JPS63170671A - Color image forming device - Google Patents

Abstract

PURPOSE:To obtain a color image forming device convenient for handling, in which it does not take labor comparatively for attaching and detaching all developing devices, and that which is attached and detached is comparatively small in size and light in weight, by constituting the titled device so that two adjacent pieces of one pair and two pairs when the number of developing devices is three pieces, and when said number is four pieces, respectively are stored in one case and attachable and detachable with the case. CONSTITUTION:In case of installing a developing device 23, etc. to a case 32, when the developing device 23, etc. are inserted into the case 32 by retreating a set pin 33 provided on the case 32, from a state projected to the inside, and the set pin 33 is projected to the inside by pushing in a compression spring 34, the push by the compression spring 34 is stopped by the set pin 33 and the developing device 23, etc. are set to the case 32. In case of taking out the developing device 23, etc. from the case 32, when the set pin 33 is retreated, the developing device 23, etc. are extruded to an opening part of the case 32 by the compression spring 34, therefore, the developing device 23, etc. can be drawn out. In such a way, the developing devices 23, 24 and 25, 26 are attached and detached to and from an image forming device together with the case 32, respectively, therefore, at the time of inspection and maintenance, etc., the developing device can be attached and detached without taking much labor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image forming apparatus, and in particular, to a color image forming apparatus that includes three to four removable developing units and electrostatic image forming means around a photoreceptor drum. (1) Apparatus for forming a color image on a photoreceptor drum by combining toner images. .

[Cost of invention]

In the conventional color image forming apparatus as described above, the developing units are individually removable, and there is a problem in that it is very time-consuming to attach and detach all the developing units for inspection, maintenance, etc. In order to create a color image forming apparatus that solves this problem, the present inventors have previously developed a system in which all of the plurality of developing units are housed in one case in an apparatus that has one electrostatic image forming means, and the entire case can be attached and detached. invented something. However, when the number of developing devices increases to three or four, the case becomes large and heavy, which not only makes it inconvenient to attach and detach, but also tends to reduce the accuracy of setting the developing devices. On the other hand, in an apparatus having a plurality of electrostatic image forming means,
Since the distance between the developing devices is large, the above-mentioned problem becomes even more serious if the developing devices are housed in one case and the entire case is detachable.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and the first object of the present invention is to make it relatively easy to attach and detach all the developing devices, and to make the devices that are attached and detached relatively small and lightweight. A second object of the present invention is to provide a color image forming apparatus that is convenient to handle, and a second object is to provide a color image forming apparatus that can form color images in a relatively short time.

[Structure of the invention]

In the present invention, three to four removable developing devices and an electrostatic image forming means are arranged around a photoreceptor drum, and an electrostatic image formed on the photoreceptor drum by the electrostatic image forming means is developed. (1) In a device that forms a color image by combining toner images on a photoreceptor drum, one set if there are three developing units, and two sets if there are four developing units. The color image forming apparatus is characterized in that two adjacent pieces of the electrostatic image forming means are housed in one case, and the case can be attached and removed. Since the electrostatic image can be formed at two locations, one upstream of the developing device and the other in the middle of the developing device, the second object can also be achieved.

〔Example〕

The present invention will be explained below using illustrated examples.

FIG. 1 is a schematic side view showing an example of the color image forming apparatus of the present invention, FIG. 2 is a partial view showing an example of a developing device storage case, and FIG. 3 is a partial view showing an example of the developing device.

In FIG. 1, A is a reading unit, B is a writing unit, C is an image forming section, D is a paper feeding section, and E is a fixing section.

The reading unit A scans and exposes a document 2 placed on a platen glass 1 using a scanning optical system consisting of an illumination lamp 4 that moves along a slide rail 3, a first mirror 5, and a mirror 6 that moves at a speed of Then, the reflected light from the original 2 is focused by a lens 7 and incident on a prism 8, and the prism 8 causes the light to be incident on charge-coupled devices (COD) 9 to 11 for each wavelength, such as blue, green, and red. do. As a result, the blue, green, and red image signals outputted by C0D9-11 are outputted to the writing unit B in a signal processing section (not shown) as yellow and magenta.

