JP2006171036A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a movable holder which is loaded with a plurality of development units and moves each development unit to a position where developing operation is applied to an image carrier, the image forming apparatus where noise problems due to operation noise, generated when the holder is moved, is reduced. <P>SOLUTION: The image forming apparatus is provided with the image carrier 26 for forming an electrostatic image on the surface; the plurality of developing units 25 for developing the electrostatic image by a developer; and the movable holder 25a, loaded with the plurality of developing units 25 and capable of moving each development unit 25 to a position where developing operation is applied to the image carrier 26, wherein image forming sequences concerned with the operation of the holder 25a are switched in a prescribed time zone to perform image forming operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention reads image information from the outside, forms an electrostatic image on an image carrier according to the image information, and develops the electrostatic image with a developing device to form a developed image (toner image). And an electrophotographic or electrostatic recording type image forming apparatus having at least one copy function, FAX function, printer function, paper discharge processing function for recording material discharged from the image forming apparatus, and the like. In particular, as a developing device, a developing device which is a developing device of a plurality of colors is arranged on a movable holder, and each developing device is moved to a developing position facing the image carrier to perform image formation for each color. The present invention relates to an image forming apparatus provided with a moving developing device.

  2. Description of the Related Art Conventionally, an image forming apparatus having one image carrier, such as a drum-shaped electrophotographic photosensitive member, that is, an image forming apparatus such as a color printer or a color copying machine having one photosensitive drum, has a rotating member. A plurality of developers containing developers containing different color toners are mounted along the outer periphery, and the rotating body rotates, so that the developing devices are sequentially brought close to the photosensitive drum to perform a developing operation. There is an image forming apparatus provided with a so-called rotary developing device. An example is shown in FIGS. 13 (a) and 13 (b).

  In FIGS. 13A and 13B, only the image carrier 1, the developing device 2, and the intermediate transfer member 26, which are main components of the image forming apparatus, are shown.

  In the configuration shown in FIG. 13A, a rotating body 2a is disposed as a developing device holder adjacent to one photosensitive drum 1, and a yellow developing device 25Y as a developing unit and a magenta developing device are disposed on the rotating body 2a. 25M, cyan developing unit 25C, and black developing unit 25K are arranged concentrically. When a color image is printed, the rotating body 2a is rotated in the direction of the arrow by a stepping motor (not shown), and the developing sleeve 25s that is a developer carrying body in each developing unit 25, that is, the development of the yellow developing unit 25Y. The sleeve 25Ys, the developing sleeve 25Ms of the magenta developing device 25M, the developing sleeve 25Cs of the cyan developing device 25C, and the developing sleeve 25Ks of the black developing device 25K are sequentially moved to the developing point P, and development is performed one color at a time. The upper electrostatic image is visualized and transferred to the intermediate transfer member 26.

  On the other hand, in the configuration shown in FIG. 13B, a yellow developing unit 25Y, a magenta developing unit 25M, and a cyan developing unit 25C are provided adjacent to one photosensitive drum 1 and on a rotating body 2a as a developing unit holder. The black developing device 25K is arranged concentrically and is positioned above the rotating body 2a independently of the other colors, and is configured to be movable in the direction of arrow A with respect to the photosensitive drum 1. The black developing device 25K is controlled so as to come into contact with the photosensitive drum 1 only during the developing operation.

  When printing a color image, the rotating body 2a is rotated in the direction of the arrow by a stepping motor or the like, and a developing sleeve 25s that is a developer carrier in each developing device 25, that is, a developing sleeve 25Ys of a yellow developing device, a magenta developing device The developing sleeve 25Ms and the developing sleeve 25s of the cyan developing device are sequentially moved to the developing point P to develop three colors, and finally the black developing device 25K is moved in the direction of the photosensitive drum 1 and developed at the developing point PK. Then, the electrostatic image is visualized and transferred to the intermediate transfer member 26.

  In FIGS. 13A and 13B, the stepping motor for rotating the rotating body 2a on which the developing means is mounted gradually accelerates from the start pulse S1 according to a pre-programmed speed table as shown in FIG. After reaching the top speed S2, the motor is rotated at a constant speed, rotated by a predetermined number of pulses, and then gradually decelerated to the start pulse S1 and stopped. By repeating this for each color yellow (Y), magenta (M), cyan (C), black (K), or each color yellow (Y), magenta (M), cyan (C) in this order, the developer for each color 25 (25Y, 25M, 25C, 25K) or the developing device 25 (25Y, 25M, 25C) is accurately moved to the development point P.

