JP2596395B2 - Color electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color electrophotographic apparatus used in a copying machine or a printer for obtaining a color image by exposing a plurality of photosensitive drums by an LD (laser diode) unit. The present invention relates to a color electrophotographic apparatus capable of achieving a reduction in size and an increase in recording speed.

[0002]

2. Description of the Related Art As shown in FIG. 5, in an electrophotographic apparatus which performs recording with a single color toner, a surface of a photosensitive drum 101 rotating in an A direction is charged by a precharger 102, and then,
The optical signal from the LD unit 103 is used to
1 is exposed to form an electrostatic latent image, and the electrostatic latent image is developed by a developing device 104 to form a toner image. Thereafter, the toner image is conveyed while being in contact with the photosensitive drum 101 by a conveying roller 107. The toner image is transferred to the recording medium 120 by the transfer device 105, and the recording medium 120 is heated and pressed by the fixing device 106, and the toner image is transferred to the recording medium 1.
20. Reference numeral 108 denotes a cleaner for removing toner remaining on the surface of the photosensitive drum 101 after transfer.

FIG. 6 is a perspective view showing the structure of the LD unit 103. The LD unit 103 receives an image signal from a control unit (not shown), converts the image signal into an optical signal, and emits it. A laser diode 103a;
A polygon mirror 103b that reflects an optical signal from the laser diode 103a while rotating and scans the optical signal in one direction (the direction of arrow H), and is disposed on an optical path of the optical signal reflected by the polygon mirror 103b. A set of f-θ lenses 103 for converging the signal in the vertical and horizontal directions
and a reflection mirror 103d for reflecting the optical signal transmitted through the f-θ lens 103c to the surface of the photosensitive drum 101.

In contrast to an electrophotographic apparatus that performs recording using such a single color toner, a color electrophotographic apparatus uses three color toners of yellow, magenta, and cyan (or four colors of yellow, magenta, cyan, and black). In addition, the above-described cycle of charging → exposure → development → transfer is repeated, and a three-color toner image is synthesized on a recording medium to obtain a color image.

Hereinafter, such a conventional color electrophotographic apparatus will be described with reference to the drawings. First, a color electrophotographic apparatus according to a first conventional example will be described. FIG. 7 is an explanatory view showing a color electrophotographic apparatus according to a first conventional example.

In FIG. 1, a color electrophotographic apparatus according to a first conventional example has a single photosensitive drum 1 by a developing device 200 having three color toners of yellow, magenta and cyan.
01, the three color toners are sequentially supplied, the recording medium 120 is passed through the photosensitive drum 101 three times, and charging, exposure, development, and transfer are performed for each color, and the three color toner images are transferred to the recording medium 120. It was configured to combine above.

Next, a color electrophotographic apparatus according to a second conventional example will be described. FIG. 8 is an explanatory view showing a color electrophotographic apparatus according to a second conventional example.

In FIG. 1, a color electrophotographic apparatus according to a second conventional example includes three monochromatic electrophotographic apparatuses shown in FIG. 5 arranged in parallel, and three photosensitive drums 101 of these electrophotographic apparatuses.
In this case, yellow, magenta and cyan toner images are respectively formed, and these three color toner images are sequentially transferred to the recording medium 120 and combined to obtain a color image.

A technique similar to the above-described conventional color electrophotographic apparatus is disclosed in Japanese Patent Application Laid-Open No. 58-108558.
JP-A-58-122570, JP-A-62-242
970 and JP-A-3-183551.

[0010]

However, in the above-described color photographic electronic printer according to the first conventional example, the yellow, magenta and cyan toner images are formed on the recording medium 120 by repeatedly using one photosensitive drum 101. Therefore, there is a problem that the development of each of the three color toners cannot be performed simultaneously and the recording speed is slow.

In the above-described color photographic electronic printer according to the second conventional example, since the development of yellow, magenta and cyan can be performed simultaneously, the recording speed is high.
Three Ls respectively corresponding to the three photosensitive drums 101
A D unit is required, and there is a problem that the apparatus becomes large and expensive.

