JPH09281770A - Color image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the lives of photoreceptors and a carrying belt by reducing wearing caused by the contact of the photoreceptors of image forming parts with a carrying belt for carrying a recording medium. SOLUTION: Respective image forming parts 2Y, 2M and 2C for yellow, magenta and cyan are constituted as one image forming unit A and an image forming part, 2K for black is constituted as one unit. An eccentric cam 22 is provided in the lower part of the color image forming unit A and can be rotated by cam shafts 21a and 21b. At the time of recording a black image, the color image forming unit A is separated from the carrying belt 20 by the rotation of the eccentric cam 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image recording apparatus for forming a color image by sequentially recording a plurality of color images on a recording medium.

[0002]

2. Description of the Related Art Conventionally, as a color recording apparatus of this type, yellow, magenta, cyan, and black image forming means having a recording head in which recording elements are arranged in a line are arranged, and a recording medium is a conveyor belt. While adsorbing, the image is conveyed in a direction orthogonal to the array direction of the recording elements, and based on each color image data, yellow, magenta, cyan, and black toners are used to sequentially record color images line by line. The recording mediums are fed one by one from the paper storage unit and sequentially conveyed to each of the image forming means, and a color image is overlaid and recorded.

[0003]

However, in the above-described conventional color recording apparatus using the conveyor belt, the image is transferred by each image forming means while the recording medium is adsorbed by the conveyor belt and conveyed. Since the conveyor belt or the recording medium is constantly in contact with the photoconductor during the operation, there is a problem that the photoreceptor and the conveyor belt are worn and the life of the conveyor belt and the photoreceptor is shortened.

[0004]

In order to solve the above problems, the present invention has a plurality of image forming means for forming an image,
In a color image recording apparatus for recording a color image by transferring an image formed by the image forming unit onto a medium conveyed by a medium carrier, the plurality of image forming units are a black image forming unit and an image forming unit of another color. And the image forming means for the other color is separable from the medium carrier, and the image forming means for the other color is separated from the medium carrier when a black image is formed by the black image forming means. To do.

In the invention having the above-mentioned structure, when a black image is recorded, the image forming means of another color is separated from the medium carrier. As a result, when recording a black image, the photoreceptor of the other color image forming means and the medium carrier do not come into contact with each other, so that the photoreceptor and the medium carrier are not worn and the life can be extended.

Another aspect of the present invention is characterized in that the rotational speeds of the photoconductors of the plurality of image forming means are different from the transport speed of the medium carrier according to the image ratio. According to this another invention, when the image ratio is low, the rotation speed of the photoconductor and the conveyance speed of the medium carrier are the same, so that the life of the photoconductor and the medium carrier can be extended without lowering the transfer efficiency.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The elements common to the drawings are given the same reference numerals. FIG. 1 is a block diagram showing a color recording apparatus according to the first embodiment, and FIG. 2 is a perspective view showing a color image forming unit according to the first embodiment.

In FIG. 1, the color recording apparatus 1 has two
A pair of printing mechanisms P1 and P2 are arranged in order from the insertion side of the recording medium to the ejection side. The first printing mechanism P1 is an electrophotographic LED (light emitting diode) printing mechanism for yellow, magenta, and cyan, and the second printing mechanism P2 is an electrophotographic LED printing mechanism for black. The first printing mechanism P1 includes a color image forming unit A in which a yellow image forming unit 2Y, a magenta image forming unit 2M, and a cyan image forming unit 2C are integrally formed, and a photosensitive member described later according to image data. LED heads 3Y, 3M, 3C and the image forming units 2Y, 2M,
The transfer rollers 4Y, 4M, and 4C transfer the toner image formed by 2C onto the recording medium. Each image forming unit 2
Y, 2M, and 2C are photoconductors 6Y, 6M, and 6C that rotate in the direction of arrow a about axes 5Y, 5M, and 5C, and photoconductors 6Y,
A charging roller 7Y for uniformly charging the surfaces of 6M and 6C,
7M, 7C and developing units 8Y, 8M, 8C. The developing units 8Y, 8M, and 8C have developing rollers 9Y and 9Y.
M, 9C, developing blades 10Y, 10M, 10C, sponge rollers 11Y, 11M, 11C, toner tank 12
It is composed of Y, 12M, and 12C. Each image forming unit 2
The above-mentioned components of Y, 2M, and 2C are supported by the frame 13.

The second printing mechanism P2 transfers a black image forming portion 2K, an LED head 3K that exposes a photoreceptor described later according to image data, and a toner image formed by the image forming portion 2K to a recording medium. It is composed of a roller 4K. The image forming unit 2K includes a photoconductor 6K that rotates in the direction of the arrow a around the shaft 5K, a charging roller 7K that uniformly charges the surface of the photoconductor 6K, and a developing unit 8K. The developing section 8K includes a developing roller 9K and a developing blade 1.
0K, sponge roller 11K, and toner tank 12K. The above-described components of the image forming unit 2K are supported by the frame 14.

The function of the yellow image forming section 2Y will be described below as a representative.
After passing through Y, it reaches the developing blade 10Y and reaches the developing roller 9Y.
It is thinned to reach the contact surface with the photoconductor 6Y. The toner is a developing roller 9Y and a developing blade 10Y when forming a thin layer.
It is strongly rubbed against and is electrostatically charged. In this embodiment, it is negatively charged by friction. The sponge roller 11Y conveys an appropriate amount of toner to the developing blade 10Y. The developing roller 9Y is made of a semiconductive rubber material. When the toner runs out, the toner can be newly supplied by replacing the toner tank 12Y.

The LED head 3Y includes an LED array and this L
Substrate 15 on which drive IC for driving ED array is mounted
It is composed of a SELFOC lens array 16Y and the like for condensing the light of Y and the LED array. The LED array is caused to emit light in response to an image data signal input from an interface section described later, and the surface of the photoconductor 6Y is exposed to static light. Form a latent image. The toner on the developing roller 9Y is attached to the electrostatic latent image portion by electrostatic force to form an image. Each LE
The D head 3Y is pressed downward in the figure by a spring 17Y. A conveyor belt 20 described later is movably arranged between the photoconductor 6Y and the transfer roller 4Y.

The developing device 8Y of the image forming portion 2Y stores yellow (Y) toner, and the developing device 8M of the image forming portion 2M.
The magenta (M) toner is stored in M, the developing device 8C of the image forming unit 2C stores cyan (C) toner, and the developing device 8K of the image forming unit 2K stores black (K) toner. It is housed. In addition, L of the first printing mechanism P1
The yellow image signal of the color image signals is input to the ED head 3Y, the magenta image signal of the color image signals is input to the LED head 3M, and the LED head 3C is input.
The cyan image signal of the color image signal is input to
The black image signal of the color image signals is input to the LED head 3K of the second printing mechanism P2.

In FIGS. 1 and 2, two camshafts 2 are provided below the frame 13 of the color image forming unit A.
1a and 21b are rotatably supported, and eccentric cams 22 are fixed to both ends of the camshafts 21a and 21b, respectively. As shown in FIG.
Guide grooves 13a that fit with the camshafts 21a and 21b are provided at the four lower corners of the. In addition, the guide groove 13
Above the a, the protruding plate portion 13b that comes into contact with the eccentric cam 22 is provided.
Is provided. Further, the frame 13 has a spring 17Y,
LED heads 3Y, 3M, 3 by 17M, 17C
Since it is pressed downward via C, the camshaft 2
When 1a and 21b rotate, the eccentric cam 22 moves the protrusion plate portion 1
3b is in contact with the eccentric cam 22.
The amount of eccentricity is moved in the direction of arrow b (vertical direction). A gear 23 is fixed to one of the camshafts 21a, and the gear 23 meshes with a motor gear 24.
The motor gear 24 is fixed to the rotating shaft of the cam motor 25. The other cam shaft 21b is also configured to rotate in the same rotation direction and rotation amount via a gear or belt (not shown). A slit disk 26 is fixed to one of the cam shafts 21a, and the slit disk 26 is provided with a slit 26a.
The position of the eccentric cam 22 can be known by detecting a with the photo sensor 27.

In FIG. 2, a color image forming unit A
At the end of each of the photoconductors 6Y, 6M, and 6C, a gear portion 91Y,
91M and 91C are formed, respectively. Photoconductor 6Y
The gear portion 91Y of the photoconductor 6M meshes with the gear 92, the gear portion 91M of the photoconductor 6M meshes with the gear 93, and the gear portion 91C of the photoconductor 6C meshes with the gear 94. A motor gear 96 is fixed to the shaft of the motor 85, and the motor gear 96 meshes with a large gear 97a of the reduction gear 97. The small gear 97b of the reduction gear 97 meshes with the planet gear 98, and the planet gear 98 meshes with the gear 99. Gear 99 is Gear 1
00 and the gear 101, and the gear 100 meshes with the gear 94. Gear 101 is gear 93 and gear 1
No. 02, gear 102 meshes with gear 103, and gear 103 meshes with gear 92. The shaft of the reduction gear 97 and the shaft of the planet gear 98 are connected by a link 104, and the shaft of the planet gear 98 and the shaft of the gear 99 are connected by a link 105.

Of the above gears, gear 92, gear 93, gear 94, gear 99, gear 100, gear 101, gear 10
2. Each shaft hole of the gear 103 has a color image forming unit A
And a shaft provided on a frame (not shown) that moves in the vertical direction (the direction of arrow b and the opposite direction) integrally with the shaft. The shaft of the reduction gear 97 and the motor 85 are fixed to a fixed frame (not shown) of the color recording apparatus 1.
The planet gear 98 rotates in the arrow direction when the color image forming unit A moves in the arrow b direction, and holds the mesh with the gear 99.

Due to the meshing of the gear trains described above, the photosensitive drums 6Y, 6M, 6C are rotated by the motor 85 regardless of whether the color image forming unit A comes into contact with the conveyor belt 20 or separates from the conveyor belt 20. Can rotate in the direction of arrow a at the same speed. Each photoconductor 6Y, 6M, 6
In order to rotate C at the same speed, it can be determined by the number of teeth of each gear. By rotating the photoconductors 6Y, 6M, and 6C, the other rotary members in the color image forming unit A, that is, the charging rollers 7Y, 7M, 7C, and the developing roller 9 are rotated.
Y, 9M, 9C, sponge rollers 11Y, 11M, 11
C and the transfer rollers 4Y, 4M, and 4C are also configured to rotate.

A gear 106 is fixed to the shaft of the drive roller 30 that drives the conveyor belt 20. This gear 106 meshes with the small gear 107a of the reduction gear 107,
The large gear 107b of the reduction gear 107 meshes with the gear 108. The gear 108 is the motor gear 110 of the motor 84.
It also meshes with the large gear 111a of the reduction gear 111. The small gear 111b of the reduction gear 111 meshes with the gear 112. The gear 112 meshes with a gear portion formed at the end of the photoconductor 6K of the black image forming portion 2K.

With the above gear train, when the motor 84 is driven to rotate, the drive roller 30 rotates in the direction of arrow c and at the same time the photosensitive member 6K rotates in the direction of arrow a. By rotating the photosensitive member 6K, the other rotating members in the black image forming section 2K, that is, the charging roller 7K, the developing roller 9K, the sponge roller 11K, and the transfer roller 4K are also rotated.

Further, in FIG. 2, each LED head 3Y, 3M, 3 is provided on the frame 13 of the color image forming unit A.
A C window hole 13c is opened. In addition, guide pin holes 13d and 13e of the LED heads 3Y, 3M, and 3C are provided, so that the LED heads 3Y, 3M, and 3E are provided.
C can be positioned with respect to the color image forming unit A.