  In this series of operations, the operation noise due to the rotation of the motor and the rotating body 2a becomes a problem.

  Each developing device 25 includes a developing sleeve 25s for transferring the developer to the photosensitive drum 1, a member for stirring the developer, a bottle for storing the developer, and the like (not shown). Can be several hundred grams. Since they are mounted on the rotating body 2a for four colors (or three colors), the total weight reaches several kilograms. By rotating such a heavy object via a gear by a stepping motor, considerable operating noise such as motor rotation noise and resonance noise due to vibration of the rotating body is generated.

  Therefore, as a means for reducing such operating noise, conventionally, the rotational speed of the rotating body equipped with the developing means (developing device) is variable, and the transfer material size, the initial operation of the rotating body, when the developing device is replaced, and in the color mode. It has been proposed to change the rotation speed accordingly (see, for example, Patent Document 1).

  However, in the proposed configuration, at the time of the transfer material size, the initial operation of the rotator, and replacement of the developing device, the rotation is only performed at a speed set in advance for each operation mode according to the color mode.

On the other hand, in the case of relatively small office equipment, the installation location is often a small office such as a small office or an apartment, and most of them have a FAX function added as an option. In addition, since the residential area and the installation location are often the same, the proposed configuration is not sufficient as a noise countermeasure. In particular, since most of the power is turned off during the transition to the sleep mode (stopped state), the initial operation and various adjustment operations when shifting from sleep to standby are suddenly executed when receiving a fax at night. This can cause discomfort for the user. In particular, it may surprise a sleeping resident.
Japanese Patent Laid-Open No. 9-6206

  An object of the present invention is to move a holding body in an image forming apparatus having a movable holding body in which a plurality of developing devices are mounted, and the developing devices are moved one by one to a position where a developing operation is performed on the image carrier. It is an object of the present invention to provide an image forming apparatus that can alleviate noise problems such as operating noise that occur when the operation is performed.

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention includes an image carrier on which an electrostatic image is formed on the surface, a plurality of developing units that develop the electrostatic image with a developer to form a developed image, and the plurality of developing units. A movable holding member that moves the developing device to a position where a developing operation is performed on the image carrier, and a transfer unit that transfers the developed image on the image carrier to a recording material. In the provided image forming apparatus,
When performing an image forming operation in a predetermined time zone, an image forming operation is performed by switching an image forming sequence related to the operation of the holding body.

  In the image forming apparatus according to the present invention, when an image forming operation is performed in a predetermined time zone, the image forming operation related to the operation of the developing device holder is switched to perform the image forming operation. And effective noise countermeasures can be taken.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
FIG. 1 is a cross-sectional view showing a schematic configuration of a digital color copying machine which is an embodiment of an image forming apparatus according to the present invention. The copying machine of this embodiment has a copy function, a printer function, and a FAX function. However, the present invention is not limited to this, and the present invention forms an image having at least one of these functions. Applicable to the device.

  In this embodiment, the digital color copying machine has an image scanner unit IS and a printer unit PR. The image scanner unit IS reads a document, outputs a digital color image signal, and transmits it to the printer unit PR. In the printer unit PR, an operation for recording a digital color image signal output from the image scanner unit IS on a recording sheet as a transfer material and obtaining a desired image formed product is performed.

  First, the operation in the image scanner unit IS will be described.

  A document placed on the platen glass 4 serving as an image information source from the outside is brought into close contact with the platen glass 4 by the document pressure plate 3.

  The image scanner unit IS has a CCD 5 that reads a document and converts image information into an electrical signal. The CCD 5 is provided in a state of being mounted on the substrate 6.

  The fluorescent lamp control circuit 17 generates a PWM pulse signal having a variable duty at a constant period in response to the lighting control signal from the image processing unit 8 and supplies the PWM pulse signal to the fluorescent lamp drive circuit 18, and the fluorescent lamp drive circuit 18 outputs the PWM pulse signal. Based on the above, the fluorescent lamp 9 for illuminating the document is turned on. At that time, the fluorescent lamp control circuit 17 looks at the output of the light quantity sensor 19 and controls the light quantity by changing the duty of the PWM pulse signal so that the output value becomes a certain value.

