JPH02135467A - Color image forming device - Google Patents

Abstract

PURPOSE:To facilitate the switching of a color mode and a black mode, to miniaturize the titled device and to reduce the cost by constituting the title device so that a unit integrating three-color developing devices and a unit which includes a black developing agent are interchangeable with each other. CONSTITUTION:A unit mounting part 40 is slid with a roll 143 provided on a main body side by a sliding part 43 and movable ring and left. The position of the unit mounting part 40 is regulated by the cam position of an eccentric cam 144 provided on the main body side. The unit mounting part 40 is provided with a first developing unit 30 and a second developing unit which is approxi mate to it in a shape both constituted along a rail 41 in such a way that they are capable of being inserted. The first developing unit 30 has developing devices 31Y, 31M and 31C provided with yellow system, magenta system and cyanogen system developing agents respectively, and the second developing unit is ar ranged in such a way that a developing device provided with the black develop ing agent is at the same position as the developing device 31M at the time of loading the first developing unit 30. Therefore, the units are mutually and readily interchanged, and the color mode and the black mode are readily switched into each other.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a color image forming apparatus using electrophotography, which is compact and capable of forming full-color images and clear black-and-white images by replacing the developing device. The present invention relates to a color image forming apparatus.

[Conventional technology]

An electrophotographic image forming apparatus that forms full-color or monochrome images includes a charger that charges a photoreceptor drum, an image exposure unit that exposes an image to the photoreceptor drum, and a developer that develops the electrostatic image on the photoreceptor drum with toner. A transfer device that transfers the toner image on the photoreceptor drum onto recording paper is disposed around the photoreceptor drum.

Among these, electrophotographic image forming devices for full color images are
Three developing units each containing yellow (Y), magenta (M), and cyan (C) toner or black (B) toner.
K) Consisting of four developing devices containing toner, for example, each of yellow (Y), magenta (M), cyan (C), or black (BK) toner is A full-color image is obtained through processes such as forming an image on a photoreceptor drum and transferring this toner image onto recording paper.

Particularly when trying to form a black image of characters or line drawings using such a full-color electrophotographic image forming apparatus, the mixing ratio of yellow, yellow (Y), magenta (M), and cyan (C) toners must be adjusted. However, it is not always in a perfect state, and the black image may be reddish or bluish, and the black image may not be clear.

Therefore, in order to obtain a clear black image, yellow (Y),
In addition to magenta (M) and cyan (C), black (BK)
), and black images can be developed with black (BK) toner instead of mixing three colors: yellow (Y), magenta (M), and cyan (C). It is being done.

However, in addition to yellow (Y), magenta (M), and cyan (C), the 4
Providing a stage developing device is very disadvantageous for making the device compact. Contrary to the fact that black images are frequently required, especially in offices, there are limits to increasing the toner capacity of a developing device containing black (BK) toner, and increasing the size of the developing device. If this is done, it will not be possible to downsize the device.

Therefore, a dedicated black and white development unit that includes a photoreceptor drum, a corona discharger for uniformly charging the surface of the photoreceptor drum, a developer, and a cleaning device was made removable from the main unit, and in place of that unit, a photoreceptor was installed. It is possible to load a color development unit that integrates a color development device with a photosensitive drum, a corona discharge device, a yellow development device, a magenta development device, and a cyan development device arranged in order in the rotational direction of the photoconductor drum, and a cleaning device. A transfer drum type image forming apparatus having the following structure is described in Japanese Patent Application Laid-Open No. 58-72159.

[Problem that the invention seeks to solve]

However, in the unit described in JP-A-58-72159, the photoreceptor drum, corona discharger, developing device, and cleaning device are integrated, so the unit that is not loaded in the main unit can be stored. A large space is required. In addition, the unit is heavy and requires effort to handle when frequently replacing the unit. Furthermore, with this unit configuration, the number of copies made by the unit dedicated to color development is approximately one-third that of the unit dedicated to black and white development, and it is necessary to replace it with a new unit dedicated to color development, but since the entire unit is replaced, However, there are problems such as increased unit cost.

[Means for solving problems]

The present invention solves the above-mentioned problems, and includes a first developing unit including a developing device having a yellow color developer, a developing device having a magenta color developer, and a developing device having a cyan color developer; This is achieved by a color image forming apparatus in which a developing device having a black developer and a second phenomenon unit including a developing device are replaceable.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a schematic configuration diagram showing an example of a color image forming apparatus of the present invention.