Processed into signals for cyan and black toner colors. It is preferable to use a commercially available warm white fluorescent lamp as the illumination lamp 4 to prevent emphasis or attenuation of specific colors as it is used as a light source when reading the color image of the document 2, and to prevent flickering. It is preferable that the tube be turned on by a high frequency power source of 40 kHz and kept warm by a heater using a resistor in order to maintain the tube's low temperature or promote warm-up. The scanning optical system is configured to expose the standard white plates 12 and 13 before and after scanning and exposing the original 2. The information output by the C0Ds 9 to 11 based on the reflected light from the standard white plate 12゜13 is used to set the developing bias and perform signal processing in the signal processing section in order to prevent fogging and adjust color balance. used in

The writing unit B has a configuration as described in Japanese Patent Application Laid-open No. 56-161566 and Japanese Patent Application Laid-Open No. 57-19764, in which a motor 14 rotates laser beams output from two semiconductor lasers. The reflected light incident on the polygon mirror 15 and scanned by it is f
After passing through the -θ lens 16, each laser beam enters the photosensitive drum 21 at different positions via a cylindrical lens 17 for scanning line correction and a mirror 18 or mirrors 19 and 20. When the laser beams outputted by the two semiconductor lasers start scanning with the polygon mirror 15, the beams are detected by the index sensor, so that the laser beams output by the two semiconductor lasers are detected by the index sensor. Modulation using the yellow image signal or magenta image signal and black image signal is started. This modulation is
After the start of modulation by the cyan image signal or magenta image signal of one laser beam, the yellow image signal or black image of the other laser beam is delayed by the time required for the photoreceptor drum 21 to pass between the incident positions of both laser beams. The start of modulation by the signal is performed, and the start of modulation of one laser beam by the cyan image signal or the start of the modulation of the other laser beam by the yellow image signal is delayed by the time required for one rotation of the photoreceptor drum 21, and then one of the laser beams is modulated by the yellow image signal. The timing is shifted so that modulation of the laser beam by the magenta image signal or modulation of the other laser beam by the black image signal is started.

In the image forming section C, the photoreceptor drum 21 rotates at a constant speed in the direction of the arrow before the laser beam is incident from the writing unit B, and a charger 22 consisting of a scorotron corona discharger charges the photoreceptor drum 21. The surface is uniformly charged, and a scanned laser beam modulated with, for example, a cyan image signal is incident on the charged surface. As a result, an electrostatic image is formed on the surface of the photoreceptor drum 21, and the electrostatic image is reversely developed into a cyan toner image by a developing device 23 using cyan toner as a developer. A charger 27 consisting of a scorotron corona discharger uniformly charges the surface on which the toner image has been formed, and a scanned laser beam modulated with a yellow image signal is incident on the charged surface to form an electrostatic image again. is formed. This electrostatic image is reversely developed by a developing device 25 using yellow toner as a developer, thereby forming a two-color image consisting of a combination of a cyan toner image and a yellow toner image on the surface of the photoreceptor drum 21. . The transfer device 281 and the separator 29, in which this two-color imaged surface is placed in an inactive state. Static eliminator 30. After passing through the cleaning device 31 and reaching the charger 22, the charger 22 uniformly charges its surface again, and a scanned laser beam modulated with a magenta image signal is incident on the charged surface. Ru. The electrostatic image thus formed is reversely developed by a developing device 24 using magenta toner as a developer, thereby forming a three-color image consisting of a combination of cyan, yellow, and magenta toner images on the surface of the photoreceptor drum 21. is formed. The charger 27 uniformly charges the surface on which the three-color image is formed again, and a laser beam modulated with a black image signal and scanned is incident on the charged surface. The electrostatic image thus formed is reversely developed by a developing device 26 using black toner as a developer, thereby cyan and yellow are formed on the surface of the photoreceptor drum 21.

