JPS61256367A - Image forming device - Google Patents

Abstract

PURPOSE:To improve picture quality without increasing the size of a device by adding the 2nd fixing device to a pedestal. CONSTITUTION:When a mode changeover switch is operated, the position of a distribution guide 18 is determined by a solenoid 20 and a spring 21. For example, when normal paper is used, the 1st fixation mode is selected. In this case, the solenoid 20 is turned off and the distribution guide 18 is set at a position 18a, so that transfer paper P is discharged to an upper tray 12 by a discharge roller 11. When the transfer paper is, for example, a color-copied OHP sheet, the 2nd fixation mode is selected. In this case, the solenoid 20 is turned on and the distribution guide 18 is positioned at 18b, so that the transfer paper is guided to the 2nd fixing device. The 2nd fixing device is provided to the pedestal, and consequently the picture quality is improved without increasing the size of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a copying machine or the like equipped with two fixing devices for fixing an unfixed powder image formed on a recording sheet onto the recording sheet. The present invention relates to an image forming apparatus.

[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 under heat or pressure are equipped with only a single fixing device. . Therefore, when fixing is performed on a special recording sheet with poor fixing properties, such as a thick recording sheet or an OHP sheet, an additional means such as adjusting the temperature of the heat-fixing roller has been 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. Therefore, in addition to the first fixing device,
An image forming apparatus has been developed in which a second fixing device is provided, and the second fixing device performs fixing in the second fixing mode on a recording sheet that has been fixed in the first fixing mode by the first fixing device. It was done. However, installing the second fixing device inside the main body of the image forming device increases the size of the device, and also has the drawback that the second fixing mode is completely useless for users who do not need it. .

Further, it is preferable that the second fixing device has a slower linear speed than the first fixing device, and this has caused problems such as the recording sheet becoming jammed in front of the second fixing device.

[Purpose of the invention]

It is an object of the present invention to solve the above-mentioned drawbacks and to provide an image forming apparatus such as a copying apparatus which can obtain a chromatic color projection image of an OHP sheet, can also improve the image density of a copy, and is easy to use. There is a particular thing.

In particular, it is an object of the present invention to provide an image forming apparatus that can improve image quality without increasing the size of the apparatus and can prevent recording sheets from clogging inside the apparatus.

[Summary of the invention]

The feature of the image forming apparatus according to the first invention of the present application is that the unfixed powder image formed on the recording sheet is transferred to the recording sheet) +f
When fixing fi, there is a first fixing device that fixes the recording sheet in a first fixing mode, and a second fixing device that fixes the recording sheet that has been fixed in the first fixing mode in a second fixing mode. The fixing device includes a fixing device and a switching means for switching to a second fixing mode after fixing in the first fixing mode, and the second fixing device is provided on the pedestal. With such a configuration, it is possible to improve image quality without increasing the size of the device. In particular, by using the second fixing device as an image quality improvement device, it is possible to provide excellent image quality that has not been previously available.

An image forming apparatus according to a second invention of the present application has the features of the first invention described above, and is characterized in that a manual feeding mode feeding mechanism is provided on the pedestal. Conventionally, the manual feed mechanism for manual feed mode has been provided on the device main body side, but providing such a manual feed mechanism on the device main body side requires a new control circuit such as unnecessary process stoppage, which increases the cost of the device. It will rise. On the other hand, by providing the manual feed mechanism on the pedestal side, image quality can be improved with a simple configuration without complicating the entire device.

An image forming apparatus according to a third invention of the present application has the features of the first invention described above, and also provides the second fixing device described above so as to be detachable from the pedestal, and detects the attachment state of the second fixing device. The present invention is characterized in that means is provided for inhibiting the conveyance of the recording sheet to the second fixing device when the recording sheet is not attached.

In such a configuration, the recording sheet is allowed to enter only when the second fixing device is in the operating position, so jamming is prevented, and the recording sheet l- is accidentally pushed onto the pedestal when the second fixing device is not needed. It is also prevented from being stored inside. Furthermore, since the second fixing device is removable, parts within the second fixing device, particularly the overfilm used in the second fixing device, can be easily replaced.

Further, an image forming apparatus according to a fourth invention of the present application has the features of the first invention described above, and is provided with an intermediate tray on the pedestal that temporarily stores the recording sheet after passing through the first fixing device. It is characterized by the fact that With such a configuration, an image forming apparatus that does not cause a jam even if the linear speed of the second fixing device is set to be low in order to maximize copy quality can be obtained.

[Embodiments of the invention]

Embodiments of the present invention will be described 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 focusing photoconductor, which slit-exposes a light image of the document image on the document table 1 onto the photosensitive drum 3 . 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 focusing photoconductor 2 to visualize an electrostatic latent image.