[0012] These problems are described in the above-mentioned Japanese Patent Application Laid-Open No. 58-1983.
This problem cannot be solved by the color electrophotographic apparatus disclosed in JP-A-108558, JP-A-58-122570, JP-A-62-242970 and JP-A-3-183551.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a color electrophotographic apparatus capable of reducing the size of the apparatus, increasing the speed of recording, and reducing the cost.

[0014]

In order to achieve the above object, a color electrophotographic apparatus according to the present invention comprises a color electrophotographic apparatus which performs color recording with at least three color toners of yellow, magenta and cyan. In a photographic apparatus, a control unit that outputs image signals for yellow, magenta, and cyan with a time difference, a laser diode that inputs these image signals and converts them into light signals for yellow, magenta, and cyan, respectively, The laser diode has three reflecting surfaces for yellow, magenta, and cyan having different inclination angles respectively corresponding to the signals, and receives each of the light signals emitted from the laser diode while rotating the light signals. A polygon mirror that reflects signals in three directions with different angles, respectively, on the optical path of each optical signal reflected by this polygon mirror F-θ lenses for yellow, magenta, and cyan, which correspond to these f-θ lenses, and which are transmitted through the respective f-θ lenses. One LD unit composed of yellow, magenta, and cyan reflection mirrors for reflecting signals, respectively, and corresponds to each reflection mirror of the LD unit, and is exposed to each optical signal reflected from these reflection mirrors. yellow, and a photosensitive drum for magenta and cyan, further, this
Photoreceptor drums for yellow, magenta and cyan
Are arranged in a V-shape .

[0015]

According to the color electrophotographic apparatus of the present invention having the above-described structure, for example, when three color toners of yellow, magenta and cyan are used, first, the control unit supplies yellow, magenta and cyan to the laser diode. Image signals are output with a time lag, and a laser diode that inputs the image signals outputs these image signals for yellow,
The light is converted into light signals for magenta and cyan and emitted.

[0016] These optical signals are yellow polygon mirror which is rotated, by the reflecting surface for magenta and cyan, are reflected in the different three directions of angles. Each optical signal reflected by this polygon mirror is converted by three yellow, magenta, and cyan f-θ lenses.
After being converged in the vertical and horizontal directions, respectively, these f
The light is reflected by the yellow, magenta, and cyan reflecting mirrors corresponding to the -θ lens, respectively, and enters the yellow, magenta, and cyan photosensitive drums, respectively.

[0017] Thus, the photosensitive drum is exposed on the surface of the photosensitive drum, for yellow toner image for magenta and cyan are respectively formed. Thereafter, these toner images are developed with the three color toners, respectively, and these three color toner images are sequentially transferred to a recording medium and synthesized, thereby obtaining a color image.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a color electrophotographic apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a color electrophotographic apparatus according to the present embodiment. In the present embodiment, a color image is formed using three color toners of yellow, magenta and cyan.

In FIG . 1, reference numerals 10, 20, and 30 denote first, second and third photosensitive drums (yellow, magenta and cyan photosensitive drums) corresponding to three color toners of yellow, magenta and cyan. ) And these first ~
One LD unit 40 is provided above the third photosensitive drums 10, 20, 30. FIG. 2 is a perspective view showing the configuration of the LD unit 40. The LD unit 40 will be described in detail with reference to FIG.

In FIG . 2, a control unit 41 alternately outputs three image signals for yellow, magenta, and cyan corresponding to the above-described three color toners with a time difference for each line. 4 (a) to 4 (c)). This one-line image signal is formed by a combination of two types of pulses, Hi and Low, corresponding to the image information of one line of the image to be recorded.

Further, the output timings of the image signals, the paper edge sensor 51 provided on the transport path of the recording medium 50
a, 51b, and 51c (see FIG. 1) and the rotation state of the optical sensors 52a, 52b, and 52c and the polygon mirror 43 described later.