In FIG. 1, the conveyor belt 20 is made of a high-resistance semi-conductive plastic film, is formed in a seamless endless shape, and is wound around a drive roller 30, a driven roller 31, and a tension roller 32. There is. The resistance value of the transport belt 20 is such that the recording medium S described later can be electrostatically adsorbed to the transport belt 20, and static electricity remaining on the transport belt 20 when the recording medium S is separated from the transport belt 20 can be naturally eliminated. It should be within the range.
The drive roller 30 is connected to a motor (not shown), and the drive roller 30 is rotated in the direction of arrow c by this motor. The tension roller 32 is biased in the direction of the arrow d by a spring (not shown), so that the conveyor belt 20 is always tensioned. The upper surface of the conveyor belt 20 is stretched between the photoconductor 6 of each of the printing mechanisms P1 and P2 and the transfer roller 4. Further, the cleaning blade 33 is pressed against the drive roller 30 side with the conveyor belt 20 interposed therebetween. The cleaning blade 33 is made of flexible rubber or plastic material. As a result, the cleaning blade 3
The tip of 3 is pressed against the conveyor belt 20 so that the residual toner adhering to the surface of the conveyor belt 20 is scraped off to the waste toner tank 34. In this embodiment, each photoconductor 6 and the transfer roller 4 are in contact with the conveyor belt 20.

On the lower right side of the color recording apparatus 1, a paper feed mechanism 4 is provided.
0 is provided. The paper feed mechanism 40 comprises a paper storage cassette, a hopping mechanism, and registration rollers. The sheet storage cassette includes a recording medium storage box 41, a push-up plate 42, and a pressing unit 43. The hopping mechanism is a discrimination means 44,
The first registration roller 5 is composed of a spring 45 and a paper feed roller 46, and the hopping mechanism guides the recording medium S to the guides 48 and 49 to face the conveyance roller 50.
It reaches the first and second registration rollers 52.

First, the discriminating means in which the recording medium S accommodated in the recording medium accommodating box 41 is pressed against the paper feed roller 46 by the pressing means 43 via the push-up plate 42 and pressed against the paper feed roller 46 by the spring 45. The sheets are separated by 44. In this state, the paper feed roller 4
When 6 is rotated in the direction of arrow f, the recording medium S sandwiched between the sheet feeding roller 46 and the discriminating means 44 is guided by the guides 48 and 49, and the conveying roller 50 and the first registration roller 5
Reach one. Further, when the transport roller 50 is rotated in the direction of arrow g by a motor (not shown), the recording medium S is guided by the second registration roller 52 to the medium guide 53 and guided between the suction roller 54 and the transport belt 20. Get burned. The first registration roller 51 and the second registration roller 52 are pressed against the transport roller 50. The attraction roller 54 is pressed against the driven roller 31 via the conveyor belt 20, charges the recording medium S sent by the paper feeding mechanism 40, and electrostatically attracts the recording medium S to the upper surface of the conveyor belt 20. It is a thing. Therefore, the suction roller 5
Reference numeral 4 is made of a high-resistance semiconductive rubber material. The recording medium S is provided between the suction roller 54 and the printing mechanism P1.
A photo sensor 55 is provided for detecting the tip of the.

Reference numeral 56 denotes a manual tray, in which the operator manually inserts the recording medium S along the manual tray 56 and the guide 57. Reference numeral 58 denotes a photosensor that detects the manually inserted recording medium S. The misaligned recording medium S is guided to the medium guide 53 by the transport roller 50 and the second registration roller 52, and the suction roller 54 and the transport belt 2 are guided.
Guided between 0 and.

A static eliminator 60 is provided on the upper surface of the drive roller 30 side with the transport belt 20 interposed therebetween. This static eliminator 6
In the case of 0, the recording medium S adsorbed by the conveyance belt 20 is discharged, and the adsorbed state is released.
It is easy to separate from. A photo sensor 61 for detecting the rear end of the recording medium S is provided on the left side of the static eliminator 60.

A guide 62 is provided on the left side of the static eliminator 60.
Also, a fixing device 63 is provided. The fixing device 63 fixes the toner image on the recording medium S to which the toner image has been transferred, which is conveyed by the conveying belt 20.
It has a heat roller 64 for heating the upper toner, and a pressure roller 65 for pressing the recording medium S together with the heat roller 64. The left side of the fixing device 63 is an outlet 66,
A discharge stacker 67 is provided on the outside thereof. The printed recording medium S is discharged to the discharge stacker 67.

FIG. 3 is a block diagram showing the control unit of the first embodiment. In the figure, reference numerals Y, M, C,
K corresponds to each printing mechanism of the yellow, magenta, cyan, and black image forming units. In the figure, 71 indicates a control circuit, and the control circuit 71 is composed of a microprocessor or the like and controls the operation of the entire color recording apparatus 1. The control circuit 71 includes an SP bias power source 72Y that supplies electric power to the sponge roller 11 of the developing device 8 of each image forming unit.
72M, 72C, 72K, developing roller 9 of each image forming unit
DB bias power supplies 73Y, 73M, 7 for supplying power to
3C, 73K, charging power supplies 74Y, 74M, 74C, 74K for supplying electric power to the charging roller 7 of each image forming portion, transfer power supplies 75Y, 75M for supplying electric power for charging the transfer roller 4 of each image forming portion, 75C and 75K are respectively connected.

Further, the control circuit 71 includes the suction roller 5
4, a charging power source 76 for supplying charging power to the 4, and a static eliminator 60
A static elimination power supply 77 that supplies high-voltage power for static elimination is connected to. The driven roller 31 is grounded so that the recording medium S can be electrostatically adsorbed to the conveyor belt 20 due to the potential difference from the adsorption roller 54. Each of the above power supplies is turned on / off according to an instruction from the control circuit 71.
Controlled off.

Further, the control circuit 71 includes print control circuits 78Y, 78M, 78 corresponding to the respective image forming units.
C and 78K are connected. Each of these print control circuits 7
8Y, 78M, 78C and 78K are memories 79Y and 79
The image data from M, 79C, and 79K is received, and these data are transmitted to the LED heads 3Y, 3M, 3C, and 3K in accordance with an instruction from the control circuit 71, and the exposure time of the LED is controlled to control each photoconductor. The control is performed to form an electrostatic latent image on the surface. Memories 79Y, 79M, 79C, 7
9K stores the image data sent from the external device via the interface unit 80 for each color.

The interface section 80 separates the image data transmitted from an external device such as a host computer by color, and the yellow image data is stored in the memory 79Y.
, Magenta image data is stored in the memory 79M, cyan image data is stored in the memory 79C, and black image data is stored in the memory 79K.

The fixing device driver 81 drives a heater (not shown) in the heat roller 64 so as to keep the temperature of the heat roller 64 in the fixing device 63 constant. The motor drive circuit 82 includes a motor 83 that rotates the paper feed roller 46,
The motors 84 and 85 and the motor 25 described above are driven. The motor 84 is not limited to the photosensitive member 6K of the second printing mechanism P2, the charging roller 7K, the developing roller 9K, the sponge roller 11K, the transfer roller 4K, and the driving roller 3K.
0, the transport roller 50, and the heat roller 64 of the fixing device 63
Also rotate. The motor 85 includes transfer rollers 4Y, 4M, 4C of the first printing mechanism P1, photoconductors 6Y, 6M, 6C of the color image forming unit A, charging rollers 7Y, 7M,
7C, developing rollers 9Y, 9M, 9C, sponge roller 1
Not only 1Y, 11M, and 11C, but also the driving roller 30, the conveying roller 50, and the heat roller 64 of the fixing device 63 are rotated. When the cam motor 25 is driven, the color image forming unit A described above moves in the direction of arrow b,
1st position (position separated from the conveyor belt 20)
And a second position shown in FIG. 4 (position in contact with the conveyor belt 20). Note that FIG. 4 is a configuration diagram showing a state in which the color image forming unit A in the first embodiment is separated from the conveyor belt 20. The distance L between the conveyor belt 20 and each photoconductor 6 of the color image forming unit A shown in FIG. 4 is set to about 7 mm in this embodiment. The rollers rotated by the motors 84 and 85 are connected by a gear or belt (not shown).

When the color image forming unit A is in the position shown in FIG. 4, even if the motor 84 is rotationally driven, the motor 85 is not driven, and the photoconductors 6Y and 6M constituting the color image forming unit A are prevented. , 6C, charging rollers 7Y, 7M, 7C, developing rollers 9Y, 9M, 9C, sponge rollers 11Y, 11M, 11C do not rotate. When the motors 84 and 85 are driven,
The peripheral speeds of the photoconductors 6Y, 6M, 6C and 6K, the conveyor belt 20 and the recording medium S are the same. The sensor receiver driver 86 includes the photo sensors 55, 58,
61 and 27 are driven, and the output waveforms thereof are received and sent to the control circuit 71.

Next, the operation of the first embodiment having the above configuration will be described. First, when the power source of the color recording apparatus 1 (not shown) is turned on, the control circuit 71 rotates the cam motor 25 via the motor drive circuit 82 and the slit 26 a of the slit disk 26 via the sensor driver receiver 81. The cam motor 25 is stopped at the position detected by the photo sensor 27. This position is the home position (second position) of the color image forming unit A shown in FIG. As can be seen from FIG. 4, at the home position, the photoconductors 6Y, 6M, 6C of the color image forming unit A do not contact the conveyor belt 20, that is, the photoconductors 6Y, 6M, 6C and the conveyor belt 20 are separated from each other. In position.

After performing a predetermined initial setting, the fixing driver 81 is driven to warm up the heat roller 64 in the fixing device 63 to a predetermined temperature.
The control circuit 71 controls so that the heat roller 64 is always kept at a constant temperature. When the heat roller 64 reaches a predetermined temperature, the control circuit 71 then controls the motor drive circuit 82.
The motor 84 is driven to rotate the drive roller 30 via the, and the conveyor belt 20 is moved in the direction of arrow e. As for the movement of the conveyor belt 20, the motor 84 is stopped and the conveyor belt 20 is stopped when the conveyor belt 20 is fed a little longer than one revolution.
As a result, the residual toner and dust adhering to the surface of the conveyor belt 20 are scraped off by the cleaning blade 33 into the waste toner tank 34. Since the motor 85 is not rotated during this cleaning operation, the photoconductors 6Y, 6M, 6 of the color image forming unit A are not rotated.
C, charging rollers 7Y, 7M, 7C, developing rollers 9Y, 9
The M, 9C and the sponge rollers 11Y, 11M, 11C are not rotated. Further, during this cleaning operation, the color image forming unit A is separated from the conveyor belt 20, so that the conveyor belt 20 or the photoconductors 6Y, 6M, 6 are formed.
C does not touch. As a result, the initial setting of the color recording apparatus 1 is completed, and it waits for the image data to be sent from the external apparatus via the interface unit 80.

When the image data sent from the external device, that is, the host computer is received through the interface section 80, the control circuit 71 gives an instruction to the interface section 80 and each of the memories 79Y, 79M, 79C and 79K. By this instruction, the interface unit 80
Separates the received image data signal for each color, and the image data for each color is stored in each memory 79Y, 79M, 79C, 7 for each color.
Store in 9K. That is, the yellow image data is stored in the memory 79Y and the magenta image data is stored in the memory 79M.
The cyan image data is stored in the memory 79C, and the black image data is stored in the memory 79K. In each of the memories 79Y, 79M, 79C, 79K, image data of each color for one page printed on the recording medium S is stored.