  The first mirror table 15 is a carriage that accommodates a fluorescent lamp 9 that irradiates a document, a reflector 10 that collects the light of the fluorescent lamp 9 on the document, and a mirror 11. A second mirror table 16 is a mirror. The first mirror base 15 is at a speed V and the second mirror base 16 is at a speed V / 2 and is mechanically perpendicular to the electrical scanning (main scanning) direction of the CCD 5. By moving to, the entire surface of the document is scanned (sub-scanning). Then, the obtained reflected light or projection light from the original document by the first mirror table 15 and the second mirror table 16 is condensed on the CCD 5 by the lens 14.

  The analog image signal converted into an electrical signal by the CCD 5 is subjected to processing such as sample hold, amplification, A / D conversion and the like in the image processing unit 8, for example, converted into a digital signal of 8 bits for each RGB, and masking processing is performed. , Γ correction and the like are performed, and the image signal is transmitted to the printer unit PR.

  Next, the configuration of the printer unit PR will be described.

  The image forming operation in the printer unit PR is controlled by a printer control unit 7 having a circuit for driving loads such as various motors.

  Here, a photosensitive drum 1 which is a drum-shaped electrophotographic photosensitive member is provided as an image carrier, and is driven at a predetermined peripheral speed (process speed) in the clockwise direction of an arrow. The photosensitive drum 1 is charged with a predetermined polarity and potential by a charging roller 21 on its peripheral surface. Then, scanning exposure is performed on the charged surface with laser light 23 that is pulse-width-modulated in accordance with the digital image signal output from the laser scanning unit 22 and input from the image processing unit 8 of the image scanner unit IS. Thus, an electrostatic image of image information is formed. The laser beam from the laser scanning unit 22 is deflected by the laser beam reflecting mirror 24 and exposed to the photosensitive drum 1.

  As described above, when electrostatic images corresponding to the color separation images of the target full-color image are formed on the rotating photosensitive drum 1, toner development of the electrostatic images is sequentially performed by the developing unit, A developed image (toner image) of each color is sequentially formed.

  In this embodiment, the developing device 2 includes a plurality of developing units along the outer periphery of a cylindrical rotating body 2a as a holding body, and in this embodiment, four developing units 25, that is, a yellow developing unit 25Y and a magenta developing unit. The rotation developing device is a rotation-switching type rotational developing device equipped with 25M, a cyan developing device 25C, and a black developing device 25K.

  Accordingly, when the rotating body 2a rotates, each developing device 25 (25Y, 25M, 25C, 25K) sequentially moves to a position facing the photosensitive drum 1. Each developing device 25 includes a replaceable toner container 25t, that is, a yellow toner container 25Yt, a magenta toner container 25Mt, a cyan toner container 25Ct, and a black toner container 25Kt.

  Each developing device 25 includes a developing sleeve 25s which is a developer carrying member for moving the toner to an electrostatic image on the photosensitive drum 1 to make a visible image, that is, a yellow developing sleeve 25Ys, magenta development. A sleeve 25Ms, a cyan developing sleeve 25Cs, and a black developing sleeve 25Ks are provided. The rotating operation of the rotating body 2a will be described in detail later.

  Each toner image formed on the photoconductive drum 1 is sequentially superimposed and transferred to an intermediate transfer drum 26 as an intermediate transfer member, and a full color corresponding to a mirror image of a target full color image is formed on the surface of the intermediate transfer drum 26. A toner image is formed.

  The intermediate transfer drum 26 is disposed in contact with or close to the photosensitive drum 1, and is rotationally driven in the forward direction with respect to the photosensitive drum 1 and at substantially the same peripheral speed as the photosensitive drum 1. In this embodiment, a drum is assumed as an intermediate transfer member.

