JPH09244470A - Recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality recorded image by eliminating an error caused by a rotation transmission means and accurately maintaining the rotation of an image carrier. SOLUTION: This recorder is constituted so that a photoreceptive drum (image carrier) 501 is driven to be rotated by an ultrasonic motor 1. Then, the rotation control means of the motor 1 is arranged outside the motor 1 and constituted by including an encoder scale 3 fitted to the drum 501 and an encoder detection part 102 arranged near the scale 3. In such a case, since the rotation control means of the motor 1 is arranged outside the motor 1, the rotation of the drum 501 driven to be rotated by the motor 1 can be directly detected and controlled. Besides, the error caused by a joint (rotation transmission means) 2 is eliminated and the rotation of the drum 501 is accurately maintained. Thus, the high-quality recorded image is stably obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus using an ultrasonic motor as a drive source for an image carrier.

[0002]

2. Description of the Related Art Conventionally, in this type of recording apparatus, an ultrasonic motor has a built-in encoder for rotation control. FIG. 7 shows a conventional example of a recording apparatus using a joint 32 as a rotation transmission means. In the recording apparatus, the ultrasonic motor 31 has an encoder 33 and an encoder detection means (not shown) built therein. The output shaft 34 of the ultrasonic motor 31 and the rotating shaft 35 of the photosensitive drum 501 are connected by a joint 32, and the rotation of the ultrasonic motor 31 is transmitted to the rotating shaft 35 through the joint 32, so that the photosensitive drum 501 is rotated in a predetermined manner. It is driven to rotate at speed.

Thus, the rotation signal of the photosensitive drum 501 detected by the encoder detection means (not shown) is input to the control means (not shown), and the control means does not set the rotation speed of the photosensitive drum 501 to match the set value. A control signal is output to the illustrated motor driver.

[0004]

However, in the conventional recording apparatus, the rotation speed of the ultrasonic motor 31 itself is controlled with high accuracy, but this rotation is transmitted to the photosensitive drum 501 via the joint 32. Therefore, the photosensitive drum 501
The rotation of contains an error (unevenness) caused by the joint 32,
There is a problem that the rotation accuracy of the photosensitive drum 501 is reduced.

Therefore, the object of the present invention is to provide a recording apparatus capable of obtaining a high quality recorded image by eliminating the error caused by the rotation transmitting means and keeping the rotation of the image carrier highly accurate. To provide.

Further, generally, in a recording apparatus, the rotation of a single motor is transmitted to a plurality of photosensitive drums via a rotation transmission means such as a toothed belt and a gear to synchronize the respective photosensitive drums. Was there.

However, in the recording apparatus using the toothed belt as the rotation transmitting means, the rotation transmitting means is caused by the expansion and contraction of the belt, the unevenness of the tooth pitch, the unevenness of the belt tension, the variation of the tooth cutting of the pulley, and the like. In a recording device that uses gears, the multiple photosensitive drums could not be accurately synchronized due to variations in gear cutting, backlash between gears, etc. There was a problem that I could not get.

Therefore, an object of the present invention is to provide a recording apparatus capable of obtaining a high quality recorded image with good registration by accurately synchronizing a plurality of image carriers. is there.

[0009]

In order to achieve the above object, the invention according to claim 1 is a recording apparatus for rotating and driving an image bearing member by an ultrasonic motor, wherein the rotation control means of the ultrasonic motor is ultrasonic. It is characterized in that it is provided outside the motor.

According to a second aspect of the present invention, in the first aspect of the present invention, the rotation control means includes an encoder scale attached to the image carrier, and an encoder detection section arranged in the vicinity of the encoder scale. It is a rotary encoder configured by.

According to a third aspect of the present invention, in the first aspect of the present invention, there is provided a plurality of recording means including the image carrier which is an electrophotographic photosensitive member on which toner images of different colors are formed. It is characterized in that the position control means of the sound wave motor is provided to enable the phase alignment of the color toner images between the respective recording means.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the position control means includes an encoder scale attached to the image carrier, and an encoder detection section arranged near the encoder scale. It is a rotary encoder configured by.

