JPH1173021A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the influence of heat to the developing device even if the distance between the developing device and the fixing device is approached as near as possible, and capable of realizing the miniaturization of the device. SOLUTION: This image forming device is provided with an image carrier 7, a developing device 5 for developing a latent image formed on the image carrier 7, and a fixing device 14 for fixing the toner image on the image carrier 7 that has been transferred to a sheet material S to the sheet material S; and the developing device 5 is provided with a cover member 21 for receiving a toner at least below and around the outer circumference thereof. In this case, the developing device 5 is arranged directly above the fixing device 14 so as to provide the cover member 21 with a heat insulating property.

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 for forming an image on a recording medium.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus in which a non-magnetic one-component toner is used as a developer, toner may leak from the developing apparatus. Occasionally, due to vibration applied to the developing device, the toner scatters from the developing device, falls, and stains the inside of the image forming apparatus main body.
Therefore, for example, a guide wall member (hereinafter, referred to as a toner scattering prevention cover) is provided around the developing device, and a container for collecting the scattered toner is provided below the guide wall member to receive the toner scattered and dropped from the developing device. There has been proposed an image forming apparatus which accommodates, prevents, and prevents the inside dirt.

FIGS. 4 and 5 show an example of such an image forming apparatus, and FIG. 4 shows a configuration of a conventional example of a color laser printer.

A laser beam 2 emitted from a laser scanner unit 1 in accordance with image data of each color is applied to a photosensitive drum 3 as an image carrier whose surface is uniformly charged by a charging device (not shown). By rotating the rotary unit 5 including the developing devices 4Y, 4M, and 4C of three colors of yellow, magenta, and cyan while drawing a latent image, the colors of yellow, magenta, and cyan, and the color of B at the point A are sequentially detected. The black developing by the black developing device 4B is performed by the respective developing sleeves 6Y, 6M, 6C, 6B.
The intermediate transfer drum is formed by winding a rubber layer around a rotating aluminum cylinder while contacting the toner image with the photosensitive drum 3 at a point C as needed during development for each color. 7 is primarily transferred. The toner image in which the four color images are superimposed is formed on the intermediate transfer drum 7 by the above process.

On the other hand, a paper feed cassette 8 or a paper feed tray 9
The sheet S fed from the intermediate transfer drum 7 is conveyed by a transfer roller 10 having a foam wound around a metal shaft at a point D, while being in contact with the intermediate transfer drum 7. The color-overlaid toner images are transferred at once.

Thereafter, the sheet passes through a nip E, which is a contact point between these two rollers, of a fixing device 14 having a fixing roller 12 containing a halogen heater 11 and a pressure roller 13 rotating while being pressed against the fixing roller 12. Thus, the transferred toner image is fixed on the sheet S, and then discharged onto the sheet discharge tray 15.

In this color image forming apparatus, O
A non-magnetic one-component toner that does not have a magnetic material is used in consideration of the light transmission when projecting it, such as when printing on an HP sheet, but a toner that does not have such a magnetic material Has a very high fluidity, and the binding force on the developing sleeve in the developing device is lower than that of a magnetic material. When the user attempts to remove the developing devices from the image forming apparatus in order to replace them, the toner is liable to be scattered or dropped due to vibration or external force, which may contaminate the inside of the image forming apparatus main body.

For this reason, a toner scattering prevention cover 20 made of a plastic material such as polycarbonate is provided to prevent the toner scattered around the rotary unit 5 from diffusing into the image forming apparatus. It has been proposed and practiced to install a scattered toner collecting tray 30, which is a tray-shaped container for collecting scattered and dropped toner.

As shown in FIG. 5, the scattered toner collecting tray 30 is slidably attachable and detachable from the front of the main body of the image forming apparatus, and is discarded when a certain amount of toner is accumulated therein. Is to be processed.

[0010]

In these image forming apparatuses, the developing device must be disposed relatively close to the fixing device, as shown in the prior art, in order to reduce the size of the device. It is not uncommon to get no.

However, if the developing device and the fixing device are arranged close to each other in such a configuration, it is considered that the toner contained in the developing device is affected by the heat generated from the fixing device and is deteriorated or deteriorated. This hindered miniaturization of the device.

An object of the first invention according to the present application is to provide an image forming apparatus which minimizes the influence of heat generated by a fixing device or the like on a developing device.

An object of a second invention according to the present invention is to provide an image forming apparatus which prevents the influence of heat on the developing device even if the distance between the developing device and the fixing device is made as short as possible, and realizes the miniaturization of the device. It is something to offer.

[0014]

According to a first aspect of the present invention, an image carrier, a developing device for developing a latent image formed on the image carrier, A fixing device for fixing the toner image on the image carrier transferred to the sheet material to the sheet material, wherein the developing device is provided with a cover member that receives toner at least around a lower outer peripheral portion. Wherein the cover member has a heat insulating property.

