JPS59191078A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent generation of wrinkles even at the time of copying of both faces, and also to simplify a manufacture by forming the circumferential surface of a heating roller to a tapered shape of a multistage extending over its axial direction. CONSTITUTION:As for a heating roller 29, its circumferential surface is formed in a tapered shape of a multistage extending over its axial direction, and made approximate to a curve shown by an expression of a bend delta. (In the expression, a load, a Young's modulus, an inertia moment, and length of a rod are denoted as W, E, I, and X, respectively.) That is to say, the roller 29 has a tapered part 31 of ten stages, whose outside diameter becomes smaller as it goes toward the center A from both ends E, E, and a difference between an outside diameter D2 of E and an outside diameter D1 is set within a range of 80mum-160mum. The outside diameter between each adjacent part of parts A-F is varied linearly. A tapered part 31 of ten stages is provided on the roller 29, but for instance, eight stages and 20 stages are also available.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fixing device used in, for example, an electronic copying machine.

[Technical background of the invention and its problems]

2. Description of the Related Art Conventionally, for example, fixing devices used in dry type electronic copying machines include an oven heater type, a heat roller type, a flannonite type, a pressure roller type, and the like.

Among these, heat roller type fixing devices account for 60 to 80% of
It is applied to most copying machines because it has high thermal efficiency and there is no risk of fire even if a jam occurs in the fixing device.Usually, as shown in Figure 1, the user roller ( It is configured to include a heat roller (heat roller) 1 and a breath roller 2. The above-mentioned user roller 1 has a piezo-shaped A
A Teflon tube is coated with Teflon, and a heater 2 is housed inside, and the temperature is maintained at a predetermined temperature (170°C to 210°C) by the heater 2. The breath roller 2 is a round bar made of iron or the like coated with silicone rubber. When the copy paper 3 is held and conveyed by the feed roller 1 and the press roller 2, a toner image previously attached to the copy paper 3 is fixed.

However, since the conventional user roller 1 and press roller 2 are formed in a cylindrical shape, wrinkles are likely to occur in the copy paper 3 when making double-sided copies. That is, in double-sided copying, the local expansion and contraction of the copy paper 3 that occurs when copying one side causes the local expansion and contraction of the copy paper 3 to occur again when copying the other side. Wrinkling is particularly likely to occur when the fuselage roller 21 and the press roller 2 are cylindrical. If wrinkles occur on the copy paper 3, the appearance of the copied image will be significantly impaired, and the function of the copy will be impaired, such as making it difficult to read the copied image at the wrinkled portions.

Therefore, in recent years, as shown in Figs. 2 to 4, a Hiser roller 1 provided with a chi groove 4 has been developed (% 7735/1983, Utility Model 51/1983). 677
No. 41).

By the way, as shown in FIG. 5, when a uniform load W is applied in the axial direction to the round bar 6 whose both ends are supported by the fulcrum 5.5, the deflection of the round bar 6 becomes δ, and the round bar 6 is nonlinear with respect to the length X.

Note that E is the Young's f-modulus of the round bar 6, and ■ is the moment of inertia.

However, the user roller 1 shown in FIGS. 2 and 3 has a shape in which the two linear tapered portions 4.4 approximate the curve expressed by the equation for the deflection δ. The generation of wrinkles cannot be effectively prevented.

Furthermore, since the tapered portion 4 of the user roller 1 shown in FIG. 4 has a curved shape similar to the curve expressed by the equation for the deflection δ, it is possible to effectively prevent the occurrence of wrinkles, but it is difficult to manufacture. There is a problem that is difficult.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its object is to provide a scale that does not generate wrinkles even when making double-sided copies, and a fixing device that is easy to manufacture.

[Summary of the invention]

The present invention is a fixing device equipped with a heat roller, characterized in that the heat roller has a multi-step tapered shape in its axial direction.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIGS. 6 to 8 (A) and (B) below.
This will be explained with reference to. FIG. 6 shows an electronic copying machine using a fixing device according to the present invention, and numeral 11 in the figure is a main body. A document mounting table 12 is provided on the upper surface of the main body 1 and is configured to move back and forth. Further, a photosensitive drum 13 is pivotally supported on a shaft inside the main body 11, and is configured to rotate in synchronization with the reciprocating movement of the document mounting table 12. Further, an exposure system 17 is provided between the photosensitive drum 13 and the original platen 12, and includes a thin f14, mirrors 15, lenses 16, etc., which illuminates the original on the original platen 12 and reflects the light. Light is guided onto the photosensitive drum 13 to form an original image. From this image forming position, the developing device 18
, a transfer device 19, a peeling device 20, a cleaning device 2, a static eliminator 22, and a charging device 23 are provided.