Reference numeral 42 denotes a laser diode,
It oscillates based on the yellow, magenta and cyan image signals from 1 and converts each image signal into yellow, magenta and cyan optical signals and emits them. That is, the laser diode 42 is turned ON / OFF based on the two types of pulses forming the image signal for one line described above.
It is configured to be turned off, and emits an optical signal composed of a combination of an output signal when laser light is emitted and a no-output signal when laser light is not emitted line by line.

The polygon mirror 43 has three peripheral surfaces cut at three different angles, and is configured to be rotationally driven at a constant speed by a drive unit (not shown). The three surfaces around the polygon mirror 43 are shown in FIGS.
As shown in (d), the reflecting surface 43a for yellow and the reflecting surface for magenta which are inclined by α ° (0 ° in this embodiment) with respect to a reference line in the same direction as the rotation axis. 43
b and a reflection surface 43c for cyan inclined by γ °.

As shown in FIG. 2, the polygon mirror 43 receives each optical signal emitted from the laser diode 43 on each of the reflection surfaces 43a to 43c while rotating, and outputs the yellow optical signal. 2α ° (0 °: light path for yellow), a light signal for magenta is reflected in three directions having different angles of 2β ° (light path for magenta), and a light signal for cyan is reflected in 2γ ° (light path for cyan). . The rotating polygon mirror 43 scans each of the reflected light signals on the first to third photosensitive drums 10, 20, 30 by one line in one direction (H direction).

In this embodiment, the polygon mirror 43 is used.
Are three surfaces 43a to 43c having three different inclination angles α °, β °, and γ °, but this is not particularly limited, and three color toners are used as in this embodiment. In this case, the number of reflecting surfaces is changed to three different inclination angles α °, β °,
It may be a multiple of 3, such as six faces, nine faces, twelve faces, etc. for each γ °.

In FIG . 2, 44a, 44b, 45a,
45b, 46a and 46b are three sets of f-θ lenses, and the first f-θ lenses (for yellow) 44a and 44b are in the yellow optical path, and the second f-θ lenses (for magenta) 45a and 45b is the third f- in the light path for magenta.
The θ lenses (for cyan) 46a and 46b are arranged in the optical path for cyan.

[0027] These first to third f-θ lens 44a, 4
The optical signals 4b to 46a and 46b respectively receive the optical signals reflected from the polygon mirror 43 and converge these optical signals. That is, the first to third f-θ lenses 44a,
45a and 46a converge the optical signal in the vertical direction, and the first to third f-θ lenses 44b, 45b and 46b converge the optical signal in the horizontal direction.

Further, the first to third f-theta lens 44a located on the polygon mirror 43 side, 45a, to one end of 46a, the optical sensor 52a for detecting that the optical signal is scanned one line, 52b , 52c are provided.

[0029] These optical sensors 52a, 52b, 52c
Is configured to output a detection signal to the control unit 41 when a laser beam forming the optical signal is incident. Then, the control unit 41 controls the paper edge sensors 51a, 51b, 51
After detecting that the recording medium 50 has been conveyed to the lower portion of each of the photoconductor drums 10, 20, and 30, when a detection signal is input from the optical sensors 52c, 52a, and 52b, yellow and magenta are used. And image signals for cyan and cyan.

The control unit 41 is provided with these optical sensors 52
Although the image signals for yellow, magenta, and cyan are output based on the detection signals from a to 52c, the optical signals from the laser diode 42 do not enter the optical sensors 52a to 52c. Sensors 52a-
There is a case where the detection signal is not output from 52c.

[0031] That is, the first to third photosensitive drum 10,
20 or 30 is not exposed (for example, FIG.
(When only yellow is exposed and cyan and magenta are not exposed), t2 and t3 (when yellow and magenta are exposed and cyan is not exposed), or light from the laser diode 42 When a non-output signal that does not output laser light is included in the signal, the control unit 41 outputs an appropriate image signal based on a detection signal of a rotation sensor attached to the polygon mirror 43.

In FIG . 2, 47, 48 and 49 are first,
Second and third reflection mirrors (reflection mirrors for yellow, magenta and cyan), and the first to third reflection mirrors 47 to 49 include first to third f-θ lenses 44a,
The first to third f-θ lenses 44a, 44b,
The optical signals transmitted through 46a and 46b are reflected by the first to third photosensitive drums 10, 20, and 30, respectively.

