JPH05229687A - Recording device - Google Patents

Abstract

PURPOSE:To reduce the misregistration in overlap transfer so as to enhance the efficiency of image transfer by providing two pulleys of the same eccentricity in such a manner that they are rotatable at the same phase, and disposing a recording paper conveyor belt the length of which is an integer multiple of the peripheral length of the pulleys, while providing the belt with a predetermined thickness and setting the belt in a predetermined position relative to the pulleys. CONSTITUTION:A recording paper conveying mechanism has its conveyor belt 31 hung between rollers 4, 5, exerted with a tensile force and driven in the direction indicated by the arrow, the rollers 4, 5 having the same diameter and roughly equal in the amount of eccentricity. The belt 31 is such that the single amplitude (f) of its thickness (t) which varies as a sine in a period of L0 is set to be equal to the amount of eccentricity of the rollers so that its peripheral length L is an integer multiple of the perpheral length L0 of the rollers 4, 5. The rollers 4, 5 are in an equal eccentric phase relation to each other, and the rollers 4, 5 and the belt 31 are positioned relative to each other such that the thickness of the belt cancels out the eccentricity of pulleys 4, 5. When such a conveyor belt 31 is driven, rolling of the belt due to the eccentricity of the rollers is canceled out and fluctuation in the velocity of the belt at the transfer position of each color is reduced so that the rate of offsetting of colors can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording device such as an electrophotographic image recording device.

[0002]

2. Description of the Related Art As a color image recording apparatus using electrophotography, as shown in FIG. 4, yellow (Y), magenta (M), cyan (C) and black (K) image forming means 10 _Y , An apparatus has been proposed in which 10 _M , 10 _C , and 10 _K are arranged in series, and the toner images formed on the respective drums are sequentially superimposed and transferred onto a recording medium to obtain a color image.

In FIG. 4, reference numeral 1 is a recording paper cassette,
The recording paper 100 in the recording paper cassette 1 is a feeding roller.
It was paid out by a few and was hung on rollers 4 and 5.
Is conveyed by the recording paper conveyance belt 6 which runs in the direction of the arrow
To be done. Image forming means 1 adjacently arranged on the belt 6.
0_Y, 10_M, 10_C, 10_KIs the image forming means 10 _Y
As illustrated with reference to FIG.
Electric device 12, exposure system 13, developing device 14, transfer device 15
And a cleaner 16 are arranged.

On the recording paper fed and conveyed on the belt 6 as described above, the photosensitive drum 1 of each of the image forming means is used.
The toner images of each color formed on 1 (formed by uniform charging by the charging device 12, formation of a latent image by the exposure system 13, and development by the developing device 14) are successively transferred by the transfer device 15. The recording paper onto which the toner images have been transferred is fixed to the fixing device 20.
And the toner image is fixed on the recording by the heat given from the fixing roller 21. On the other hand, the surface of the photosensitive drum 11 that has completed the transfer is cleaned by the cleaner 16.

[0005]

In such a conventional image recording apparatus, the thickness of the recording paper conveying belt is constant,
If the roller is eccentric, the effective radius changes even if the rotation angle of the roller is constant. Therefore, at each rotation position of the belt, a color misregistration position deviation occurs due to the occurrence of speed fluctuation. Further, the transfer efficiency is lowered due to the vertical movement of the outer circumference of the belt.

It is an object of the present invention to provide a recording apparatus capable of reducing the positional deviation at the time of overlapping transfer and further improving the transfer efficiency.

[0007]

In order to achieve the above object, the present invention provides a recording apparatus using a belt driven by being tensioned by two rollers having the same eccentricity and having the same diameter. The rollers are arranged so that the phase relationships of the eccentricities of the rollers are the same, and the belt is
The perimeter is an integer multiple of the perimeter of the roller, and
The thickness is set so as to sinusoidally change with the circumferential length of the roller as a cycle, and the one-sided amplitude of the belt that changes sinusoidally is set to be equal to the eccentricity of the roller. The configuration (first configuration) is performed.

Further, in the recording apparatus of the first construction, the phase relationship between each roller and the belt is set so that the eccentricity of the roller is canceled by the thickness of the belt (second construction). ).

[0009]

The circumference of the belt is an integral multiple of the circumference of the roller, and the thickness of the belt changes sinusoidally with the circumference of the roller as a cycle. The phase relationship between the belt and each pulley is set so that the belt thickness cancels the eccentricity of the pulley. Therefore, the effective radius of the roller is constant.

[0010]

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

FIG. 1 is a side view showing a recording sheet conveying mechanism for a recording apparatus according to the present embodiment. The recording sheet conveying mechanism comprises rollers 4 and 5 and a recording sheet conveying belt 31 which is stretched over the rollers. That is, the belts 31 have almost the same eccentricity (eccentricity ε).
Tension is applied by the two rollers 4 and 5 having the same diameter, and the rollers are driven in the arrow direction. The recording paper is supplied onto the belt 31 from the right side and is conveyed by the belt 31.

