JP2000214746A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the unevenness of temperature in a direction nearly orthogonal to a paper carrying direction with a simple configuration in a carrying path after transfer. SOLUTION: In this device for forming an image simultaneously with cooling operation by suction and exhaust through a suction port 14 and an exhaust port 15, a heat conductive member 121 is disposed in contact with a paper carrying body 122 and an aperture 123 is formed in a state where its area on the exhaust port 15 side is gradually made larger than that on the suction port 14 side of the carrying body 122.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a copier, a printer,
The present invention relates to an image forming apparatus used for a facsimile or the like, and particularly to a cooling structure inside the apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic process, the temperature inside the apparatus has been increased due to a heat source such as a fixing device of a thermal type. It is known that defects occur in the formation.
In order to solve this problem, a method is used in which an exhaust fan is provided on the outer wall of the device housing to take in outside air into the device and form an image while cooling the image. The cooling air is sent from a direction substantially perpendicular to the sheet conveying direction in order to uniformly cool the rotation axis direction of the photosensitive drum and the fixing device.

[0003]

However, in such a case, the heat generated by the fixing device tends to accumulate on the exhaust side, and the temperature of the photosensitive drum becomes uneven in the axial direction.
The fixing temperature also has a non-uniform temperature distribution in the axial direction, resulting in a problem of deteriorating image quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus which can eliminate temperature non-uniformity on a side substantially orthogonal to a sheet conveying direction with a simple configuration. .

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention guides a sheet on which an unfixed toner image is formed to a fixing device via a sheet conveying path and sends the sheet to the outside of the apparatus housing. An image forming apparatus configured to blow cooling air from a side substantially perpendicular to a sheet conveying direction to a cooling air outlet provided on an outer wall of the apparatus housing, wherein the sheet conveying path includes a high heat conductive member. The sheet transporter is configured such that holes are formed in the sheet transporter so that the area where the cooling air contacts the high heat conductive member gradually increases toward the exhaust port side.

According to the above-mentioned invention, the paper transport path is generally made of a material having a relatively low thermal conductivity such as resin, but the heat is dispersed by the high thermal conductive member placed on the surface thereof. In addition, since the opening area on the paper transport path gradually increases as the opening on the paper transport path approaches the exhaust port side, heat easily escapes from the opening on the exhaust port side where heat easily accumulates, In addition, since the holes are closed in contact with the lower portion of the high heat conductive member, the holes are blocked by the high heat conductive member. Is not disturbed. Note that an intake port may be provided on the opposite side via the sheet transport path on the exhaust port side, but the present invention is not limited to this.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to the present invention. Reference numeral 1 denotes an image forming apparatus main body, and an image forming portion includes a photosensitive drum 2, a charger 3, an exposure unit 4, a developing unit 5, and a transfer unit 6. , A cleaning device 7 and a fixing device 8. The paper supply section includes a paper supply cassette 9, a paper supply roller 10 for feeding out paper from the paper supply cassette 9, a registration roller 11 for adjusting the leading end of the fed paper and image forming timing, and a fixing device 8 for transferring the paper after transfer. Transport path 1 leading to
2, a paper receiving tray 13 for receiving a sheet after fixing.

The paper transport path 12 will be described in detail with reference to FIGS. 2, 3 and 4. FIG. 2 is a perspective view of the paper transport path 12, and FIG. FIG. 4 is a plan view of a sheet conveying body 122 used for the sheet conveying path 12.

Reference numeral 14 denotes an intake port formed on an outer wall of the apparatus housing and having a fan (not shown) for taking in cooling air outside the apparatus housing; 15 denotes an exhaust port for discharging the introduced cooling air;
21 is a high heat conductive member.

The high thermal conductive member 121 is preferably a metal-based member having a high thermal conductivity. The term “high thermal conductivity” in the present invention means that the thermal conductivity is 8 × 10 ^{-1 to} 5 × 10 ¹ w.・ Cm ^-1
-Refers to a member of ° C ^-1 (under an environment of 25 ° C). The thickness is 0.5 to 2 mm, preferably 0.5 to 1.6 mm. Iron, aluminum, copper, silver or the like or an alloy thereof is good as a material made of the high heat conductive member, and an iron plate is preferable in terms of cost.

The paper transporting body 122 is provided with a transport surface 122a between the transfer position 6 'and the fixing position 8' shown in FIG. The transport surface 122a is provided with a plurality of ribs 122b in parallel in the transport direction by integral molding, so as to reduce the transport friction of the paper.
An opening 123 is formed between each of the plurality of ribs 122b. The opening 123 has a larger opening area as the cooling air taken in from the intake port 14 goes to the exhaust port 15 (by making L1 longer than the opening length L3 of the opening 123 in the transport direction on the intake port 14 side). Has been formed.

