JPH08101556A - Image forming device - Google Patents

Abstract

PURPOSE: To eliminate the problems that the size of the device and power consumption are increased by using a stepping motor as a driving source and driving a load via a clutch with high rated torque in an image forming device. CONSTITUTION: The image forming device uses the stepping motor 201 as its driving source, has a clutch 202 in a drive transmission mechanism between the driving source and load with an encoder 205, and highly accurately positions the load. The image forming device is provided with a means 303 for detecting an amount of slip caused on the side of the load, and a means 304 for correcting an amount of the movement of the load according to the detected amount of slip, permits slip to a certain degrees, and allows the use of the clutch with low rated torque.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image by electrophotography or the like, and more specifically, a stepping motor is used as a drive source and a clutch is provided in a drive transmission system between the drive source and a load. The present invention relates to an image forming apparatus having a positioning mechanism that controls

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus, as a drive source for selectively driving a plurality of developing cartridges for developing a toner image on an image bearing member, the developing cartridges, other developing sleeves, and pressurizing / separating of developing means are used. In the case where one stepping motor commonly used for driving the developing cartridge is arranged and the developing cartridge is to be selectively driven, the stepping motor is used as a drive source and a clutch in a positioning mechanism having a clutch or the like in a drive transmission system. By turning on, a desired developing cartridge is selectively moved to perform a predetermined development on the image carrier, and then the developed image is transferred to a transfer material and fixed to complete the image formation.

[0003]

However, in the conventional image forming apparatus, in order to realize a positioning mechanism for positioning the developing cartridge, which is a load, with high precision, slippage occurs by using a clutch or the like having a high rated torque. It didn't happen. The use of such a clutch having a high rated torque has a problem that the entire image forming apparatus becomes large and power consumption increases. Further, if a clutch having a high rated torque is adopted, there is a problem that the stepping motor cannot rotate regardless of the application of the excitation voltage and becomes out of step if the load is too large compared with the holding torque of the stepping motor.

The present invention solves the above problems,
An object of the present invention is to provide an image forming apparatus capable of accurately positioning a load and preventing step-out by using a clutch having a low rated torque.

[0005]

According to the present invention, in the image forming apparatus which uses the stepping motor as a drive source, has the clutch in the drive transmission mechanism, and performs the high-precision positioning control of the load, the slip on the load side is provided. By having a means for detecting the amount and a correcting means for correcting the movement amount of the load according to the detected slip amount, highly accurate positioning control can be performed without increasing the rating of the clutch.
Slip on the load side by providing an encoder on the load side and using the drive command signal of the stepping motor as a trigger to detect the difference between the actual movement amount detected by the encoder and the theoretical movement amount obtained by the stepping motor drive command signal. Detect the amount. By increasing the number of drive steps of the stepping motor by the integral amount of the slip amount obtained by the slip amount detecting means, the movement amount of the load can be corrected and the load can be stopped at the regular position.

Further, the stepping motor can be prevented from step-out by making the rated torque of the clutch on the drive transmission system lower than the holding torque of the stepping motor and using it as a torque limiter. Further, when the detected slip amount exceeds a certain allowable value or continuous slips occur, it is considered that an abnormality has occurred during operation and an alarm is issued, and the device is stopped.

[0007]

【Example】

<Embodiment 1> An embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS. In FIGS. 1 and 2, first, the optical unit 10 is based on the reading signal of the original document.
Drum cleaner unit C for each latent image by 7
Is formed on the image carrier 1. Developing device selection mechanism 203
Is a developing cartridge holding member 108 rotatable about an axis 110 parallel to the axis of the image carrier 1, a control / driving mechanism for rotating the holding member 108 to selectively move the developing cartridge, and , Each developing cartridge D
The developing device selecting mechanism 20 includes a driving mechanism for maintaining y, Dc, Dm, and Db in a specific posture.
3, each developing cartridge is selectively made to face the image carrier to form the latent image into a toner development image of each color.

