in front of the mainspring 41, and the detailed means will be described with reference to FIG.

Reference numeral 3 denotes a rack forming a gear train attached to the document table 2, and the document table 2 can be moved by engaging with a forward gear 5 forming the gear train.

At this time, the rack 3 meshes with the forward gear 5, so that the movement of the document table 2 is decelerated due to frictional resistance and viscous resistance during rotation. That is, the rack 3 and the forward gear 5 form a speed reduction means.

The forward gear 5 is rotatably held by a swing lever 4 as a holding member which is swingably supported in a direction of an arrow a1-a2 around a swing fulcrum 4a.
The input gear 7 is always driven in the direction of arrow a1 by a motor as a drive source that rotates in one direction (not shown). There is no means for switching the rotation direction. Therefore, while the copying machine is operating, the input gear 7,
The drive is transmitted to the idler gear 6 and the forward gear 5, so that the forward gear 5 is always rotating in the direction of arrow b.

Further, 8 is a damper gear as a damping means, which is held by the rocking lever 4 and is provided at a position facing the forward gear 5 about the rocking fulcrum 4a.

The damper gear 8 generates load torque substantially proportional to the rotation speed by utilizing frictional resistance and viscous resistance during rotation, and by engaging with the rack 3,
The moving speed of the document table 2 is controlled. The damper gear 8 does not mesh with other gears and functions independently of the forward gear 5 and the like.

Reference numeral 9 is a solenoid fixed to the apparatus main body 1, and is a movable element 9a which can reciprocate in the directions of arrows c1-c2.
One end of the movable element 9a is inserted into the elongated hole 4b provided in the swing lever 4 and moves in the direction of arrow c2 when the solenoid 9 is energized.
By pulling in, the swing lever 4 can be rotated in the direction of arrow a2 until it comes into contact with the butting pin 11 provided on the apparatus body 1.

Further, 10 is a spring as a biasing means for biasing the rocking lever 4 in the direction of arrow a1, one end of which is a pin 13 on the apparatus main body 1 side, and the other end of which is a hole 4c of the rocking lever 4. Is attached to. When the solenoid 9 is not energized by the spring 10, the mover 9a is pushed out in the direction of arrow c1, the swing lever 4 is rotated in the direction of arrow a1, and the apparatus main body 1
The abutment pin 12 provided on the above is abutted and held.

The operation of the reciprocating drive device having the above structure will be described with reference to FIGS. 1 and 3 to 5.

First, FIG. 1 shows the state of the switching means 40 at the initial stage when the power is turned off or turned on. At this time, the original table 2 is biased in the backward direction by the elastic force of the mainspring 41, but the abutting pin 14 and the rack 3 are pushed.
Since the end portions of the document are in contact with each other, the document table 2 can be reliably held at the initial position. Further, since the solenoid 9 is not energized, the swing lever 4 is held in contact with the butting pin 11 by the biasing force of the spring 10. Therefore, the forward gear 5 does not engage with the rack 3 and the document table 2 is not moved even if the forward gear 5 is rotating.

At this time, the damper gear 8 meshes with the rack 3 but does not mesh with the other gear trains. Therefore, by resisting the elastic force of the mainspring 41, the document table 2 is manually moved in the forward direction. It is possible to move. Therefore, it is possible to easily replace the process cartridge 23 and perform a jam process when a sheet, which is a recording medium, is jammed in the paper transport path of the apparatus main body 1 for some reason.

Next, when a copying operation start signal is given, the solenoid 9 is energized with a voltage sufficient to resist the urging force of the spring 10, and the forward / reverse switching means 4 is provided.
0 works.

As shown in FIG. 3, when the mover 9a of the solenoid 9 is pulled in the direction of arrow c2, the swing lever 4 rotates in the direction of arrow a around the swing fulcrum 4a.
The abutting pin 11 is brought into contact with and held. By this rotation operation, the forward gear 5 meshes with the rack 3, the driving force is transmitted from a motor (not shown) as a drive source, the input gear 7, and the idler gear 6, and the forward gear 5 rotates in the direction of the arrow b to move the rack 3 to the rack 3. When the forward gear 5 is engaged, it is decelerated and the document table 2 moves in the forward direction, that is, the forward movement of the document table 2 is started.

After that, the above-mentioned copying process is performed on the sheet which is the recording medium to form an image.

