JPH07319238A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of appropriately setting a temperature condition in a fixing part in accordance with not only the size or the kind of a transfer material but also the difference of image information. CONSTITUTION:When a user selects a halftone mode (photograph mode or dot mode or the like), a latent image developing condition is changed and an image for the halftone mode is formed on a photo-receptor (step 1-6 to step 1-7). It is known at a stage where the latent image developing condition is decided that the image on the photoreceptor is formed in the halftone mode, so that control temperature in fixing is set high at that time (step 1-8) and copying is started (step 1-9).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic system, a transfer material (paper, OH
The fixing temperature is changed according to the size and type of the P sheet or the like. Similarly, the operation speed (process speed) of the apparatus is changed, and the pre-rotation operation is performed before the image forming operation.

[0003]

However, in the above-mentioned conventional example, the operating speed of the apparatus, the temperature change of the fixing portion, the pre-rotation operation, etc. are all determined by the information such as the size and type of the transfer material. Although it was possible to change the fixing condition according to the change of the transfer material, it was not possible to change the fixing condition due to the difference of the image information on the same transfer material.

For example, image information includes halftone images, thin lines, solid black, solid white, etc.
The fixability varies depending on the image information such that the halftone image having a low image density has a lower fixability than the black image having a high image density. However, in the conventional image forming apparatus, It was not possible to change the fixing conditions according to the difference in fixing property.

The first invention according to the present application solves the above-mentioned problems, and appropriately sets the temperature condition in the fixing portion not only by the size and type of the transfer material but also by the difference in the image information. It is an object of the present invention to provide an image forming apparatus that can be used.

The second invention according to the present application solves the above-mentioned problems, and appropriately performs the pre-rotation operation in the fixing unit not only by the size and type of the transfer material but also by the difference in the image information. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

Further, the third invention according to the present application solves the above problems, and not only the size and type of the transfer material,
It is an object of the present invention to provide an image forming apparatus capable of appropriately setting the operation speed of the apparatus depending on the difference in image information.

[0008]

According to the first invention of the present application, the above-mentioned object is to rotatably arrange a latent image carrier and to uniformly charge the surface of the latent image carrier. And a charging means for exposing the surface of the latent image carrier that has been charged, and an exposure means that exposes the surface of the latent image carrier corresponding to the original image. The electrostatic latent image formed on the surface of the latent image carrier by the exposure is developed with a developer. The latent image carrier is provided with a developing means for pressing, a transferring means for transferring the developed image on a transfer material, and a fixing means for fixing the image on the transfer material by heating and pressurizing the image on the transfer material. In an image forming apparatus in which a normal image and an image having a higher resolution than usual are selectable as an image formed on the body, the image formed on the latent image carrier has a higher resolution than usual. If the image is high, the fixing temperature is usually It is achieved by having a set control unit to also increase.

According to the second invention of the present application,
The above object corresponds to a latent image carrier rotatably arranged, a charging means for uniformly charging the surface of the latent image carrier, and a document image on the charged surface of the latent image carrier. Exposure means for performing the exposure, developing means for developing the electrostatic latent image formed on the surface of the latent image carrier by the exposure with a developer, transfer means for transferring the developed image onto a transfer material, and A fixing means for fixing the image on the transfer material by heating and pressing the transfer material, and as the image formed on the latent image carrier, a normal image and an image having a higher resolution than usual When the image formed on the latent image carrier is an image having a higher resolution than usual, in the image forming apparatus in which and are selectable, the fixing unit is fixed before the exposure unit operates. Perform pre-rotation processing to operate It is achieved by having a constant by control means.

Further, according to the third invention of the present application, the above object is to provide a latent image carrier rotatably arranged,
Charging means for uniformly charging the surface of the latent image carrier,
Exposure means for exposing the charged surface of the latent image carrier to an image corresponding to an original image; developing means for developing an electrostatic latent image formed on the surface of the latent image carrier by exposure with a developer; The latent image carrier is provided with a transfer means for transferring the developed image onto a transfer material and a fixing means for fixing the image on the transfer material by heating and pressurizing the transfer material. Image as a normal image,
In an image forming apparatus in which an image having a higher resolution than usual is selectable, if the image formed on the latent image carrier is an image having a higher resolution than usual, the operation speed of the apparatus is slowed down. This is achieved by having the control means set to

[0011]

According to the first invention of the present application, when the image formed on the latent image carrier has a higher resolution than usual, the fixing temperature is set higher than usual. A high-resolution image, which is less fixable than usual, can be fixed well.

According to the second invention of the present application,
When the image formed on the latent image bearing member has a higher resolution than usual, the pre-rotation process for operating the fixing unit is performed, so that the fixing unit is sufficiently warmed and the fixing property is higher than usual. Fixes bad high resolution images well.