A color image with excellent contrast is formed by combining magenta and black toner images. This color image is transferred to the recording paper P fed from the paper feed section by the transfer device 28, the transferred recording paper P is separated from the surface of the photoreceptor drum 21 by the separator 29, and the color image is transferred to the fixing section E. The image is fixed and ejected from the machine. The surface of the photosensitive drum 21 on which the color image has been transferred is made easy to remove residual toner by the static eliminator 30, and the residual toner is removed by the cleaning device 3, and the next image forming process is repeated. Return to

That is, according to this image forming apparatus, four colors or three colors can be used.
A color image consisting of a combination of colored toner images can be formed by two rotations of the photoreceptor drum 21, and a color image consisting of a combination of toner images of not only a single color but also two colors can be formed in one rotation.

The developing units 23, 24, 25, and 26 in this image forming apparatus are housed in a case 32 and arranged around the photosensitive drum 21, respectively, as shown in detail in FIG. This point will be explained with reference to FIG.

The developing units 23 and 24 or 25 and 26 are installed in the case 32 when the case 32 is removed from the image forming apparatus.
It is attached to and detached from the case 32 through the left opening in FIG. That is, when attaching the developing device 23 etc. to the case 32, the set pin 33 provided in the case 32 is moved back from the inward protruding state, the developing device 23 etc. is inserted into the case 32, and the set pin 33 provided in the case 32 is inserted into the case 32. The set bin 33 is made to protrude inward by pushing in the compression spring 34 until it is sufficiently compressed. As a result, the developing device 23 and the like are stopped from being pushed by the compression spring 34 by the cent bin 33, and are cented in the case 32. The developing device 23 and the like are secured to the set bin 33 at the tip of the position adjustment screw 35, whereby the developing device 23 and the like are secured to the set bin 33.
etc. The cent position can be adjusted. When taking out the developing device 23 etc. from the case 32, if the set pin 33 is moved back, the developing device 23 etc. will be pushed out to the opening of the case 32 by the compression spring 34. Good, but not limited to, for example,
By simply inserting the developing device 23 etc. into the case 32 and attaching the case 32 to the main body of the apparatus as described later, the developing device 2
A rotatable spacer roller coaxial with a third developing roller or the like may be placed in contact with both peripheral surfaces of the photosensitive drum 21 to set the position of the developing device 23 or the like.

The case 32 with the developing unit 23 and the like mounted thereon is viewed from the front side of the paper surface of the figure, with the rack 36 of the case 32 meshing with a pinion 37 provided on the apparatus main body side, and the spring hook of the case 32 being inserted into the hole 38 on the apparatus main body side. The provided tension spring 39 is inserted into the device so that the distal end hook portion is inserted therein. Then, the inserted case 32 rotates the pinion 37 and the tension spring 3
Stop pin 40 provided on the device main body side to resist the tensile force of 9
At that stage, the set hook 42 provided on the shaft 41 on the apparatus main body side engages with the set hole 44 of the case 32 under the bias of the spring 43, thereby setting it in the image forming apparatus. . The reason for taking out the case 32 from the image forming apparatus is that when the shaft 41 is rotated and the set hook 42 is removed from the set hole 44 of the case 32, the case 32 is moved back to the right by the tensile force of the tension spring 39. Alternatively, the case 32 may be further pulled out from the position where it has been retreated to the right by the pinion 37 toward the front in the drawing. In addition, when attaching and detaching the case 32, the case 32 is fixed to the guide 45 and the shaft 41 to receive the device main body side. The case 32 in FIG. 2 also includes a motor 4 for driving movable members such as a developing roller and a developer stirring roller of the developing device 23 and the like that are housed therein.
6.47 and a transmission mechanism (not shown),
This eliminates the need for a motion transmission mechanism to be connected between the case 32 and the device main body.

As described above, by attaching and detaching the developing units 23, 24 and 25, 26 to and from the image forming apparatus together with the case 32, it is possible to efficiently attach and detach the developing units for inspection, maintenance, and the like.