Next, the operation of recording a monochrome (black) image will be described. As described above, when the monochrome image data sent from the host computer is received via the interface section 80, the control circuit 71 issues an instruction to the interface section 80 and the memory 79K.
In response to this instruction, the interface section 80 stores the received image data signal in the memory 79K. That is,
Only black image data is stored in the memory 79K,
The yellow image data, magenta image data, and cyan image data are not stored in 79Y and 79M, and the memory 79C. The memory 79K stores one page of black image data to be printed on the recording medium S. Since a command indicating whether the image data is a monochrome image or a color image is sent from the host computer prior to the image data, the control circuit 71 asks whether the image data sent from the interface unit 80 is monochrome. You can know if it is color. When the image data is only monochrome, the color image forming unit A is moved to the home position shown in FIG. From this state, the image data is printed on the recording medium S housed in the paper feed mechanism 40.

The control circuit 71 drives the motor 83 via the motor drive circuit 82 to rotate the paper feed roller 46. By the rotation of the paper feed roller 46, only one recording medium S in the paper storage box 41 is sent to the guides 48 and 49, and the leading end of the recording medium S is conveyed by the transport roller 50 and the first registration roller 51.
The motor drive circuit 82 is controlled so as to convey the recording medium S slightly longer than the distance to reach. As a result, the recording medium S has the leading end of the conveyance roller 50 and the first registration roller 5
When the recording medium S is pressed while it is in a state of being slightly bent, the skew of the recording medium S is corrected by this bending.

Next, the control circuit 71 controls the motor drive circuit 82.
The motor 84 is driven via the heat source of the photoconductor 6K, the charging roller 7K, the developing roller 9K, the sponge roller 11K, the transfer roller 4K, the driving roller 30, the conveying roller 50, and the fixing device 63 of the second printing mechanism P2. The rollers 64 are each rotated. At the same time, the control circuit 71 turns on the attraction charging power source 76 to supply a voltage to the attraction roller 54. Since the transport roller 50 rotates in the direction of arrow g, the recording medium S is transported by being guided by the medium guide 53 by the first registration roller 51 and the second registration roller 52, and the leading end of the recording medium S is attracted by the suction roller 54. And the conveyor belt 20. At this point, the leading edge of the recording medium S is attracted to the transport belt 20 by the electrostatic force between the attraction roller 54 and the driven roller 31. Further, when the conveyance roller 50 rotates in the direction of arrow f, the recording medium S is conveyed in the direction of arrow e while being attracted to the conveyance belt 20, and the control circuit 71 causes the leading end of the recording medium S to pass through the sensor receiver driver 86. It is detected by the photo sensor 55. After the trailing edge of the recording medium S is ejected from the discriminating means 24 by the paper feed roller 26, the control circuit 71 causes the motor drive circuit 82 to
The motor 83 is stopped.

Now, returning to the description of the recording operation, the recording medium S
When the photo sensor 55 detects the tip of the sheet, the control circuit 71 supplies a voltage to the charging roller 7K, the developing roller 9K, and the sponge roller 11K of the second printing mechanism P2, and the control circuit 71 supplies the charging power source 74K and the DB bias, respectively. Power supply 7
3K, SP bias power supply 72K is turned on. As described above, the surface of the photoconductor 6K of the second printing mechanism P2 is uniformly charged through the charging roller 7K, and the sponge roller 11K and the developing roller 9K of the printing mechanism P2 are charged to a predetermined high voltage.

Next, the control circuit 71 issues a command to the memory 79K storing the black image data, and outputs one line of black image data from the memory 79K to the print control circuit 78K of the second printing mechanism P2. Send. The print control circuit 78K of the second printing mechanism P2 changes the image data sent from the memory 79K to a form that can be sent to the LED head 3K of the second printing mechanism P2 in response to a command from the control circuit 71, and this LED Send to head 3K. LED
The head 3K uses the LE corresponding to the image data sent.
D is turned on, and an electrostatic latent image for one line corresponding to image data is formed on the surface of the charged photoconductor 6K. In this manner, the black image data sent from the memory 79K for each line is successively converted into an electrostatic latent image on the surface of the photoconductor 6K, and the black image data corresponding to the length in the sub-scanning direction is hidden. The exposure is completed after being imaged. Black toner is attached to the surface of the photoconductor 6K on which the electrostatic latent image is formed by the charged developing roller 9K. By rotating the photoconductor 6K, the electrostatic latent images are successively developed with black toner.

The recording medium S is indicated by an arrow e by the conveyor belt 20.
Transported in the direction. At this time, since the distance between the color image forming unit A and the conveyor belt 20 is L, even if the leading edge of the recording medium S is slightly raised, the photoconductor 6 of the color image forming unit A is formed.
There is no contact with Y, 6M, 6C. When the front end of the recording medium S reaches between the photoconductor 6K and the transfer roller 4K, the control circuit 71 turns on the transfer power supply 75K of the second printing mechanism P2. As a result, the toner image on the surface of the photoconductor 6K is electrically transferred onto the recording medium S by the transfer roller 4K. Due to the rotation of the photoconductor 6K, the toner images are successively transferred onto the recording medium S, and the black image for one page is transferred onto the recording medium S. As described above, the transfer of the black toner image onto the recording medium S by the second printing mechanism P2 is completed. The rear end of the recording medium S is the photoconductor 6
When it reaches between K and the transfer roller 4K, the control circuit 7
1 turns off the transfer power supply 75K, the charging power supply 74K, the SP bias power supply 72K, and the DB bias power supply 73K of the second printing mechanism P2.

The conveyor belt 20 continues to move, and then the recording medium S is sent by the conveyor belt 20 to the static eliminator 60, where the control circuit 71 turns on the static elimination power source 77 to neutralize the recording medium S. . As a result, the recording medium S is
It becomes easy to separate from the conveyor belt 20, separates from the conveyor belt 20 above the drive roller 30, and is guided to the fixing device 63 by the paper guide 62. When the recording medium S is separated from the static eliminator 60, the control circuit 71 turns off the static elimination power source 77.

In the fixing device 63, the toner image is fixed on the recording medium S by the heat roller 64 that has already reached the fixing temperature and the pressure roller 65 that is in pressure contact with the heat roller 64.
When the fixing is completed, the recording medium S is ejected to the ejection stacker 67. This ejection can be known to the control circuit 71 by the photo sensor 61 detecting the rear end of the recording medium S. When the discharge is completed, the control circuit 71 stops the motor 84 via the motor drive circuit 82.

As described above, it is possible to record an image of only black on the recording medium S fed from the paper feeding mechanism 20. Here, if the control circuit 71 determines that the image data to be recorded next is the same monochrome image, the above-described monochrome image is kept in the state shown in FIG. 4 without moving the color image forming unit A. The recording operation of is continued. The motor 85 is not driven while the above monochrome image is recorded. Therefore, each rotating body (photoreceptor or the like) in the color image forming unit A does not rotate.

It should be noted that monochrome image data can be similarly recorded on the recording medium S inserted from the manual tray 56. That is, the operator sets the recording medium S on the manual tray 56. When the control circuit 71 detects this by the photo sensor 58 through the sensor receiver driver 86, the control circuit 71 causes the cam motor 2 through the motor drive circuit 82.
5 is driven to bring the color image forming unit A to the home position shown in FIG.
Further, the motor 84 is driven to convey the conveyance roller 50 and the printing mechanism P.
2 photoconductor 6K, charging roller 7K, developing roller 9K, sponge roller 11K, transfer roller 4K, drive roller 30
The heat roller 64 of the fixing device 63 is rotated. At the same time, the control circuit 71 causes the adsorption charging power source 76
Is turned on to supply a voltage to the suction roller 54.

Since the conveying roller 50 rotates in the direction of the arrow g, the recording medium S inserted into the second registration roller 52
Thus, the recording medium S is guided and conveyed by the medium guide 53, and the leading end of the recording medium S reaches between the suction roller 54 and the conveyance belt 20. At this point, the leading edge of the recording medium S is moved by the electrostatic force between the suction roller 54 and the driven roller 31 to the conveying belt 20.
Adsorb to. Further, when the transport roller 50 rotates in the direction of arrow g, the recording medium S is transported in the direction of arrow e while being attracted to the transport belt 20, and the control circuit 71 moves the leading end of the recording medium S via the sensor receiver driver 86. It is detected by the photo sensor 55. Since the recording operation is the same as that described above, the description thereof will be omitted.

Next, the operation of recording a color image will be described. When the image data sent from the external device, that is, the host computer is received through the interface unit 80, the control circuit 71 issues an instruction to the interface unit 80 and each of the memories 79Y, 79M, 79C, and 79K. According to this instruction, the interface unit 80 decomposes the received image data signal for each color, and stores the image data for each color in the memories 79Y, 79M, 79C, 79K for each color. That is, the yellow image data is stored in the memory 79.
Y, magenta image data are stored in the memory 79M, cyan image data are stored in the memory 79C, and black image data are stored in the memory 79K. In each of the memories 79Y, 79M, 79C, 79K, image data of one color for one page printed on the recording medium S is stored.

When the control circuit 71 knows that the received image data is color image data, the control circuit 71 rotates the cam motor 25 via the motor drive circuit 82,
The color image forming unit A is moved to the second position shown in FIG. Then, the photoconductor 6 of the color image forming unit A
The cam motor 25 is stopped at the position where Y, 6M, and 6C come into contact with the conveyor belt 20. The movement from the position shown in FIG. 4 to the position shown in FIG. 1 can be controlled by the number of rotation steps of the cam motor 25.

From this state, the operation of printing the image data on the recording medium S housed in the paper feed mechanism 40 will be briefly described. The control circuit 71 drives the motor 83 via the motor drive circuit 82 to rotate the paper feed roller 46. By the rotation of the paper feed roller 46, only one recording medium S in the paper storage box 41 is sent to the guides 48 and 49, and the leading end of the recording medium S is conveyed by the transport roller 50 and the first registration roller 51.
The motor drive circuit 82 is controlled so as to convey the recording medium S slightly longer than the distance to reach. As a result, the recording medium S has the leading end of the conveyance roller 50 and the first registration roller 5
It is pressed between the rollers of No. 1 and slightly bent,
Due to this deflection, the skew of the recording medium S is corrected.

Next, the control circuit 71 controls the motor drive circuit 82.
The motor 84 and the motor 85 are driven via the photoconductors 6Y, 6M, 6C, 6K of the printing mechanisms P1, P2, the charging rollers 7Y, 7M, 7C, 7K, and the developing rollers 9Y, 9M, 9
C, 9K, sponge rollers 11Y, 11M, 11C, 1
1K, the transfer rollers 4Y, 4M, 4C, 4K, the driving roller 30, the conveying roller 50, and the heat roller 64 of the fixing device 63 are rotated. At the same time, the control circuit 7
1 turns on the attraction charging power supply 76 to supply a voltage to the attraction roller 54. Since the transport roller 50 rotates in the direction of arrow g, the recording medium S is transported by being guided by the medium guide 53 by the first registration roller 51 and the second registration roller 52, and the leading end of the recording medium S is attracted by the suction roller 54. And the conveyor belt 20. At this point, the recording medium S
The front end of is attracted to the conveyor belt 20 by the electrostatic force between the attraction roller 54 and the driven roller 31. Further, the transport roller 5
When 0 rotates in the direction of arrow g, the recording medium S is conveyed in the direction of arrow e while being sucked by the conveyor belt 20, and the control circuit 71 causes the photointerrupter 55 to move the leading end of the recording medium S through the sensor receiver driver 86. Detect. After the trailing edge of the recording medium S is ejected from the discriminating means 44 by the paper feed roller 46, the control circuit 71 stops the motor 83 via the motor drive circuit 82.

