JPH01319048A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image faithful to an original on a transfer material by disposing a means for adjusting the eccentric quantities of an image carrier and a driving gear to be in the same direction. CONSTITUTION:After fixing a photosensitive body 1 on a shaft 4, the eccentricity of the photosensitive body 1 is measured by proper measuring means 61 and 62, such as a dial gauge, etc., and a fitting gap between the gear 2 and the shaft 4 is adjusted by screws 51 and 52, etc., based on the measured result so as to adjust the eccentricity of the gear 2 to be in the same direction as that of the photosensitive body 1 according to the designation of a measuring means 63. Thus, the latent image and the image faithful to the original can be obtained without making the eccentric quantity smaller.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) This invention relates to an image forming apparatus that utilizes an electrostatic recording process such as an electrostatic copying machine or a printer, and particularly to an image forming apparatus that uses a rotating cylindrical image carrier. The present invention relates to an image forming apparatus having the present invention.

(Prior art and issues to be solved) An optical image signal is applied to the surface of a uniformly charged and running image carrier to form an electrostatic latent image, and charged toner is supplied to this latent image to make it visible. After converting into a toner image, a sheet-shaped transfer material such as paper is brought into close proximity or brought into contact with the toner image.)
Among well-known image forming apparatuses that repeat the process of transferring a toner image onto a transfer material, it has been very common to use a cylindrical photoreceptor that rotates twice as an image carrier.

By the way, if a rotating cylinder is used in this way, due to machining errors, mainly eccentricity, of the rotating cylinder itself or its driving means, even if the latent image is formed on the photoreceptor at a certain timing, it will not be possible to actually form it on the photoreceptor. It is inevitable that differences will occur in the printing intervals of the images (indicated by 21 to 13 in FIG. 8) due to changes in peripheral speed due to eccentricity of the photoreceptor.

This also applies to the drive means for driving the photoreceptor, and the eccentricity of the drive gear causes fluctuations in the circumferential speed of the photoreceptor, resulting in periodic changes in the printing interval similar to the above.

Furthermore, although the above-mentioned problems are also caused by uneven rotation of the motor that is the drive source, the writing of images onto the photoreceptor is often controlled by a constant clock, and the drive is controlled by, for example, using a PLL to drive the motor. Since it is controlled, rotation unevenness and writing timing irregularities can be suppressed to a sufficiently low level for practical purposes, so the errors that actually appear in the final image mainly depend on the eccentricity of the photoreceptor and drive gear as described above. It can be said that.

Therefore, the manner in which errors occur will be discussed with reference to FIG. 9 and subsequent figures.

In FIG. 9, reference numeral 1 denotes a rotating body such as a photoreceptor, and 2 denotes a gear that is coaxial with this and transmits rotation to it.

The radius of the gear 2 is rg, the amount of eccentricity is @g2, the radius of the rotating body 1 is rd, the amount of eccentricity is ad, and the phase difference between the gear and the rotating body in the eccentric direction is α (radian).

In addition, in this figure, in order to make it easier to understand, the amount of eccentricity is shown to be extremely large compared to the rotating body, gears, etc.

With such a configuration, the distance between the shafts of the gear 2 is 2r.
It is assumed that the rotating body is driven at a constant speed by the gear 10, and the difference in printing interval on the rotary body is determined as the difference between the trajectory when there is eccentricity as shown in FIG. 9 and the trajectory when there is no eccentricity.

Assuming that gear 2 rotates defQ when gear 10 rotates dθ, the circumferential speeds of gears 2 and 10 are equal, and therefore the gear 2 rotates dθG.

Therefore, the length variation 45111ΔL on the rotating body is
bL-1, -'rct9]).

As mentioned above, since the error during latent image formation is mainly due to the eccentricity of the photoreceptor and the drive device, the amount thereof can be expressed by the above equation (4).

It is easy to understand that fluctuations in circumferential speed due to eccentricity as described above naturally affect the transfer process as well.

However, in this case, if the transfer material is adsorbed to the photoreceptor and travels synchronously, the image will not change, and the image will be affected only if there is slippage between the two.

Here, if the sliding ratio between the photoreceptor (rotating member 1 in FIG. 9) and the transfer material is Cs, then it is 7.

Here, @g=15IL layer, @d=501Lm.

α=0.45,90,135,180゜225.270
and the change in length ΔL on the photoreceptor at 315°
When t is calculated, the result is as shown in Fig. 10.

As you can see from the same figure.

When α=0°, ΔLt is the minimum, When α=180°, this value is the maximum, Also, the difference from the true value is The maximum value is reached when α is 1,000 90° and 2706 degrees.

Thus, it can be seen that the value of ΔLt largely depends not only on the amount of eccentricity but also on the phase difference α in the eccentric direction.

Based on the above results, the above-mentioned printing interval sentence l, intersection 2Φ・−
φ can be determined by the formula % Formula % As shown in FIG. 11, image signals applied at regular intervals are displayed as an image in a state in which the density is periodically repeated.

In order to avoid such inconveniences, it is obvious that it would be better to increase the processing accuracy of each part, but due to cost considerations, there is a limit to heat output, and it is also possible to increase the accuracy to a certain degree. However, as long as there are processing tolerances, sufficient results cannot always be obtained due to the cumulative effect.

The present invention has been made to deal with this situation, and even if there is eccentricity in the photoconductor, drive gear, or other component parts, the adverse effect on images due to eccentricity can be suppressed to a minimum, and high-quality images can be produced. Along with being obtained.

