JPH04371966A - Process cartridge - Google Patents

Abstract

PURPOSE:To provide a process cartridge whose internal equipment is matched to each image density is selected in the case of forming the images with plural of image density. CONSTITUTION:The process cartridges 5 which is constituted at least of an image carrier 1 or a developing means 3 and attachably/detachably disposed in the device main body 100 of an image forming device which can form the images with plural of image density is provided with an image density specifying signal transmitting means for transmitting a specifying signal concerning the image density matched to the internal equipment of the cartridge 5 to a control part 20 on the device main body 100 side in the case of attaching the cartridge 5. Therefore, in the case of forming the images with plural of image density, the cartridge 5 having the equipment matched to each image density is attached in the device main body 100 so as to form the image, and the high-quality image is formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge used in an image forming apparatus such as a laser beam printer employing an electrophotographic method.

0002

2. Description of the Related Art A laser beam printer using a semiconductor laser is known as an electrophotographic image forming apparatus. Such laser beam printers typically use 240,30
It is common to form an image with an image density of 0,400 dpi, but recently it is 480,600, 800, 12
Those that form images at high image density such as 00 dpi are also used. This is because such a high image density allows diagonal lines and curved parts of characters to be output smoothly, and characters with a large number of strokes such as kanji can be clearly output, and in the case of photographic images, etc. This is because the number of gradations is larger, and the size of one image representing an intermediate tone can be made smaller, allowing finer output.

On the other hand, laser beam printers and the like that form images at such high image densities require the use of conventional software, peripheral equipment, etc., and connection with conventional host computers. However, it is necessary to be able to form images. Therefore, one laser beam printer can print multiple image densities (for example, 300 dp).
Some printers are capable of image formation (such as i and 600 dpi, or 300 dpi and 800 dpi, etc.).

[0004] When changing the image density, it is necessary to change the scanning line density of the photosensitive drum (image carrier) by the laser beam, but this changing the scanning line density requires rotation of the polygon mirror of the optical scanning system. It is necessary to change the speed or the number of rotations of the photosensitive drum. Further, in order to switch the image density, it is necessary to change the photosensitive drum, developing device, etc. to one suitable for the image density.

[0005]

[Problems to be Solved by the Invention] However, in the above conventional example, when changing the image density, even though the scanning line density of the photosensitive drum is changed, the photosensitive drum and developing device are not changed to match the image density. For example, when creating an image with high image density, diagonal lines and curved parts of large characters may be printed smoothly, but small characters with many strokes, such as kanji, cannot be printed with fine lines and may be skipped. There was an inconvenience that it would be stored away or crushed.

[0006]Also, a dither pattern is generally used in photographic image output processing, but by changing to a high image density in the above cases, each dot of this dither pattern has an even smaller area, which improves print reproduction. However, there was a problem in that the quality of the photographic image was deteriorated.

On the other hand, some image forming apparatuses have process devices such as photosensitive drums and developing devices removably installed in the image forming apparatus main body as a process cartridge. It is also possible to install a photosensitive drum and a developing device suitable for the image forming apparatus into the main body of the image forming apparatus.

[0008] However, in the conventional process cartridges, it is not clear what kind of process cartridge should be specifically used depending on the image density.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a process cartridge in which internal equipment suitable for each image density can be selected when images are formed at a plurality of image densities. be.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises at least an image carrier or a developing means, and is capable of being detachably attached to the main body of an image forming apparatus capable of forming images at a plurality of image densities. The process cartridge installed in the process cartridge is characterized by being provided with image density designation signal transmission means for transmitting a designation signal regarding the image density suitable for the internal equipment to a control unit on the apparatus main body side when the process cartridge is installed.

[0011]

[Operation] When forming an image with a plurality of image densities, it is necessary to change the scanning line density of the scanning unit to the image carrier, but this alone cannot form a sufficient image suitable for the image density. That is, since the image carrier and the developing means also have optimum characteristics for image density, when forming an image with a different image density, it is necessary to form the image with an image carrier and developing means that match the image density. .