Further, according to the third invention of the present application, when the image formed on the latent image carrier has a higher resolution than usual, the operation speed of the apparatus is slowed down. The transfer material and the image on the transfer material are sufficiently heated so that a high-resolution image having poorer fixing property than usual can be fixed well.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 2 is a view showing the schematic arrangement of the image forming apparatus according to this embodiment. In the apparatus of this embodiment, as shown in FIG.
3 and are separated one by one by the paper feed roller 27 or the paper feed roller 24.
5, or the paper feed rollers 23 and 22 are carried to the carrying path. Further, the sheet is conveyed to the registration roller pair 28 by the conveyance roller 20 or the conveyance roller 21 and the conveyance roller 19 in the conveyance path, and the registration roller pair 28 performs the image forming operation of the image forming unit as described below. The sheet is conveyed to the photoconductor drum 30, which is a latent image carrier, at the timing of.

On the other hand, the document placed on the document table 6 is illuminated by the halogen lamp 4, and the reflected light is reflected by the slit 3, the first mirror 5, the second mirror 2, the third mirror 1 and other optical systems. It is read by the CCD 15 via 13, 14. The read image is electrically image-processed, and then irradiated onto the photosensitive drum 30 as laser light from the laser unit 7 which is an exposing unit. At this time, the photosensitive drum 30 is rotationally driven in the clockwise direction, and the surface thereof is uniformly charged by the primary charger 11 which is a charging means. Therefore, an electrostatic latent image is formed on the photosensitive drum 30. It is formed.

This latent image is visualized as a toner image by a developing device 17 which is a developing means, and this visible image is transferred to a sheet conveyed to the photosensitive drum 30 by the pair of registration rollers 28 and a transfer means. It is transferred by the barrel transfer charger 29. Then, the transferred toner image on the paper is fixed by a fixing device 34 as a fixing means, and is discharged by a paper discharge unit 36.

The fixing device 34 includes a fixing roller 51 having a heater 53 as a heat source, and the fixing roller 51.
And a pressure roller 52 disposed so as to be in pressure contact with the fixing roller 51. The temperature is controlled to a predetermined temperature by a control means (not shown).

After the toner image has been transferred, the photosensitive drum 30 has residual toner removed by the drum cleaner 9 having a cleaning blade, and the photosensitive drum 3
The toner removed from 0 is collected and stored in the waste toner collecting section of the drum cleaner section 9.

The apparatus of this embodiment as described above is capable of switching between a normal copy mode such as a character mode and a halftone mode such as a photographic mode or a halftone dot mode, and the halftone mode is selected. In this case, an image having a higher resolution than that in the normal copy mode is formed.

However, this high-resolution image has a poorer fixing property than a normal image. Therefore, in this embodiment, the fixing condition is changed as follows.

FIG. 1 is a flow chart of the fixing condition changing control in the first embodiment of the present invention. As shown in the flowchart of FIG. 1, when a user makes a copy, a copy mode is selected (step 1-1), and if the mode is a normal copy mode (for example, a character mode), the normal mode is used. The image and development conditions are determined (step 1-2), and the image on the photosensitive drum 30 is determined accordingly (step 1-3). Therefore, the fixing temperature is set to a normal temperature based on the determined conditions (step 1-4), and copying is started (step 1).
-5).

On the other hand, when the user selects the halftone mode (photograph mode, halftone dot mode, etc.), the latent image condition is changed and the image for the halftone mode is formed on the photosensitive drum 3.
0 (step 1-6 to step 1-
7). The fact that the image on the photoconductor drum 30 is in the halftone mode can be known at the stage when the latent image and the developing conditions are determined. At that time, therefore, the fixing control temperature is set to a high temperature (step 1-8). ), And start copying (step 1-9).

As described above, according to the present invention, it is possible to change the fixing temperature depending on the image mode, and to improve the fixing property for a halftone image having a poor fixing property as compared with a black image, for example. Become.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 3 is a flow chart of the fixing condition changing control in the second embodiment of the present invention.

As shown in the flow chart of FIG. 3, when the user makes a copy, a copy mode is selected (step 3-1), and if the mode is a normal copy mode (for example, character mode), a normal copy mode is selected. The latent image and development conditions are determined by the mode (step 3-2), and the image on the photoconductor drum 30 is determined accordingly (step 3-).
3). Then, copy is started (step 3-
4).

On the other hand, when the user selects the halftone mode (photograph mode, halftone dot mode, etc.), the latent image and developing conditions are changed, and an image for the halftone mode is formed on the photosensitive drum 30 (step 3-5 to step 3
-6). The fact that the image on the photosensitive drum 30 is in the halftone mode can be known at the stage when the latent image and the developing conditions are determined, and therefore the pre-rotation is performed before the copy start (step 3-7). That is, the copy starts after the pre-rotation is performed for several seconds to several tens of seconds (step 3-
8).