It is an object of the present invention to provide an image forming apparatus that can suppress variations between products.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides an image forming system that includes a rotating cylindrical image bearing member and a drive gear that drives the image bearing member. The apparatus is characterized in that means is provided for adjusting the amount of eccentricity of the image carrier and the drive gear in the same direction.

With this configuration, it is possible to compensate for the eccentricity of each member and obtain an image faithful to the original on the transfer material.

(Description of Embodiments) FIG. 1 is a perspective view showing only a rotating cylindrical photoreceptor and a drive gear disposed coaxially with the photoreceptor in an image forming apparatus such as a copying machine.

A drive gear 2 is attached to a shaft 4 of the photoreceptor 1, and the gear 2, and thus the photoreceptor 1, is rotated via a drive source and gear train (not shown). A flange 7 is integrally formed on the photoconductor 1, and an appropriate number of screws 81, 82, 83 (three screws are visible in the illustration) are attached to the flange. It is assumed that the photoreceptor 1 is fixed to the shaft 4 by +1e (not limited thereto).

Further, the drive gear 2 is fixed to the collar 10 that is loosely fitted to the shaft 4, and the collar 102 is fixed with an appropriate number of screws 51, 52, -φ (the number of screws is usually at least 3 and can be determined as appropriate). Therefore, the gear 2 is fixed to the shaft 4.

After the photoreceptor 1 is fixed to the shaft 4 in this way, the eccentricity of the photoreceptor is measured by an appropriate measuring means 61, 62 such as a dial gauge, and then the screw 51, 52
Based on the above measurement results, the fitting gap between the gear 2 and the shaft 4 is adjusted, and the eccentricity of the gear is made to be in the same direction as that of the photoreceptor according to instructions from the measuring means 63.

By doing this, it is possible to obtain a latent image or image that is faithful to one original without particularly reducing the two eccentricities (eg and ed in the above explanation), as discussed above with reference to FIG. 9 et seq. can.

FIGS. 2 to 5B show other embodiments of the present invention, and are partial side sectional views showing a structure in which a photoreceptor 1 and a gear 2 are disposed on a shaft 4, similar to the above embodiment. The same reference numerals are given to the parts corresponding to those in the above embodiment.

In FIG. 2, a gear 2 is fixed to a shaft 4 with a screw 9, and the eccentricity of the gear is made to match that of the photoreceptor 1 with a screw 5, as in the case of the previous embodiment. It is something.

FIG. 3 shows a configuration in which a screw hole of the flange 9 of the drive gear 2 is provided on the same generatrix of the drive shaft 4 so that the eccentric directions are aligned.

4A and 4B, a plurality of grooves extending in the axial direction are formed on the outer periphery of the drive shaft 4, the teeth of the drive gear are made eccentric, and a key 2° formed integrally with the gear is The gear is engaged with one of the grooves to match the eccentricity of the gear and the photoreceptor.

5A and 5B, a plurality of screw holes are formed in the circumferential direction in the flange portion of a gear that is made eccentric in the same way as the gear described above, and after adjusting the eccentricity of gear 2 and photoreceptor l, It is constructed so that the gears are fixed.

Figure 6 shows photoreceptor 1. The method of adjusting and attaching the drive gear 2 and the like to the shaft 4 is generally the same as that shown in FIG.
The eccentricity is measured, the amount of eccentricity and the direction of eccentricity are determined by the microcomputer 12, and the rotational fluctuation is determined from the above-mentioned equations 4 and 5.

In addition, since the motor has rotational fluctuations called jitter, this is detected by markings 13-1.13-2.13-3 using the sensor 6, and the amount of eccentricity of the gear 2 is determined.
Even better results can be obtained by controlling the actuator 14 to minimize the direction.

FIG. 7 is a flowchart showing the operation in this case.

(3) Effects of the Invention As is clear from the above description, the present invention enables processing of the movable parts of an image forming apparatus in which an image bearing member that rotates or otherwise runs in an endless manner is driven by a drive source such as a motor. Even in the presence of one assembly error, the mismatch with the original that appears in the final image can be minimized by extremely simple means, and a high-quality image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts showing an embodiment in which the present invention is applied to an image forming apparatus equipped with a rotating cylindrical image carrier, and FIGS. 2 to 5B are main parts showing other embodiments of the present invention. 6 is a perspective view of essential parts showing another embodiment of the present invention, FIG. 7 is a flowchart showing the same operation as above, and FIGS. 8 to 11 are rotating cylindrical image carriers. FIG. 3 is an explanatory diagram illustrating a state in which an image on a body causes uneven rotation due to its eccentricity, and this appears as misalignment in the final image. DESCRIPTION OF SYMBOLS 1...Photoreceptor, 2. Drive gear, 4... Axis, 6.
...Sensor, 7.Flange, 10.Φ.Color. Figure 1? Figure J2 Figure 3 Figure 4A Figure 48 Figure 5A Figure 58 Figure 7 w&9 Figure 11

Claims (1)

[Claims] An image comprising a rotating cylindrical image carrier, a drive shaft for driving the same, a drive gear for driving the shaft, and a drive source, and an image forming means for forming an image on the image carrier. An image forming apparatus characterized in that the image forming apparatus further comprises means for aligning the eccentric directions of the image carrier and the drive gear.