JPH095656A - Color electrophotographic device - Google Patents

Abstract

PURPOSE: To provide a color electrophotographic device which is miniaturized. CONSTITUTION: In order to expose three photoreceptor drums by generating laser beams corresponding to three colors of toner, three pairs of laser diodes 42a to 42c and polygon mirrors 43a to 43c are required. The three pairs of laser diodes 42a to 42C and polygon mirrors 43a to 43c are formed to be superposed lengthwise and housed in one LD unit. The polygon mirrors 43a to 43C respectively correspond to three colors of toner and three laser beams from three laser diodes 42a to 42c are reflected by corresponding polygon mirrors and reflected by reflection mirrors 47 to 49 through integrated f-θ lenses 44a to 46a and 44b and 46b, thereby exposing the photoreceptor drum.

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, and more particularly to a color electrophotographic apparatus. The present invention relates to a color electrophotographic apparatus that can be downsized and the recording speed can be increased.

[0002]

2. Description of the Related Art In an electrophotographic apparatus for recording with a single color toner, as shown in FIG. 3, the surface of a photosensitive drum 101 rotating in the A direction is charged by a pre-charger 102, and then,
The optical signal from the LD unit 103 is used to
The surface of No. 1 is exposed to form an electrostatic latent image, the electrostatic latent image is developed by the developing device 104 to form a toner image, and then the toner is conveyed by the conveying roller 107 while being in contact with the photosensitive drum 101. The toner image is transferred onto the recording medium 120 by the transfer device 105, and the recording medium 1 is transferred by the fixing device 106.
20 is heated and pressed to fix the toner image on the recording medium 120.

FIG. 4 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. The diode 103a, a polygon mirror 103b that reflects the optical signal from the laser diode 103a while rotating, and scans in one direction (direction of arrow H), and is arranged on the optical path of the optical signal reflected by the polygon mirror 103b. , A set of f-θ lens 103c for adjusting the focus of the optical signal, and this f-θ lens 1
And a reflection mirror 103d that reflects the optical signal that has passed through 03c onto the surface of the photosensitive drum 101.

In contrast to the electrophotographic apparatus for recording with such a single color toner, the color electrophotographic apparatus is
Three colors of magenta and cyan (or yellow, magenta,
The above-mentioned charging-exposure-developing-transfer cycle is repeated for each toner of cyan and black).
The toner images of these three colors are combined 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 the first conventional example will be described. FIG. 5 is a schematic view showing a color electrophotographic apparatus according to the first conventional example. In the figure, in the color electrophotographic apparatus of the first conventional example, a developing device 200 having three color toners of yellow, magenta and cyan supplies these three color toners to a single photosensitive drum 101 in order. At the same time, the recording medium 120 is passed through the photosensitive drum 101 three times to perform charging, exposure, development and transfer for each color, and the toner images of these three colors are combined on the recording medium 120.

Next, a color electrophotographic apparatus according to a second conventional example will be described. FIG. 6 is a schematic view showing a color electrophotographic apparatus according to the second conventional example. In the figure, in the color electrophotographic apparatus of the second conventional example, three monochromatic electrophotographic apparatuses shown in FIG. 3 are arranged in series, and three electrophotographic apparatus photosensitive drums 101 of yellow, magenta and cyan are respectively arranged. A toner image is formed, and these three color toner images are sequentially transferred to the recording medium 120 and combined to obtain a color image.

[0008]

However, in the color electrophotographic printer according to the above-described first conventional example, one photosensitive drum 101 is repeatedly used to form yellow, magenta, and cyan toner images on the recording medium 120. However, since the three color toners cannot be simultaneously developed, there is a problem that the recording speed is slow.

Further, in the color electrophotographic printer according to the second conventional example described above, since the yellow, magenta, and cyan developments can be performed simultaneously, the recording speed is high, but 3
Three LDs corresponding to one photosensitive drum 101
There is a problem that the unit becomes necessary, the apparatus becomes large and the cost becomes high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a color electrophotographic apparatus capable of downsizing the apparatus, increasing the recording speed, and reducing the cost.

