JPH1185283A - Driving device for position switching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for maintenance and to securely perform switching between pressure application and separation by engaging a rotary member with a driving shaft and rotating them in one body, arranging a return member which engages the rotary member rotatably, and energizing the return member with an energizing spring. SOLUTION: When a motor 4 rotates clockwise in the separation state of a cam 2, the rotation is transmitted to the cam shaft 1 through an input gear 5 to rotate the cam 2 counterclockwise. When the cam 2 reaches an abutting position, the motor 4 stops and stays in this state. When the motor 4 is rotated counterclockwise, the cam 2 is switched from the pressure application state to the separation state. An engagement part 9 formed on the input gear 5 rotates engaging the return member 6 when the input gear 5 rotates counterclockwise and when the return member 6 rotates, the energizing spring 7 expands to apply a clockwise force to the cam shaft 1. If a momentary break of power supply is caused owing to a power failure while the cam 2 is at the pressure application position, the cam shaft 1 rotates clockwise with the energizing force of the energizing spring 7. Consequently, the switching can be secured without any maintenance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position switching drive provided in an image forming apparatus.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional position switching driving device.

FIG. 5 is a perspective view of a conventional position switching drive device, in which 11 is a camshaft, and 12 is a camshaft 1.
1, a cam frame 13 is rotatably supporting the camshaft 11; 14, a spring clutch;
Reference numeral 15 denotes a drive gear of the spring clutch 14, and reference numeral 16 denotes a solenoid. In the position switching drive device configured as described above, for example, two positions are switched between pressurization and separation by performing half-rotation control of the camshaft 11 using the spring clutch 14. Here, the spring clutch 1
Although a detailed description of the operation of No. 4 is omitted, a drive is input to the drive gear 15 from a drive source (not shown).

However, since the claw of the solenoid 16 is engaged with the corner of the control ring of the spring clutch 14, the spring in the spring clutch 14 is loosened and the drive is not transmitted to the camshaft 11, and the camshaft 11 Remains stopped.

FIG. 6 shows a state where the cam 12 is waiting at the separated position. The solenoid 16 turns ON from this state
Then, the corner of the control ring of the spring clutch 14 comes off the claw of the solenoid 16 and becomes free. Then, the drive input to the drive gear 15 is transmitted to the camshaft 11 via the spring, the control ring, and the fixed boss.

On the other hand, another corner is provided on the side of the control ring of the spring clutch 14 opposite to the corner of the control ring. The spring is loosened, the drive to the camshaft 11 is cut off, the cam 12 rotates half a turn, and the camshaft 11 stops in a state where it has reached the pressing position as shown in FIG.

When the solenoid 16 is turned off, the drive is transmitted to the camshaft 11 again, and the cam 12 returns to the separated position as shown in FIG.

However, depending on the use of such a position switching drive, if the cam 12 is kept in contact during a momentary power interruption, the machine may be damaged.
2 may need to be forcibly retracted to the separated position.

In the position switching drive device using the spring clutch 14 described above, the solenoid 16 is turned off when the power supply is momentarily interrupted. It can return to the separated position. For example, in an electrophotographic apparatus typified by a copying machine or a laser beam printer (LBP), for example, switching of a plurality of developing units to and from a photosensitive drum, switching of a transfer drum to and from a photosensitive drum, and the like. Is mentioned.

Here, a full-color image forming apparatus employing an electrophotographic system will be described with reference to FIG.

FIG. 8 is a cross-sectional view of the full-color image forming apparatus. In FIG. 8, reference numeral 100 denotes an image forming apparatus main body, 101 denotes a photosensitive drum, and the photosensitive drum 101 is driven clockwise by a driving means (not shown). It is driven to rotate at a peripheral speed (process speed). Reference numeral 102 denotes a transfer drum, which is driven to rotate counterclockwise with respect to the photosensitive drum 101 at the same peripheral speed as the photosensitive drum 101.