  A transfer material S as a recording material is fed from the paper feed cassettes 28 and 29 to the intermediate transfer drum 26 by paper feed rollers 30 and 31, and a mirror image full color on the intermediate transfer drum 26 side with respect to the transfer material S. The toner image is transferred by the transfer roller 32 to form a full color toner image on the surface of the transfer material. The transfer roller 32 transfers a toner image from the intermediate transfer drum 26 to the transfer material S by supplying a charge having a polarity opposite to that of the toner from the back surface of the transfer material S.

  The transfer material S that has received the transfer of the full-color toner image is separated from the intermediate transfer drum 26 and introduced into the fixing device 33, where the toner image is heated and fixed, and the paper discharge conveying roller 36 serving as the paper discharge processing means and the switching flapper 37. The paper is discharged to the paper discharge tray 35 or 38.

  If necessary, it is possible to provide a sort mechanism, a stapling mechanism, etc. in the paper discharge tray section so that various discharged paper processing such as sorting and stapling is performed on the discharged recording paper. .

  The surface of the intermediate transfer drum 26 after the transfer of the toner image to the transfer material S is cleaned by a cleaning device 27 to prepare for the next image formation.

  The overall configuration of the digital color copying machine in the present embodiment described above is the same as the configuration shown in FIG. 13A described in the conventional example.

  That is, in the printer unit PR, four developing devices 25 as developing means are mounted on the rotating body 2a, and when the rotating body 2a rotates, the developing unit 25 sequentially moves to the developing point P and performs a developing operation. It is supposed to be configured.

  Note that the number of developing units 25 mounted on the rotating body 2a as the holding body may be one including three developing units as shown in FIG. 13B, and may include five or more developing units. It may be mounted and is not particularly limited as long as it is two or more.

  A position flag 302 (302Y, 302M, 302C, 302K) is provided at the end of the rotating body 2a so that the developing sleeve 25s of each color can be accurately moved to the developing point P, and the detection surface of the position sensor 301 is set to each position. The flag 302 is arranged so that the development sleeves 25s (25Ys, 25Ms, 25Cs, 25Ks) of the respective colors come to the development point P when the flag 302 is shielded from light. Further, during non-image formation, the home position flag 302HP is moved to a position where the position sensor 301 is shielded (home position) in order to prevent scratches and dirt on the surface of the photosensitive drum 1, and the developing sleeve 25s is moved to the developing point. Retreat to a position shifted from P.

  In this embodiment, the stepping motor 411 (FIG. 2) is used as the driving means for driving the rotating body 2a. Therefore, even if the position flag 302 is not provided, the number of pulses driven from the home position P is managed. In this case, the developing sleeve 25s can be accurately moved to the developing point P.

  With respect to such an image forming apparatus that rotates the rotating body 2a, a plurality of developing units 25 are heavier, so that there is a problem that considerable operating noise such as motor rotation noise and resonance noise due to vibration of the rotating body is generated. It was. In particular, if the FAX function is added as an option, there may be a noise problem when receiving a FAX at night.

  As a noise prevention measure due to the rotation of the rotating body 2a during the image forming operation, in the present invention, when operating in a specific time zone such as nighttime when such noise is a problem, for example, the rotating operation of the rotating body is performed. The image forming sequence is switched. In this embodiment, the rotational speed of the rotating body 2a is switched so as to decelerate in the designated time zone.

  Here, the system configuration of the digital color copying machine of this embodiment for controlling the image forming sequence will be described with reference to FIG.

  The image processing unit 8 provided in the image scanner unit IS of the digital color copying machine of this embodiment is connected to a LAN that issues a print job (image forming operation) instructed from the host computers 401 and 402.

  In addition to the CPU 403, ROM 404, and RAM 405, the image processing unit 8 includes an HDD 406 for storing image data and a LAN I / F 407 for connecting to the LAN. The RAM 405 includes a storage area for temporarily storing image data, in addition to being used as a work area for arithmetic processing accompanying control. The image processing unit 8 is connected to the FAX unit 408, encodes and compresses the document image read from the image scanner unit IS, and transmits the document image to the partner FAX via the public line (telephone line). After the image data sent from the FAX is decompressed and decoded and once stored in the HDD 406, the printing operation can be performed.

  Further, the image processing unit 8 is provided with a clock IC 409, which monitors the initial operation, the printing operation, and the FAX arrival time, and is driven by a stepping motor 411 which is a driving means for rotationally driving the rotating body 2a of the rotary developing device 2. It is used for how control is performed. Then, it is possible to set or cancel the time zone for controlling the rotation of the rotating body 2a from the operation unit 412 provided in the digital color copying machine image scanner unit IS.