On the other hand, the recording sheet, that is, the transfer paper P is fed by the paper feed roller 6.
The image is then sent to the citram surface by the register roller 7, and the image on the drum is transferred by the transfer charger 8. After that, the transfer paper is separated from the drum by the separating means 13,
It passes through the guide 9 and is sent to the first fixing device 10 . 1st
The fixing device 1° is a device that performs fixing in the normal first fixing mode, and the toner image on the transfer paper is fixed by this fixing device, and the transfer paper is transferred to the upper tray 1 by the ejection roller 11.
2 is discharged on top. The toner remaining on the photosensitive drum 3 is removed and collected by the cleaning means 14. Reference numeral 15 denotes an illumination system for illuminating the original, and 16 filters such as a heat gauze absorption filter.

In addition to the first fixing device 10, for fixing on recording sheets with poor fixing properties such as thick transfer paper or OHP sheets,
A second fixing device 17 that performs fixing in a second fixing mode, and a distribution guide 18 that guides the transfer paper discharged from the first fixing device 10 to the second fixing device 17 are provided.

FIG. 2 shows the vicinity of the first fixing device 10 in detail. Depending on the type of transfer paper used, the position of the guide 18 is determined by turning on and off a mode changeover switch (not shown), which is caused by the rendoid 20 and spring 21.

For example, when using plain paper, the first fixing mode is selected. In this case, the lens 20 is turned off, the guide 18 is set at the position 18a, and the transfer paper P is discharged onto the upper tray 12 by the discharge roller 11. When the transfer paper is, for example, an OHP sheet on which color copies have been made, the second fixing mode is selected. In this case, the transfer paper is guided to the second fixing device 17 by positioning the guide 18 at the position 18b when the lens 20' (i-ON) is turned on.

The second fixing device is provided on the pedestal, thereby making it possible to improve image quality without increasing the size of the device. However, by using the second fixing device as an image quality improving device, it is possible to obtain excellent image quality that could not be obtained conventionally.

An intermediate tray 32 is provided between the first fixing device 10 and the second fixing device 17 to temporarily store the transfer paper P after passing through the first fixing device.

When the second fixing mode is selected, the Lenoid 20
By turning on the transfer paper, the guide 18 is positioned at 18b, and the transfer paper is guided to the second fixing device 17 provided on the pedestal 38 shown in FIG. 234, the transfer paper is guided to the intermediate tray 32 by the conveyance guide 33, and the transfer paper is temporarily transferred to the intermediate tray 32.
The paper is stocked at the feed roller 235, and is then re-fixed by the second fixing device 17.
is discharged to the lower tray 28. Intermediate tray 32
This is mainly necessary because the line speed of the second fixing device is set slower than that of the first fixing device.

When the intermediate tray 32 is full of transfer paper, a full amount detector 40 is activated.
When the shift is detected, the control device (not shown) automatically selects the first fixing mode and maintains the guide 18 at a position of 18 m during the shift.

In the second fixing device 17, an endless oat N-film 22 is sandwiched between a fixing roller 25 and a pressure roller 26, and rotates at a linear speed that is almost synchronized with the fixing roller 25. . Rollers 23 and 24 are holding rollers for the overfilm 22.

The toner image surface of the transfer paper sent to the second fixing device 17 is fixed by pressure and heat via the over film 22, and the OHP film on which the color copy has been made is in a state where a chromatic color projection image is obtained. It is then discharged onto the lower tray 28.

A manual feed mechanism 36 for manual feed mode is provided on the pedestal (FIG. 1). This is for manually feeding a recording sheet into a copy that requires re-fixing, and the inserted sheet is fed into the second fixing device 17 by a manual feed roller 37 and is re-fixed. It is discharged to the lower tray 28. This manual feed mechanism is provided with a device that detects the manual feed and starts the operation of the second fixing device.

Also, while the feed roller 35 is under rotation control, the intermediate tray 3
2 is in use, the manual feed roller 37 is controlled not to rotate so that the manual feed mechanism 36 does not operate.

If a manual feed mechanism such as the one shown in the figure is installed on the main body of the device, a new control circuit would be required to stop the process, but by providing the manual feed mechanism on the pedestal as shown in the figure, the overall device would be complicated. With a simple configuration, it is possible to improve image quality by feeding the sheet to the second fixing device when necessary.

The second fixing device 17 is removably attached to the pedestal, and is held by a pair of guide rails 42 so that it can be pulled out in the direction of arrow 43. A detector 41 is provided to detect when the second fixing device is installed and detect whether the second fixing device 17 is installed securely. If the second fixing device 17 is not installed in the predetermined working position, a control device (not shown) will move the guide 18 to the first position.
It is controlled so that it is in the fixing mode position, and at the same time it is controlled so that it is not in the @2 fixing mode position. In other words, the recording sheet is allowed to enter only when the second fixing device is in the operating position, thereby preventing the occurrence of a jam, and also preventing the sheet (13) from being stored in the pedestal by mistake when the second fixing device is not needed. Moreover, since it is removable, it is easy to replace the internal parts of the second device, particularly preferably the oat 4-film.