The developing units 23 to 26 are non-operating devices that do not damage the toner images that have already been formed and can be easily switched between a developing state and an inactive state by stopping the rotation of the developing roller or switching the bias voltage. It is preferable to develop under contact development conditions; the developing device shown in FIG. 3 is an example of this;
8 and a magnet 49 inside the developing roller attracts the developer in the developer reservoir 50 to the surface of the sleeve 48 by the magnetic force of the magnet 49, and at least one of the sleeve 4 and the magnet 49 rotates in the direction of the arrow. As a result, the adsorbed developer is conveyed in the same direction as the rotating direction of the sleeve 48, and during the conveyance, a layer thickness regulating blade 51 made of a urethane rubber plate adjusts the layer thickness of the developer between the photoreceptor drum 21 and the sleeve 48.
The sleeve 48 is formed on the photoreceptor drum 21 by forming a layer thinner than the gap, and applying a developing bias voltage in which an AC voltage and a DC voltage are superimposed from a bias power source including an AC power source 52 and a DC power source 53 to the sleeve 48 . In the opposing development area, toner flies from the developer layer and adheres to the electrostatic image, thereby performing development. The developer layer that has passed through the development area is scraped off from the surface of the sleeve 48 by a cleaning blade 54 using a Mylar plate with a thickness of 80 μm and returned to a developer reservoir 50. The developer reservoir 50 is supplied with toner from the toner chamber 55 by a toner replenisher 56 and a sponge roller 57.
The developer is uniformly stirred by stirring rollers 58 and 59, and the toner is triboelectrically charged.

Note that the developing device can be brought into an inoperative state by grounding or floating the sleeve 48, or by actively applying a DC voltage of opposite polarity to the charging of the toner to the sleeve 48, or by turning the developing roller into a non-operating state. This is done by stopping the transport rotation, etc. When this developing device is attached to the case 32, the wiring of the sleeve 48 and the case 32 are connected to each other.
The wiring of the case 32 is connected with a connector, and the connection between the wiring of the case 32 and the bias source on the device main body is connected to the motor 46.47.
Connection to the power supply is made by a socket provided on the cord.

The color image forming apparatus of the present invention is not limited to the above-mentioned example, and even when the image exposure onto the photoreceptor drum is performed by a slit exposure device, there are three developing devices, and the upstream or downstream developing device is conventional. It may also be one that can be attached and detached independently like the above. Examples of images in which image exposure is performed by a slit exposure device include JP-A-61-63856 and JP-A-61-652.
62, the photoreceptor drum is equipped with a color separation function, and a primary latent image including a latent image of each color separation is formed by -times of image exposure, and the -second latent image is formed. Preferably, the surface is uniformly exposed to specific light to draw out a color-separated electrostatic image.

〔Effect of the invention〕

In the color image forming apparatus of the present invention, it is relatively easy to attach and detach all the developing units for inspection, maintenance, etc., and since the units that are attached and detached are small and lightweight, they are convenient to handle. This has the effect that it is easy to maintain the positional accuracy of the device, and also has the effect that color images can be formed in a relatively short time.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing an example of the color image forming apparatus of the present invention, FIG. 2 is a partial view showing an example of a developing device storage case, and FIG. 3 is a partial view showing an example of the developing device. A...Reading unit, B...Writing unit, C...Image forming section, D.
...Paper feed section, E...Fixing section, 32...Case, 33...Set bin, 34...Compression spring,
35...position adjustment, 36...rank, 3
7... Binion, 38... Spring hook is hole, 39
...Tension spring, 40...Stop pin, 41...
・Shaft, 42...Set footer, 43...Spring,
44... Set hole, 45... Receiver is a guide,
46, 47...Motor.

Claims (4)

[Claims] (1) Three to four removable developing devices and an electrostatic image forming means are arranged around the photosensitive drum, and the electrostatic image formed on the photosensitive drum by the electrostatic image forming means is transferred to the developing device. In an apparatus that forms a color image by repeating development into a toner image on a photoreceptor drum by combining toner images, one set is used when there are three developing devices, and two sets are used when there are four developing devices.
A color image forming apparatus characterized in that two adjacent pieces of a set are housed in one case, and the case can be attached and detached. (2) The electrostatic image forming means is located on the upstream side of the developing device and 1
2. The color image forming apparatus according to claim 1, wherein an electrostatic image is formed on a photoreceptor drum between each developing device and the case or between cases. (3) The color image forming apparatus according to claim 1 or 2, wherein two developing devices are removably attached to the case. (4) The color image forming apparatus according to any one of claims 1 to 3, wherein the case is provided with a driving device for moving members of two developing devices.