In the figure, II is a photosensitive drum having a photoconductor layer such as an organic semiconductor, and 12 is a photosensitive drum 1 rotating in the direction of the arrow.
This is a charger that uniformly charges the surface of 1.

A document placed on the platen glass 21 (not shown)
However, the image data of the document read by the image reading device 22 is supplied to the laser exposure device 23 after being subjected to image processing. The laser exposure device 23 irradiates the photoreceptor drum 11 with image light modulated by image data light of the original, and this image light creates an electrostatic latent on the surface of the photoreceptor drum 11 that is uniformly charged by the charger 12. An image is formed.

This electrostatic latent image is converted into a toner image on the surface of the photoreceptor drum 11 by a developer 31C, a developer 31M, and a developer 31Y provided in the first developing unit 30. Developing device 31
G is a developing device having cyan (C) color developer, developing device 31
M is a developing device having magenta (M) color developer, developing device 3
1Y is a developing device having a yellow (Y) color developer.

13 is a transfer material supply means; 14 is a transfer device that transfers the toner image formed on the photoreceptor drum 11 onto the transfer material sent by the supply means 13; and 15 is a transfer material onto which the toner image has been transferred, which is exposed to light. a separator for separating from the body drum 11;
Reference numeral 6 denotes a conveying means for sending the separated transfer material to the fixing device 17, 18 a paper discharge plate for receiving the transfer material to which the toner image has been fixed by the fixing device 17, and 19 a remainder on the photoreceptor drum 11 after the toner image has been transferred thereto. A pre-cleaning static eliminator 20 is a cleaning device that removes residual toner from the surface of the photoreceptor drum 11 to facilitate toner removal.

In this color image forming apparatus, there is an image forming body unit 10 that includes at least a photosensitive drum 11 and a cleaning device 20, and the image forming body unit 10 and the first developing unit 30 are separated and separated from each other with respect to the main body of the apparatus. It is possible to put on and take off. Note that lOa and lOb are image forming unit l
This is a guide member that guides the mounting and removal of O.

The developing devices 31G, 31M, and 31Y form a developer layer thinner than the gap between the developing sleeve and the photoreceptor drum 11 on the developing sleeve of the developing device and convey it, and the toner is caused to fly from the developer layer to be exposed to light. The development is performed under non-contact development conditions in which the toner image is adhered to the electrostatic image on the photoreceptor drum 11, and the development is performed without disturbing the toner image previously formed on the photoreceptor drum 11. This is preferable because the state can be easily switched by switching the bias voltage applied to the developing sleeve, and there is no need to move the developing device when switching.

The developing units 31C, 31M, and 31Y installed in the first developing unit 30 in a substantially parallel arrangement have substantially the same structure, as shown in FIG. 2.

However, FIG. 2 shows the developing device 31Y.

In FIG. 2, inside the developing device 31Y, a toner storage device 310, a stirring impeller 31L, a stirring impeller 312, a developing sleeve 313, a magnet roll 314, and a toner supply roller 315 are provided. A lid part 319 is provided on the top of the developing device 31Y, and covers the internal toner storage device 310, stirring impeller 3111, stirring impeller 312, developing sleeve 313, magnet roll 314, and toner replenishment roller 315 to prevent toner from being removed. Prevents scattering. Note that the gap between the developing sleeve 313 and the photosensitive drum ll is maintained by a roller (not shown) that is provided coaxially with the developing sleeve 313 and abuts against the photosensitive drum roller.

Toner T is stored at the bottom of the toner storage device 310,
The toner T is scooped up toward the upper left in FIG. 2 by rotating the wiper plate 310a clockwise.

The toner T scooped up by the wiper plate 310a is moved to the left in FIG. 2 by the rotation of the toner supply roller 315, and is supplied to the stirring impeller 311. The stirring impeller 311 stirs the magnetic carrier and the toner T together with the stirring impeller 312 . The stirring impeller 311 and the stirring impeller 312 are rotated in opposite directions, thereby increasing the conveyance distance and sufficiently stirring and mixing the magnetic carrier and toner. The two-component developer consisting of the magnetic carrier and toner T is stirred and mixed and then supplied to the developing sleeve 313. A magnet roll 314 having a fixed magnetic pole is disposed inside the developing sleeve 3, and the developing sleeve 313 and the magnet roll 314 form the above-described magnetic brush by the developer.