Further, a transport path 25 for copy paper 24 passing between the photosensitive drum 13, a transfer device 19, and a peeling device 20 is provided at the bottom of the main body 1, and its base end is connected to a paper feed device 26.
The end is connected to the paper output tray 2 via the fixing device 27.
It is facing 8.

The fixing device 27 includes a fuse roller 29 as a heat roller and a press roller 30. As shown in FIG. 7, the fuselage roller 29 has a curved shape with multiple stages in the axial direction, and is approximated by a curve expressed by the equation of the deflection δ.

Ru. That is, the lower row 229 has both ends E
, from E to the center part A, the outer diameter becomes smaller as it goes toward the center part A.
The difference between the outer diameter D2 of the center part A and the outer diameter D1 of the central part A is 80 μm.
It is set within the range of ~1.60 μm. for example,
The total length is 334 mm, and the outer diameter Di of the central part A is 39 mm.
．． 98m, distance L2” to both ends of this central part AJ Niji
The outer diameter at part B, which is 40 steps away, is 39.99 rms.
, this part B.

The outer diameter at a portion C1C, which is a distance L3 = 40 mm away from B to both ends, is 40.01 mm, and the outer diameter at D, which is a distance L4 = 35 mm from this portion C1C to both ends, is 40.01 mm.
05 Cabinet, this part, distance L5 = 35s from D to both ends
The outer diameter of the parts F and F that are i apart is 40.10 m++, and the outer diameter of the areas E and E from these parts F and F to both ends is D2 =
It is formed into a cylindrical shape with a diameter of 40.10 mm and a length of 17 rran. As a result, it has an inward crown shape with a D2D portion of 120 μm. In addition, parts A, B, C,
The outer diameter between adjacent portions D and F changes linearly.

According to the above configuration, not only wrinkles do not occur even when double-sided copies are made, but also manufacturing is easy.

That is, as a result of various experiments on the user rollers 1 and 29 shown in FIGS. 2, 3, and 5, it was found that the user roller 29 shown in FIG. 5 was less likely to wrinkle during double-sided copying. From this, it can be seen that wrinkles are less likely to occur in the user roller when its circumferential surface is approximated to the curve expressed by the above equation for the deflection δ. In addition, compared to the user roller 1 shown in FIG. 4, the user roller 29 shown in FIG. 5 has a multi-step linear chain shape, so it is easy to manufacture and can be provided at a low cost.

In addition, the outer diameter D2 of both ends E and E and the outer diameter of the central part A,
As a result of various changes in the difference D2-DI, when D2-D is 80 μm and 1g is lower, wrinkles appear on the copy paper 24 as shown in FIG. As shown in (b), wrinkles appeared on the copy paper 24. Note that the arrow in FIG. 8 indicates the direction in which the copy paper 24 travels. Therefore, D2 D+'! 1=80μ
By setting it within the range of m to 16011 m, the generation of wrinkles can be effectively prevented.

In the above embodiment, the user roller 29 is provided with the taper portion 31 in 10 steps, but the present invention is not limited to this, and may be provided with 8 steps or 20 steps, for example. Any number of stages may be used depending on the purpose.

Further, as shown in FIG. 9, both end portions E and E may also be tapered, that is, all regions may be tapered in the axial direction.

〔Effect of the invention〕

As explained above, according to the present invention, in the fixing device equipped with a heat roller, the surface of the heat roller is formed into a multi-step chi-shape in the axial direction, so that even when making double-sided copies, It is easy to manufacture and has an equivalent effect without causing wrinkles.

[Brief explanation of the drawing]

Figure 1 is a front view showing a conventional example, Figures 2 to 4 are front views showing different conventional examples, and Figure 5 is a reading when a uniform load is applied to a round bar with both ends fixed. Figures 6 to 8 (A) and (B) show an embodiment of the invention - ζ, Figure 6 is a V-shaped side view showing an electronic photocopier,
Figure 7 is a front view showing the Hude roller, Figure 8 (a)
(B) is a diagram showing experimental results, and FIG. 9 is a front view showing another embodiment of the present invention. 27... Foot monitoring device, 29... Heat roller (Hyuu l'o-7), 31... 7-ノ'? Department. Applicant's agent Patent attorney Takehiko Suzue ) (B)

Claims (3)

[Claims] (1) A fixing device equipped with a heat roller, characterized in that the heat roller has a multi-stage chi-flat shape in its axial direction. (2) The heater o-ra has a difference (D2 D+) between the outer diameter (D2) of both ends and the outer diameter (Dl) of the central part within the range of 80 μm to 160 μm. Fixing device as described. (3) The fixing device according to claim 1, wherein the groove shape is formed in four or more stages in the axial direction of the heat roller.