According to a fifth aspect of the invention, in the third or fourth aspect of the invention, each of the image carriers is irradiated with information light by a digital optical system to form yellow, magenta, cyan and black toner images, respectively. It is characterized in that it is formed to obtain a full-color image.

A sixth aspect of the present invention is characterized in that, in the third, fourth or fifth aspect of the invention, the encoder scale is provided with a rotation control scale and a position control scale.

According to a seventh aspect of the invention, in the invention according to the third to fifth or sixth aspects, the position control means is used to perform synchronous control for starting the rotational drive of each image carrier of the plurality of recording means. Characterize.

According to an eighth aspect of the invention, in the seventh aspect of the invention, the synchronization control is performed when the power is turned on, when the image recording is started, or when the manual operation is performed.

According to a ninth aspect of the invention, in the invention according to the first to seventh or eighth aspects, the same number of the ultrasonic wave sensors as the image carrier are provided.

Therefore, according to the first or second aspect of the present invention, since the rotation control means of the ultrasonic motor is provided outside the ultrasonic motor, the rotation of the image carrier rotated by the ultrasonic motor is directly detected. Then, the rotation of the image carrier can be controlled, the error caused by the rotation transmitting means such as a joint can be eliminated, and the rotation of the image carrier can be maintained with high accuracy, thereby stabilizing a high quality recorded image. Can be obtained.

Further, according to the invention described in claims 3 to 8 or 9, since the position control means of the ultrasonic motor is provided to enable the phase matching between the respective recording means, the invention according to claim 1 or 2 is achieved. In addition to the effect, synchronization of the image bearing members included in each recording unit (synchronization control of rotation drive start) is performed with high accuracy, and a high quality recorded image with good registration can be obtained.

[0020]

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

<First Embodiment> First, a recording apparatus according to the present invention will be outlined with reference to FIG.

FIG. 2 is a sectional view of the main part of the multicolor recording apparatus.
In the multicolor recording apparatus, process units I, II, III and IV which are recording means are arranged in parallel, and each process unit I, II, III and IV is an electrophotographic photosensitive member (image carrier). Hereinafter referred to as photosensitive drums) 501, 502, 5
03, 504 and charging means C1, C arranged around them
2, C3, C4, exposing means E1, E2, E3, E4, and developing means D including developing sleeves S1, S2, S3, S4
1, D2, D3, D4 and transfer blades T1, T2, T
3, T4 is included. Below the process units I, II, III, IV, the rollers TR1, T
A transfer belt TF1 stretched over R2 is arranged, and a fixing device F1 is arranged on the downstream side (right side in FIG. 2) of the transfer belt TF1 in the recording paper conveyance direction. The exposure means E
1, E2, E3 and E4 form a digital optical system including an LED and a Selfoc lens.

When recording a color image, first, in the process unit I, the photosensitive drum 501 rotating in the direction of the arrow in the figure is uniformly charged by the charging means C1, and the photosensitive drum 501 is exposed by the exposing means E1. Then, a latent image is formed on the photosensitive drum 501. Then, the latent image formed on the photosensitive drum 501 is developed by the developing device D1 and visualized as a black toner image.

On the other hand, the recording paper P is guided onto the transfer belt TF1, and the recording paper P is moved by the transfer belt TF1 to a black transfer position installed so as to be sandwiched between the photosensitive drum 501 and the transfer blade T1. The black toner image on the photosensitive drum 501 is transferred onto the recording paper P by the action of the transfer blade T1.

Thereafter, the process units II and II are similarly processed.
Cyan toner image formed by I and IV,
The magenta toner image and the yellow toner image are recorded at the cyan transfer position between the photosensitive drum 502 and the transfer blade T2, the magenta transfer position between the photosensitive drum 503 and the transfer blade T3, and the yellow transfer position between the photosensitive drum 504 and the transfer blade T4. The desired multicolor toner image is formed by being sequentially transferred onto the above. In addition, each process unit I, II,
Between III and IV, the photosensitive drums 501, 502,
Since 503 and 504 rotate with high precision, image registration is favorably performed among the process units I, II, III, and IV.