3 and 4 are diagrams showing the state of the toner 30 on the OHP film 29 before and after passing through the second fixing device 17. Figure 3 is a diagram before passing, and the toner particles 30m on the OHP film 29 have unevenness on the toner particle surface, and the transmitted light path is as shown by 311L.The projection light is refracted and scattered, and a chromatic projection image is not obtained. do not have. FIG. 4 shows the state after passing through the second fixing device, where the toner 30b on the OHP film 29 is melted together and re-fixed via the overfilm, so that the toner surface layer is smooth and transparent. The original path is improved as 31b.

Although the above embodiments have shown the effects on OHP films, they are also effective in improving the density of toner images on patterned paper.

Furthermore, it goes without saying that the pressure and linear velocity of the second fixing device are more effective if the pressure is set higher and the linear velocity is set lower than those of the first fixing device.

FIG. 5 shows that the normal fixing process performed by the first fixing device 10 and the image quality improvement process performed by the second fixing device 17 are selectively switched by an image quality improvement signal to adjust the image quality according to the quality of the recording sheet. FIG. 1 is a block diagram showing a system that performs image quality improvement processing.

Although the above embodiment is configured to temporarily stop the function of the manual feed mechanism 36 by not operating the manual feed roller 37 while the intermediate tray 32 is in use, the function of the manual feed mechanism 36 is not limited to the manual feed roller. A similar effect can be obtained by controlling a stopper that prevents manual paper from being inserted.

In addition, in the illustrated embodiment, the guide 18 is driven by the solenoid 20, but this can also be done by mechanical means such as a link mechanism or a cam mechanism. However, it is also possible to wind it in one direction. Further, although the second fixing device 17 is removed in the left direction of the copying machine, it may be removed in another direction, for example, toward the front side.

〔Effect of the invention〕

By adding the second fixing device to the pedestal, the present invention can improve image quality without increasing the size of the device, and also saves space for users who do not need it. It is possible to easily provide high-quality copy images only to those necessary for the device without any economic waste.

Furthermore, in order to maximize the copy quality, it is possible to obtain an image forming apparatus that does not have any problems with paper feeding even if the linear speed of the second fixing device is set to a low value, and a manual feed mechanism is added to the pedestal. In particular, it becomes possible to provide an easy-to-use image forming apparatus that can support any copy mode without complicating the entire apparatus.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an embodiment in which the present invention is applied to an electrophotographic copying machine, FIG. 2 is a detailed diagram of the peripheral portion of the first fixing device, and FIG.
The figure shows the state of the toner on the OHP film before it passes through the second fixing device, and Figure 4 shows the state of the toner on the OHP film after passing through the second fixing device.
FIG. 5, which is a diagram showing the state of toner on the HP film, is a diagram showing a system in which normal fixing processing and image quality improvement processing are switched by an image quality improvement signal. DESCRIPTION OF SYMBOLS 10... First fixing device 17... Second fixing device 18... Distribution guide 20... Solenoid 21
...Spring 22...Over film 12...Upper tray 28...Lower tray 29
... OHP film 30... Toner 32...
Intermediate 1-ray 40...Full detector 41...Detector 42...Guide rail 36...Manual feed mechanism 37...Manual feed row 538...Pedestal Fig. 2 Fig. 3 Fig. 4

Claims (4)

[Claims] (1) When fixing an unfixed powder image formed on a recording sheet to the recording sheet, a first fixing device that fixes the unfixed powder image to the recording sheet in a first fixing mode; A second fixing device that performs fixing in a second fixing mode on a recording sheet that has been fixed, and a switching device that switches to a second fixing mode after fixing in the first fixing mode, the second fixing device as described above. An image forming device characterized in that it is installed on a pedestal. (2) When fixing the unfixed powder image formed on the recording sheet to the recording sheet, a first fixing device that fixes the unfixed powder image to the recording sheet in a first fixing mode; The above-mentioned second fixing device includes a second fixing device that performs fixing in a second fixing mode on a recording sheet that has been fixed, and a switching device that switches to the second fixing mode after fixing in the first fixing mode. An image forming apparatus characterized in that the pedestal is provided with a manual feed mechanism for manual feed mode. (3) When fixing the unfixed powder image formed on the recording sheet to the recording sheet, a first fixing device that fixes the unfixed powder image to the recording sheet in a first fixing mode; A second fixing device that performs fixing in a second fixing mode on a recording sheet that has been fixed, and a switching device that switches to a second fixing mode after fixing in the first fixing mode, the second fixing device as described above. An image forming apparatus characterized in that the image forming apparatus is provided removably with respect to the pedestal, and is provided with means for detecting the attachment state of the second fixing device and prohibiting conveyance of the recording sheet to the second fixing device when the second fixing device is not attached. . (4) When fixing the unfixed powder image formed on the recording sheet to the recording sheet, a first fixing device that fixes the unfixed powder image to the recording sheet in a first fixing mode; A second fixing device that performs fixing in a second fixing mode on a recording sheet that has been fixed, and a switching device that switches to a second fixing mode after fixing in the first fixing mode, the second fixing device as described above. An image forming apparatus characterized in that the pedestal is provided with an intermediate tray for temporarily storing a recording sheet after passing through a first fixing device.