The original 103 is an original illumination lamp 10.
4, the reflected light is bent by the first mirror 105, the second mirror 106, and the third mirror 107, the focus is adjusted by the lens 108, and then read as an image by the photoelectric sensor 109. Generally, in the case of a full-color original, four scanning operations are performed to read the magenta, cyan, yellow, and black components in the original.

First, a laser oscillator 1 corresponding to the image of the magenta component read by the photoelectric sensor 109 is used.
A laser beam is emitted from 10 and a latent image in the scanning direction is formed on the photosensitive drum 101 via the mirror 112 by the rotating polygon 111. Then, the latent image on the photosensitive drum 101 is developed by the magenta developing device 113 as a toner image.

On the other hand, the transfer paper includes an upper cassette 117, a middle cassette 119, a lower cassette 121, a multi-tray 1
23, but here, the lower cassette 12
1 will be described.

The transfer sheets stacked in the lower cassette 121 are separated one by one in a sheet feed separation unit 122.
Vertical path rollers 124, 125, 126, horizontal path roller 1
27 and the registration roller 1
29.

Then, the transfer paper is registered with a registration roller 129 so that the position thereof matches the image position on the photosensitive drum 101.
After the timing is adjusted, the transfer drum 102 is conveyed to the transfer drum 102 and
Absorbed on top.

Next, in the transfer section 131, the photosensitive drum 1
Magenta toner image developed on the transfer drum 1
02 is transferred to the transfer paper adsorbed on the sheet 02. And
The transfer paper rotates while being adsorbed on the transfer drum 102 as it is.

The toner remaining on the photosensitive drum 101 without being transferred in the transfer section 131 is collected by a cleaner 135.

After the potential on the photosensitive drum 101 is made uniform by the primary charger 136, a latent image corresponding to the cyan component image is formed on the photosensitive drum 101 by the same process as the magenta component image. The latent image is formed and is developed as a toner image by the cyan developing device 114. Then, in the transfer section 131, the cyan toner image is transferred onto the transfer paper that has been attracted onto the transfer drum 102 that has made one rotation.

Similarly, the image of the yellow component and the image of the black component are transferred onto the transfer paper, and the images of the four color components are all transferred onto the transfer paper. In addition, 115 is a yellow developing device, and 116 is a black developing device.

Here, it is needless to say that the latent image is controlled to be formed on the photosensitive drum 101 by the laser beam so that the images of the four color components on the document 103 all coincide on the transfer paper.

The transfer paper onto which the four color toner images have been transferred through the above process is separated from the transfer drum 102 by the push-up rollers 132 and the separation claws 133, and the transfer unit 13
4 transports to the fixing device 137. In the fixing device 137, the transfer paper is nipped and conveyed by the fixing roller 143 heated by the heater 144 and the pressure roller 145 heated by the heater 146, and the toner image carried on the transfer paper is melted. And is fixed on the transfer paper.

The transfer paper having the toner image fixed by the fixing device 137 is discharged out of the image forming apparatus main body by the discharge roller 139 and is stacked on the tray 147.

[0024]

However, in the above-described conventional position switching drive device, while the spring clutch 14 is being driven, the space between the boss portion of the drive gear 15 and the spring always idles. Therefore, the idle rotation time is longer than the operation time, which causes the following problem.

That is, in the spring clutch 14, a lubricant is sealed to prevent abrasion between the drive boss and the spring which are always slid due to idling, so that the spring bites into the drive boss during operation. In addition, there are problems such as the occurrence of problems and the necessity of maintenance for periodically injecting a lubricant.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to perform a maintenance-free switching between pressurization and separation without fail.
It is an object of the present invention to provide a position switching drive device capable of forcibly moving from a pressurized position to a separated position when a power supply is momentarily interrupted to prevent damage to a machine.

[0027]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a position switching drive device for switching at least two positions, comprising a drive means, and a drive shaft driven by the drive means. A rotating member locked to the drive shaft and integrally rotating, a return member rotatably disposed to engage with the rotating member, and a biasing spring for biasing the return member And characterized in that:

According to a second aspect of the present invention, in the first aspect of the present invention, the driving means is a stepping motor.