The recording paper P on which the multicolor toner image has been transferred through the above process is fed to the fixing device F1 to undergo the fixing of the multicolor toner image, thus obtaining a desired multicolor image.

Even in a recording apparatus using a single photosensitive drum, it is possible to record an image by using a single process unit, and the recording process and the like are the same, so the description thereof will be omitted.

By the way, in the multi-color recording apparatus shown in FIG. 2, the photosensitive drums 501 to 504 are independently driven to rotate by the ultrasonic motors provided for them, respectively. Process unit I
The rotation control system of the photosensitive drum 501 will be described with reference to FIG. Since the rotation control systems of the photosensitive drums 502, 503, 504 of the other process units II, III, IV are also the same as that of the photosensitive drum 501, the description thereof will be omitted.

In FIG. 1, reference numeral 1 denotes an ultrasonic motor for driving the photosensitive drum 501 to rotate. An output shaft 4 of the ultrasonic motor 1 is connected to a rotary shaft 5 of the photosensitive drum 501 by a joint 2.

Thus, in the present embodiment, the photosensitive drum 5
An encoder scale 3 is provided on one side end surface of 01, and an encoder detection unit 102 is installed near the encoder scale 3. The encoder scale 3 and the encoder detection unit 102 form an optical rotary encoder for rotation detection, and the encoder detection unit 102 is electrically connected to the counter 103. The counter 103 is the controller 1 which is the control means.
04 electrically connected to the controller 104
Are electrically connected to a motor driver 101 for driving the ultrasonic motor 1.

The ultrasonic motor 1 is rotated by being driven by the motor driver 101, and the rotation of the output shaft 4 is transmitted to the rotating shaft 5 through the joint 2 and the photosensitive drum 501.
Is driven to rotate at a predetermined speed.

By the way, the signal on the encoder scale 3 which rotates integrally with the photosensitive drum 501 is detected by the encoder detection unit 102, and the signal amount moved during the rotation of the photosensitive drum 501 is counted by the counter 103 and taken into the controller 104. . Then, the controller 104 outputs a control signal to the motor driver 101 so that the count value of the signal amount becomes equal to the set value, and the motor driver 101 drives the ultrasonic motor 1 to move the photosensitive drum 501 to a predetermined value. It is driven to rotate at the rotation speed.

As described above, in the present embodiment,
The encoder scale 3 is provided on the photosensitive drum 501 itself,
The encoder scale 3 and the encoder detection unit 102 installed in the vicinity thereof constitute an optical rotary encoder that is a rotation detection unit of the photosensitive drum 501, and the rotary encoder directly controls the rotation of the photosensitive drum 501 that is a rotation control target. Since it is detected, the joint 2
The rotation of the photosensitive drum 501 can be maintained with high accuracy by eliminating the error caused by the above, and a high-quality recorded image with small image pitch unevenness can be stably obtained. Incidentally, when a toner image with a print diameter of about 80 μm was recorded in a pattern of repeating 1 dot printing and 2 dot spaces, the standard deviation of the image pitch unevenness was 6 μm in the recording apparatus adopting the conventional rotation control system. On the other hand, in the recording apparatus according to the present embodiment, the standard deviation of image pitch unevenness could be suppressed to 4 μm.

In this embodiment, the photosensitive drum 501
Although the encoder detection unit 102 is arranged so that the signal on the encoder scale 3 provided at one side end can be detected from the direction perpendicular to the axis of the photosensitive drum 501, the encoder detection unit 102 can be provided if the characteristics of the encoder can be sufficiently exhibited. May be arranged at a position where detection is performed from any direction.
Further, the rotary encoder configured by the encoder scale 3 and the encoder detection unit 102 is not limited to the optical encoder, but may be a magnetic encoder or any other type.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. 3 is a block diagram showing the configuration of the rotation control system and position control system of the photosensitive drum of the recording apparatus according to the second embodiment.

Since the basic structure of the recording apparatus according to the present embodiment is the same as that of the recording apparatus according to the first embodiment shown in FIG. 2, the description thereof will be omitted.

