JPH0346947A - Transfer device - Google Patents

Abstract

PURPOSE:To prevent the appearance of irregular feed on photoconductive sheets, which arises in harmonic drive, by installing a belt-shaped elastic transmission member between the output shaft and the drive roller of the harmonic drive, and constituting in such a way that a half turn of a motor equals an amount of carrier for a scan in the secondary scanning direction of photoconductive sheets. CONSTITUTION:It is so set up that irregular feed arising on a harmonic drive 2 for a period, i.e., a half turn of a motor 1 on an input shaft side, corresponds with a scan in the secondary scanning direction. Irregular feed can be removed by this with rotary transmission error arising at a rate of once every half turns of the harmonic drive 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a conveying device such as a laser plate making device. In particular, the present invention relates to a conveying device used in an image forming apparatus such as a laser engraving device, for eliminating uneven feeding that occurs in a harmonic drive, which is a reduction gear tank.

(Prior Art) FIG. 2 shows a conventional conveying device for a laser plate making device using a harmonic drive as a speed reduction mechanism.

In this conventional conveying device, a laser beam from a light source 10 passes through a collimator lens 9, is reflected on the surface of a rotating polygon mirror 7 driven by a scanner motor 8, and further passes through an fo lens 6, where the laser beam passes through a collimator lens 9. The conductive sheet 4 is exposed to light. Here, since the rotating polygon R7 is rotating at a constant speed, the photoconductive sheet 4 is scanned at regular intervals for each -plane. For this reason, it is necessary to convey the photoconductive sheet 4 at a constant speed in the sub-scanning direction, but here, in the sub-scanning direction, the rotation of the motor 1 is rotated by the drive roller 3 via the harmonic drive 2 of the reducer. , feed the photoconductive sheet 4. At this time, the motor rotation speed, the reduction ratio of the harmonic drive 2, and the radius r of the drive roller 3 were set so as to feed the photoconductive sheet 4 at a predetermined speed.

However, in the conventional conveying device, a rotation transmission error occurs in the harmonic drive 2, which is a speed reducer, and this causes uneven feeding.

In order to solve the above problem, the present inventors have proposed
037, that is, in the conveyance device of an image forming apparatus that uses harmonic drive 2 as a deceleration mechanism, motor 1
By configuring so that 1/2 rotation of the photoconductive sheet 4 corresponds to the conveyance amount for one scan in the sub-scanning direction, uneven feeding caused by the harmonic drive 2 does not appear on the photoconductive sheet 4. can do.

(Problems to be Solved by the Invention) However, in the conventional conveyance mechanism, there is a limit to the reduction ratio of the harmonic drive 2, so if the conveyance amount for one scan in the sub-scanning direction of the photoconductive sheet 4 is small, that is,
For high resolution image forming devices, motor 1
There is a problem in that it is difficult to configure the photoconductive sheet 4 so that 1/2 rotation corresponds to the conveyance amount for one scan in the sub-scanning direction.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and
To explain with reference to FIG. 1 corresponding to the embodiment, in order to two-dimensionally scan the photoconductive sheet 4, which is irradiated with a light beam deflected in the -dimensional direction and main scanning is performed, the light beam is directed perpendicular to the main scanning direction. A pair of rollers 3 and 5 that grip and convey the photoconductive sheet 4 in the sub-scanning direction, and one driving roller 3 of the pair of rollers 3.5 are driven through a harmonic drive 2 that is a speed reduction mechanism. In a conveying device driven by a motor 1 rotating at a constant speed, a belt-like elastic transmission member 20 is provided between the output shaft of the harmonic drive 2 and a drive roller 3, and the reduction ratio of the harmonic drive 2 is R. By setting the relationship between the reduction ratio R2 of the member 20, the radius of the drive roller 3, and the conveyance amount X of the photoconductive sheet 4 for one scan in the sub-scanning direction to be (r/RL・R,)×π=X. 172 rotations of the motor corresponds to the conveyance amount for one scan in the sub-scanning direction of the photoconductive sheet.

(Function) According to the present invention, one cycle of uneven feeding occurring in the harmonic drive, that is, 1/2 rotation of the motor on the input shaft side, is set to match the conveyance amount for one scan in the sub-scanning direction. can do.

Therefore, it is possible to eliminate uneven feeding due to a rotational transmission error that occurs once every 1/2 rotation of the harmonic drive.