Now, returning to the description of the recording operation, when the photo interrupter 55 detects the front end of the recording medium S,
The charging rollers 7Y, 7M, 7C of the printing mechanisms P1, P2,
7K, developing rollers 9Y, 9M, 9C, 9K, and sponge rollers 11Y, 11M, 11C, 11K, the control circuit 71 controls the charging power source 74 to supply voltage.
Y, 74M, 74C, 74K, DB bias power supply 73
Y, 73M, 73C, 73K, SP bias power supply 72
Turn on Y, 72M, 72C and 72K. From the above,
Photoreceptors 6Y, 6M, 6C, 6K of each printing mechanism P1, P2
The surface is uniformly charged through the charging rollers 7Y, 7M, 7C, and 7K, and the sponge rollers 11Y, 11M, 11C, and 11K and the developing rollers 9Y, 9M, 9C, and 9K of the printing mechanisms P1 and P2 have a predetermined height. Charge to voltage.

Next, the control circuit 71 issues a command to the memory 79Y in which the yellow image data is stored and sends the yellow image data for one line from the memory 79Y to the print control circuit 78Y of the first printing mechanism P1. To do. In response to a command from the control circuit 71, the print control circuit 78Y of the first printing mechanism P1 converts the image data sent from the memory 79Y into a form that can be sent to the LED head 3Y of the first printing mechanism P1 and uses this LED. Send to head 3Y. LED
The head 3Y uses the LE corresponding to the image data sent.
D is turned on and an electrostatic latent image for one line corresponding to the image data is formed on the surface of the charged photoconductor 6Y. In this way, the yellow image data sent from the memory 79Y for each line is sequentially converted into an electrostatic latent image on the surface of the photoconductor 6Y, and the yellow image data for the length in the sub-scanning direction is latently formed. The exposure is completed after being imaged. Yellow toner is attached to the charged developing roller 9Y on the surface of the photoconductor 6Y on which the electrostatic latent image is formed. As the photoconductor 6Y rotates, the electrostatic latent images are successively developed with yellow toner.

When the front end of the recording medium S reaches between the photoconductor 6Y and the transfer roller 4Y, the control circuit 71 turns on the transfer power supply 75Y. As a result, the toner image on the surface of the photoconductor 6Y is electrically recorded on the recording medium S by the transfer roller 4Y.
Transcribed above. Due to the rotation of the photoconductor 6Y, the toner images are successively transferred onto the recording medium S, and the yellow image for one page is transferred onto the recording medium S. As a result, the transfer of the yellow toner image onto the recording medium S by the image forming unit 2Y is completed. Then, when the trailing edge of the recording medium S reaches between the photoconductor 6Y and the transfer roller 4Y, the control circuit 71
Is a transfer power supply 75Y for the image forming unit 2Y and a charging power supply 7
4Y, SP bias power source 72Y, DB bias power source 73
Turn Y off.

The transport belt 20 continues to move, the recording medium S moves from the image forming section 2Y to the image forming section 2M, and then the magenta toner image is transferred by the image forming section 2M.

The control circuit 71 issues a command to the memory 79M in which magenta image data is stored, and sends the magenta image data for one line from the memory 79M to the print control circuit 78M of the image forming section 2M. Image forming unit 2M
In response to a command from the control circuit 71, the print control circuit 78M converts the image data sent from the memory 79M into a form that can be sent to the LED head 3M of the image forming unit 2M, and sends the image data to the LED head 3M. LED head 3
M turns on the LED corresponding to the sent image data, and 1 according to the image data on the surface of the charged photoconductor 6M.
An electrostatic latent image for a line is formed. In this way, the magenta image data sent from the memory 79M for each line is converted into an electrostatic latent image on the surface of the photoconductor 6M one after another, and the magenta image data for the length in the sub-scanning direction is latent image. Exposure is completed. Hereinafter, the operation related to the transfer of magenta is the same as that of the above-mentioned yellow, and the description thereof will be omitted.

The recording medium S is further moved from the image forming section 2M to the image forming section 2C, and then the cyan toner image is transferred by the image forming section 2C. When the transfer of the cyan toner image is completed, the recording medium S is transferred to the image forming unit 2
C to the second printing mechanism P2, then the second printing mechanism P2
Transfer of the black toner image is performed. In addition,
Generally, even when a color image is recorded, black is used as black ink by undercolor removal (UCR) or the like, and thus it is not necessary to separate the black image forming portion from the conveyor belt. Recording examples that do not use black are very rare.

As described above, the toner images of the respective colors are transferred onto the recording medium S in an overlapping manner. After that, the recording medium S is sent to the static eliminator 60 by the conveyor belt 20, where the control circuit 71 turns on the static elimination power source 77 to eliminate the electric charge on the recording medium S. As a result, the recording medium S is easily separated from the conveyor belt 20, separated from the conveyor belt 20 above the driving roller 30, and guided to the fixing device 63 by the paper guide 62.
When the recording medium S leaves the static eliminator 60, the control circuit 7
1 turns off the static elimination power supply 77.

In the fixing device 63, the toner image is fixed on the recording medium S by the heat roller 64 that has already reached the fixing temperature and the pressure roller 65 that is in pressure contact with the heat roller 64.
When the fixing is completed, the recording medium S is ejected to the ejection stacker 67. This discharge can be known to the control circuit 71 by the photo interrupter 61 detecting the rear end of the recording medium S.

When the discharge is completed, the control circuit 71 stops the motor 84 and the motor 85 via the motor drive circuit 82. It should be noted that at the time when the transfer of the toner is completed in each printing mechanism, the charging power sources 74Y, 74M, 74C, 74K, SP
The bias power sources 72Y, 72M, 72C, 72K, the DB bias power sources 73Y, 73M, 73C, 73K, and the transfer power sources 75Y, 75M, 75C, 75K are turned off. As described above, a color image can be recorded on the recording medium S fed from the paper feeding mechanism 40.

Color image data can be similarly recorded on the recording medium S inserted from the manual tray 56. That is, the operator sets the recording medium S on the manual tray 56. When the control circuit 71 detects this by the photo sensor 58 through the sensor receiver driver 86, the control circuit 71 causes the cam motor 25 through the motor drive circuit 82.
When recording a color image, the color image forming unit A is brought to the position shown in FIG. Charging roller 7K, developing roller 9
K, sponge roller 11K, transfer roller 4K, photoconductors 6Y, 6M, 6C of printing mechanism P1, charging rollers 7Y, 7
M, 7C, developing rollers 9Y, 9M, 9C, sponge rollers 11Y, 11M, 11C, transfer rollers 4Y, 4M, 4
C, drive roller 30 and heat roller 6 of fixing device 63
Rotate 4 respectively. At the same time, the control circuit 71
Turns on the attraction charging power supply 76 to supply a voltage to the attraction roller 54.

Since the conveying roller 50 rotates in the direction of the arrow g, the inserted recording medium S has the second registration roller 52.
Thus, the recording medium S is guided and conveyed by the medium guide 53, and the leading end of the recording medium S reaches between the suction roller 54 and the conveyance belt 20. At this point, the leading edge of the recording medium S is moved by the electrostatic force between the suction roller 54 and the driven roller 31 to the conveying belt 20.
Adsorb to. Further, when the transport roller 50 rotates in the direction of arrow g, the recording medium S is transported in the direction of arrow e while being attracted to the transport belt 20, and the control circuit 71 moves the leading end of the recording medium S via the sensor receiver driver 86. It is detected by the photo sensor 55. Since the recording operation is the same as that described above, the description thereof will be omitted.

As described above, according to the first embodiment,
When recording only a monochrome image, the color image forming unit A is separated from the conveyor belt 20, so that wear of each photoconductor of the color image forming unit A and the conveyor belt 20 can be reduced, and the life of the apparatus can be reduced. It has the effect of extending the time.

Further, since the color image forming unit A is set in the non-operating state during monochrome image recording, unused yellow, magenta and cyan toners stored in the color image forming unit A may be mechanically damaged. In addition, it is possible to maintain good color image quality without degrading the quality when recording a color image.

In the first embodiment, the cam is used as the means for moving the color image forming unit A. However, the means is not limited to this, and a rack and a pinion are used. Is also good. Further, in the above-described embodiment, the LED head has been described as the means for writing the latent image on the photoconductor, but the present invention is not limited to this, and it is also possible to realize an apparatus using a writing means such as a laser or a liquid crystal shutter. .

Next, a color recording apparatus according to the second embodiment of the present invention will be described. FIG. 5 is a block diagram showing the color recording apparatus of the second embodiment. The color recording apparatus according to the second embodiment is configured so that the rotation speed of the photoconductor of the image forming unit and the conveyance speed of the conveyance belt can be changed.

In FIG. 5, only the differences from the first embodiment will be described. In the magenta and cyan image forming portions 2M and 2C of the first printing mechanism P1, the photoconductors 6M and 6C are provided.
In order to guide the elastic blades 18M and 18C made of rubber or the like supported by a holder (not shown) so as to contact the surface with edges and the toner scraped off by the elastic blades 18M and 18C and guided to the bottom, to a collection box (not shown) Screw conveyors 19M and 19C are provided. The other mechanical structure is similar to that of the first embodiment.

The control unit of the second embodiment has the same structure as that of the first embodiment shown in FIG. Of these, the memory will be described. Of the image data transmitted from the host computer and separated by color in the interface section 80, the yellow image data is the memory 7
9Y, magenta image data is stored in the memory 79M, cyan image data is stored in the memory 79C, and black image data is stored in the memory 79K. In the second embodiment, the memories 79Y, 79M, 79C are
The control circuit 7 counts the number of image data sent.
The count value can be transmitted to the control circuit 71 by the instruction of 1.

The motor drive circuit 82 includes a motor 83 for rotating the paper feed roller 46, a photoconductor 6K of the second printing mechanism P2, a charging roller 7K, a developing roller 9K, a sponge roller 11K, a transfer roller 4K, and a drive roller. 30, a motor 84 for rotating the transport roller 50 and the heat roller 64 of the fixing device 63, and the transfer roller 4 of the first printing mechanism P1.
Photoconductor 6 of Y, 4M, 4C, color image forming unit A
Y, 6M, 6C, charging rollers 7Y, 7M, 7C, developing rollers 9Y, 9M, 9C, sponge rollers 11Y, 11
The motor 85 that rotates the M, 11C, the drive roller 30, the transport roller 50, and the heat roller 64, and the cam motor 25 that moves the color image forming unit A in the direction of arrow b are driven.

Here, when the motor 84 is driven, the peripheral speeds of the conveyor belt 20 and the photoconductor 6K are set to 1: 1, that is, the same peripheral speed. On the other hand, the motor 85 has a first rotation speed at which the peripheral speeds of the photoconductors 6Y, 6M, and 6C are the same as the peripheral speed of the photoconductor 6K, and a second rotation speed slower than the first rotation speed. It can be switched.
Since the motor 85 is a pulse motor, the rotation speed can be easily switched by switching the number of pulses per second. This switch is
The description is omitted because it is a known technique, but it is performed by an instruction from the control circuit 71. The other configuration of the control system is the same as that of the first embodiment.