[0011]

In order to achieve the above object, a color electrophotographic apparatus according to claim 1 is provided with a yellow,
Color recording is performed with three color toners of magenta and cyan, and the laser diode (LD) unit of the color electrophotographic apparatus has an image signal generator that outputs image signals for yellow, magenta, and cyan. , Inputting these image signals and converting them into yellow, magenta, and cyan optical signals, respectively, and three laser diodes close to each other, and rotating the mutually parallel optical signals emitted from the three laser diodes, respectively. The same-axis polygon mirror to be reflected and the optical signals of the respective optical signals reflected by the polygon mirror are respectively arranged, and these optical signals are respectively incident to focus the respective optical signals, yellow, magenta and cyan. F-connected to each other
The θ lens and the yellow, magenta, and cyan reflection mirrors corresponding to these f-θ lenses and reflecting the optical signals transmitted through the respective f-θ lenses are housed. The color electrophotographic apparatus further includes yellow, magenta, and cyan photoconductor drums corresponding to the respective reflection mirrors of the LD unit and exposed to the respective optical signals reflected from the reflection mirrors.

According to the third aspect, the reflection angles of the reflection mirrors for the respective colors are different from each other by θ1, θ2, and θ3, and the drum shafts of the photoconductor drums of the respective colors are arranged not in the same plane but in a shifted manner.

The present invention is also applicable to four color electrophotographic devices of yellow, magenta, cyan and black.

[0014]

According to the color electrophotographic apparatus of the present invention having the constitution of claim 1, for example, when toners of three colors of yellow, magenta and cyan are used, first, from the control section, the laser diode is used for yellow and magenta. And cyan image signals are output, and the three laser diodes that have input the image signals respectively convert these image signals into yellow, magenta, and cyan optical signals and emit them as parallel beams. These optical signals are reflected by the polygon mirror having the same axis. Each optical signal reflected by the polygon mirror is transmitted through three yellow, magenta, and cyan f-θ lenses for focusing, and then the yellow signals corresponding to these f-θ lenses, The light is reflected by the reflection mirrors for magenta and cyan, and is made incident on the photoconductor drums for yellow, magenta and cyan, respectively. Since the polygon mirror and the f-θ lens are not independent for each color but integrated, it is possible to reduce the size of the device and reduce the cost due to the size reduction. According to the third and fourth aspects, the miniaturization of the device is made more effective.

[0015]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing a color electrophotographic apparatus according to this embodiment. In this embodiment, a color image is formed by using three color toners of yellow, magenta and cyan. In FIG. 1, the present embodiment is yellow,
First, second and third photoconductor drums (photoconductor drums for yellow, magenta and cyan) 10, 20, 30 corresponding to three color toners of magenta and cyan, and these first to third photoconductors It is configured to include one LD unit 40 installed above the body drums 10, 20, and 30.

FIG. 2 is a perspective view showing the internal optical system of the LD unit 40. In FIG. 2, the control unit 41 supplies three image signals for yellow, magenta, and cyan corresponding to the above-described three color toners to the laser diodes 42a, 42 for yellow, magenta, and cyan, respectively.
b, 42c. The output timings of these image signals are as shown in FIG. 1, the paper edge sensors 51a, 51b and 51c provided on the conveyance path of the recording medium 50, and the first to third f-θ lenses 44a, 45a and 46a of FIG. It is determined based on the respective outputs of the optical sensors 52a, 52b, 52c fixed to.

The yellow, magenta, and cyan laser diodes 42a to 42c oscillate based on the yellow, magenta, and cyan image signals from the control unit 41, and the respective image signals for yellow and magenta. And cyan and converted into optical signals for emission. The laser diodes 42a to 42c are connected to each other, and the optical signals of the respective colors are parallel to each other.

The polygon mirrors 43a to 43c are rotationally driven at a constant speed by a driving unit (not shown). The polygon mirrors 43a to 43c include a polygon mirror 43a for yellow, a polygon mirror 43b for magenta, and
The cyan polygon mirror 43c and the cyan polygon mirror 43c are stacked in three stages on the same axis.

Such polygon mirrors 43a to 43c
Respectively receives the optical signals emitted from the laser diodes 42a to 42c while rotating and reflects the optical signals for yellow, magenta and cyan. In the present embodiment, the reflecting surfaces of the polygon mirrors 43a to 43c are illustrated as four surfaces, but this is not particularly limited, and three surfaces or more may be used. Further, the polygon mirrors 43a to 43c are integrated into one unit.
It may be one polygon mirror.