  For example, when setting a time zone for low-speed operation, the touch panel display unit of the operation unit 412 is provided with a start time input unit 501 schematically shown in FIG. 3, and this portion is touched to input the start time. . Subsequently, the end time input unit 502 is touched to input the end time. The input time zone is set by touching the setting button 503, and when canceling the setting, the cancel button 504 is touched. Then, when confirming the setting, the OK button 505 is touched to complete the setting. In some cases, a time zone in which normal operation is performed is set instead of low-speed operation.

  The I / F of the image processing unit 8 communicates with the I / F provided in the printer control unit 7 of the printer unit PR, and transmits an image signal and instruction information from the operation unit 412 to the printer unit PR. Then, the printer control unit 7 drives a stepping motor 411 that performs the rotating operation of the rotating body 2a.

  In this embodiment, the stepping motor 411 is driven by a two-phase excitation method. That is, as shown in FIG. 2, the CPU 401 generates A-phase, B-phase, A * -phase, and B * -phase patterns and outputs them to the motor driver 410 that drives the stepping motor 411. 4A and 4B show excitation patterns when the motor 411 is driven by the two-phase excitation method. The stepping motor 411 starts rotating step by step in accordance with the phase signals input in the order of pattern 1 → 2 → 3 → 4 → 5. By gradually shortening the time T, the rotational speed gradually increases.

  In this embodiment, the image forming sequence is switched by the system shown in FIG. 2, and the stepping motor 411 is controlled to reduce the rotational speed of the rotating body 2a and move or stop at night when noise is likely to be a problem. The timing at which the operation is performed is increased (hereinafter referred to as “low speed operation”).

  Here, a time zone during which the operation is performed at a low speed is designated from the operation unit 412. Here, it is assumed that the setting is made from PM 22:00 to the next AM 7:00. Assume that the power switch of the main body is turned on in this state. That is, when receiving a FAX at night, the image forming apparatus is started from the sleep state and image formation is performed.

  First, the control of the rotator 2a from the start of the apparatus to the preparation of image formation will be described with reference to the flowchart of FIG. (A), (B), (C), and (D) of FIG. 5 show the relationship between the rotational speed (a) of the rotating body 2a and the output (b) of the position sensor 301 at this time. .

  In FIG. 6, after the power is turned on (S 1), the CPU 403 checks the time (S 2, S 3). If AM 0:00, the CPU 401 in the printer control unit 7 is notified and the RAM 413 is added for low-speed driving. The deceleration table is developed (S4).

  Then, the rotating body 2a is rotated at a constant speed by the stepping motor 411, and the home position detection operation is performed (S5). At this time, as the rotating body 2a is rotating, the position flags 302Y, 302M, 302C, and 302K of the respective colors shield the position sensor 301 at equal time intervals, and the output waveform b of the position sensor 301 is shown in (A As shown in (), the waveform is shifted upward at the same length at equal intervals. Since the home position flag 302HP is narrower than the position flags 302 of other colors, the light shielding time is shorter than the other colors. Therefore, it is determined that this is the home position, and the vehicle is immediately decelerated and stopped.

  Subsequently, in order to check the remaining amount of toner of each color, the yellow developing unit 25Y is moved at the developing point P (S6), a specific patch pattern is transferred onto the photosensitive drum 1, and the toner density and the like are detected by a sensor (not shown). Is read.

  Subsequently, the developing unit 25 is moved in the order of magenta, cyan, and black, and similar toner remaining amount detection is performed (S7 to S9).

  At this time, as the operation of the rotating body 2a, the operation is stopped during the patch forming operation for each color, and the operation of rotating and switching the developing device is performed when the color of the patch is switched. The stop time, moving time, and moving speed of the rotating body 2a at this time are the same.

  Therefore, the rotational speed a of the rotating body 2a and the output waveform b of the sensor 301 are as shown in FIG. That is, the rotating body 2a increases and decreases in speed at regular time intervals, periodically stops to perform patch formation, and before the rotating body 2a stops rotating for the color switching operation, the sensor 301 The position flag 302 for each color is periodically shielded from light.

