JPS61256366A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a copy of good quality even when a form which is inferior in fixing property is used by providing a normal fixing device, a picture quality improving device, and a selection processing means. CONSTITUTION:The picture quality improving device 17 is provided in addition to the normal fixing device 10 so as to improve the picture quality of a toner image fixed on thick transfer paper or recording sheet inferior in fixing property such as an OHP sheet. Further, the selection processing means is provided to perform normal fixation by the normal fixing device 10 when there is no picture quality improvement signal, or send the recording sheet to the picture quality improving device 17 after the normal fixation of the normal fixing device 10 according to the picture quality improving signal and improve the picture quality selectively when the picture quality improvement signal is supplied. Consequently, images are fixed normally or improved in picture quality selectively according to the quality of recording sheets.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a general fixing device that fixes an unfixed powder image formed on a recording sheet onto the recording sheet, and a fixing device that improves the quality of the fixed image thereby. The present invention relates to an image forming apparatus including an image quality improvement device.

[Background of the invention]

Generally, electrophotographic copying machines and other image forming apparatuses that form a powder image (hereinafter referred to as a toner image) on a recording sheet and fix it by heating or pressure are equipped with only a single fixing device. Therefore, please use a thick recording sheet or
When fixing is performed on a special recording sheet with poor fixing properties, such as a HP sheet, additional means such as adjusting the temperature of the heat fixing roller are provided.

In particular, when a color copy of an OHP sheet is in a normal fixing state, projection light is refracted and scattered due to the unevenness of the toner surface, resulting in a problem in that a chromatic color projection image cannot be obtained.

[Purpose of the invention]

The purpose of the present invention is to solve the above-mentioned drawbacks, improve the image quality selectively according to the quality of the recording sheet, make it possible to obtain a chromatic color projection image even in the case of an OHP sheet, and improve the image density of copies. The object of the present invention is to provide an image forming apparatus that can also provide improvements.

[Summary of the invention]

The image forming apparatus according to the present invention includes a normal fixing device, an image quality improvement device, and a selection processing means that performs image quality improvement after normal fixing according to an image quality improvement signal, and performs normal fixing when there is no image quality improvement signal. It is characterized by this.

[Embodiments of the invention]

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

FIG. 1 is an explanatory diagram of the configuration of an embodiment in which the present invention is applied to an electrophotographic copying machine. In FIG. 1, reference numeral 1 denotes a document mounting table made of a transparent member, which reciprocates in the direction of the arrow. Reference numeral 2 denotes a converging light transmitting body which exposes a light image of the original image on the original table 1 onto the photosensitive drum 3 through a slit. The photosensitive drum 3 rotates in the direction of the arrow.

4 is a corona charger which uniformly charges the photosensitive drum. A developing device 5 exposes a uniformly charged photosensitive drum to a light image through the convergent light transmitting member 2 to visualize an electrostatic latent image formed thereon.

On the other hand, the recording sheet, ie, the transfer paper P, is fed onto the drum surface by the paper feed roller 6 and the register row 27, and receives the image transfer on the drum 2 by the transfer charger 8. Thereafter, the transfer paper is separated from the citrum by a separating means 13 and sent through a guide 9 2 to a fixing device 10.

The fixing device 10 is a normal fixing device that performs fixing in a normal fixing mode, and the fixing device 10 fixes the toner image on the transfer paper, and the transfer paper is discharged onto the upper tray 12 by a paper discharge row 211. .

The toner remaining on the photosensitive drum 3 is removed by cleaning means 1.
Dropped and recovered by 4. 15 is an illumination system for exposing the original, and 16 is a filter such as a heat ray absorption filter.

In addition to the fixing device 10, an image quality improving device 17 is usually provided in order to improve the image quality of a toner image fixed on a recording sheet with poor fixing properties, such as a thick transfer paper or an OHP sheet.

The present invention provides an apparatus that can selectively improve the image quality of a fixed image according to the quality of the recording sheet, and for this purpose, when there is no image quality improvement signal, normal fixing is performed only by the normal fixing device 10, Further, when an image quality improvement signal is given, a selection processing means is provided which selectively improves the image quality by sending the recording sheet to the image quality improvement device 17 after normal fixing by the normal fixing device 10 in response to this signal. An example of such means is shown in FIG.

In the example shown in FIG.
However, in the case of image quality improvement, a switch pack mechanism is provided to switch pack the recording sheet and send it to the image quality improvement device 17. This switch pack mechanism includes a guide plate 18 pivotally mounted within the path of the recording sheet, and an actuator constituted by an optical sensor 20 and a swinging lever 22 pivotally mounted at a fulcrum 21. In the figure, 2
3 is a displacement means for displacing the guide plate 18 between the positions 18a and 18b, 24 is a control means for controlling the movement of the switch pack mechanism, and 25 is a paper ejecting four-ra in the direction of arrow a or b.
26 indicates an image quality improvement signal given to the above control means.