In this embodiment, the first to third photosensitive drums 10, 20, and 30 are arranged in a V-shape to reduce the size of the apparatus and to reduce the size of the first to third photosensitive drums.
Third photoconductor drums 10, 20, 30 and LD unit 40
To prevent interference between optical signals emitted from the optical signals.

Furthermore, as shown in FIG. 1, each of the first to third photosensitive drums 10, 20, 30, in a conventional manner precharger 11, 21, 31, developing device 12, 22,
32, transfer units 13, 23, 33 and cleaners 14, 2
4, 34 are provided.

[0035] Next, the operation of the color electrophotographic apparatus of this embodiment having the above construction, FIG. 1 will be described with reference to FIGS. 2 and 4. Here, FIG. 4 is a time chart showing an image signal output from the control unit 41.

In FIG . 1, when the recording medium 50 is conveyed to the first photosensitive drum 10, the paper end sensor 51a
Detects the leading end of the recording medium 50 and outputs a detection signal. This detection signal is input to the control unit 41 (not shown in FIG. 1), and the control unit 41 starts outputting the yellow image signal (t1 in FIG. 4A).

As shown in FIG . 2, the image signal for yellow output from the controller 41 is input to a laser diode 42, which converts the image signal into a light signal for yellow and emits it. . The yellow optical signal is reflected in the direction of 2α ° (0 °) by the yellow reflecting surface 43a of the rotating polygon mirror 43, and converged by the first f-θ lenses 44a and 44b.

[0038] Then, the first f-θ lens 44a, 44b
Is reflected by the first reflection mirror 47 to the first photosensitive drum 10, and is scanned in the H direction on the first photosensitive drum 10 by the rotation of the polygon mirror 43. Thereby, the first photosensitive drum 10
Are exposed.

[0039] Then, the polygon mirror 43 is rotated once, the reflection surface 43a and the laser diode 42 is opposed again, the rotation sensor not shown detects that the polygon mirror 43 is rotated once, the detection signal to the control unit 41 Is output. Then, the control unit 41 outputs an image signal for yellow on the second line based on the detection signal.

Thereafter , such an operation is repeated, and a yellow image signal is output from the control section 41 (t1 to t).
2), an electrostatic latent image is formed on the surface of the first photosensitive drum 10. Then, the yellow toner image is transferred to the recording medium 50 conveyed.

Thereafter, as shown in FIG. 1, the recording medium 50
Is transported to the second photosensitive drum 20 side, and the paper end sensor 51
When detected by b, the control unit 41 starts outputting the magenta image signal (t2 in FIG. 4B).

The optical signal for emitted magenta from the laser diode 42, the reflecting surface 43b of the polygon mirror 43
Is reflected in the direction of 2β °, passes through the second f-θ lenses 45a and 45b, and reaches the second reflection mirror 48. The second reflection mirror 48 reflects the optical signal to the second photosensitive drum 20, as shown in FIG. As a result, the first line of the second photosensitive drum 20 is exposed.

[0043] After that, the polygon mirror 43 is rotated,
When the reflection surface 43a and the laser diode 42 face each other, the rotation sensor outputs a detection signal, and the control unit 41 outputs a yellow image signal based on the detection signal.
When a yellow image signal is output from the laser diode 42, the optical sensor 52a outputs a detection signal, and the control unit 41 outputs a magenta image signal.

Thereafter , such an operation is repeated, and the image signals for yellow and magenta are alternately output from the control section 41 (t2 to t3). An electrostatic latent image is formed. Then, the magenta toner image is combined with the yellow toner image transferred to the recording medium 50.

[0045] Thereafter, as shown in FIG. 1, the recording medium 50
Is transported to the third photosensitive drum 30 side, and the paper edge sensor 51
When c is detected, the control section 41 starts outputting the image signal for cyan (t3 in FIG. 4C).