Next, the operation of the second embodiment will be described. First, when the power source of the color recording apparatus 1 (not shown) is turned on, the control circuit 71 rotates the cam motor 25 via the motor drive circuit 82 and the slit 26 a of the slit disk 26 via the sensor driver receiver 86. The cam motor 25 is stopped at the position detected by the photo sensor 27. This position is the home position of the color image forming unit A shown in FIG. Then, after performing a predetermined initial setting, the fixing driver 81 is driven to warm up the heat roller 64 in the fixing device 63 to a predetermined temperature. When the heat roller 64 reaches a predetermined temperature, the control circuit 71 then causes the motor 84 via the motor drive circuit 82.
To drive the conveyor belt 20 by rotating the driving roller 30.
Is moved in the direction of arrow e. As a result, the conveyor belt 20
Residual toner or dust adhering to the surface is scraped off by the cleaning blade 33 into the waste toner tank 34. Since the motor 85 is kept from rotating during this cleaning operation, the photoconductors 6Y, 6M, 6C of the color image forming unit A, the charging rollers 7Y, 7C are formed.
M, 7C, developing rollers 9Y, 9M, 9C and sponge rollers 11Y, 11M, 11C are not rotated. As a result, the initial setting of the color recording apparatus 1 is completed, and the image data is sent from the external device.

When the image data sent from the host computer is received via the interface section 80, the control circuit 71 causes the interface section 80 and the memories 7 to operate.
Give instructions to 9Y, 79M, 79C, 79K. According to this instruction, the interface unit 80 decomposes the received image data signal for each color, and stores the image data for each color in the memories 79Y, 79M, 79C, 79K for each color. That is, yellow image data is stored in the memory 79Y, magenta image data is stored in the memory 79M, cyan image data is stored in the memory 79C, and black image data is stored in the memory 79M.
Are stored in K. At the same time, the memory 79
Y, 79M and 79C count the number of image data sent.

Next, the operation of recording a monochrome image will be described. This operation is performed in exactly the same manner as the recording operation of a monochrome image in the first embodiment. That is, when recording a monochrome image, the rotation speed of the photoconductor 6K of the black second printing mechanism P2 and the peripheral speed of the conveyor belt 20 are made the same while the color image forming unit A is separated from the conveyor belt 20. Perform recording operation.

Next, the recording operation of the color image in the second embodiment will be described. First, the relationship between the peripheral speed ratio of the photoconductor 6 and the recording medium S and the transfer efficiency will be briefly described with reference to FIG. FIG. 6 is a graph showing the relationship between the peripheral speed ratio of the photoconductor and the recording medium and the transfer efficiency. The values shown in this graph are obtained by experiments. As is apparent from FIG. 6, when the peripheral speed ratio between the photoconductor and the recording medium is 1: 1, that is, when there is no difference in the peripheral speed between the photoconductor and the recording medium,
It can be seen that the transfer efficiency is the worst and the transfer efficiency is greatly improved only by providing the peripheral speed difference of about 5%. The peripheral speed difference has the same effect whether the photosensitive member is faster or slower.

When the control circuit 71 knows that the image data sent from the host computer is color image data, the control circuit 71 rotates the cam motor 25 via the motor drive circuit 82, and the color image forming unit A is rotated. Is moved to the position shown in FIG. As a result, the photoconductors 6Y, 6M and 6C of the color image forming unit A are transferred to the conveyor belt 2
Touch 0.

Now, according to the count value obtained by counting the number of image data in each of the memories 79Y, 79M, 79C, the control circuit 71 causes the rotation speed of the motor 85 to be the first rotation speed or the first rotation speed via the motor drive circuit 82. Switch to a second rotation speed that is slower than the rotation speed. The count value of the memory 79Y is Ny, the count value of the memory 79M is Nm, and the memory 79
When the count value of C is Nc, the second rotation speed is selected when the largest value is larger than a certain threshold Ns, and the first rotation speed is selected when it is smaller than Ns. Assuming that the total number of image data on the recording medium S for one page is Nt, for example, the threshold value Ns is Ns / Nt =
Decide as 0.08. That is, the threshold Ns is determined when the image ratio (image density) reaches 8%. In general,
When printing characters or the like, the image ratio is said to be around 5%. In addition, the information printed on one page has many characters. Therefore, when the image data has an image ratio lower than 8%, it can be determined that a large amount of character information is included.

As can be seen from FIG. 5, the magenta and cyan image forming portions 2M and 2C of the first printing mechanism P1 are designed to remove the transfer residual toner by the elastic blades 18M and 18C and to discard it. If the transfer efficiency is low when printing magenta and cyan image data having a high image ratio, the amount of waste toner also increases. Therefore, it is necessary to improve the transfer efficiency for at least magenta and cyan.
In the case of a low image ratio, since the amount of toner transferred originally is not large, even if the transfer efficiency is poor to some extent, the elastic blade 18
The amount of toner removed by M and 18C is small.
The yellow and black image forming units 2Y and 2K are
Toner is collected and reused. This will be described later.

Next, the operation of recording a color image having a low image ratio will be described. Image data counts Ny, Nm, Nc sent from the memories 79Y, 79M, 79C
If the control circuit 71 determines that the image ratio is 8% or less, the control circuit 71 stores the fact.

From this state, the operation of printing the image data of the low image ratio on the recording medium S housed in the paper feeding mechanism 40 will be briefly described. The control circuit 71 drives the motor 83 via the motor drive circuit 82 to drive the paper feed roller 4
Rotate 6. Due to the rotation of the paper feed roller 46, only one recording medium S in the paper storage box 41 is sent to the guides 48 and 49, and the leading end of the recording medium S is slightly longer than the distance to reach the transport roller 50 and the first registration roller 51. The recording medium S is conveyed. As a result, the recording medium S is in a state of being slightly bent by pressing the leading end between the transport roller 50 and the rollers of the first registration roller 51, and the skew of the recording medium S is corrected by this bending.

Next, the control circuit 71 controls the motor drive circuit 82.
The motor 84 and the motor 85 are driven via the photoconductors 6Y, 6M, 6C, 6K of the printing mechanisms P1, P2, the charging rollers 7Y, 7M, 7C, 7K, and the developing rollers 9Y, 9M, 9
C, 9K, sponge rollers 11Y, 11M, 11C, 1
1K, the transfer rollers 4Y, 4M, 4C, 4K, the driving roller 30, the conveying roller 50, and the heat roller 64 of the fixing device 63 are rotated. At this time, since the image ratio is low, the motor 85 selects the first rotation speed so that the peripheral speeds of the photoconductors 6Y, 6M, and 6C are the same as the peripheral speed of the photoconductor 6K. Therefore, in this case, the photoconductors 6Y, 6M, 6C, 6
The peripheral speed of K is the same as that of the conveyor belt 20 and the recording medium S. At the same time, the control circuit 71 turns on the attraction charging power source to supply a voltage to the attraction roller 54.

Since the conveying roller 50 rotates in the direction of arrow g, the recording medium S is conveyed by being guided by the medium guide 53 by the first registration roller 51 and the second registration roller 52, and the leading end of the recording medium S is conveyed. It reaches between the suction roller 54 and the transport belt 20. At this point, the leading edge of the recording medium S is attracted to the transport belt 20 by the electrostatic force between the attraction roller 54 and the driven roller 31. Further, the transport roller 50
When the recording medium S rotates in the direction of arrow g,
While being sucked to 0 and conveyed in the direction of arrow e, the control circuit 71 detects the front end of the recording medium S by the photo interrupter 55 via the sensor receiver driver 86.
The trailing end of the recording medium S is a sheet feeding roller 46 and a discriminating means 44.
After being output from the control circuit 71, the control circuit 71
The motor 83 is stopped via.

Now, returning to the description of the recording operation, when the photo interrupter 55 detects the front end of the recording medium S,
The charging rollers 7Y, 7M, 7C of the printing mechanisms P1, P2,
7K and developing rollers 9Y, 9M, 9C, 9K, and sponge rollers 11Y, 11M, 11C, 11K.
Y, 74M, 74C, 74K, DB bias power supply 73
Y, 73M, 73C, 73K, SP bias power supply 72
Turn on Y, 72M, 72C and 72K. From the above,
Photoreceptors 6Y, 6M, 6C, 6K of each printing mechanism P1, P2
The surface is uniformly charged through the charging rollers 7Y, 7M, 7C, and 7K, and the sponge rollers 11Y, 11M, 11C, and 11K and the developing rollers 9Y, 9M, 9C, and 9K of the printing mechanisms P1 and P2 have a predetermined height. Charge to voltage.

Next, the control circuit 71 issues a command to the memory 79Y which stores the yellow image data, and outputs the yellow image data for one line from the memory 79Y as the first image.
It is transmitted to the print control circuit 78Y of the printing mechanism P1. In response to a command from the control circuit 71, the print control circuit 78Y of the first printing mechanism P1 converts the image data sent from the memory 79Y into a form that can be sent to the LED head 3Y of the first printing mechanism P1 and uses this LED. Send to head 3Y. LE
The D head 3Y has L corresponding to the image data sent.
The ED is turned on to form an electrostatic latent image for one line according to the image data on the surface of the charged photoconductor 6Y. In this way, the yellow image data sent from the memory 79Y for each line is sequentially converted into an electrostatic latent image on the surface of the photoconductor 6Y, and the yellow image data for the length in the sub-scanning direction is latently formed. The exposure is completed after being imaged. Yellow toner is attached to the surface of the photoconductor 6Y on which the electrostatic latent image is formed by the charged developing roller 9Y. As the photoconductor 6Y rotates, the electrostatic latent images are successively developed with yellow toner.

When the leading edge of the recording medium S reaches between the photoconductor 6Y and the transfer roller 4Y, the control circuit 71 turns on the transfer power supply 75Y. As a result, the toner image on the surface of the photoconductor 6Y is electrically recorded on the recording medium S by the transfer roller 4Y.
Transcribed above. Due to the rotation of the photoconductor 6Y, the toner images are successively transferred onto the recording medium S, and the yellow image for one page is transferred onto the recording medium S. As described above, the transfer of the yellow toner image onto the recording medium S by the image forming unit 2Y is completed. The rear end of the recording medium S is the photoconductor 6
When it reaches between Y and the transfer roller 4Y, the control circuit 7
Reference numeral 1 denotes a transfer power supply 75Y for the image forming unit 2Y, a charging power supply 74Y, an SP bias power supply 72Y, and a DB bias power supply 7.
Turn off 3Y.

The image forming section 2 of the second embodiment
In Y and 2K, the developing process and the toner recovery can be performed at the same time, the toner used is a non-magnetic one-component toner, the developing roller 9 has elasticity and conductivity, and a thin layer of the non-magnetic one-component toner is used. It is in light contact with the surface of the photoconductor 6 through At the same time that the toner is attached to the exposed portion of the photoconductor 6 by the LED head 3 to develop, the untransferred residual toner attached to the unexposed portion is attracted to the surface of the developing roller 9 by a strong electric field and collected. It The collected toner is returned to the toner storage section of the developing section 8 for reuse.

The conveyor belt 20 continues to move, the recording medium S moves from the image forming section 2Y to the image forming section 2M, and then the magenta toner image is transferred by the image forming section 2M.