According to a third aspect of the present invention, in the first aspect of the present invention, when the rotating member is rotated by the driving means in a direction facing the biasing spring, the return from the beginning of rotation. It is characterized by having a certain predetermined distance before engaging with the member.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the time until the rotating member is engaged with the return member is set longer than the acceleration time when the stepping motor starts up. It is characterized by the following.

A fifth aspect of the present invention is characterized in that, in the first aspect of the present invention, there is provided means for detecting a phase of the drive shaft.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the phase of the drive shaft is detected for each contact operation.

[0033]

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

FIG. 1 is a perspective view of a position switching driving device according to the present invention. In FIG. 1, reference numeral 1 denotes a cam shaft, 2 denotes a cam connected to the cam shaft 1, and 3 denotes a cam shaft. A drive frame 4 freely supported is a motor as a drive source, and 5 is an input gear connected to the camshaft 1.
Inputs the drive from the motor 4 to the camshaft 1.

Reference numeral 6 denotes a return member rotatably mounted on the camshaft 1. Reference numeral 7 denotes an urging spring for urging the return member 6. One end of the urging spring 7 is a return member 6. The other end is locked to the frame 3 respectively.

Reference numeral 8 denotes a stopper for holding the return member 6 urged by the urging spring 7 at a predetermined position. The stopper 8 is attached to the frame 3. Reference numeral 9 denotes an engaging portion that engages with the return member 6, and the engaging portion 9 is formed integrally with the input gear 5.

FIG. 2 shows a state where the cam 2 is at the separated position. In this state, when the motor 4 rotates in the direction of arrow A shown in the figure (hereinafter, the direction of arrow A is referred to as forward rotation and the reverse direction is referred to as reverse rotation), the rotation is transmitted to the camshaft 1 via the input gear 5, 1 and the cam 2 connected thereto rotate in the direction of arrow B in FIG.

When the motor 4 rotates by a predetermined angle and the cam 2 reaches the contact position, the motor 4 stops as shown in FIG. 3, and this state is held. When the cam 2 is switched from the pressurized state to the separated state, the motor 4 may be rotated in the reverse direction by a predetermined angle.

The engaging portion 9 formed on the input gear 5 engages with the return member 6 when the input gear 5 rotates forward,
The return member 6 is configured to rotate on the camshaft 1. When the return member 6 rotates, the urging spring 7 is extended, and a force in the reverse rotation direction is urged to the camshaft 1 via the return member 6 and the input gear 5.

As shown in FIG. 3, when the cam 2 is in the pressurized position and the power is momentarily interrupted due to a power failure or the like, the camshaft 1 is rotated in the reverse rotation direction by the urging force of the urging spring 7. The spring force of the biasing spring 7 is set so as to exert a torque enough to return the cam 2 until a necessary separation distance is obtained from the pressurized state.

When the cam 2 is driven by the motor 4 as in the present embodiment, a stepping motor is often used as the motor 4 from the viewpoint of easy positioning. However, when using a stepping motor, care must be taken in setting the conditions for startup.

As shown in FIG. 2, the angle α is secured until the engaging portion 9 formed on the input gear 5 is rotated by the motor 4 and engages with the return member 6.

For example, when α = 0 °, when the stepping motor 4 starts up, the total of acceleration torque + load torque + spring biasing torque becomes the total load of the stepping motor 4, and if this total load is not less than the pull-in torque, the stepping motor 4 4 steps out. Therefore, the size of the stepping motor 4 is increased.

Therefore, by setting the angle α larger than the acceleration start-up region of the stepping motor 4, the spring biasing torque is not applied to the total load during the acceleration start-up, and only the acceleration torque + load torque is applied to the total load. It can be made to be torque. After the acceleration is completed and the engaging portion 9 is engaged with the return member 6, the load torque + spring bias torque becomes the total load of the stepping motor 4, and the acceleration torque is not applied to the stepping motor 4. Miniaturization can be achieved.