(Example) The present invention will be explained below with reference to the drawings. FIG. 1 is a diagram illustrating an embodiment of the present invention, and the same parts as the conventional one shown in FIG. 2 are given the same reference numerals, and detailed explanation will be omitted. A motor 1 rotating at a constant speed is coupled to the input side of a harmonic drive 2, which is a speed reduction mechanism, and the rotation of the output side of the harmonic drive 2 is transmitted at a reduced speed to a drive roller 3 via a belt-shaped elastic transmission member 20. Ru. Here, this belt-shaped transmission member 20 is a harmonic drive 2
The timing pulley 23 is attached to the output shaft of the roller 3, the timing pulley 22 is attached to the moving roller 3, and the timing belt 21 connects them. Further, the photoconductive sheet 4 is held between a tension roller 5 and a drive roller 3, and is conveyed as the drive roller 3 rotates.

Therefore, 1/2 rotation of the motor 1 becomes 1/2 R□ rotation on its output shaft due to the reduction ratio R of the harmonic drive 2, and the number of teeth Z of the timing pulley 23 and the number Z of teeth of the timing pulley 22.

The reduction ratio R2 (=z
x / Z □), it is transmitted to the drive roller 3 by 1/2R rotation/R8 rotation, and at the outer periphery of the drive roller 3 with radius r, (1/2R1・R,)X2xXr=r・π/R,・R
.

The amount of rotation will be .

To show an example in which the rotary lid of (r・π/R,・Rl) and the transport amount X for one scan in the sub-scanning direction are the same, the transport amount X for one scan in the sub-scanning direction is 0.11, and the reduction ratio Rt of the harmonic drive 2 = 10° and the reduction ratio R2 of the timing belt 21 = 2, the radius r of the drive roller 3 is given by the formula r・π/R・R,=X. 6.37mm
becomes.

With the above configuration, 172 rotations of the motor 1 in the sub-scanning direction 1
The amount of conveyance can be made to match the amount of conveyance for scanning, and therefore, the transmission error that occurs once every 1/2 rotation of the motor that occurs in the harmonic drive 2 does not appear on the photoconductive sheet 4.

(Effects of the Invention) As described in detail above, according to the present invention, in the conveyance device of an image forming apparatus using a harmonic drive as a reduction mechanism, a belt-like elastic material is provided between the output shaft of the harmonic drive and the drive roller. By providing a transmission member, the motor
By configuring the photoconductive sheet so that 72 rotations corresponds to the conveyance amount for one scan in the sub-scanning direction, uneven feeding caused by the harmonic drive can be prevented from appearing on the photoconductive sheet. Moreover, since uneven feeding can be eliminated regardless of the precision of the harmonic drive, there is an advantage that a harmonic drive with lower precision, that is, cheaper, can be used.

Furthermore, the frequency component of uneven transmission that occurs in a harmonic drive consists of a fundamental wave whose period is 1/2 rotation of the motor and its harmonics. Due to its elasticity, it is not transmitted to the drive roller, and as a result, printing position accuracy can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG. 2 is a configuration diagram showing a driving section of a laser plate making apparatus using a harmonic drive and a timing belt as a belt-like elastic transmission member. 1...Motor 2...Harmonic drive 3...Drive roller 4...Photoconductive sheet 5...Tension roller 6... ... f/theta lens 7 ... Rotating polygon mirror 8 ... Scanner motor 9 ... Collimator lens 10 ... Light source 20 ... Belt-shaped elastic transmission member 21...
·Timing belt

Claims (1)

[Claims] In order to two-dimensionally scan the photoconductive sheet 4, which is irradiated with a light beam deflected in one-dimensional direction to perform main scanning,
A pair of drive rollers 3 and tension rollers 5 that sandwich and convey the photoconductive sheet 4 in the sub-scanning direction perpendicular to the main-scanning direction, and a harmonic speed reduction mechanism that is used to connect the drive rollers 3 and tension rollers 5 to each other. In a conveyance device driven by a motor 1 that rotates at a constant speed via a drive 2, a belt-shaped elastic transmission member 20 is provided between the output shaft of the harmonic drive 2 and the drive roller 3, and the reduction ratio R_1 of the harmonic drive 2, the belt The relationship between the reduction ratio R_2 of the shaped elastic transmission member 20, the radius of the drive roller 3, and the conveyance amount X of the photoconductive sheet 4 for one scan in the sub-scanning direction is (r/R_1・R_2)×π=X. As a result, 1/2 rotation of the motor 1 rotates the photoconductive sheet 4 in the sub-scanning direction 1.
A conveyance device characterized in that the conveyance amount is equal to the amount of scanning.