  Here, if the time is PM20: 00 which is not the low-speed operation time zone in S2, a normal drive acceleration / deceleration table is developed in the RAM 413 (S10), and the process proceeds to S5.

  The rotation speed in this case is naturally faster than that at the time of low-speed driving, and both the rotation time and the stop time are shortened. Therefore, the rotation speed a and the output waveform b of the sensor are as shown in FIG. In addition, when patch detection is performed, the result is as shown in FIG. That is, the time interval is narrower than the waveform during the low-speed operation, and the rotation speed a chart of the rotating body 2a is shifted upward during the movement than during the low-speed operation.

  When the apparatus is started up, an image forming operation is subsequently performed. Next, when it is assumed that the time zone for low-speed operation is set from PM 22:00 to the next AM 7:00, FAX reception is performed in the standby state and the image is received. Control of the rotating body 2a when performing the forming operation will be described with reference to the flowchart shown in FIG. 7A and 7B show the relationship between the rotational speed (a) of the rotating body 2a and the output (b) of the position sensor 301 at this time. At this time, since the apparatus is standing up and the rotating body 2a has already moved to the home position, the operation of moving to the home position can be omitted.

  When it is detected that data has been sent to the FAX unit during standby (S1), the CPU 403 checks the time (S2, S3), and if it is AM 0:00, it notifies the CPU 401 in the printer control unit 7; An acceleration / deceleration table for low-speed driving is developed in the RAM 413 (S4).

  Then, the rotational speed (process speed) of the rotating drum 20 is kept as it is, and only the rotating speed of the rotating body 2a is decreased, and the mode is shifted to the low speed copy mode (S5).

  At this time, after the yellow development is completed first, the rotating body 2a is rotated at a low speed. However, since the photosensitive drum 1 rotates at the same speed as usual, the movement of the magenta developing device 25M is in time for the magenta image formation timing. Absent. Therefore, the intermediate transfer drum 26 is rotated one more dummy turn, and magenta image formation is performed at the next image formation timing. At this time, since the intermediate transfer drum 26 is rotated more than usual, the image forming speed is reduced.

  The rotational speed (a) of the rotating body 2a and the output waveform (b) of the sensor 301 at this time are as shown in (B) of FIG. That is, at the time of image formation, the rotator 2a stops for each color for a time equal to or longer than the time for which the intermediate transfer drum 26 rotates twice, and when rotating, the rotation speed when switching the developing device 25 is also reduced more than usual. .

  If the time is PM20: 00 in S2, the normal drive acceleration / deceleration table is developed in the RAM 413 (S6), and the normal copy mode is entered (S7). Since the rotation speed in this case is naturally faster than that during low-speed driving, dummy rotation is not necessary, and the rotation speed and the output waveform of the sensor 301 are as shown in FIG.

  That is, at the time of image formation, the rotating body 2a stops for a time longer than the time for which the intermediate transfer drum 26 makes one rotation, but stops for a shorter time than when the time is AM 0:00, and the rotation speed when the developing device 25 is switched is high. Become.

  As described above, in this embodiment, during the apparatus start-up operation and the image forming operation at the designated predetermined time, the rotational speed of the rotating body 2a is reduced, so that the rotating body 2a in that time zone is reduced. The operating noise can be reduced, and the noise problem has been alleviated.

  Needless to say, the time zone during which the deceleration operation is performed can be freely selected, and the configuration of the image forming operation control system described above, the dimensions, materials, shapes, and relative positions of the components of the image forming apparatus are as follows. Unless otherwise specified, the scope of the present invention is not limited to these. That is, the present invention can also be applied to a direct transfer method in which an image is directly transferred from a photosensitive drum to a transfer material without providing an intermediate transfer member, and an electrostatic recording image forming apparatus.

Example 2
Next, another embodiment of the present invention will be described. Since the basic configuration and operation of the image forming apparatus according to the present exemplary embodiment are the same as those of the first exemplary embodiment, elements having the same function and configuration are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, in addition to the effects of the first embodiment, by simultaneously switching the voltage applied to the stepping motor 411 or the current value of the winding, the vibration of the motor can be suppressed and further noise reduction can be realized. .