After the stepping motor 4 starts up, the step-out torque of the motor 4 is a pull-out torque larger than the pull-in torque, so that the margin of the stepping motor 4 is also improved. Of course, if the torque of the stepping motor 4 is compared with the load and the motor torque has a margin, the angle α is set to be small,
There is no problem even if the urging spring force is applied during the acceleration. That is, the angle α is determined by the pull-in torque and the pull-out torque of the stepping motor 4, the inertia of the contact / separation oscillating portion,
It is determined by the load torque, the urging force of the urging spring 7, and the like.

As described above, by appropriately setting the angle α, the pressure / separation operation can be stabilized without increasing the size of the stepping motor 4.

Although the return member 6 is provided on the camshaft 1 in this embodiment, the return member 6 may not be coaxial with the camshaft 1 but may be provided at a position where the same action can be obtained. Further, in the present embodiment, switching between pressurization and separation has been described. However, it is needless to say that the present invention is not limited to this, and can be applied to all switching drive devices at at least two positions.

When it is desired to accurately position the contact / separation position, it is desirable to provide a sensor. An example is shown in FIG.

As shown in FIG. 4, a sensor flag 10 is formed integrally with the input gear 5, and a sensor 11 is mounted on a mounting plate mounted on the frame 3.

The input gear 5 is rotated by the motor 4 and the sensor flag 10 shields the sensor 11 from light, so that the phase of the cam shaft 1 and the cam 2 with respect to the frame 3 can be detected. By driving the stepping motor 4 by a predetermined number of pulses using this phase as a home position, accurate positioning between contact and separation can be performed. It should be noted that this home position detection may be determined to be performed, for example, every time the power of the apparatus body is turned on or each time the contact operation is started.

[0051]

As is apparent from the above description, according to the present invention, a position switching drive device for switching at least two positions includes a drive means, a drive shaft driven by the drive means, A rotating member that is locked to a shaft and rotates integrally, a return member that is rotatably disposed and engages with the rotating member, and a biasing spring that biases the return member. With this configuration, switching between pressurization and separation can be performed reliably without maintenance, and when the power supply is momentarily interrupted, the position switching drive is forcibly moved from the pressurization position to the separation position to reduce machine damage. The effect that it can be prevented is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a position switching drive device according to the present invention.

FIG. 2 is a diagram showing a state in which a cam of the position switching drive device according to the present invention is at a separated position.

FIG. 3 is a diagram showing a state in which a cam of the position switching drive device according to the present invention is in a pressing position.

FIG. 4 is a diagram showing another embodiment of the position switching drive device according to the present invention.

FIG. 5 is a perspective view of a conventional position switching drive device.

FIG. 6 is a diagram showing a state in which a cam of a conventional position switching drive device is at a separated position.

FIG. 7 is a view showing a state in which a cam of the conventional position switching drive device is at a pressing position.

FIG. 8 is a sectional view of the full-color image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 cam shaft (drive shaft) 2 cam 4 motor (drive means) 5 input gear (rotating member) 6 return member 7 biasing spring 11 sensor

Claims (6)

[Claims] 1. A position switching drive device for switching at least two positions, comprising: a drive unit; a drive shaft driven by the drive unit;
A rotating member locked to the drive shaft and integrally rotating, a return member disposed rotatably and engaged with the rotating member,
And a biasing spring for biasing the return member. 2. The driving device according to claim 1, wherein said driving means is a stepping motor. 3. When the rotating member is rotated by a driving means in a direction facing an urging spring, the rotating member has a predetermined distance from the start of rotation to engagement with the return member. 2. The position switching drive according to claim 1, wherein: 4. The position switching drive according to claim 2, wherein a time until the rotating member is engaged with the return member is set longer than an acceleration time when the stepping motor starts up. apparatus. 5. The position switching drive device according to claim 1, further comprising means for detecting a phase of said drive shaft. 6. The position switching drive device according to claim 5, wherein the phase detection of the drive shaft is performed for each contact operation.