At this time, since the forward gear 5 rotates in the direction of the arrow b and meshes with the rack 3, its reaction force is
A moment in the direction of arrow a2 acts on the swing lever 4. Therefore, once the forward gear 5 and the rack 3 engage with each other, the escape is not generated, and the power is reliably transmitted and the forward linear motion is performed.

Since the reaction force in the arrow a2 direction is generated, the driving force in the arrow c2 direction by the solenoid 9 becomes unnecessary, and the solenoid 9 is de-energized after a predetermined time from the operation start signal, but the forward movement is not performed. You can continue as it is.

Further, as the document table 2 moves forward, the mainspring 41 is stretched and retains its elastic force.
As a matter of course, the torque and the reduction gear of the motor (not shown) as a drive source are set in advance so that the forward drive force that resists the elastic force is input from the forward gear 5.

After that, the document table 2 moves forward, and FIG.
As shown in FIG. 4, when the switching position in the scanning direction is reached, the rack 3 attached to the document table 2 serves as the end portion of the gear, and thereafter, the gear is set not to exist. In this state, the rack 3 and the forward gear 5 are no longer meshed with each other, and the reaction force thereof also disappears automatically.

As described above, since the solenoid 9 is not energized and the driving force of the solenoid 9 in the arrow c2 direction is lost, the swing lever 4 is rotated in the arrow a1 direction by the urging force of the spring 10. Then, it comes into contact with the abutment pin 12 and is held, and it is automatically switched as shown in FIG.

In the state of FIG. 5, the force applied to the document table 2 is only the elastic force in the backward direction from the mainspring 41,
The document table 2 moves in the backward direction, that is, starts backward movement. At this time, the rack 3 meshes with the damper gear 8 and moves while applying a forward-direction damping load that is substantially proportional to the speed, so that the document table 2 does not suddenly move backward.

By setting the magnitude of the damping load of the damper gear 8 and the restoring force of the mainspring 41 to appropriate values, the reverse speed can be set freely and can be made several times faster than the forward speed. Is. Further, regardless of the weight placed on the document table 2, the backward movement is continued at substantially the same speed.

Eventually, as shown in FIG. 1 which is the initial position of the original table 2, the end of the rack 3 comes into contact with the abutment pin 14 and the backward movement is stopped. A standby state is prepared for the next reciprocating movement, and the solenoid 9 is energized to switch to the forward movement again.

Further, this embodiment has the following unique effects.

1) Since the energization of the solenoid 9 is completed only in the initial stage of the forward movement, the power consumed is reduced,
It becomes possible to make an electrophotographic copying machine that is energy efficient.

2) Since the change from forward to reverse is automatically performed, it is not necessary to separately provide a detecting means for detecting the position at the end of scanning.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is different from the above-described first embodiment only in the forward / reverse switching means 40, and therefore only the part thereof will be described and other configurations and actions are the same as those in the first embodiment, and therefore the description thereof will be omitted.

In FIG. 6, reference numeral 103 denotes a rack forming a gear train attached to a document table (not shown), and the document table can be moved by engaging with a forward gear 105 forming the gear train.

The forward gear 105 is rotatably held by a shaft 104d of a swing lever 104 as a holding member which is supported along the guide shaft 115 so as to be movable in parallel in the directions of arrows d1 and d2, and passes through an idler gear 106. Although it is connected to an input gear (not shown), it is always driven and there is no means for switching the rotation direction.

Reference numeral 108 denotes a damper gear which is a damping means, which is held by the rocking lever 104 and is held by the forward gear 10.
It is provided at a position opposite to 5.

Reference numeral 109 is a solenoid fixed to the main body of the apparatus. One end of the mover 109a is locked in a hole 104b provided in the rocking lever 104, and when the solenoid 109 is energized, the mover 109a is retracted. Abutment pin 11 provided on the main body of the swing lever 104
It is translated in the direction of arrow d2 until it abuts 1 (see FIG. 6).

Reference numeral 110 indicates the swing lever 104 by the arrow d.
It is a spring as a biasing means for biasing in one direction, and has one end hooked on the pin 113 on the apparatus main body side and the other end hooked on the hole 104c of the swing lever 104. With this spring 110, when the solenoid 109 is not energized, the swing lever 1
04 moves in parallel in the direction of the arrow d1 and comes into contact with and is held by the abutting pin 112 provided on the apparatus body (see FIG. 7).