The first f-θ lens (for yellow) 44a,
44b is in the optical path for yellow, the second f-θ lenses (for magenta) 45a, 45b are in the optical path for magenta, and the third f-θ lenses (for cyan) 46a, 46b are in the optical path for cyan. Is located in. These first to third f-θ
The lenses 44a, 44b to 46a, 46b serve to respectively enter the optical signals reflected from the polygon mirrors 43a to 43c and focus the optical signals on a straight line. The f-θ lenses 44a, 45a, 46a are integrated, and the f-θ lenses 44b, 45b, 46b are also integrated. The integration is performed with an adhesive or the like.

The first to third reflecting mirrors 47 to 49 are arranged corresponding to the first to third f-θ lenses 44a, 44b to 46a and 46b, respectively, and the first to third f-θ lenses are arranged.
The optical signals transmitted through the lenses 44a, 44b to 46a, 46b are converted into first to third photoconductor drums 10, 20, 30.
Is reflected in each direction.

The bending angles θ1 to θ3 of the optical axis of the reflected light from each reflecting mirror are θ1>θ2> θ3, and θ2≈90 °.
It is. In addition, the first to third photoconductor drums 10, 20, 3
0s are arranged in a V shape. As a result, the size of the device is made smaller than that of the conventional example shown in FIG. 6, and the interference of the optical signals emitted from the first to third photosensitive drums 10, 20, 30 and the LD unit 40 is prevented. The bending angles θ1 to θ3 are determined so that the reflected light from the first to third reflecting mirrors 47, 48, 49 strikes the surface of each photosensitive drum perpendicularly. The drum axes are parallel to each other.

As shown in FIG. 1, each of the first to third photoconductor drums 10, 20, 30 has a pre-charging device 11, 21, 31, a developing device 12, 22, 32, respectively, as in the conventional case. Transfer devices 13, 23, 33 and cleaners 14, 24, 34 are provided.

Next, the operation of the color electrophotographic apparatus of this embodiment having the above structure will be described with reference to FIGS. 1 and 2. When the recording medium 50 is conveyed to the side of the first photoconductor drum 10, the paper edge sensor 51a causes the recording medium 5 to move.
The leading edge of 0 is detected and a detection signal is output. This detection signal is supplied to the control unit 41 of FIG. 2, and the control unit 41 starts outputting the image signal for yellow. The image signal for yellow output from the controller 41 is the laser diode 4
2a, and the laser diode 42a converts this image signal into an optical signal for yellow and emits it. The yellow optical signal is reflected by the rotating yellow polygon mirror 43a, and the first f-θ lens 44a,
Focused by 44b. The optical signal transmitted through the first f-θ lenses 44a and 44b is reflected by the first reflecting mirror 47 to the first photosensitive drum 10,
The rotation of the polygon mirror 43a causes the first photosensitive drum 10 to scan in parallel with the drum axis.

As a result, the surface of the first photosensitive drum 10 is exposed and an electrostatic latent image is formed. Then, the yellow toner image is transferred to the recording medium 50 conveyed.

Similarly, in FIG. 1, the recording medium 50
Is conveyed to the second photoconductor drum 20 side, the paper edge sensor 51b detects the leading end of the recording medium 50 and outputs a detection signal. This detection signal is supplied to the control unit 41, and the control unit 41 starts outputting the image signal for magenta. The magenta image signal output from the control unit 41 is supplied to the laser diode 42b, and the laser diode 42b converts the image signal into a magenta optical signal and emits it. The magenta optical signal is reflected by the rotating magenta polygon mirror 43b and focused by the second f-θ lenses 45a and 45b. The optical signal transmitted through the second f-θ lenses 45a and 45b is reflected by the second reflecting mirror 48 to the second photoconductor drum 20, and the polygon mirror 43b rotates to drum on the second photoconductor drum 20. Scanned parallel to the axis.

As a result, the surface of the second photosensitive drum 20 is exposed and an electrostatic latent image is formed. Then, the magenta toner image is transferred onto the conveyed recording medium 50.

Similarly, the surface of the third photosensitive drum 30 is exposed to form an electrostatic latent image, and the recording medium 5 is conveyed.
The cyan toner image is transferred to 0.

According to the color electrophotographic apparatus of this embodiment having such a structure, one LD unit 40 is used, and three first to third photoconductor drums 10 for yellow, magenta and cyan are used. , 20, 30 can be exposed at the same time, the size of the apparatus and the recording speed can be increased. Further, since only one LD unit 40 is required, the cost of the apparatus can be reduced.