Although the image carrier and the developing means can be changed by replacing the process cartridge, in the present invention, the process cartridge is provided with an image density designation signal transmission means, and the image density designation signal transmission means allows the internal information to be changed. Information regarding the optimal image density for the device is now transmitted to the control section on the device's main body. Therefore, when changing the image density, if a necessary process cartridge is selected, an image can be easily formed using an image carrier and a developing means that match the image density.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a cross section of an image forming apparatus capable of forming images at a plurality of image densities. Image forming devices such as a container 2, a developing device 3, and a cleaning device 4 are provided. The photosensitive drum 1 is composed of a photosensitive member such as a phthalocyanine-based organic photoelectric material or a selenium-based photosensitive material that is sensitive to laser light of a wavelength of 770 to 800 nm from a semiconductor laser. In addition, the developing device 3
A developing device main body 3a containing one-component magnetic toner, etc., and a developing sleeve 3b, etc., which are arranged with a certain gap from the photosensitive drum 1 and rotate while holding the toner on the outer periphery by the action of magnetic force, etc. The toner is supplied to the photosensitive drum 1 by applying a bias voltage to the developing sleeve 3b.

The photosensitive drum 1, primary charger 2, developing device 3, cleaning device 4, etc. described above are integrally housed in the cartridge body 5a, and are detachably arranged in the apparatus body 100 as a process cartridge 5. It is set up. The process cartridge 5 is adapted to be installed and removed along the main body guides 100a and 100b of the apparatus main body 100 in the vertical direction of the plane of the drawing, that is, in the axial direction of the photosensitive drum 1 as shown in FIG. .

In FIG. 1, a paper feed tray 6, a registration roller 7, and a transfer charger 8 are arranged on the paper feed side below the process cartridge 5, and a conveyance guide 9, a fixing device 10, and a paper ejection side are arranged on the paper ejection side. A stand 11 etc. are arranged.

Further, on the right side and above the process cartridge 5, a scanner unit 12 and an optical system 13 for exposing the photosensitive drum 1 in the process cartridge 5 to laser light (image light) L are disposed. The scanner unit 12 uses a semiconductor laser (for example, a wavelength of 770 to 800 nm).
It is composed of a polygon mirror, a scanner motor that rotates the polygon mirror, a collimator lens, etc., and a laser beam (which emits a laser beam emitted from a semiconductor laser and made into parallel light by a collimator lens).
Image light) L is incident on a polygon mirror rotating at high speed,
The polygon mirror directs this laser light to the photosensitive drum 1.
The photosensitive drum 1 is exposed to light by scanning. Here, the rotation speed of the scanner motor is variable, and by changing the rotation speed of the polygon mirror, it is possible to form images at a plurality of image densities including high image density. The optical system 13 includes an fθ lens, a folding mirror, and the like.

In the figure, reference numeral 14 denotes a pre-exposure lamp composed of a halogen lamp, an incandescent lamp, an LED, or the like.

That is, when the image light L is exposed to the photosensitive drum 1 uniformly charged by the primary charger 2 via the scanner unit 12 and the optical system 13, an electrostatic latent image is formed on the photosensitive drum 1. Ru. The electrostatic latent image is directed toward the developing device 3 as the photosensitive drum 1 rotates, toner is supplied through the developing sleeve 3b of the developing device 3, and the image is visualized as a toner image. The toner image is directed towards a transfer charger 8;
The photosensitive drum 1 is transferred onto the transfer paper P by the transfer charger 8, and after the transfer, the residual toner is cleaned by the cleaning device 4, and the residual charge is removed by the pre-exposure lamp 14. Provided for image formation.

On the other hand, the transfer paper P on the paper feed table 6 is conveyed toward the registration rollers 7, and then conveyed toward the photosensitive drum 1 at the same timing as the registration rollers 7.
A toner image is transferred from this photosensitive drum 1. and,
The transfer paper P on which the toner image has been transferred is conveyed to a fixing device 10 via a conveyance guide 9, and after the toner image is fixed as a permanent image by the fixing device 10, it is stacked on a paper output table 11. Ru.

Reference numeral 20 in FIG. 1 is a controller which is a control section on the apparatus main body side, and each device within the apparatus main body 100 is operated via the controller 20. Below, the operation of this controller 20 will be explained with reference to FIG.
is rotated at a predetermined number of rotations. This main motor 22 rotates the main rotating equipment in the main body of the apparatus, such as the photosensitive drum 1. Further, the signal from the controller 20 is transmitted to the scanner motor driver 23, and the scanner motor 24 of the scanner unit 12 is rotated via the scanner motor driver 23 at a rotation speed matching a predetermined image density.