A first configuration for realizing the object of the second invention according to the present application comprises an image carrier, a developing device for developing a latent image formed on the image carrier, and a developing device for transferring the latent image to a sheet material. A fixing device for fixing the toner image on the image carrier to the sheet material, wherein the developing device is provided with a cover member that receives toner at least around a lower outer peripheral portion. The developing device is disposed right above the fixing device, and the cover member has heat insulation.

When the cover member has an average temperature of 50 ° C., the thermal conductivity λ is 2.5 × 10 ⁻⁴ (cal / cm sec).
C.) or less and a substance of 1 × 0 ⁻⁶ (cal / cm sec ° C.) or more.

The material of the cover member is a heat insulating material based on ceramic fibers.

A second configuration for realizing the object of the first invention according to the present application is an image carrier, a developing device for developing a latent image formed on the image carrier, and a developing device for transferring a latent image formed on the sheet material. A fixing device for fixing the toner image on the image carrier to the sheet material, wherein the developing device is provided with a cover member that receives toner at least around a lower outer peripheral portion. The wall surface of the cover member is formed in a double wall structure having an air layer flowing therein.

A second configuration for realizing the object of the second invention according to the present application is an image carrier, a developing device for developing a latent image formed on the image carrier, and a developing device for transferring a latent image formed on the sheet material. A fixing device for fixing the toner image on the image carrier to the sheet material, wherein the developing device is provided with a cover member that receives toner at least around a lower outer peripheral portion. The developing device is disposed right above the fixing device, and a wall surface of the cover member is formed in a double wall structure having an air layer flowing therein.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.

FIG. 1 is a schematic view of an image forming apparatus according to the present embodiment, and shows a color laser printer.

A laser beam 2 emitted from a laser scanner unit 1 in accordance with image data of each color is applied to a photosensitive drum 3 as an image carrier whose surface is uniformly charged by a charging device (not shown). By rotating the rotary unit 5 including the developing devices 4Y, 4M, and 4C of three colors of yellow, magenta, and cyan while drawing a latent image, the colors of yellow, magenta, and cyan, and the colors of B at point A are sequentially turned on. The black developing by the black developing device 4B is performed by the respective developing sleeves 6Y, 6M, 6C, 6B.
The intermediate transfer drum is formed by winding a rubber layer around a rotating aluminum cylinder around the rotating aluminum cylinder while contacting the toner image with the photosensitive drum 3 at a point C as needed during development for each color. 7 is primarily transferred. The toner image in which the four color images are superimposed is formed on the intermediate transfer drum 7 by the above process.

On the other hand, the sheet cassette 8 or the sheet tray 9
The sheet S fed from the intermediate transfer drum 7 is conveyed by a transfer roller 10 having a foam wound around a metal shaft at a point D, while being in contact with the intermediate transfer drum 7. The color-overlaid toner images are transferred at once.

Thereafter, the paper passes through a nip E, which is a contact point between these two rollers, of a fixing device 14 having a fixing roller 12 containing a halogen heater 11 and a pressure roller 13 rotating while being pressed against the fixing roller 12. Thus, the transferred toner image is fixed on the sheet S, and then discharged onto the sheet discharge tray 15.

Further, there is provided a toner scattering prevention cover 20 for preventing the toner scattered around the rotary unit 5 from diffusing into the image forming apparatus, and collects the toner scattered and dropped in the toner scattering prevention cover 21. A scattered toner collecting tray 30, which is a tray-shaped container, is disposed.

The basic configuration of the above-described color laser printer of the present embodiment is the same as that of the conventional example shown in FIGS. 4 and 5. However, in the present embodiment, the fixing device 14 is disposed immediately below the rotary unit 5. The arrangement reduces the size of the entire apparatus.

In the present embodiment, the scattering toner diffusion preventing cover 21 is set at about 2 ° C. when the thermal conductivity (λ) is 50 ° C.
It is formed of a so-called inorganic fiber-based heat insulating material which is a mixture of ceramic fiber of × 10 ^-4 cal / cm sec ° C. and glass fiber. When the scattering toner diffusion prevention cover 21 formed of this heat insulating material is used, heat generated from the surface of the fixing roller 12 whose surface temperature is controlled to about 180 ° C. can be effectively insulated, and includes a developing device. The temperature of the rotary units 5 could be maintained at about 45 ° C. or less where the quality of the toner contained therein deteriorated.

The mixed material of ceramic fiber and glass fiber that can be used as the heat insulating material generally has a thermal conductivity of λ = 1 × 10 ^{−6 to} 2.5 × 1 at 50 ° C.
It is within the range of 0 ^-4 (cal / cm sec ° C.), and it has been confirmed that any substance having a substance within these ranges can sufficiently exhibit the effects of the present invention.

(Second Embodiment) FIGS. 2 and 3 show a second embodiment.