  FIG. 9 shows a circuit block diagram relating to the stepping motor 411 in the present embodiment.

  As shown in FIG. 9, the image forming apparatus of this embodiment includes a switch unit 121 that switches a current detection resistor that detects a current value flowing through the stepping motor 411, and uses an analog switch or the like by a control line from the CPU 401. The current detection resistor connected to the motor driver 410 is switched. Further, it has switch means 122 for switching the power supply voltage to be applied to the stepping motor 411, and a plurality of power supply voltages (24V, 12V, 6V in this embodiment) are supplied from the CPU 401 by an FET array (not shown) or the like. Use to switch.

  Here, using the flowchart shown in FIG. 10, it is assumed that the time zone for low-speed operation is set from PM 22:00 to the next AM 7:00, and the power switch of the main body is turned on in that state.

  After the power is turned on (S1), the CPU 403 checks the time (S2, S3), and if it is AM 0:00, notifies the CPU 401 in the printer controller 7 and develops an acceleration / deceleration table for low-speed driving in the RAM 413. (S4).

  Subsequently, the switch means 121 or 122 is switched so that the current value or voltage value becomes lower than normal (S5).

  Then, the stepping motor 411 is rotated to perform a home position detection operation (S6). The subsequent operation is the same as S6 to S9 in FIG.

Example 3
Next, another embodiment of the present invention will be described. Since the basic configuration and operation of the image forming apparatus according to the present exemplary embodiment are the same as those of the first exemplary embodiment, elements having the same function and configuration are denoted by the same reference numerals, and detailed description thereof is omitted.

  By the way, in addition to performing the deceleration operation of the rotating body 2a at a predetermined time as described in the first and second embodiments, when a print command is received within a predetermined time, the image data is forcibly black and white even when the image data is full color. It is also possible to suppress noise in a predetermined time zone by switching to an image sequence that is output at.

  In other words, if the image formation is performed with only one developing device 25, the rotating body 2a only needs to move the developing device 25 to the developing position and stop as it is. The operating noise accompanying it can be suppressed. Here, the image forming operation is switched to an image sequence in which black and white image forming operation is performed for a predetermined time (hereinafter referred to as “black and white limited operation”), and the developing operation is performed only by the black developing device 25K. Of course, it goes without saying that the developing operation may be performed only by the developing devices 25 of other colors.

  Assuming that the time period for the black and white limited operation is set from PM 22:00 to the next AM 7:00, the operation of the rotating body 2a at this time will be described with reference to the flowchart shown in FIG.

  When a print command is received in the standby state (S1), the CPU 403 checks the time (S2), and then confirms whether the image data is full color or monochrome based on the color information included in the data (S3).

  If it is a full-color image, it is checked in S4 whether or not it is a time period during which black-and-white limited operation is performed.

  If the time is AM 0:00, the CPU 401 in the printer control unit 7 is notified, an acceleration / deceleration table for low-speed driving is developed in the RAM 413, and the black developing device 25K is moved to the developing point P at low speed (S5). ), A black and white copy operation is performed (S6).

  FIG. 11A shows the rotational speed a of the rotating body 2a and the output waveform b of the position sensor 301 when the apparatus is started up at this time. Also at this time, the rotating body 2a rotates at a constant speed, and during that time, the position flags 302Y, 302M, 302C, and 302K for each color shield the position sensor 301 from light at regular intervals. It is more preferable to reduce the rotational speed of the rotating body a at this time than usual.

  Thereafter, the patch detection operation is not performed, and the black and white copy operation is performed. At this time, the rotation of the rotating body 2a stops and the position flag 302 does not shield the position sensor 301. The output waveform b is a straight line as shown in FIG.

  When the time is PM19: 00 in S3, the normal drive acceleration / deceleration table is developed in the RAM 413 to perform normal color copying (S7).

  By performing such an operation, the rotating operation of the rotating body is stopped after one developing device is fixed at the developing position, so that there is no operating noise. Therefore, the noise problem is alleviated.