Furthermore, the signal from the controller 30 is transmitted to the semiconductor laser 25, the pre-exposure section 26, and the developing bias power supply 28, and operates the semiconductor laser 25 and the pre-exposure lamp 12, thereby applying a developing bias to the developing sleeve 3b of the developing device 3. At the same time, a signal from the controller 20 is transmitted to the high voltage power supply 27, and a high voltage is applied to a charger such as the primary charger 2. Note that 29 is a host computer.

Now, when forming images with different image densities, for example, images with high image density, it is necessary to increase the rotation speed of the scanner motor 24 via the controller 20 and increase the rotation speed of the polygon mirror. It is also necessary to change the photosensitive drum 1 and developing device 3 to ones suitable for high image density.

Therefore, in the present invention, when forming images with a plurality of image densities, the process cartridge 5 is replaced in order to change the photosensitive drum 1 and the developing device 3 to ones suitable for the image densities. This process cartridge 5 is provided with a transmitting means for transmitting information regarding the image density suitable for the process cartridge 5 to the apparatus main body 100 side. That is, the photosensitive drum 1 of the process cartridge 5
A plurality of protrusions 40a as shown in FIG. 4 are provided on the shaft end side of the
40b, 40c, 40d, and 40e, an image density designation signal transmission means 40 is provided to notify the apparatus main body 100 of the optimum image density for this process cartridge 5, and the image density designation signal transmission means 40 is also provided on the apparatus main body 100 side. A plurality of microswitches 41a, 41 that receive signals from
An image density detection switch 41 consisting of 41b, 41c, 41d, and 41e is provided, and a signal from the image density detection switch 41 is transmitted to the controller 20 via an image density reception circuit 42 shown in FIG.

Here, some of the protrusions 40a, 40b, 40c, 40d, and 40e of the image density designation signal transmitting means 40 (for example, 40b, 40c, and 40e as shown in FIG. 4) differ depending on the type of image density to be transmitted. This image density detection switch 41 is removed because the protrusion that has fallen off does not press some of the microswitches 41a, 41b, 41c, 41d, and 41e of the image density detection switch 41.
This makes it possible to detect what kind of image density the process cartridge 5 is suitable for.

[0026] For example, high image density (for example, 600
dpi), the process cartridge 5 that can form an optimal image at this image density is installed in the apparatus main body 1.
00, the image density detection switch 41 detects the image density (60
0dpi) and sends this signal to the image density receiving circuit 42.
The information is transmitted to the controller 20 via the . For this purpose, the controller 20 rotates the scanner motor 24 via the scanner motor drive 23 at a rotation speed corresponding to an image density (scanning line density) of 600 dpi, and the scanner motor 24 rotates the polygon mirror. Also,
When forming an image with a normal image density (for example, 300 dpi), a process cartridge 5 that can form an optimal image at this image density may be similarly installed in the apparatus main body 100.

As described above, when forming images with different image densities with one image forming apparatus, the scanner unit 12
In addition to changing the rotation speed of the polygon mirror, the process cartridge 5 is also replaced, and the photosensitive drum 1 and developing device 3 are also replaced with the ones that are most suitable for the image density. This makes it possible to form high-quality images. In this case, the process cartridge 5
An image density designation signal transmitting means 40 is provided in the apparatus main body 10.
Since the optimum image density information suitable for the process cartridge 5 is notified to the 0 side, the photosensitive drum 1 and the developing device 3 can be easily replaced via the process cartridge 5.

Here, the image density designation signal transmitting means 40 of the process cartridge 5 is connected to the microswitches 41a and 41 of the image density detection switch 41 to the apparatus main body 100 side.
In addition to the mechanical ones that give signals to the terminals b, 41c, 41d, and 41e, there is also a barcode display that conveys the image density displayed on the outer surface of the process cartridge 5, and this is displayed on the device main body 10.
Of course, it may be an optical type that is read by a reader on the 0 side, or it may be a magnetic type.

Further, in the above description, the process cartridge 5 is provided with the image density designation signal transmitting means 40, and the process cartridge 5 is replaced according to the image density. However, the present invention is not limited to this. The photosensitive drum 1 or the developing device 3 alone forms a cartridge (in this embodiment, this is also expanded to be interpreted as a process cartridge), and an image density designation signal transmitting means 40 that indicates the optimum image density for the internal equipment to the cartridge. By setting up
Of course, this cartridge may be replaced.