The control circuit 71 issues a command to the memory 79M which stores the magenta image data, and sends the magenta image data for one line from the memory 79M to the print control circuit 78M of the image forming section 2M. Image forming unit 2M
In response to a command from the control circuit 71, the print control circuit 78M converts the image data sent from the memory 79M into a form that can be sent to the LED head 3M of the image forming unit 2M, and sends the image data to the LED head 3M. LED head 3
M turns on the LED corresponding to the sent image data, and 1 according to the image data on the surface of the charged photoconductor 6M.
An electrostatic latent image for a line is formed. In this way, the magenta image data sent from the memory 79M for each line is converted into an electrostatic latent image on the surface of the photoconductor 6M one after another, and magenta image data for the length in the sub-scanning direction is latently formed. The exposure is completed after being imaged. Hereinafter, the operation related to the transfer of magenta is the same as that of the above-mentioned yellow, and the description thereof will be omitted. The recording medium S further includes image forming units 2M to 2C.
Then, the cyan toner image is transferred by the image forming unit 2C.

Photosensitive member 6 of magenta and cyan printing mechanism
Since the elastic rubbers 18M and 18C are in contact with the M and 6C, the fog toner and the transfer residual toner are generated by the elastic rubbers 18M and 18C.
It is scraped off by M and 18C. The scraped toner is dropped to the bottom of the cases 13M and 13C, and guided to a recovery box (not shown) by the screw conveyors 19M and 19C.
It will be discarded as appropriate. When the transfer of the cyan toner image is completed, the recording medium S is transferred from the image forming unit 2C to the second printing mechanism P.
Then, the second printing mechanism P2 transfers the black toner image.

As described above, the toner images of the respective colors are transferred onto the recording medium S in an overlapping manner. After that, the recording medium S is sent to the static eliminator 60 by the conveyor belt 20, where the control circuit 71 turns on the static elimination power source 77 to eliminate the electric charge on the recording medium S. As a result, the recording medium S is easily separated from the conveyor belt 20, separated from the conveyor belt 20 above the driving roller 30, and guided to the fixing device 63 by the paper guide 62.
When the recording medium S leaves the static eliminator 60, the control circuit 7
1 turns off the static elimination power supply 77.

In the fixing device 63, the toner image is fixed on the recording medium S by the heat roller 64 that has already reached the fixing temperature and the pressure roller 65 that is in pressure contact with the heat roller 64.
When the fixing is completed, the recording medium S is ejected to the ejection stacker 67. This discharge can be known to the control circuit 71 by the photo interrupter 61 detecting the rear end of the recording medium S.

When the discharge is completed, the control circuit 71 stops the motor 84 and the motor 85 via the motor drive circuit 82. It should be noted that at the time when the transfer of the toner is completed in each printing mechanism, the charging power sources 74Y, 74M, 74C, 74K, SP
Bias power sources 72Y, 72M, 72C, 72K, DB bias power sources 73Y, 73M, 73C, 73K Transfer power sources 75Y, 75M, 75C, 75K are turned off.

As described above, a color image can be recorded on the recording medium S fed from the paper feeding mechanism 40. The recording medium S inserted from the manual tray 56
Similarly, color image data can be recorded. Since this recording operation is the same as that described above, description thereof will be omitted.

Next, the recording operation when the image data has a high image ratio will be described. Memories 79Y, 79M, 79
Count number Ny, N of image data sent from C
If the control circuit 71 determines that the image ratio is 8% or higher from m and Nc, the control circuit 71 stores the fact.

From this state, the operation of printing the image data with a high image ratio on the recording medium S housed in the paper feed mechanism 40 will be briefly described. The control circuit 71 drives the motor 83 via the motor drive circuit 82 to drive the paper feed roller 4
Rotate 6. Due to the rotation of the paper feed roller 46, only one recording medium S in the paper storage box 41 is sent to the guides 48 and 49, and the leading end of the recording medium S is slightly longer than the distance to reach the transport roller 50 and the first registration roller 51. The recording medium S is conveyed. As a result, the recording medium S is slightly bent by pressing the leading end between the transport roller 50 and the first registration roller 51, and the skew of the recording medium S is corrected by this bending.

Next, the control circuit 71 controls the motor drive circuit 82.
The motor 84 and the motor 85 are driven via the photoconductors 6Y, 6M, 6C, 6K of the printing mechanisms P1, P2, the charging rollers 7Y, 7M, 7C, 7K, and the developing rollers 9Y, 9M, 9
C, 9K, sponge rollers 11Y, 11M, 11C, 1
1K, the transfer rollers 4Y, 4M, 4C, 4K, the driving roller 30, the conveying roller 50, and the heat roller 64 of the fixing device 63 are rotated. At this time, since the image data has a high image ratio, the motor 85 drives the photoconductors 6Y, 6M,
The second rotation speed at which the peripheral speed of 6C is lower than that of the photoconductor 6K is selected. Therefore, in this case, the photoconductors 6Y, 6M, 6
A speed difference occurs at the contact portion between C, the conveyor belt 20 and the recording medium S. This makes yellow,
The transfer efficiency of magenta and cyan will be improved.

The recording operation is the same as that described above, so the description thereof is omitted. However, the emission timings of the yellow, magenta, and cyan LED heads 3Y, 3M, and 3C are different. This will be described below.

When the first rotation speed is set to be 5% faster than the second rotation speed, for example, the LED heads 3 are separated by one line.
The LED head 3 sets the light emission timing times of Y, 3M, and 3C.
It is necessary to make it later than the K light emission timing time. If this is not done, the line spacing for black and color images will not match. For example, when the first rotation speed (the rotation speed of the photoconductor 6K) is made 5% faster than the second rotation speed (the rotation speeds of the photoconductors 6Y, 6M, and 6C), the angular velocity of the photoconductor 6K is ω.
Let k be the angular velocity of the photoconductors 6Y, 6M, and 6C, and
ωk = 1.05ωc. The distance of one line interval is d, the radii of the photoconductors 6Y, 6M, 6C, and 6K are the same r, and the photoconductor 6 is
Letting θ be the angle at which Y, 6M, 6C, and 6K rotate by one line (the distance on the surface of the photoconductor is d), d = rθ. When the photoconductor 6K rotates for the angle θ,
k and the photoconductors 6Y, 6M, and 6C are Tc, Tk = θ
/ Ωk and Tc = θ / ωc. From above, Tc = 1.05T
The relationship k is obtained. Therefore, the LED heads 3Y, 3
By setting the light emission timing time interval Tc of M and 3C to be 1.05 times slower than the light emission timing time interval Tk of the LED head 3K, the line intervals of the respective colors can be matched. The control of the light emission timing time interval is performed by the print control circuits 78Y, 78M, 78C and 78K. Since the recording operation is the same as that described above, the description thereof will be omitted.

According to the second embodiment, the following effects are obtained. That is, the peripheral speed of the photoconductor of the color image forming unit and the peripheral speed of the black photoconductor are controlled to be different, and when the image ratio is low, the peripheral speed of the photoconductor of the color image forming unit and that of the black photoconductor are Since the peripheral speeds are the same and the peripheral speed of the photoconductor of the color image forming unit and the peripheral speed of the black photoconductor are controlled to be different at a high image ratio, the transfer efficiency should be improved at a high image ratio. Therefore, the amount of waste toner is reduced, and the running cost of toner can be reduced. Further, when the image ratio is high, which is frequently used, the photoconductor, the conveyor belt, and the recording medium are driven at the same speed, so that the abrasion of the color image forming unit and the conveyor belt can be reduced, and the life of the apparatus can be reduced. It has the effect of extending it.

In the second embodiment, the threshold for switching the peripheral speed is set to 8% of the image ratio, but the threshold is not limited to this and can be arbitrarily selected. Further, in the second embodiment, the second rotation speed is set to the first
Although the example has been described in which the rotation speed is lower than the rotation speed, the second rotation speed may be higher than the first rotation speed.

Next, a color image recording apparatus according to the third embodiment of the present invention will be described. FIG. 7 is a configuration diagram showing a state in which the image forming units according to the third embodiment are separated. In the color image recording apparatus according to the third embodiment, the position where the color image forming unit A is separated from the conveyor belt is further provided by one step as compared with the first embodiment, and the color image forming is performed at two steps. The unit A is separated in two stages.

FIG. 7 shows a state in which the color image forming unit A is separated from the conveying belt 20, but the conveying belt 20 of each of the photoconductors 6Y, 6M and 6C of the color image forming unit A is shown.
The separation distance ΔL from is set to be smaller than the second position shown in FIG. 4, and is, for example, about 1 mm. Hereinafter, the position of the color image forming unit A shown in FIG. 7 will be referred to as the third position. The first position shown in FIG. 1 or the second position shown in FIG.
The movement of the color image forming unit A from the position 3 to the position 3 is performed by the cam motor 25 as in the first embodiment.
It is performed by That is, the color image forming unit A is positioned at the third position by rotating the cam motor 25 from the first position or the second position by a predetermined number of steps. Further, the separation distance ΔL is set to the minimum as long as the recording medium S can be conveyed by the conveying belt 20. Other configurations are the same as those of the first embodiment.

Next, the operation of the third embodiment will be described.
When the power source of the color image recording apparatus 1 is turned on, the control circuit 71 rotates the cam motor 25 in the direction of arrow Q shown in FIG. 2 via the motor drive circuit 82. The cam motor 25 is rotated by a predetermined number of steps, and the color image forming unit A moves to the position shown in FIG. That is, each of the photoconductors 6Y, 6M, and 6C of the color image forming unit A is at a position (third position) away from the conveyor belt 20 by ΔL, and this position is the home position.

After that, as in the first embodiment, a predetermined initial setting is executed and image data is received from an external device. If the received image data is monochrome image data, it is stored in the memory 79K, and if it is color image data, the memories 79Y, 79M, 79C,
It is stored at 79K. First, the operation of recording a monochrome image will be described.

When the control circuit 71 knows that the image data is monochrome image data, the control circuit 71 causes the motor drive circuit 82 to rotate the cam motor 25 and the motor 83 at the same time.
By rotating the cam motor 25 in the direction of arrow Q shown in FIG. 2, the color image forming unit A is moved to the second position shown in FIG. The amount of movement of the color image forming unit A from the third position to the second position is controlled by the number of rotation steps of the cam motor 25. Further, by rotating the motor 83, as described above, the recording medium S is fed out from the paper storage box and conveyed in the direction of the conveyance roller 50. The movement of the color image forming unit A is performed during the feeding operation of the recording medium S.

The monochrome image recording operation is performed in the same manner as in the first embodiment. During the operation of recording a monochrome image, the color image forming unit A is separated from the conveyor belt 20, and the photoconductors 6Y, 6 of the color image forming unit A are separated.
The motor 95 that rotates M and 6C is stopped. As a result, the other rotating members in the color image forming unit A, that is, the charging rollers 7Y, 7M and 7C and the developing rollers 9Y and 9 are used.
M, 9C, sponge rollers 11Y, 11M, 11C and transfer rollers 4Y, 4M, 4C also do not rotate, and the toner in the color image forming unit A is not mechanically damaged.

During the image recording operation, the control circuit 71 determines whether or not there is image data for the next page. If the image data to be recorded next is monochrome image data,
Without moving the color image forming unit A, the second
The black-and-white image is continuously recorded while keeping the position.
If the image data to be recorded next is color image data, the control circuit 71 rotates the cam motor 25 in the direction of arrow P shown in FIG. 2 to move the color image forming unit A from the second position to the third position. To move. By performing this movement, as will be described later, the recording operation of the color image can be performed without delay.