The optical signal for emitted cyan from the laser diode 42, the reflecting surface 43c of the polygon mirror 43 is to be reflected in the direction of the 2 [gamma °, the third f-theta lens 46a, passes through the 46b, third The light reaches the reflection mirror 49. The third reflection mirror 49 reflects the optical signal to the third photosensitive drum 30, as shown in FIG. Thus, the first line of the third photosensitive drum 30 is exposed.

[0047] Then, first to third f-θ lens 44a,
Optical sensors 52a to 52 provided in 44b to 46a and 46b
Based on the detection signal c, the control unit 41 outputs image signals in the order of yellow → magenta → cyan (t)
3 to t4), 10, 20, 3 on the first to third photosensitive drums
At 0, an electrostatic latent image is formed. Then, a cyan toner image is combined with the yellow and magenta toner images combined on the recording medium 50 to form a color image.

[0048] According to the color electrophotographic apparatus of the present embodiment having such a configuration, by a single LD unit 40, for yellow, the first to third photosensitive member of the three units for magenta and cyan drum 10 , 20, and 30 can be simultaneously exposed, so that the size of the apparatus can be reduced and the recording speed can be increased. Further, since only one LD unit 40 is required, the cost of the apparatus can be reduced.

[0049] Note that the color electrophotographic apparatus of the present invention is not limited to the above embodiments. In the above embodiment,
The case where recording is performed using three color toners of yellow, magenta, and cyan has been described, but this is not particularly limited, and the present invention relates to yellow, magenta, and cyan.
The present invention can also be applied to a color electrophotographic apparatus that performs recording using four color toners of cyan and black.

[0050]

As described above, according to the color electrophotographic apparatus of the present invention, a single LD unit can simultaneously expose a plurality of photosensitive drums. Speed and low cost can be achieved. In addition, the present invention relates to a plurality of photosensitive drums.
Are arranged in a V-shape to reduce the size of the device.
At the same time as making the mold, each photosensitive drum and LD unit
Also has the effect of preventing interference of each optical signal emitted from
I do.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a color electrophotographic apparatus according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an LD unit of the color electrophotographic apparatus.

3A and 3B show a polygon mirror of the LD unit, wherein FIG. 3A is a plan view and FIGS. 3B to 3D are side views.

FIGS. 4A to 4C are time charts showing image signals output from a control unit of the LD unit.

FIG. 5 is an explanatory diagram illustrating an electrophotographic apparatus using a general single-color toner.

FIG. 6 is a perspective view illustrating a configuration of an LD unit of the electrophotographic apparatus.

FIG. 7 is an explanatory view showing a color electrophotographic unit according to a first conventional example.

FIG. 8 is an explanatory view showing a color electrophotographic unit according to a second conventional example.

[Explanation of symbols]

10, 20, 30 First to third photosensitive drums 40 LD unit 41 Control unit 42 Laser diode 43 Polygon mirror 44a, 44b to 46a, 46b First to third f-θ lenses 47 to 49 First to third reflection mirror

Claims (1)

(57) [Claims] 1. A color electrophotographic apparatus for performing color recording by developing with at least three color toners of yellow, magenta and cyan, comprising: a control unit for outputting image signals for yellow, magenta and cyan with a time difference; A laser diode that receives these image signals and converts them into light signals for yellow, magenta, and cyan, respectively, and reflecting surfaces for yellow, magenta, and cyan with three different inclination angles corresponding to these light signals, respectively. A polygon mirror that receives each of the optical signals emitted from the laser diode while rotating, receives the light on these reflection surfaces, and reflects each of the optical signals in three directions having different angles, and each of the light reflected on the polygon mirror. Each of these light signals is arranged on the optical path of the signal, and each of these light signals is incident to converge the light signal. For
F-θ lenses for magenta and cyan, these f-θ
One LD unit consisting of yellow, magenta and cyan reflection mirrors corresponding to lenses and reflecting optical signals transmitted through each f-θ lens, respectively, and corresponding to each reflection mirror of this LD unit. A photoreceptor drum for yellow, magenta and cyan respectively exposed to each optical signal reflected from the reflection mirror; and further, for yellow, magenta and cyan.
A color electrophotographic apparatus, wherein photosensitive drums are arranged in a V-shape .