As described above, by performing the pre-rotation before the start of copying, the pressure roller 52 of the fixing device 34 is heated so that the copying can be started after the temperature is sufficiently warmed. The amount of heat increases, and the fixability improves.

That is, according to the present invention, it is possible to obtain the same effect as that of the first embodiment in that the fixing property in the halftone mode can be improved by performing the pre-rotation.

(Third Embodiment) In the same way as in the first or second embodiment, the process speed can be reduced in the halftone mode.
Since it takes a longer time for the transfer material to pass through the fixing portion and the amount of heat increases, it is possible to obtain the same effect that the fixing property is improved.

(Fourth Embodiment) Furthermore, the modification of the fixing conditions described in the first to third embodiments is not limited to the case where the halftone mode is selected as the image mode, For example, it may be applied to a mode for changing the image density such as a shading process or gradation performed in a digital copying machine, which deteriorates the fixing property, and it is needless to say that the same effect can be obtained. Yes.

In the above-described embodiment, the fixing conditions are changed as described above according to the size and type of the transfer material as in the conventional case. For example, in the case of a large size transfer material, the fixing temperature is raised. That is, the present invention changes the fixing condition according to the size and type of the transfer material as described above, and further changes the fixing condition according to the image mode.

[0035]

As described above, the first aspect of the present application
According to the invention, when an image having a higher resolution than usual is formed on the latent image carrier according to the image mode selected by the user, the fixing temperature is raised so that the halftone (medium -It is possible to improve the fixability in low density areas.

According to the second invention of the present application,
When the image mode selected by the user forms an image with a higher resolution than usual on the latent image carrier,
By performing the pre-rotation process before the operation of the exposure unit, it is possible to improve the fixability in the halftone (medium / low density) portion where the fixability is poor.

Further, according to the third invention of the present application, when the image having a higher resolution than usual is formed on the latent image carrier according to the image mode selected by the user, the operation of the exposing means is performed. Before that, by lowering the operation speed of the device, it is possible to improve the fixability in the halftone (medium / low density) portion where the fixability is poor.

[Brief description of drawings]

FIG. 1 is a flowchart of fixing condition change control according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 3 is a flowchart of a fixing condition changing control according to the second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 7 laser unit (exposure means) 11 charger (charging means) 17 developing device (developing means) 29 transfer charger (transfer means) 30 photoconductor drum (latent image carrier) 34 fixing device (fixing means)

Claims (3)

[Claims] 1. A rotatably arranged latent image carrier, charging means for uniformly charging the surface of the latent image carrier, and a document image on the charged surface of the latent image carrier. Exposure means for performing corresponding exposure, developing means for developing the electrostatic latent image formed on the surface of the latent image bearing member by exposure with a developer, transfer means for transferring the developed image onto a transfer material, A fixing means for fixing the image on the transfer material by heating and pressurizing the transfer material is provided, and as the image formed on the latent image carrier, a normal image and a higher resolution than usual. In the image forming apparatus in which the image is selectable, the image formed on the latent image carrier is
An image forming apparatus comprising: a control unit that is set so that the fixing temperature is higher than usual when the image has a higher resolution than usual. 2. A rotatably arranged latent image carrier, a charging unit for uniformly charging the surface of the latent image carrier, and a document image on the charged surface of the latent image carrier. Exposure means for performing corresponding exposure, developing means for developing the electrostatic latent image formed on the surface of the latent image bearing member by exposure with a developer, transfer means for transferring the developed image onto a transfer material, A fixing means for fixing the image on the transfer material by heating and pressurizing the transfer material is provided, and as the image formed on the latent image carrier, a normal image and a higher resolution than usual. In the image forming apparatus in which the image is selectable, the image formed on the latent image carrier is
In the case of an image having a higher resolution than usual, the image forming apparatus has a control unit set to perform a pre-rotation process for operating the fixing unit before the exposure unit operates. . 3. A latent image carrier rotatably disposed, charging means for uniformly charging the surface of the latent image carrier, and a document image on the charged surface of the latent image carrier. Exposure means for performing corresponding exposure, developing means for developing the electrostatic latent image formed on the surface of the latent image bearing member by exposure with a developer, transfer means for transferring the developed image onto a transfer material, A fixing means for fixing the image on the transfer material by heating and pressurizing the transfer material is provided, and as the image formed on the latent image carrier, a normal image and a higher resolution than usual. In the image forming apparatus in which the image is selectable, the image formed on the latent image carrier is
An image forming apparatus having a control unit set to slow down the operation speed of the apparatus when the image has a higher resolution than usual.