Next, a color image recording operation in the third embodiment will be described. When it is known that the image data from the host computer is color image data, the control circuit 71 causes the motor drive circuit 82 to rotate the cam motor 25 in the direction of arrow P shown in FIG. The rotation of the cam motor 25 moves the color image forming unit A from the third position to the first position. As a result, it is possible to form a color image by the first printing mechanism P1. Further, the paper feed roller 46 is rotated by the rotation of the motor 83, and the recording medium S is delivered. In this way, the color image forming unit A is moved by the recording medium S.
Is carried out during the feeding operation.

The color image recording operation is performed in the same manner as in the first embodiment. Then, when the transfer of the cyan toner image by the image forming unit 2C of the color image forming unit A is completed, the control circuit 71 rotates the cam motor 25 in the direction of arrow Q shown in FIG. The forming unit A is moved from the first position to the third position. As a result, the photoconductors 6Y, 6M, 6C of the color image forming unit A are separated from the conveyor belt 20. At the time of moving to the third position, the control circuit 71 stops the cam motor 25 and also the rotation of the motor 85. As a result, each rotating body in the color image forming unit A becomes inoperative. Then, the second printing mechanism P2 records a black image.

At the time when the recording operation of the color image is completed, the color image forming unit A is always in the third position shown in FIG. Therefore, when the image data to be recorded next is color image data, the above operation is repeated. That is, while the recording medium S is being fed, the color image forming unit A is moved from the third position to the first position to perform the recording operation. When the image data to be recorded next is monochrome image data, the color image forming unit A is moved from the third position to the second position while the recording medium S is being fed out, as described in the monochrome recording operation. Moving.

As described above, according to the third embodiment,
Before the recording operation is started, the color image forming unit A is made to stand by at the third position, that is, the position close to the conveyor belt 20, so that it is possible to record a monochrome image or a color image. The moving distance of the color image forming unit A can be minimized, and the abrasion due to the movement of the color image forming unit A can be reduced as much as possible. In particular, even when a color image is recorded, the color image forming unit A is controlled to be separated from the conveyor belt 20 at the time when the cyan image data is transferred before the recording of the black image data is completed.
The above effect becomes more remarkable.

Next, a fourth embodiment of the present invention will be described. In the color image recording apparatus according to the fourth embodiment of the present invention, the color image forming unit can be separated from the conveyor belt, and the power source for supplying the voltage to the supply destination portion of the voltage in the color image forming unit is shared. It was done. FIG. 8 is a block diagram showing the control unit of the color recording apparatus according to the fourth embodiment.

In FIG. 8, the control circuit 71 includes an SP bias power supply 72YMC for simultaneously supplying power to the sponge rollers 11Y, 11M and 11C of the image forming sections 2Y, 2M and 2C in the color image forming unit A, and an image forming section. Two
DB bias power source 73YMC for simultaneously supplying electric power to the developing rollers 9Y, 9M and 9C of Y, 2M and 2C and charging rollers 7Y, 7M and 7C of image forming sections 2Y, 2M and 2C.
A charging power source 74YMC for simultaneously supplying power is connected to. Other configurations are the same as those of the first embodiment. That is, also in the fourth embodiment, the color image forming unit A is movable between the first position shown in FIG. 1 and the second position shown in FIG. 4, and is positioned at both positions. Has become.

Next, the operation of the fourth embodiment will be described.
When the power source of the color image recording apparatus 1 is turned on, the control circuit 71 rotates the cam motor 25 in the direction of arrow Q shown in FIG. 2 via the motor drive circuit 82. The cam motor 25 is rotated by a predetermined number of steps, and the color image forming unit A moves to the position shown in FIG. That is, each of the photoconductors 6Y, 6M, and 6C of the color image forming unit A is at a position (second position) apart from the transport belt 20 by L, and this position is the home position.

Thereafter, similar to the first embodiment, a predetermined initial setting is executed and image data is received from an external device. If the received image data is monochrome image data, it is stored in the memory 79K, and if it is color image data, the memories 79Y, 79M, 79C,
It is stored at 79K. First, the operation of recording a monochrome image will be described.

During the image recording operation, the control circuit 71 determines whether or not there is image data for the next page. If the image data to be recorded next is monochrome image data,
Without moving the color image forming unit A, the second
The black-and-white image is continuously recorded while keeping the position.
If the image data to be recorded next is color image data, the control circuit 71 rotates the cam motor 25 in the direction of arrow P shown in FIG. 2 to move the color image forming unit A from the second position to the first position. To move.

Next, a color image recording operation in the fourth embodiment will be described. When it is known that the image data from the host computer is color image data, the control circuit 71 causes the motor drive circuit 82 to rotate the cam motor 25 in the direction of arrow P shown in FIG. The rotation of the cam motor 25 moves the color image forming unit A from the second position to the first position shown in FIG. As a result, it is possible to form a color image by the first printing mechanism P1. Further, the paper feed roller 46 is rotated by the rotation of the motor 83, and the recording medium S is delivered.
In this way, the movement of the color image forming unit A is performed during the feeding operation of the recording medium S.

Next, the control circuit 71 controls the motor drive circuit 82.
The motors 84 and 85 are driven via the
2 photoconductors 7Y, 7M, 7C, 7K, charging roller 7Y,
7M, 7C, 7K, developing rollers 9Y, 9M, 9C, 9
K, sponge rollers 11Y, 11M, 11C, 11K,
Transfer rollers 4Y, 4M, 4C, 4K, drive roller 30,
The transport roller 50 and the heat roller 64 of the fixing device 63 are rotated.

When the photointerrupter 55 detects the leading edge of the recording medium S that has been drawn out, the control circuit 71
Is a charging power supply 74YMC, 74K, DB bias power supply 7
3YMC, 73K, SP bias power supply 72YMC, 72
Turn on each K. As a result, each printing mechanism P1,
P2 charging rollers 7Y, 7M, 7C, 7K, developing rollers 9Y, 9M, 9C, 9K and sponge roller 11Y,
Voltages are supplied to 11M, 11C, and 11K, and the surfaces of the photoconductors 6Y, 6M, 6C, and 6K are uniformly charged,
The developing rollers 9Y, 9M, 9C and 9K and the sponge rollers 11Y, 11M, 11C and 11K are charged to a predetermined high voltage.

The color image recording operation is performed in the same manner as in the first embodiment. When the transfer of the cyan toner image by the image forming unit 2C of the color image forming unit A is completed, the control circuit 71 turns off the transfer power supply 75C and also causes the cam motor 25 to operate via the motor drive circuit 82.
The color image forming unit A is moved from the first position to the second position by rotating the color image forming unit A in the direction of arrow Q shown in FIG. As a result, the photoconductors 6Y, 6M of the color image forming unit A,
6C is separated from the conveyor belt 20. At the time of moving to the second position, the control circuit 71 stops the cam motor 25 and also the rotation of the motor 85. As a result, each rotating body in the color image forming unit A becomes inoperative.
At the same time, the control circuit 71 controls the charging power source 74YMC,
74K, DB bias power supplies 73YMC and 73K, and SP bias power supplies 72YMC and 72K are turned off. Then, the second printing mechanism P2 records a black image.

At the time when the recording operation of the color image is completed, the color image forming unit A is always in the second position shown in FIG. Therefore, when the image data to be recorded next is color image data, the above operation is repeated. That is, while the recording medium S is being fed, the color image forming unit A is moved from the second position to the first position to perform the recording operation. If the image data to be recorded next is monochrome image data, as described in the monochrome recording operation, the color image forming unit A uses the second image data.
Since it is in the position of, the recording operation is started without moving.

As described above, according to the fourth embodiment,
Since the charging power supply for supplying the voltage to the charging roller in the color image forming unit A, the bias power supply for supplying the voltage to the developing roller and the bias power supply for supplying the voltage to the sponge roller are shared, it is possible to reduce the number of kinds of power supplies. There is a unique effect that the device becomes smaller and cheaper.

Next, a fifth embodiment of the present invention will be described. The color image recording apparatus according to the fifth embodiment of the present invention is capable of separating the color image forming unit from the conveyor belt in a plurality of steps as in the third embodiment, and
The color image forming unit shares a power supply for supplying a voltage to a voltage-supplied portion. FIG. 9 shows the fifth
A perspective view showing a color image forming unit of the embodiment of
FIG. 10 is a block diagram showing the control unit of the color recording apparatus of the fifth embodiment.

In FIG. 9, a color image forming unit A
At the bottom of the frame 13 of the contact terminals 121, 1
22, 123, and 124 are fixed. The contact terminal 121 is connected to each of the charging rollers 7Y, 7M and 7C in the color image forming unit A by a wiring (not shown),
The contact terminal 122 is connected to each of the photoconductors 6Y, 6M, 6C by a wire or the like not shown. The contact terminal 123 is connected to each of the developing rollers 9Y, 9M and 9C by a wire or the like not shown, and the contact terminal 124 is connected to each of the sponge rollers 11Y, 11M and 11C by a wire or the like not shown. These contact terminals 121,
Voltage supply terminals 13 corresponding to 122, 123 and 124
1, 132, 133 and 134 are fixed to a main body frame (not shown) of the color recording apparatus 1. Voltage supply terminal 1
31 is connected to a charging power source, which will be described later, and is connected to the voltage supply terminal 13
3 is connected to the DB bias power supply described later, and the voltage supply terminal 134 is connected to the SP bias power supply described later. The voltage supply terminal 135 is connected to the ground. The contact terminals 121, 122, 123, 124 and the voltage supply terminals 131, 132, 133, 134 described above are formed of a material having conductivity and elasticity, for example, a phosphor bronze spring material.

In the fifth embodiment, the color image forming unit A is positioned at the first position shown in FIG. 1, the second position shown in FIG. 4 and the third position shown in FIG. There is. When the color image forming unit A is in the first position and the third position, the contact terminal 121 is in contact with the voltage supply terminal 131, the contact terminal 122 is in contact with the voltage supply terminal 132, and the contact terminal 123 is in the voltage supply terminal. The contact terminal 124 contacts the voltage supply terminal 134. When the color image forming unit A is in the second position, each contact terminal 121, 12
2, 123 and 124 are voltage supply terminals 131 and 1, respectively.
There is a positional relationship away from 32, 133, and 134.

In FIG. 10, the control circuit 71 includes a sponge roller 11Y, 11M, 11C, 1C for each image forming section.
To the SP bias power source 72 that supplies power to 1K, the DB bias power source 73 that supplies power to the developing rollers 9Y, 9M, 9C, and 9K of each image forming unit, and the charging rollers 7Y, 7M, 7C, and 7K of each image forming unit. Charging power supply 7 that supplies electric power
4 are connected to each other. The SP bias power supply 72 is connected to the voltage supply terminal 134 shown in FIG. 9, the DB bias power supply 73 is connected to the power supply terminal 133, and the charging power supply 74 is connected to the power supply terminal 131. Also SP
The bias power source 72 is connected to the sponge roller 11K of the black image forming portion 2K, the DB bias power source 73 is connected to the developing roller 9K of the black image forming portion 2K,
The charging power source 74 is connected to the charging roller 7K of the black image forming portion 2K.

The other structure is the same as that of the third embodiment.

Next, the operation of the fifth embodiment will be described.
When the power source of the color image recording apparatus 1 is turned on, the control circuit 71 rotates the cam motor 25 in the direction of arrow Q shown in FIG. 2 via the motor drive circuit 82. The cam motor 25 is rotated by a predetermined number of steps, and the color image forming unit A moves to the position shown in FIG. That is, each of the photoconductors 6Y, 6M, and 6C of the color image forming unit A is at a position (third position) away from the conveyor belt 20 by ΔL, and this position is the home position. At this time, the contact terminals 121, 122, 123, 124 are in contact with the voltage supply terminals 131, 132, 133, 134, respectively.