Next, how the developing device 3 and the photosensitive drum 1 affect the image density will be explained below.

In the developing device 3, the toner particle size and the materials used affect the image density, and the toner particle size has a particularly large effect. Therefore, 240, 300, 400 dpi
A toner with a particle size of about 12 μm is used for normal image densities such as 600, 800 dpi, etc., and a toner with a particle size of about 6 μm can be used for high image densities such as 600, 800 dpi to improve image quality.

At the same process speed, the sensitivity of the photosensitive drum 1 affects the image density. That is, the photosensitive drum 1 has an optimum sensitivity depending on the image density. For example, in an image forming apparatus with a process speed of 37.7 mm/sec, the optimum sensitivity of the photosensitive drum 1 when the image density is 300 dpi is 2.0 μj. /cm2 and 600dp
When i, it is 2.7 μj/cm2. This is thought to be due to the fact that when the image density is high and the scanning density is high, there is less decrease in the amount of exposure light between scanning lines, and the surface potential rise characteristics depending on the amount of light on the photosensitive drum 1 are affected. However, the higher the image density, the lower the sensitivity.

Furthermore, in the developing device 3, the diameter of the developing sleeve 3b and the gap between the developing sleeve 3b and the photosensitive drum 1 affect the image density. For example, the diameter of the developing sleeve 3b is 16 mm, the gap between the developing sleeve 3b and the photosensitive drum 1 is 250 μm, and the sensitivity of the photosensitive drum 1 is 2.0 μj/c.
m2, the diameter of the developing sleeve 3b is 20 mm, the gap between the developing sleeve 3b and the photosensitive drum 1 is 150 μm, and the sensitivity of the photosensitive drum 1 is 3.
With a process cartridge 5B having a value of 0 μj/cm2,
When used in an image forming apparatus with a process cartridge of 37.7 mm/sec, if the image density is 300 dpi, use the process cartridge 5A, and the image density is 508 dpi.
When forming an image using the process cartridge 5B in the case of dpi, which process cartridge 5A,
5B was also able to form high quality images corresponding to the respective image densities. In addition, if a toner with a smaller particle size is used in the process cartridge 5B, the image density will be 5.
The image quality at 0.08 dpi has further improved.

In the above embodiments, the image density was switched by changing the rotational speed of the scanner motor 24 to change the scanning line density to the photosensitive drum 1, but the present invention is not limited to this. Of course, the process speed for image formation, that is, the rotational speed of the photosensitive drum 1 may be changed. In this case, the process speed of the process cartridge 5 for high image density is slow, and there is an advantage that a photosensitive drum 1 having lower sensitivity than that for normal image density can be used.

[0035]

As is clear from the above description, according to the present invention, since the process cartridge is provided with an image density designation signal transmitting means, the process cartridge can be replaced when forming images with a plurality of image densities. This makes it possible to easily form an image by replacing the image bearing member and developing means of the image forming device with those having an image density that matches the characteristics of the image forming device.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an image forming apparatus.

FIG. 2 is a perspective view showing a state in which a process cartridge is attached to and detached from the main body of the image forming apparatus.

FIG. 3 is a block diagram illustrating the operation of a controller within the image forming apparatus.

FIG. 4 is a perspective view showing image density designation signal transmitting means on the process cartridge side and an image density detection switch on the apparatus main body side.

[Explanation of symbols]

1 Photosensitive drum (image carrier) 3
Developing device (developing means) 5 Process cartridge (cartridge) 20 Controller (control unit) 40 Image density designation signal transmitting means 100 Apparatus body

Claims (3)

[Claims] Claim 1: A process cartridge that is configured of at least an image carrier or a developing means and that is removably disposed within the main body of an image forming apparatus that is capable of forming images at a plurality of image densities; A process cartridge characterized in that it is provided with image density designation signal transmission means for sending a designation signal regarding a suitable image density to a control section on the apparatus main body side when the process cartridge is mounted. 2. The process cartridge according to claim 1, wherein the image density designation signal transmission means sends a designation signal regarding an image density suitable for the toner particle size of the developing means to the control section. 3. The process cartridge according to claim 1, wherein the image density designation signal sending means sends to the control unit a designation signal regarding an image density suitable for the photosensitivity of the image carrier.