The switch pack mechanism described above operates as follows.

When there is no image quality improvement signal 26, the guide plate 18 is at the position 18a, and the paper discharge roller 11 is rotating in the direction shown by arrow a. The recording sheet P is normally fixed by a fixing device 10, is sent on a guide plate 18 to a paper discharge roller 11, and is discharged onto a tray 12. Next, when the image quality improvement signal 26 is given, the leading edge of the recording sheet P passing through the fixing device 10 normally turns on the actuator, that is, raises the swing lever 22 and causes the recording sheet 22 to pass the optical sensor 20. This allows the presence of the recording sheet to be detected. At this time, the guide plate 18 is at the position 18a, and the recording sheet is sent to the paper discharge roller 11. When the rear end of the recording sheet passes and the actuator is turned off by lowering the swing lever 22 and returning to the predetermined position, the paper ejection roller 1
1 is stopped from rotating in the direction of arrow a, and is switched to rotation in the direction of arrow A. At the same time, the guide plate 18 is displaced to the isb position. As a means for this, known means such as rotation of a rotating shaft or a plansha can be used.

When the paper ejection roller stops, the edge of the recording sheet is placed on the paper ejection roller 211.
The sheet is held between a pair of sheets, guided downward by the guide plate 18 by the reverse rotation of the sheet discharge roller, and introduced into the image quality improvement device 17 by the id 40.

In the image quality improvement device 17, an endless overfilm 27 is inserted between a motorized roller 28 and a pressure roller 29, and rotates at a linear speed synchronized with the roller 28. Roller 30°31 is over film 27
This is a holding roller.

The over film 27 is made of a synthetic resin film having a smooth surface, such as polyester or polyethylene, with a thickness of 30 μm, for example. The image is fixed under pressure and heat to obtain a chromatic color projection image, and is discharged onto the lower tray 33 by the discharge roller 32.

In this way, the recording sheet fixed by the normal fixing device passes through the guide 40 and the image surface is treated with an overfilm made of a thin film, thereby improving the image quality.

3 and 4 show 0 before and after passing through the image quality improvement device 17.
I(P) is a diagram showing the state of the toner 30 on the P film 34. FIG. As a result, the projection light is refracted and scattered, making it impossible to obtain a chromatic projection image.

Figure 4 shows the state after passing through the λth image quality improvement device.
The toners 35b on the P film 34 are melted together, and the surface layer is smoothed by the overfilm, so that the transmitted light path is improved as shown in 36b.

The above examples show the effect on OHP films; 7
However, it is also effective in improving the density of toner images on general paper. It goes without saying that the pressure and linear velocity of the image quality improvement device will be more effective if the pressure is set higher and the linear velocity is lower than that of a normal fixing device.

In the illustrated embodiment, the overfilm is of an endless type, but it is also possible to use a type of winding in one direction. In addition, as an image quality improvement signal, image formation on a translucent resin sheet (resin sheet), especially the selection or command signal of color image formation, is appropriate. It may also be a signal from a selection designation key that can be used even when desired image quality improvement is desired.

〔Effect of the invention〕

The present invention is configured as described above, and it is possible to selectively fix an image to normal fixation or to improve the image quality depending on the quality of the recording sheet. For example, even in the case of an OHP sheet, it is possible to print a chromatic projection image Furthermore, high-quality copies can be obtained even when paper with poor fixing properties is used.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram of the configuration of an embodiment of the present invention applied to an electrophotographic copying machine, Fig. 2 is a detailed view of the vicinity of a normal fixing device and an image quality improvement device, and Fig. 3 is an image quality FIG. 4 shows the state of the toner on the OHP film before passing through the image quality improving device, and FIG. 4 shows the state of the toner on the OHP film after passing through the image quality improving device. 1... Document mounting table 2... Focusing light transmission body 3.
...Photosensitive drum 4...Corona charger 10...
- Normal fixing device 11... Paper ejection roller 12... Tray 17... Image quality improvement device 18... Guide plate 2o... Optical sensor 22... Rocking lever 23... Displacement means 24.・Control means
25... Drive means 26... Image quality improvement signal 27.
...Over film 28.29...Roller 30
．． 31... Holding roller 34 ・OHP film 3
5 a e 35 b ・”）ner 36a, 36b・
...Transmitted light path.

Claims (1)

[Claims] 1. An image characterized by comprising a normal fixing device, an image quality improvement device, and a selection processing means that improves the image quality after normal fixing according to an image quality improvement signal and performs normal fixing when there is no image quality improvement signal. Forming device.