Thereafter, similar to the first embodiment, a predetermined initial setting is executed and image data is received from an external device. If the received image data is monochrome image data, it is stored in the memory 79K, and if it is color image data, the memories 79Y, 79M, 79C,
It is stored at 79K. First, the operation of recording a monochrome image will be described.

When the control circuit 71 knows that the image data is monochrome image data, the control circuit 71 causes the motor drive circuit 82 to rotate the cam motor 25 and the motor 83 at the same time.
By rotating the cam motor 25 in the direction of arrow Q shown in FIG. 2, the color image forming unit A is moved to the second position shown in FIG. The amount of movement of the color image forming unit A from the third position to the second position is controlled by the number of rotation steps of the cam motor 25. By moving to the second position,
The contact terminals 121, 122, 123, 124 are separated from the voltage supply terminals 131, 132, 133, 134, respectively. Further, by rotating the motor 83, as described above, the recording medium S is fed out from the paper storage box and conveyed in the direction of the conveyance roller 50. The movement of the color image forming unit A is performed during the feeding operation of the recording medium S.

When the front end of the recording medium S is detected by the photo sensor 55, the control circuit 71 causes the charging power source 74,
The DB bias power source 73 and the SP bias power source 72 are turned on. As a result, the photoconductor 6K of the second printing mechanism P2
Are uniformly charged by the charging roller 7K, and the developing roller 9K and the sponge roller 11K are charged to a predetermined high voltage. At this time, the charging power source 74 and the DB bias power source 7
3. Even if the SP bias power source 72 is turned on, the charging rollers 7Y, 7M and 7C of the color image forming unit A, the developing rollers 9Y, 9M and 9C, the sponge rollers 11Y and 11
No voltage is supplied to M and 11C.

The monochrome image recording operation is performed in the same manner as in the first embodiment. During the operation of recording a monochrome image, the color image forming unit A is separated from the conveyor belt 20, and the photoconductors 6Y, 6 of the color image forming unit A are separated.
The motor 95 that rotates M and 6C is stopped. As a result, the other rotating members in the color image forming unit A, that is, the charging rollers 7Y, 7M and 7C and the developing rollers 9Y and 9 are used.
M, 9C, sponge rollers 11Y, 11M, 11C and transfer rollers 4Y, 4M, 4C also do not rotate, and the toner in the color image forming unit A is not mechanically damaged.

During the image recording operation, the control circuit 71 determines whether or not there is image data for the next page. If the image data to be recorded next is monochrome image data,
Without moving the color image forming unit A, the second
The black-and-white image is continuously recorded while keeping the position.
When the image data to be recorded next is color image data, the control circuit 71 causes the charging power supply 74, the DB bias power supply 73, and the SP bias power supply 72 to be turned off.
The cam motor 25 is rotated in the direction of arrow P shown in FIG. 2 to move the color image forming unit A from the second position to the third position. By performing this movement, as will be described later, the recording operation of the color image can be performed without delay.

Next, a color image recording operation in the fifth embodiment will be described. When it is known that the image data from the host computer is color image data, the control circuit 71 causes the motor drive circuit 82 to rotate the cam motor 25 in the direction of arrow P shown in FIG. The rotation of the cam motor 25 moves the color image forming unit A from the third position to the first position. As a result, each contact terminal 121 shown in FIG.
122, 123, and 124 are voltage supply terminals 13 respectively.
1, 132, 133, 134 are contacted, and the charging rollers 7Y, 7M, 7C, the developing rollers 9Y, 9M, 9C, the sponge rollers 11Y, 11M in the color image forming unit A,
The voltage can be supplied to 11C, and the first printing mechanism P
It is possible to form a color image according to 1. Also the motor 8
The rotation of 3 rotates the paper feed roller 46, and the recording medium S is fed. In this way, the movement of the color image forming unit A is performed during the feeding operation of the recording medium S.

The color image recording operation is performed in the same manner as in the first embodiment. Then, when the transfer of the cyan toner image by the image forming unit 2C of the color image forming unit A is completed, the control circuit 71 rotates the cam motor 25 in the direction of arrow Q shown in FIG. The forming unit A is moved from the first position to the third position. As a result, the photoconductors 6Y, 6M, 6C of the color image forming unit A are separated from the conveyor belt 20. At the time of moving to the third position, the control circuit 71 stops the cam motor 25 and also the rotation of the motor 85. It depends.

When the color image forming unit A is in the third position, the contact terminals 121 and 12 shown in FIG.
2, 123 and 124 are voltage supply terminals 131 and 1, respectively.
32, 133, 134, and the second printing mechanism P
Since the black image recording operation is being performed by 2, the charging rollers 7Y, 7M and 7C, the developing rollers 9Y, 9M and 9C, the sponge rollers 11Y and 1 in the color image forming unit A are being recorded.
Although the voltage is supplied to 1M and 11C, since each rotator in the color image forming unit A is inactive,
No recording operation is performed in the color image forming unit A.

At the time when the recording operation of the color image is completed, the color image forming unit A is always in the third position shown in FIG. Therefore, when the image data to be recorded next is color image data, the above operation is repeated. That is, while the recording medium S is being fed, the color image forming unit A is moved from the third position to the first position to perform the recording operation. When the image data to be recorded next is monochrome image data, the color image forming unit A is moved from the third position to the second position while the recording medium S is being fed out, as described in the monochrome recording operation. Moving.

As described above, in the fifth embodiment, when the color image forming unit A is in the second position, the charging rollers 7Y, 7M, 7 in the color image forming unit A are arranged.
C, developing rollers 9Y, 9M, 9C, sponge roller 11
Since the voltage cannot be supplied to Y, 11M, and 11C, the charging power source 74, the DB bias power source 73, and the SP bias power source 72 can be further shared as compared with the fourth embodiment, and the device can be further downsized. Can be realized at low cost.

The present invention is not limited to the above embodiments, but various modifications can be made. For example, in each of the above embodiments, the color image forming unit is arranged on the upstream side of the black image forming unit in the transport direction of the recording medium. On the contrary, the black image forming unit forms the color image forming unit. It can also be applied to an apparatus arranged upstream of the unit.

[0137]

As described in detail above, according to the present invention, a plurality of image forming means for performing color recording is constituted by a black image forming means and another color image forming means, and another color image forming means. When a monochrome image is recorded, the image forming means of the other color is separated from the medium carrier, so that the photoreceptor of the image forming means of the other color and the medium carrier do not come into contact with each other. The life of the body and the medium carrier can be extended.

Further, in the case where the rotational speeds of the photoconductors of the plurality of image forming means are made different from the transport speed of the medium carrier according to the image ratio, when the image ratio is low, the rotational speed of the photoconductor and the transport speed of the medium carrier are changed. By making the same, the life of the photoconductor and the medium carrier can be extended.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a color recording apparatus according to a first embodiment.

FIG. 2 is a perspective view showing a color image forming unit according to the first embodiment.

FIG. 3 is a block diagram showing a control unit according to the first embodiment.

FIG. 4 is a configuration diagram illustrating a state in which the color image forming units according to the first embodiment are separated from each other.

FIG. 5 is a configuration diagram showing a color recording apparatus according to a second embodiment.

FIG. 6 is a graph showing the relationship between the peripheral speed ratio and the transfer efficiency.

FIG. 7 is a configuration diagram showing a state in which a color image forming unit according to a third embodiment is separated.

FIG. 8 is a block diagram showing a control unit according to a fourth embodiment.

FIG. 9 is a perspective view showing a color image forming unit according to a fifth embodiment.

FIG. 10 is a block diagram showing a control unit according to a fourth embodiment.

[Explanation of symbols]

 1 Color Recording Device P1 First Printing Mechanism P2 Second Printing Mechanism 2Y, 2M, 2C, 2K Image Forming Sections 6Y, 6M, 6C, 6K Photoreceptor 20 Conveying Belts 21a, 21b Camshaft 22 Eccentric Cam 25 Cam Motor Control Circuit 71A Color image forming unit S Recording medium

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shinichi Murakami 4-11-22 Shibaura, Minato-ku, Tokyo Stock data off the stock company (72) Inventor Masato Sakai 4-11-22 Shibaura, Minato-ku, Tokyo Shares Offshore company data (72) Inventor Makoto Otake 4-11-22 Shibaura, Minato-ku, Tokyo Stock data Offshore company (72) Inventor Yoshiki Okiyama ▲ Dragon ▼ 4-11-22 Shibaura, Minato-ku, Tokyo Oki Data, Inc. (72) Makoto Yabuki, 4-11-22 Shibaura, Minato-ku, Tokyo Incorporated Oki Data, Inc. (72) Shuichiro Ogata 4-11-22, Shibaura, Minato-ku, Tokyo Stock Association In the company Oki data

Claims (11)

[Claims] 1. A color image recording apparatus having a plurality of image forming means for forming an image, wherein the image formed by the image forming means is transferred to a medium conveyed by a medium carrier to record a color image. When the black image forming means forms the black image by the black image forming means and the other color image forming means, the other color image forming means can be separated from the medium carrier. A color image recording apparatus characterized in that an image forming means of another color is separated from the medium carrier. 2. The color image recording apparatus according to claim 1, wherein the image forming means for the other color is integrally separable from the medium carrier. 3. A color image recording apparatus having a plurality of image forming means for forming an image, wherein the image formed by said image forming means is transferred onto a medium carried by a medium carrier to record a color image The color image recording apparatus is characterized in that the rotational speeds of the photoconductors of the plurality of image forming means are different from the transport speed of the medium carrier. 4. The plurality of image forming means includes a black image forming means and an image forming means of another color, and the photoconductor of which the conveyance speed of the medium carrier is different is the photoconductor of the image forming means of the other color. A color image recording apparatus according to claim 3. 5. The color image recording apparatus according to claim 4, wherein the photosensitive member of the image forming unit of the other color is different from the conveyance speed of the medium carrier when the image ratio is high. 6. The image forming means of the other color is separable from the medium carrier, the image forming means of the other color is separated from the medium carrier at the time of recording a black image, and the image forming means of the other color is made different according to an image ratio at the time of recording a color image. The color image recording apparatus according to claim 4, wherein the rotational speed of the photoconductor of the color image forming means is different from the transport speed of the medium carrier. 7. The color image recording apparatus according to claim 1, wherein the other-color image forming means is inoperative during black image recording. 8. The image forming means for the other color has a plurality of rotating bodies, the plurality of rotating bodies are driven by a single driving source, and the single driving source is not driven during black image recording. The color image recording apparatus according to claim 7. 9. The image forming unit for the other color is controlled to stop at a first position separated from the medium carrier and a second position closer to the medium carrier than the first position, 2. The color image recording apparatus according to claim 1, wherein said image forming means stands by at said second position, and said other color image forming means is stopped at said first position during black image recording. 10. The color according to claim 1, wherein the image forming unit of the other color has a plurality of voltage-supplied supply units of the same type, and a power supply unit that supplies a voltage to the voltage-supplied supply units of the same type is shared. Image recording device. 11. The image forming unit of the other color and the black image forming unit have voltage-supplied supply units of the same type, and share a power supply unit that supplies a voltage to the voltage-supplied supply units of the same type. 10. The color image recording apparatus according to claim 9, wherein at the same time as the black image is recorded, the image forming means for the other color is separated so that power cannot be supplied to the voltage-supplied part of the image forming means for the other color.