A thin layer of developer is formed on the surface of the developing sleeve 313 by the above-mentioned magnetic brush. Developer thin layer forming means 3 such as a magnetic cylindrical rod provided opposite to the magnetic pole of the roll 314
17 is pressed against the developing sleeve 313, the developer layer is shaped. From the surface of the thin layer of developer, the toner T flies towards the electrostatic latent image on the photoreceptor drum 11 due to the alternating current bias, develops the electrostatic latent image formed on the surface of the photoreceptor drum 11, and becomes the toner. Get the statue.

During this development, a bias voltage consisting of a direct current component and an alternating current component is applied to the developing sleeve 313, and by controlling the bias voltage as described later, variations in developing conditions between the developing devices are adjusted. I try to do that.

FIG. 3 shows a cross section of the first developing unit 30 in which developing units 31G, 31M, and 31Y are installed.
It is removable.

The first developing unit 30 is a housing having an opening on the photosensitive drum 11 side, and a guide member 39 consisting of three sets of rollers etc. is provided inside. It is guided and pressed toward the photosensitive drum 11 by an elastic member 32 provided behind the developing device and urged. A retaining portion 33 is provided on the outside of the first developing unit 30, and a retaining portion 33 is provided outside the first developing unit 30.
The first developing unit 30 is inserted along the rail 41 from the front in the drawing. Additionally, a marking portion 3 such as a protrusion is provided on the outside of the first developing unit 30.
4, and when the first developing unit 30 is installed in the unit mounting part 40, the first developing unit 30 is Detects that it is attached.

The unit mounting part 40 is provided with a sliding part 43, which is in a sliding relationship with a roller 143 provided on the main body side, and is movable from side to side in the figure. In addition, there is an eccentric cam 144 on the main body side that can swing 90 degrees.
engages with a cam guide 44 provided on the unit mounting portion 40. Therefore, the position of the unit mounting portion 40 is regulated by the cam position of the eccentric cam 144.

In the position shown in FIG. 3 in which the unit mounting portion 30 is regulated to the left, the developing devices 3IC, 31CjJ, and 31Y located inside the mounted first developing unit 30 are urged leftward by the elastic member 32. A gap suitable for the set development is formed between the photoreceptor 11 and the developing sleeve 313 of each developing device. In the operating position that enables such development, the blocking plate 145 coaxial with the eccentric cam 144 is in the position shown by the chain line, and the developing unit 30 cannot be inserted or removed.

When the eccentric cam 144 is rotated by 90 degrees, the unit mounting portion 40 moves to the right, and the developing unit 31 moves toward the photosensitive drum 11.
The developing sleeves 313 of G, 31M, and 31Y are retracted,
It becomes a non-operating position. In this non-operating position, the blocking plate 145 is also retracted, allowing the first developing unit 30 to be attached to and removed from the unit mounting portion 40.

There is a second developing unit 50 which has an external shape similar to that of the first developing unit 30 and can be attached to the unit mounting portion 40 in place of the first developing unit 30. Second developing unit 5
0 includes a developing device 518K containing black (BK) developer. The structure of the developing device 51BK is the same as that of the developing device 31 described earlier.
Since it is the same as Y, it will be omitted, but since the consumption amount of black toner is large compared to other color toners, a toner replenishing section 521 that enables toner replenishment is provided, and the toner storage device 510 is supplied with toner. Replenishment is possible.

FIG. 4 shows the second developing unit 50 mounted on the unit mounting portion 40 and set in the operating position.

A developing device 518 using black (BK) developer is located in the second developing unit 50 and guided by a guide member 59, and is pressed toward the photosensitive drum 11 by an elastic member 52 provided behind and biased. ing. The engaging portion 33 of the first developing unit 30 is located outside the second developing unit 50.
A retaining portion 53 is provided at a location corresponding to , and is adapted to be inserted into and removed from the unit mounting ffl 40 along the rail 41. Therefore, when the second developing unit 50 is mounted on the unit mounting section 40 and the eccentric cam 144 is operated to regulate the unit mounting section 40 to the left position, the developing sleeve of the developing device 518 is placed against the photoreceptor drum 11. The set development gap is maintained and development is possible. Note that the second developing unit 50 also has a marker portion 5 corresponding to the detected portion.
4 is provided, and the detection member 42 detects that the second developing unit 50 is attached. In other words, the detection member 42 detects whether the first developing unit 30 is attached by detecting the marking portion 3.1 or 54. or whether the second developing unit 50 is attached.