In the multicolor recording apparatus according to the present embodiment, the photosensitive drums 501 to 504 are independently driven to rotate by the ultrasonic motors 1 provided for them, respectively. The rotation control system of the photosensitive drum 501 of the process unit I will be described with reference to FIG. The rotation control system of the photosensitive drums 502, 503, 504 of the other process units II, III, IV is also the photosensitive drum 5.
Since it is the same as the rotation control system of No. 01, description of these is omitted.

In FIG. 3, reference numeral 1 denotes an ultrasonic motor for driving the photosensitive drum 501 to rotate. An output shaft 4 of the ultrasonic motor 1 is connected to a rotary shaft 5 of the photosensitive drum 501 by a joint 2.

Thus, in the present embodiment, the photosensitive drum 5
The encoder scale 3 is attached to one side end surface of the encoder 01, and encoder detectors 102 and 102B are installed in the vicinity of the encoder scale 3. The encoder scale 3 is provided with a rotation control scale and a position control scale.
The rotation control scale and the encoder detection unit 102 constitute an optical rotary encoder for rotation control,
The position control scale of the encoder scale 3 and the encoder detection unit 102B constitute an optical rotary encoder for absolute position detection. The encoder detection units 102 and 102B are electrically connected to the counters 103 and 103B, and the counters 103 and 103B are electrically connected to the controllers 104 and 104B that are the control means. Also, the controllers 104 and 104B are
Motor driver 1 for driving the ultrasonic motor 1
01 is electrically connected.

The ultrasonic motor 1 is driven by the motor driver 101 to rotate, and the rotation of the output shaft 4 is transmitted to the rotating shaft 5 via the joint 2 and the photosensitive drum 501.
Is driven to rotate at a predetermined speed.

By the way, the signal on the encoder scale 3 that rotates integrally with the photosensitive drum 501 is detected by the encoder control unit 102 for rotation control, and the photosensitive drum 50 is detected.
The signal amount moved during the rotation of 1 is counted by the counter 103 and taken into the controller 104. Then, the controller 104 outputs a control signal to the motor driver 101 so that the count value of the signal amount becomes equal to the set value, and the motor driver 101 drives the ultrasonic motor 1 to move the photosensitive drum 501 to a predetermined value. It is driven to rotate at the rotation speed. In the present embodiment as well, as in the first embodiment, the rotation of the photosensitive drum 501 is directly detected by the optical rotary encoder for rotation control. The rotation of the drum 501 can be maintained with high precision, and a high quality recorded image can be stably obtained.

The position control sequence is executed when the power is turned on, when the print is started, or when the manual switch is turned on, and the signal on the encoder scale 3 is detected by the encoder detecting unit 102B for absolute position control, and the photosensing is performed. The signal amount corresponding to the absolute position of the drum 501 during rotation is counted by the counter 103B and taken into the controller 104B. Then, the controller 104
B outputs a control signal to the motor driver 101 so that the count value of the signal amount matches the set value (value when the photosensitive drum 501 is located at the home position), and the motor driver 101 is an ultrasonic motor. 1 is driven to position the photosensitive drum 501 at the home position, and the photosensitive drum 501 is set to standby: OK.

When the position control sequence is executed, the position control is performed on the other photosensitive drums 502, 503, 5
The same applies to 04, and these photosensitive drums 50
When 2, 503 and 504 are respectively located at their home positions and each is set to standby: OK, a desired color image is recorded through the aforementioned electrophotographic process.

As described above, in the present embodiment, the position control sequence is executed when the power is turned on, when the print is started, or when the manual switch is turned on to position all the photosensitive drums 501 to 504 at their home positions. Therefore, synchronization of these photosensitive drums 501 to 504 (synchronization control of rotation drive start) is performed with high accuracy,
A high quality color image with good registration can be obtained.

Now, the procedure of synchronous control of the photosensitive drums 501 to 504 will be described with reference to the flowchart shown in FIG.

First, it is judged whether or not the power is turned on, the print is started, or the manual switch is turned on (STEP 1 in FIG. 4). If the judgment result is YES, the position control sequence is executed, Photosensitive drum 50
1, 502, 503, and 504 (see FIG. 2) are synchronized (synchronous control of rotation drive start).