Example 4
In the first, second, and third embodiments, the image forming apparatus has been described in which the rotating body is used as the developing device holder, and the developing device is moved to the developing position by rotational movement. As the body, a plane or curved parallel moving body may be used in addition to the rotating body. For example, a plurality of developing devices are arranged in a vertical or horizontal direction on a holder that is movable in the vertical or horizontal direction so as to face the image carrier, and the holder is vertically or horizontally arranged. The developing device can be moved so as to be in contact with and separated from the image carrier.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention. 1 is a block diagram illustrating an embodiment of a control system for an image forming apparatus according to the present invention. It is explanatory drawing of the operation part which designates the predetermined | prescribed time slot | zone based on this invention. It is a figure which shows the excitation pattern in the case of driving a stepping motor by a two-phase excitation system. It is a figure which shows the relationship between the rotational speed of the rotary body at the time of initial setting operation | movement in the predetermined time slot | zone of Example 1, and the output of a position sensor. 3 is a flowchart illustrating an initial setting rotating body control operation in a predetermined time period in the first embodiment. FIG. 6 is a diagram illustrating a relationship between a rotation speed of a rotating body and an output of a position sensor during an image forming operation in a predetermined time zone according to the first exemplary embodiment. 6 is a flowchart illustrating a rotating body control operation during image formation in a predetermined time period according to the first exemplary embodiment. FIG. 10 is a block diagram illustrating a driving unit for a rotating body in the second embodiment. 10 is a flowchart illustrating an initial setting rotating body control operation in a predetermined time period in the second embodiment. FIG. 10 is a diagram illustrating a relationship between a rotation speed of a rotating body and an output of a position sensor during an initial setting operation in a predetermined time period in the third embodiment. 10 is a flowchart illustrating a rotating body control operation in a predetermined time period in the third embodiment. It is a schematic block diagram which shows an example of the conventional image forming apparatus. It is a timing chart which shows the drive control operation | movement of the conventional rotary body.

Explanation of symbols

IS Image scanner part PR Printer part 1 Photosensitive drum (image carrier)
2 Development device (moving development device)
2a Rotating body (holding body)
7 Printer Control Unit 8 Image Processing Unit 25 Developing Device 301 Position Sensor 302 Position Plug 401 Printer Unit CPU
403 Image processing unit CPU
408 FAX
410 Motor driver 411 Stepping motor (drive means)
412 Device operation unit

Claims (10)

An image carrier on which an electrostatic image is formed on the surface, a plurality of developing units that develop the electrostatic image with a developer to form a developed image, and the plurality of developing units are mounted. An image forming apparatus comprising: a movable holder that moves the image carrier to a position where a developing operation is performed; and a transfer unit that transfers a developed image on the image carrier to a recording material.
An image forming apparatus that performs an image forming operation by switching an image forming sequence related to the operation of the holder when an image forming operation is performed in a predetermined time zone.   The image forming apparatus according to claim 1, wherein the image forming sequence in the predetermined time period is switched so as to reduce a moving speed of the holding body.   3. The image forming apparatus according to claim 2, wherein when the moving speed of the holding body is lowered, a current value or a voltage value applied to the driving means of the holding body is lowered.   2. The image sequence in the predetermined time zone is switched between when the holding body moves to a home position, when an image forming apparatus is initially set, and when an image is formed. The image forming apparatus according to any one of items 1 to 3.   The initial setting of the image forming apparatus includes detection of developer concentration stored in the developing device, developer stirring operation in the developing device, and developer replenishment operation to the developing device. Item 5. The image forming apparatus according to Item 4.   The image forming apparatus according to claim 4, wherein when the moving speed of the holding body is lowered, the image forming speed is also lowered.   7. The image forming sequence in the predetermined time zone is switched to perform image formation using only one developing device among the plurality of developing devices. The image forming apparatus described in the item.   The image forming apparatus according to claim 1, wherein the holding body is a rotating body, and the plurality of developing devices are arranged and mounted along an outer periphery.   The image forming apparatus according to claim 1, wherein the holding body is a flat or curved parallel moving body, and the plurality of developing devices are mounted in parallel. apparatus.   The image forming apparatus has at least one of a copy function, a FAX function, a printer function, and a paper discharge processing function for a recording material on which the image is formed and discharged from the image forming apparatus. 10. The image forming apparatus according to claim 1, wherein the image forming apparatus has at least one of a function that can be arbitrarily selected, a function that can set a priority, and a setting cancellation function.

Images