The color electrophotographic apparatus of the present invention is not limited to the above embodiment. In the above embodiment,
The case where recording is performed with toners of three colors of yellow, magenta, and cyan has been described, but this is not particularly limited, and the present invention performs recording with toners of four colors of yellow, magenta, cyan, and black. It can also be implemented in a color electrophotographic apparatus.

[0032]

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.
It is possible to reduce the size of the device, increase the recording speed, and reduce the cost. Further, the optical signals for the three colors or the four colors emitted from the laser diode are lights parallel to each other, and the polygon mirror reflects these optical signals on the reflecting surface rotating on the same rotation axis, and the f-θ lens. Are connected to each other, the space for disposing the entire optical system is small, and the LD unit itself can be downsized.

Further, the optical axis bending angles θ1, θ2, θ3 of the reflected light from the reflection mirrors of the respective colors are different from each other, and the drum axes of the photoconductor drums of the respective colors are parallel to each other and are not on the same plane, so that they are displaced from each other. The storage space for the photosensitive drum can be reduced.

[0034]

[Brief description of drawings]

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

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

FIG. 3 is a schematic view showing a conventional electrophotographic apparatus using a general monochromatic toner.

4 is a perspective view showing an optical system of an LD unit of the electrophotographic apparatus of FIG.

FIG. 5 is a schematic view showing a color electrophotographic unit according to a first conventional example.

FIG. 6 is a schematic view showing a color electrophotographic unit according to a second conventional example.

[Explanation of symbols]

10, 20, 30 1st-3rd photoconductor drum 40 LD unit 41 Control part 42a, 42b, 42c Laser diode 43a, 43b, 43c Polygon mirror 44a, 44b-46a, 46b 1st-3rd f-theta
Lens 47-49 First-third reflecting mirror

Claims (4)

[Claims] 1. A color electrophotographic apparatus which develops with three color toners of yellow, magenta and cyan and performs color recording, and an image signal generating section for outputting image signals for yellow, magenta and cyan, respectively. Of the yellow, magenta, and cyan laser diodes that input the image signals of the above and convert them into optical signals and emit them as parallel optical signals, and the reflection surface that reflects the optical signals emitted from the laser diodes are the same. A reflecting polygon mirror that rotates on a rotation axis, and a yellow mirror, a magenta mirror, and a polygon mirror that are respectively arranged on the optical paths of the optical signals reflected by the polygon mirror and that focus the optical signals by respectively entering these optical signals. The f-θ lenses connected to each other for cyan, and the optical signals corresponding to these f-θ lenses and transmitted through each f-θ lens LD unit containing yellow, magenta, and cyan reflection mirrors for reflecting the light, and yellow corresponding to each reflection mirror of this LD unit and exposed to each optical signal reflected from these reflection mirrors. , A magenta and cyan photosensitive drum, and a color electrophotographic apparatus. 2. An image which outputs image signals for yellow, magenta, cyan and black in a color electrophotographic apparatus which develops with four color toners of yellow, magenta, cyan and black and records in color. A signal generator, a yellow, magenta, cyan, and black laser diode that inputs each image signal, converts it into an optical signal, and emits it as parallel optical signals, and the light emitted from each laser diode. A polygon mirror whose signal-reflecting surface is rotated about the same axis of rotation, and is arranged on the optical path of each optical signal reflected by this polygon mirror. Yellow that focuses each optical signal by making these optical signals incident for,
F-θ lenses connected to each other for magenta, cyan and black, and these f-θ lenses correspond to each f-θ lens.
The LD unit that accommodates the yellow, magenta, cyan, and black reflection mirrors that respectively reflect the optical signals transmitted through the θ lens, and the reflection mirrors of the LD unit correspond to and reflect from these reflection mirrors. And a photoconductor drum for yellow, magenta, cyan, and black, which is exposed to each optical signal, and a color electrophotographic apparatus. 3. The optical axis bending angles of reflected light from the reflecting mirrors for yellow, magenta, and cyan are different from each other, and the drum axes of the respective photosensitive drums are not parallel to each other and not on the same plane. The color electrophotographic apparatus according to claim 1, wherein: 4. The light turning angles of reflected light from the reflecting mirrors for yellow, magenta, cyan and black are different from each other, and the drum axes of the respective photosensitive drums are parallel to each other and on the same plane. 3. The color electrophotographic apparatus according to claim 2, wherein