That is, for example, regarding the photosensitive drum 501, it is judged by the rotary encoder for absolute position detection whether or not the photosensitive drum 501 is at a predetermined position (home position) (STEP 2 in FIG. 4), and the result is NO
If the result is YES, the ultrasonic motor 1 is driven to rotate the photosensitive drum 501 until the result is YES (STEP in FIG. 4).
3) The photosensitive drum 501 is positioned at a predetermined home position and the photosensitive drum 501 is in standby: OK (STEP 4 in FIG. 4). Since the photosensitive drum 501 is located at the home position from the beginning, ST
If the determination result of EP2 is YES, the photosensitive drum 501 is not rotationally driven and remains stationary.
About 01: Immediate standby: OK.

With respect to the other photosensitive drums 502, 503, 504 as well, the photosensitive drums 502, 503, 504 are set to the home position in the same manner as described above, and the respective photosensitive drums 502, 503, 504 are set to standby: OK (STEP 4 in FIG. 4) and all the photosensitive drums are exposed. Standby for the drums 501 to 504: When it becomes OK, the above electrophotographic process is performed to obtain a desired color image (STEP 5 in FIG. 4).

Also in this embodiment, the encoder detectors 102 and 102B are provided so that the signal on the encoder scale 3 provided at one end of the photosensitive drum 501 can be detected from the direction perpendicular to the axis of the photosensitive drum 501. I placed it,
If the characteristics of the encoder can be sufficiently exhibited, the encoder detection units 102 and 102B may be arranged at positions where detection is performed from any direction. Further, the rotary encoder for rotation control and absolute position control, which is composed of the encoder scale 3 and the encoder detectors 102 and 102B, is not limited to the optical encoder, but a magnetic encoder or any other type encoder may be adopted. it can.

By the way, in the above-mentioned Embodiments 1 and 2, the recording apparatus employing the joint 2 as the rotation transmitting means has been described, but any other means can be used as the rotation transmitting means. Examples thereof are shown in FIGS. 5 and 6.

That is, in the recording apparatus shown in FIG. 5, the gear transmission means G is adopted as the rotation transmission means, and the output shaft 14 of the ultrasonic motor 11 and the rotation shaft 15 of the photosensitive drum 501 are formed by the gear pair 12. The rotation of the ultrasonic motor 11 is transmitted to the rotary shaft 15 via the gear pair 12, and the photosensitive drum 501 is rotationally driven at a predetermined speed to be used for image recording.

Thus, even in the recording device shown in FIG.
As in the first embodiment, the rotation of the photosensitive drum 501 is directly detected by the optical rotary encoder including the encoder scale 13 attached to the photosensitive drum 501 itself, thereby eliminating the error caused by the gear pair 12. Accordingly, the rotation of the photosensitive drum 501 can be maintained with high accuracy, and a high quality recorded image can be stably obtained. Incidentally, when a toner image having a print diameter of about 80 μm is recorded in a pattern of repeating 1 dot printing and 2 dot spaces, the standard deviation of the image pitch unevenness is 12 μm in the recording apparatus adopting the conventional rotation control system. On the other hand, FIG.
In the recording apparatus according to the present invention which employs the gear transmission means G shown in (4), the standard deviation of image pitch unevenness could be suppressed to 4 μm.

Further, in the recording apparatus shown in FIG. 6, the belt transmission means B is adopted as the rotation transmission means, and the belt transmission means B is connected to the output shaft 24 of the ultrasonic motor 21 and the pulley 22A. , The rotary shaft 25 of the photosensitive drum 501
22B and both pulleys 22A and 22B bound to
The output shaft 24 of the ultrasonic motor 21 and the rotary shaft 2 of the photosensitive drum 501 are constituted by a belt 22C wound between them.
5 is connected by the belt transmission means B.

The rotation of the ultrasonic motor 21 is controlled by the belt transmission means B (pulley 22A, belt 22C and pulley 2).
2B) and transmitted to the rotary shaft 25, and the photosensitive drum 501
Is rotated at a predetermined speed and is used for image recording.