The material forming the paper transporting body 122 is a commonly used insulating material such as resin, and is 3 ×
A material having a thermal conductivity of 10 ⁻⁴ to 4 × 10 ⁻³ w · cm ⁻¹ · ° C. ⁻¹ is used. The reason for using such an insulating material is that if a member (metal or the like) having good electrical conductivity is used, the unfixed toner after transfer is disturbed because the sheet after transfer is electrostatically attracted. In addition, since resin or the like generally has a low thermal conductivity, heat tends to accumulate in a part of the paper transporting body 122. It is configured to be. Also,
The high thermal conductive member 121 not only disperses heat but also
23 can dissipate more heat and make the temperature in the axial direction of the photosensitive drum uniform. Further, the ribs 122b corresponding to the positions where the ribs 122b formed on the sheet transport
And a notch (not shown) into which the heat conductive member 121 can be fitted. When the high heat conductive member 121 is disposed on the surface of the transfer surface 122a, the rib 122
b is projected, and the opening 123 is formed in the heat conductive member 121.
Closed with. The opening 123 is closed by the paper transport path 12.
The reason is to prevent an adverse effect on an unfixed toner image due to an air leak in an unexpected direction since the sheet immediately after the transfer passes.

Here, the width of the high thermal conductive member 121 needs to be wider than at least the width of the printable sheet on the transport surface 122a (the side substantially orthogonal to the transport direction).

[0014]

EXAMPLE In order to confirm the operation and effect of the present invention, the change in the surface temperature of the photosensitive drum was measured by the following experimental machine using the basic structure of FIGS. The experimental machine used was a Kyocera Ecosys printer FS9000 improved machine (36-sheet machine). next,
The following photoconductor drum surface temperatures (1) to (3) were measured after continuous printing on both sides of 60 sheets of A4 paper in a normal temperature environment of 20 ° C. (temperature at which the internal temperature of the machine is saturated).

(1) Position of photoconductor drum surface near intake port (FT) (2) Position of axial center of photoconductor drum surface (CR) (3) Position of photoconductor drum surface near discharge port (RR) PPO (polyphenylene oxide) was used for the paper transport body, and an aluminum alloy was mounted thereon as a high thermal conductive member. An opening formed in the paper transport path was provided as follows.

(1) From the measurement position FT of the photosensitive drum to R
R is defined as the opening area of the paper transport path corresponding to the opening width ratio L1,
L2 and L3 (described in FIG. 4, the same applies hereinafter) are represented by L1: L2: L
3 = 10: 50: 1 (Example 1) (2) A case in which an aperture is not provided in a sheet transport body (Comparative Example 1) (3) From the measurement position FT of the photosensitive drum The ratio of the width of the opening of the paper transport path corresponding to RR is L1: L2: L3 = 10:
When substantially the entire surface of the sheet conveyance surface is opened at 50:10 (Comparative Example 2) (4) The ratio of the opening area of the sheet conveyance path corresponding to RR from the measurement position FT of the photosensitive drum to the opening width ratio is L1. : L2: L3
= 1: 50: 10 (Comparative Example 3) Table 1 shows the measurement results of the above experiments. In this case, the temperature at the measurement position CR of Comparative Example 1 in which no opening was provided was used as a reference.

[0017]

[Table 1]

As a result of the experiment, it can be seen that in the case of the first embodiment, the temperature in the axial direction of the photosensitive drum is substantially uniform.
On the other hand, when there is no opening in Comparative Example 1, the measurement position FT
And RR have a temperature difference. In the case of Comparative Example 2, the temperature difference is lower as compared with the case where there is no opening. Further, in the case of Comparative Example 3, the temperature is decreased only on the measurement position FT side, and FT
And the temperature difference of RR is large.

[0019]

According to the structure of the present invention, the sheet conveying member on which the high thermal conductive member is mounted is opened such that the area where the cooling air contacts the high thermal conductive member gradually increases toward the exhaust port. The holes disperse heat in the axial direction of the photoconductor drum, making it easier for heat to escape from the openings on the exhaust port side where heat easily accumulates. , The surface temperature becomes constant, the temperature variation is eliminated, and the printing quality can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic view of an image forming apparatus of the present invention.

FIG. 2 is a perspective view of a paper transport path.

FIG. 3 is a cross-sectional view taken along line AA ′ of the paper transport path.

FIG. 4 is a plan view of a paper transport body.

[Explanation of symbols]

 1: Image forming apparatus main body 2: Photoreceptor drum 3: Charger 4: Exposure device 5: Developing device 6: Transfer device 7: Cleaning device 8: Fixing device 9: Paper feed cassette 10: Paper feed roller 11: Registration roller 12 : Paper transport path 121: thermal conductive member 122 a: transport surface 122 b: rib 122: paper transport body 123: aperture 13: paper discharge tray 14: intake port 15: exhaust port

Claims (1)

[Claims] A sheet on which an unfixed toner image is formed is guided to a fixing device via a sheet conveying path, and is sent out of the apparatus housing; and a cooling air outlet provided on an outer wall of the apparatus housing. On the other hand, in an image forming apparatus configured to blow cooling air from a side substantially orthogonal to a sheet conveying direction, the sheet conveying path includes a sheet conveying member on which a high heat conductive member is placed, and the sheet conveying member includes: An image forming apparatus, wherein an opening is formed so that an area where the cooling air contacts the high thermal conductive member gradually increases toward the exhaust port side.