The paper 102 fed from the paper feed unit 101
Is held at the outer periphery of the transfer drum 103 by sandwiching its tip by the gripper 103f of the transfer drum 103,
The developed images on the image carrier, which have been developed into images for each color by the selection mechanism 203, are sequentially transferred to the paper 102, which is a transfer material on the transfer drum 103, and a multicolor image is formed.
It is separated from the transfer drum 103, fixed by a fixing unit, and ejected from the paper ejection unit 105 to the paper ejection tray unit 106.

Next, a drive mechanism for selectively driving the developing device selection mechanism 203 will be described with reference to FIGS. 2 and 3, and 201 is a stepping motor as a drive source.
Reference numeral 202 designates a clutch for providing a driving force transmission path, that is, a gear train, between the stepping motor as a driving source and the developing device selecting mechanism 203, for turning the driving force transmission on and off, and 204 a member other than the developing device selecting mechanism. The clutch 202 is a load clutch, and the clutch 202 is turned on when the stepping motor 201 is stopped so that the driving force of the motor 201 can be transmitted to the developing device selection mechanism 203. Two
Reference numeral 05 is an encoder attached to the developing device selection mechanism.

Positioning of the developing device selection mechanism 203 is performed by the number of drive command pulses of the stepping motor generated by the controller 305. As shown in FIG. 4, the controller 305 causes the pulse counter 30 of the encoder to start by driving the developing device selection mechanism (step 401).
2 is reset (402b), and the moving amount of the developing device selection mechanism 203 is converted into the number of pulses of the motor 201 (Step).
= POSITION, set to Buffer Step (4
02c), generation of a drive command pulse is started. Before the start of this pulse generation, the clutch slip Sl = 0 (40
2a), and the total slip T_Sl = 0 (402d) for accumulating the Sl. The driver 301 generates the phase excitation signals A, / A (knot A), B, / B of the stepping motor from the drive command pulse to drive the motor. The slip amount detecting means 303 detects Sl by comparing the amount of rotation of the encoder from the encoder counter 302 using the drive command pulse as a trigger. That is, the movement amount conversion obtained based on the drive command pulse indicates the theoretical movement amount of the stepping motor or the developing device selecting mechanism, while the rotation amount of the developing device selecting mechanism is detected by the encoder 205 in an analog manner. The slip Sl is obtained by comparing the converted movement amount by each drive command pulse and the analog movement amount from the encoder 205 for each pulse or step (404).
b). The Sl is stored in the buffer Counter and the counter is reset. When the content of the buffer Sl is 1 or more, it is determined that slip has occurred (405), the movement amount of the developing device selection mechanism 203 is corrected, that is, the number of driving steps of the stepping motor is increased by the slip amount, and the total amount is also increased. The slip amount T_Sl is accumulated (406).
When the cumulative slip amount T_Sl exceeds a certain allowable value (LIMIT) (407), it is determined that the clutch continuously slips and an abnormality occurs in the operation (40
8) After the warning is issued by a warning means (not shown) such as acoustic or optical, the apparatus is stopped. The slip amount is detected by the controller 305 until the positioning of the developing device selection mechanism is completed. After the positioning is completed, the stop position accuracy of the developing device selection mechanism becomes equal to or less than the minimum movement amount of the stepping motor 201.

As described above, according to this embodiment, even if the clutch slips, it can be corrected, so that a clutch having a relatively low rated torque can be used, and the image forming apparatus can be made compact. Power consumption can be reduced. Also, the rated torque of the clutch can be set lower than the holding torque of the stepping motor, in which case the clutch can act as a torque limiter, and the stepping motor can be prevented from stepping out without being stopped by an excessive load. To be done. Despite taking the above correction measures,
When the accumulated slip amount becomes excessive and exceeds a predetermined value, the warning device issues a warning and stops the device, so that the device can be operated safely. Further, the slip amount detecting means can also be used as the operation abnormality detecting means, and the device can be simplified.