Thus, even in the recording device shown in FIG.
As in the first embodiment, the rotation of the photosensitive drum 501 is directly detected by the optical rotary encoder configured to include the encoder scale 23 attached to the photosensitive drum 501 itself, so that the error caused by the belt transmission unit B is eliminated. The rotation of the photosensitive drum 501 can be eliminated and the rotation of the photosensitive drum 501 can be maintained with high precision, and a high-quality recorded image can be stably obtained. Incidentally, when a toner image having a print diameter of about 80 μm is recorded in a pattern of repeating 1 dot printing and 2 dot spaces, the standard deviation of the image pitch unevenness is 8.5 μm in the recording apparatus adopting the conventional rotation control system. On the other hand, in the recording apparatus according to the present invention which employs the belt transmission means B shown in FIG. 6, the standard deviation of image pitch unevenness could be suppressed to 4 μm.

[0056]

As is apparent from the above description, claim 1
According to the invention described in claim 2, since the rotation control means of the ultrasonic motor is provided outside the ultrasonic motor, the rotation of the image bearing member which is rotationally driven by the ultrasonic motor is directly detected to rotate the image bearing member. The rotation of the image bearing member can be maintained with high accuracy by eliminating the error caused by the rotation transmitting means such as the joint, so that a high quality recorded image can be stably obtained.

Further, according to the invention of claims 3 to 8 or 9, since the position control means of the ultrasonic motor is provided to enable the phase matching between the respective recording means, the invention according to claim 1 or 2 is achieved. In addition to the effect, synchronization of the image bearing members included in each recording unit (synchronization control of rotation drive start) is performed with high accuracy, and a high quality recorded image with good registration can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a rotation control system of a recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the recording apparatus according to the first embodiment of the invention.

FIG. 3 is a block diagram showing a configuration of a rotation control system and a position control system of the recording apparatus according to the second embodiment of the invention.

FIG. 4 is a flowchart showing a procedure of synchronous control of photosensitive drums in the recording apparatus according to the second embodiment of the present invention.

FIG. 5 is a configuration diagram of a main part of a recording apparatus that employs gear transmission means as rotation transmission means.

FIG. 6 is a configuration diagram of a main part of a recording apparatus that employs gear transmission means as rotation transmission means.

FIG. 7 is a configuration diagram of a main part of a conventional recording apparatus.

[Explanation of symbols]

 1, 11, 21 Ultrasonic motor 3, 13, 23 Encoder scale 101 Motor driver 102, 102B Encoder detector 103, 103B Counter 104, 104B Controller 501-504 Photosensitive drum (image carrier) I-IV process unit (recording means) )

Claims (9)

[Claims] 1. A recording apparatus in which an image bearing member is rotationally driven by an ultrasonic motor, wherein the rotation control means of the ultrasonic motor is provided outside the ultrasonic motor. 2. The rotation control means is a rotary encoder including an encoder scale attached to the image carrier and an encoder detection unit arranged in the vicinity of the encoder scale. Item 1
The recording device according to any one of the preceding claims. 3. A plurality of recording means including the image carrier, which is an electrophotographic photosensitive member on which toner images of different colors are formed, and a position control means of the ultrasonic motor is provided, and the recording means is provided between the recording means. The recording apparatus according to claim 1, wherein the color toner images can be phase-matched with each other. 4. The position control means is a rotary encoder including an encoder scale attached to the image carrier and an encoder detection unit arranged in the vicinity of the encoder scale. Item 3
The recording device according to any one of the preceding claims. 5. A full-color image is obtained by irradiating each image carrier with information light from a digital optical system to form yellow, magenta, cyan, and black toner images, respectively. Or the recording device according to item 4. 6. The recording apparatus according to claim 3, wherein the encoder scale is provided with a rotation control scale and a position control scale. 7. The recording apparatus according to claim 3, wherein the position control means is used to perform synchronous control for starting the rotational drive of each image carrier of the plurality of recording means. 8. The recording apparatus according to claim 7, wherein the synchronization control is performed when power is turned on, when image recording is started, or when manual operation is performed. 9. The recording apparatus according to claim 1, wherein the same number of the ultrasonic wave sensors as the image carrier are provided.