Further, in this example, the developing device 51BK is the first developing unit 3.
It should be arranged so that it is in the same position as the developing device 31M when it is loaded with zero, so that the mechanical or electrical connections and connections for driving the sleeve etc. and applying the bias voltage are performed in the same way as the developing device 31M. be.

However, the arrangement of the developing device 51BK in the second developing unit is not limited to this, and the developing device 3 in the first developing unit 30 is
It can also be placed in the same position as 1G or 31Y and used to share the development drive and development bias.

When the developing device 51BK is arranged at the same position as the developing device 31Y, the toner replenishing section 521 can be made large to increase the toner replenishing capacity. Further, in the case where the toner replenishing unit 521 is arranged at the same position as the developing device 31C, it is conceivable to provide the toner replenishing section 521 below the developing device 51BK and replenishing the toner using a conveying means such as a bendable spiral and a pipe.

When reading a document placed on the platen glass 21 with the image reading device 22, the colors may be separated through a filter and read using a COD, or the original may be read using a color image sensor without using a filter, etc. is available. This will be explained below using an example using a filter. As shown in FIG. 5, the filter 9 includes filters 9R,
Consisting of filter 9G, filter 9B, and filter 9ND, when reading a document, filter 9
R, filter 9G filter 9B, filter 9ND
Reading is performed after passing through one of the following. Filter 9R, Filter 9G, Filter 9
The selection of filter B and filter 9ND is achieved by moving filter 9 in the left-right direction in FIG. 5 (in the direction perpendicular to the plane of the paper in FIG. 1) using filter selection device #22a, which will be described later. Note that the filter 9R filter 9G filter 9B is a filter that allows red light, green light, and blue light to pass through, respectively, and the filter 9ND is a neutral filter that matches human vision and allows all three color lights to pass through.

When the first developing unit 30 is attached to the unit mounting section 40, the detection member 42 detects this, and the control circuit shown in FIG. 6 inputs the discrimination signal obtained through the developing unit discrimination circuit 60 to the CPU 61. Ru. In the first developing unit 30, developing devices 31C, 31M, and 31Y containing cyan (C), magenta (M), and yellow (Y) toner are arranged at predetermined positions. Yellow (Y) every 3 rotations.

Magenta (M) and cyan (C) toner images are sequentially formed on the latent image portion formed by the image light irradiated onto the photoreceptor drum 11 from the laser exposure device ff4.

The toner image formed in this manner is transferred by a transfer device 14 onto recording paper (not shown) supplied from a paper feeding device 13. The transferred toner image is heated and fixed in a fixing device 17, and after being fixed, it is discharged outside the machine.

In developing with each toner, the filter 9 is selected in accordance with the developing device to be operated.

That is, in FIG. 6, the determination result of the developing unit determination circuit 60 from the detection member 42 is supplied to the CPU 61. In FIG. C
Upon receiving this determination result, the PU 61 issues a command to the image reading device 22 and the prohibition mode setting circuit 67.

A command is issued to the image reading device 22 as follows.

That is, the filter 9R is used to develop the developing device 31G with cyan (C) toner, the filter 9G is used to develop the developing device 31M with magenta (M) toner, and the filter 9G is used to develop the developing device 31Y with yellow (Y) toner. A command is issued for the filter 9B to respond, and filter settings are made by the filter selection circuit 22a.

Further, when the second developing unit 50 is installed in the unit mounting section 40, the detection member 42 detects this, and the determination signal obtained through the developing unit determination circuit 60 is input to the CPU 61. Since the second developing unit 50 is provided with a developing device 51BK containing black (BK) toner, a monochrome image is developed. When the CPU 61 receives a determination signal indicating that the second developing unit 50 is attached, it issues a command to the image reading device 22 to select the green filter 9G or 9ND.

The green filter has spectral characteristics close to human visual perception and can be used in place of filter 9ND. In this case, it is not necessary to provide the filter 9ND.

For the prohibition mode setting circuit 67, the developing unit 30
Or, when 50 cents are spent, it is indicated that one of the image forming modes described below is disabled, and in the prohibited mode, devices such as the image reading device 22, photoreceptor 11, laser exposure device 23, and developing device do not operate. Outputs a setting signal to do so.