The operation of the reciprocating drive device having the above structure will be described with reference to FIGS. 6 and 7. The moving direction of the rocking lever 104 is different from that of the first embodiment described above, and the forward gear 105 is different. Since the reaction force in the engagement direction with the rack 103 does not act in the movement direction of the swing lever 104, the only difference is that the solenoid 109 is continuously energized during the forward movement.

Further, the present embodiment has the following unique effects.

1) Since the forward / backward movement direction can be switched depending on whether the solenoid 109 is energized or not, the scanning time is shortened by changing the scanning range of the document table in the electrophotographic copying machine according to the size of the document. It becomes possible.

In each of the above-described embodiments, the drive unit of the original moving table, which is a member that reciprocates in the electrophotographic copying machine, is illustrated as the reciprocating drive device, but the present invention is not limited to this. It goes without saying that the present invention can be applied to a reciprocating member, for example, a driving unit such as a mirror moving table of an electrophotographic copying machine as an image forming apparatus.

[0067]

As described above, the first embodiment according to the present application is described.
According to the invention, the damping means is operated only in the backward movement, and in the forward movement, the forward-reverse switching means which does not activate the damping means causes the forward-backward movement at a constant speed irrespective of the load variation and the high-speed movement. By realizing the stable backward movement, the reciprocating cycle can be shortened, and the stable reciprocating drive device can be provided.

According to the second aspect of the present invention,
The switching between the forward and backward movements is performed at a low cost and with a small size by a simple forward and backward switching means with a small number of parts, in which a holding member that holds a deceleration means and a damping means and is swingably supported is operated by a solenoid. A reciprocating drive device can be provided.

According to the third invention of the present application,
The solenoid operates only at the start of the forward movement, and the switching operation to the reverse movement is performed depending on whether the gear train is engaged or not.Therefore, the sudden sound generated by the solenoid is reduced as much as possible, and quietness and energy saving of the product can be realized. A reciprocating drive device can be provided.

According to the fourth invention of the present application,
Since the reciprocating driving device itself is downsized, the image forming device can be downsized.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an initial state of a forward / rearward travel switching means of a reciprocating drive device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an electrophotographic copying machine as an image forming apparatus that employs the reciprocating drive device according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining a forward movement start state of the forward / rearward movement switching means of the reciprocating drive device according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a forward end state of forward / reverse switching means of the reciprocating drive device according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a reverse drive starting state of the forward / reverse switching means of the reciprocating drive device according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a forward movement state of a forward / rearward movement switching unit of the reciprocating drive device according to the second embodiment of the present invention.

FIG. 7 is a diagram for explaining a backward movement state of the forward / backward movement switching means of the reciprocating drive device according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic copying machine main body (image forming apparatus main body) 2 Original platen 3 Rack (decelerating means) 4,104 Swing lever (holding member) 5,105 Forward gear (decelerating means) 8,108 Damper gear (damping means) 9 , 109 Solenoids 10, 110 Spring (biasing means) 40 Forward / reverse switching means 41 Spring (elastic force holding means)

Claims (4)

[Claims] 1. A driving source that rotates while giving a driving force only in one direction, and the driving force is decelerated by engaging the gear train by a speed reduction means composed of a gear train to perform a forward motion, and the forward motion is performed. A reciprocating drive device that performs a backward movement by a restoring force of an elastic force holding means that holds a stored elastic force, comprising a damping means for damping the speed of the movement, the damping means operating only the backward movement, and the forward movement. In the case of the above, the reciprocating drive device is provided with a forward / rearward travel switching means for switching the damping means to a non-operation. 2. The forward / backward switching means has a holding member that holds the deceleration means and the damping means and is swingably supported, and urges the holding member in a direction in which the damping means operates. The reciprocating drive device according to claim 1, wherein switching is performed by an urging means and a solenoid that moves the holding member against the urging means in a direction in which the damping means is deactivated. 3. The reciprocating mechanism according to claim 2, wherein the solenoid operates only when the forward movement is started, and the switching operation to the reverse movement is performed depending on whether the gear train is engaged or not. Drive. 4. An image forming apparatus, wherein the reciprocating driving device according to claim 1, 2, or 3 is used for a driving portion of a member that reciprocates.