<Second Embodiment> FIGS. 5 to 7 show a second embodiment of the present invention. In this embodiment, the same components as those in the above embodiment are designated by the same reference numerals. In this embodiment, an encoder 505 that detects the rotation amount of the motor is provided on the step motor 201 side, and an encoder 205 that detects the rotation amount of the mechanism is provided on the developing device selection mechanism side. Then, the controller 305 turns on the clutch 202 before driving the developing device selection mechanism 203 to enable drive transmission. As shown in FIG. 7, before generating the controller drive command pulse signal, the encoder counter 30 of the load side encoder 205 attached to the load side.
2 (E_Counter) and the encoder counter 602 of the motor side encoder 505 attached to the motor side
Reset (M_Counter) (block 70)
2). The movement amount of the developing device selection mechanism is converted into the number of pulses of the motor 201 and stored in the buffer Step. The rotation amounts of the developing device selection mechanism and the stepping motor detected by the encoders 205 and 505 are compared by the comparator 601 to detect the slip amount (703), and the slip amount Sl is determined to be larger than the cumulative slip T_Sl. And (704), the slip amount and the number of steps are corrected (7
05). Also, the encoder 502 mounted on the motor side
When the encoder counter 602 of No. does not change more than a certain allowable value during continuous sampling, that is, the motor rotation amount (P_M_Counter) before a certain time point is compared with the current motor rotation amount (M_Counter) (706),
When it is determined that the difference An is smaller than the predetermined value LIMIT (707), it is considered that an abnormality has occurred during operation (70).
8), the warning is issued and the apparatus is stopped as in the above embodiment.

In addition to the same effects as the above-described embodiment, this embodiment detects the rotation amount of the stepping motor by detecting the rotation amount of the motor itself by the encoder 505, so that the drive command pulse number and the motor The rotation amount of the motor can be detected more accurately without causing a deviation from the rotation amount.

[0014]

As described above, according to the present invention,
An image forming apparatus that uses a stepping motor as a drive source, has a clutch in a drive transmission mechanism, and performs high-precision positioning control of a load is provided with a unit that detects a slip amount on the load side, and a drive signal according to the detected slip amount. By providing a correction means for correcting the load movement amount to correct the load movement, it is possible to realize high-precision positioning even when slip occurs due to the clutch on the drive transmission system, so use a clutch with a low rated torque. You can As a result, it is possible to realize a small-sized and power-consuming device. Further, the rated torque of the clutch on the drive transmission system is made lower than the holding torque of the stepping motor, and the clutch is used as a torque limiter to prevent the stepping motor from being out of step and improve the operation reliability. Further, the device can be simplified by using the slip amount detecting means also as the operation abnormality detecting means.

[Brief description of drawings]

FIG. 1 is an overall view of an image forming apparatus embodying the present invention.

FIG. 2 is a schematic diagram of a drive system according to a first embodiment of the present invention.

FIG. 3 is a block diagram of a first embodiment of the present invention.

FIG. 4 is a flowchart of the first embodiment of the present invention.

FIG. 5 is a schematic diagram of a drive system according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a second embodiment of the present invention.

FIG. 7 is a flowchart of a second embodiment of the present invention.

[Explanation of symbols]

203 ... Developing device selection mechanism 201 ... Stepping motor 202 ... Clutch on transmission mechanism 205 ... Load side encoder 303 ... Slip amount detecting means 304 ... Movement amount correcting means 505 ... Motor side encoder

Claims (5)

[Claims] 1. An image forming apparatus that uses a stepping motor as a drive source, has a clutch in a drive transmission mechanism between the drive source and a load, and performs high-precision positioning of the load, and detects a slip amount on the load side. An image forming apparatus comprising: a means for performing the correction and a correction means for correcting the movement amount of the load according to the detected slip amount. 2. An encoder is provided on the load side, and a difference between an actual movement amount detected by the encoder and a theoretical movement amount obtained by the stepping motor drive instruction signal is detected by using the drive instruction signal of the stepping motor as a trigger. The image forming apparatus according to claim 1, wherein the slip amount on the load side is detected thereby. 3. The image forming apparatus according to claim 1, further comprising a correction unit that increases the driving step number of the stepping motor by a pulse integer of the slip amount obtained by the slip amount detection unit. 4. The image according to claim 1, wherein the rated torque of the clutch is set lower than the holding torque of the stepping motor on the drive transmission system to act as a torque limiter to prevent out-of-step of the stepping motor. Forming equipment. 5. The image forming apparatus according to claim 1, wherein the slip amount detecting means is also used as an operation abnormality detecting means.