The belt 31 has a peripheral length L that is an integral multiple of the peripheral length L _O of the peripheral lengths of the rollers 4 and 5, and has a thickness L _O.
Is set so as to change sinusoidally, and the one-sided amplitude f of the thickness t of the belt 31 which changes sinusoidally is set to be equal to the roller eccentricity amount ε. The eccentricity of the rollers 4, 5 is the same, and the positional relationship between the rollers 4, 5 and the belt 31 is set so that the eccentricity of the pulleys 4, 5 is canceled by the thickness of the belt 31. (The thin belt portion contacts the long roller diameter portion, and the thick belt portion contacts the short roller diameter portion). Such a structure can be realized by the following means.

First, the optical head 4 as shown in FIG.
A laser displacement meter 41 using 0 measures the diameter variation of the two rollers 4 and 5. 4a (or 5a) is the axis of the roller. Further, a mark M is attached near the outer circumference of the end surface of the roller 4 (or the roller 5) so that the position of the maximum diameter can be identified. 1/2 the difference between the maximum and minimum measured values
Is the eccentricity amount ε of the rollers 4 and 5.

Next, the relationship between the belt length 1 and the thickness t will be determined. As shown in FIG. 3, the origin O is the center O of the roller cross section.
Consider the y-coordinate system. The eccentricity of the roller is ε, and the position of the coordinates (0, −ε) is the axis O ′ of the roller. When the intersection P between the maximum diameter of the roller and the outer circumference is on the y-axis (in the positive direction), the initial state is set, and the intersection of the outer circumference of the belt and the y-axis is Q. Based on this figure, the relationship between the rotation angle α of the roller and the thickness t of the belt is obtained as follows.

Let L be the length from the axis center O'to the intersection P'of the roller outer circumference and the y-axis when the roller is rotated rightward by α around O '. L is equal to the length of O'P 'in FIG. Let H be the point where the perpendicular line drawn from the O point to the straight line P'O 'intersects with P'O'.

[Equation 1]

[Equation 2]

From the above, the relationship between the rotation angle α and the belt thickness t was obtained. Thereby, the shape of the belt 31 can be determined. The belt 31 and the rollers 4, 5
Are the marks P (positions with the smallest thickness t),
Corresponding positions are determined and arranged so that M has the relationship shown in FIG.

By driving the recording paper conveying belt 31 having the above-described shape and the phase relationship with each roller, it is possible to cancel the runout of the belt due to the eccentricity of the roller, and the belt at the transfer position of each color. It is possible to reduce speed fluctuations and color shift position deviations. Further, since the belt does not swing up and down, it is possible to improve the transfer efficiency. The present invention can also be applied to an intermediate transfer type printer that uses a belt as an intermediate transfer medium.

[0018]

As described above, according to the present invention, two pulleys having the same eccentricity are installed so as to rotate in the same phase, and the recording paper is conveyed with an integral multiple of the circumference of the pulley. Since the belt is arranged with a thickness and relative position that cancel the eccentricity of the pulleys, it is possible to reduce the belt speed fluctuation at the transfer position of each color and reduce the overlay position deviation of each color. It is possible to improve the recording quality.
Further, it is possible to suppress the vertical swing of the belt, and it is possible to improve the transfer efficiency.

[Brief description of drawings]

FIG. 1 is a side view showing a recording paper conveyance mechanism for a recording apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a roller eccentricity measuring method according to an embodiment of the present invention.

FIG. 3 is an analysis diagram for determining a belt shape according to an embodiment of the present invention.

FIG. 4 is a side view showing a schematic structure of a conventional color image recording apparatus.

[Explanation of symbols]

 4,5 rollers 4a. 5a axis 31 recording paper conveyance belt f single-sided amplitude ε eccentricity

Claims (2)

[Claims] 1. A recording apparatus using a recording paper conveying belt (31) driven by being tensioned by two rollers (4, 5) having the same eccentricity and having the same diameter. ) Are arranged so that the phase relationships of the eccentricities of the rollers (4,5) are the same, and the circumference of the belt (31) is an integral multiple of the circumference of the rollers (4,5). In addition, the thickness of the belt (31), which varies sinusoidally with the circumferential length of the rollers (4, 5) as a cycle, has a one-sided amplitude. A recording device, wherein the recording device is set so as to be equal to the eccentricity amount of (4,5). 2. The recording apparatus according to claim 1, wherein the phase relationship between the rollers (4,5) and the belt (31) is such that the eccentricity of the rollers (4,5) cancels the thickness of the belt (31). A recording device characterized by being set to.