When the first developing unit 30 and the second developing unit 50 are replaced, the image forming mode is also changed as shown below.

(a) When the first developing unit 30 is installed Color mode (Y, M, C) Available single color mode (B, G, R) Available single color mode (Y, M, C) Available single color Color mode (BK) Available (b) When the second developing unit 50 is installed Color mode (y, M,
c) Unavailable single color mode (B, G,
R) Unusable single color mode (Y, M, C
) Unavailable single color mode (BK)
The color modes (Y, M, C) that can be used are developer 31G.

This is a mode in which a color toner image is formed using the developing device 31M1 and the developing device 31Y.
, G, R) means that the developing device 31C1 is used for the same latent image.
This is a mode in which toner of any two colors in the developer 31M or 31Y is superimposed to form a single color. In addition, the monochrome color mode (BK) is used to form a monochrome color (black) by superimposing three colors of toner in the developer 31C, developer 31M, and developer 31Y on the same latent image, and Single color (black) using 518K
Say both sides when forming. Furthermore, the monochromatic color mode (Y, M, C) refers to a mode in which a monochromatic color is formed using toner of any one color of the developing device 31G, the developing device 31M, and the developing device 31Y. Further, the developing bias is controlled by a developing bias control circuit (FIG. 6) in accordance with the image forming mode.

Of course, when the first developing unit 30 is attached, the image is developed in the color mode (Y, M, C), and when the second developing unit 50 is attached, the image is developed in the monochromatic color mode (BK). It is also possible to control the decision so that there is no choice.

Although filter switching control based on mode settings has been described above, process control can also be switched at the same time. In a mode that forms an image consisting of a two-color image depending on the mode setting, the photoreceptor drum rotates twice, during which it is charged and
After the process of image exposure and development is performed for each rotation, the process is controlled so that the image is transferred to the recording paper in the second rotation, and the surface of the photoreceptor after the transfer is cleaned. In addition, in a mode that forms an image consisting of a single color image depending on the mode setting, charging, image exposure, and development are performed during one rotation of the photoreceptor drum, and then the image is transferred to the recording paper, and the photoreceptor drum that has completed the transfer is transferred to the recording paper. Control is provided to ensure that the surface is cleaned.

This embodiment shows an example in which a toner image is completely formed on the surface of a photoreceptor drum without using a transfer drum and then transferred to recording paper. The device can be downsized. Further, there is no need for a complicated groove that separates the transfer drum from the photosensitive drum when the photosensitive drum is inserted or removed.

〔Effect of the invention〕

The color image forming apparatus according to the present invention can easily switch between a color copy mode and a black copy mode by replacing a unit that integrates color developing devices for three colors with a unit that includes a black developer. . Furthermore, since the units can be easily exchanged, when the developer is consumed, it is possible to cope with the problem by replacing the units.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing an embodiment of a color image forming apparatus according to the present invention, FIG. 2 is a schematic front view showing a developing device of the color image forming apparatus according to the present invention, and FIG. 3 is a schematic front view showing a first developing unit. FIG. 4 is a schematic front view of the second developing unit installed and in operation; FIG. 4 is a schematic front view of the second developing unit installed and in operation;
FIG. 5 is a front view showing a filter used for color separation in the color image forming apparatus shown in FIG. 1, and FIG.
FIG. 2 is a block diagram showing a control circuit of the color image forming apparatus shown in the figure. 901. Filter IO... Image forming unit 11... Photosensitive drum 12... Charger 13... Supply means (transfer material) 14... Transfer device 15...
... Separator 16 ... Conveyance means (transfer material) 17 ... Fixing device 18 ... Paper discharge tray 1
9... Pre-cleaning static eliminator 20... Cleaning device 21... Platen glass 22... Image reading device 23... Laser exposure device 30... First developing unit 31Y, 31M,
31C...Developer 34...Marker section 4
0... Unit mounting part 42... Detection member
50...Second developing unit 518K...Developing device
54...Applicant for the sign section Konica Co., Ltd. Figure 2 Figure 3

Claims (1)

[Scope of Claims] A first developing unit including a developing device having a yellow color developer, a developing device having a magenta color developer, and a developing device having a cyan color developer; a developing device having a black developer. A color image forming apparatus having a second developing unit that is replaceable.