FIG. 2 is a schematic view of a color laser printer, and FIG. 3 is a perspective view of the toner scattering prevention cover in FIG.

In this embodiment, similarly to the first embodiment, the fixing device 14 is disposed directly below the rotary unit 5 to reduce the size of the entire apparatus. The difference is that the toner scattering prevention cover 22 is made of a plastic material and has a hollow case shape (double wall structure).
And a plurality of intake holes 40 on the front side of the main body of the cover and an exhaust hole 50 on the rear side of the main body. This realizes the flow of air (arrow) from the hole 40 to the rear exhaust hole.

In this configuration, a hole such as a louver is provided on the exterior cover (not shown) on the front surface of the main unit at a position close to the air intake hole 40 of the scattering prevention cover 20, so that it is more efficient. Outside air can be taken into the cover 20, the temperature inside the cover 20 can be reduced, and the heat insulation effect can be increased.

According to the present embodiment, the cover itself does not need to use an expensive heat-insulating material, and can be formed of a general-purpose plastic material such as polycarbonate, and maintains a high heat-insulating effect by the internal air flow. You can do it.

[0034]

According to the first, third and fourth aspects of the present invention,
Since the cover member has heat insulation, the heat generated in the image forming apparatus such as the fixing device does not affect the developer in the developing device. Images can be provided.

According to the second, third and fourth aspects of the invention, the cover member of the developing device has a heat insulating effect with respect to the fixing device, so that the effect of the heat generated by the fixing device on the developer in the developing device. The developing device can be disposed directly above the fixing device, and the size of the image forming apparatus can be reduced.

According to the fifth aspect of the present invention, since the wall surface of the cover member has an air layer to be air-cooled, the heat insulating effect on the developing device is further improved, and an expensive heat insulating member is not required, and the cost is low. The cover member can be formed using a plastic material.

According to the sixth aspect of the present invention, in addition to the high cost of the fifth aspect, the developing device can be disposed directly above the fixing device, so that the size of the image forming apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus according to a first embodiment of the present invention.

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

FIG. 3 is a perspective view of the toner scattering cover of FIG. 2;

FIG. 4 is a schematic diagram of a conventional image forming apparatus.

FIG. 5 is a perspective view showing a scattered toner collecting tray of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laser scanner unit 2 ... Laser beam 3 ... Photosensitive drum 4Y, 4M, 4C, 4B ... Each color developing device 5 ... Rotary unit 6Y, 6M, 6C, 6B ... Each color developing sleeve 7 ... Intermediate transfer drum 8 ... Feeding cassette 9 ... Paper feed tray 10 ... Transfer roller 11 ... Halogen heater 12 ... Fixing roller 13 ... Pressurizing roller 14 ... Fixing device 15 ... Discharge tray S ... Paper 20,21,22 ... Toner scattering prevention cover 30 ... Scattered toner collection tray 40 … Intake hole 50… exhaust hole 60… exhaust fan

Claims (6)

[Claims] An image carrier, a developing device for developing a latent image formed on the image carrier, and a fixing device for fixing a toner image on the image carrier transferred to a sheet material to the sheet material. An image forming apparatus, wherein the developing device is provided with a cover member for receiving toner at least around a lower outer peripheral portion, wherein the cover member has heat insulation properties. 2. An image carrier, a developing device for developing a latent image formed on the image carrier, and a fixing device for fixing a toner image on the image carrier transferred to a sheet material to the sheet material. An image forming apparatus provided with a cover member for receiving toner at least around a lower outer peripheral portion of the developing device, wherein the developing device is disposed directly above the fixing device, and the cover member An image forming apparatus characterized by having heat insulating properties. 3. The cover member has a thermal conductivity λ of 2.5 ×.
10 ^-4 (cal / cm sec ° C) or less, 1 × 0
The image forming apparatus according to claim 1, wherein the image forming apparatus is formed of a material having a temperature of ⁻⁶ (cal / cm sec ° C.) or higher. 4. The image forming apparatus according to claim 1, wherein the material of the cover member is a heat insulating material based on ceramic fibers. 5. An image carrier, a developing device for developing a latent image formed on the image carrier, and a fixing device for fixing the toner image on the image carrier transferred to a sheet material to the sheet material Wherein the developing device is provided with a cover member for receiving toner at least around a lower outer peripheral portion, wherein the wall surface of the cover member has an air layer in which a wall flows. An image forming apparatus having a structure. 6. An image carrier, a developing device for developing a latent image formed on the image carrier, and a fixing device for fixing a toner image on the image carrier transferred to a sheet material to the sheet material. An image forming apparatus provided with a cover member for receiving toner at least around a lower outer peripheral portion of the developing device, wherein the developing device is disposed directly above the fixing device, and the cover member An image forming apparatus, wherein the wall surface of the image forming apparatus has a double wall structure having an air layer flowing therein.