JPH079715A - Image forming device - Google Patents

Abstract

PURPOSE:To form high quality image on recording medium at all times by a method wherein the driving conditions of a carrying roller are determined on the basis of data obtained from a judging means and carrying characteristics data obtained from a retaining means. CONSTITUTION:By setting recording paper 1 to a carrier system under the state that a main carrying roller 5 is stopped at its rotational position, at which the light of a photointerruptor 4 is shielded, the carrying of the recording paper by which the surface of the main carrying roller 5 during the subsequent carrying of the recording paper can be judged. A CPU 10 judges the carrying surface of the main carrying roller 5 of the recording paper 1 by calculating and recording the total rotational angle of a pulse motor 7 since the setting of the recording paper so as to determining the driving conditions such as the number of driving steps, speed and the like of the pulse motor 7 with reference to carrying characteristics table 11. Further, by issuing commands to a pulse motor drive circuit 9, the circuit 9 drives the pulse motor 7 in accordance with the commands.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, it relates to an image forming apparatus having a conveying roller for conveying a recording medium.

[0002]

2. Description of the Related Art Conventionally, there has been known an image forming apparatus for rotating a roller to convey a recording medium to form an image. FIG. 7 shows a recording medium carrying mechanism in such an image forming apparatus.

In FIG. 7, reference numeral 66 is a recording medium such as paper. A recording head 68 forms an image on the recording medium 68. 64 is a main conveyance roller for conveying the recording medium. Each time an image is formed on the recording medium 66 by the recording head 68, the main transport roller 64 is driven to move the recording medium 6 to the recording head 68.
The recording medium 66 is moved so that the recording position next to 6 comes.

Further, 60 is a pulse motor, and 62 is a rubber belt for transmitting the drive of the pulse motor 60 to the main conveyance roller 64. 70 is a pulse motor drive circuit, 72 is a CPU for controlling the pulse motor 60
Is. When parameters such as the amount of rotation and speed are given from the CPU 72 to a predetermined output port, the pulse motor drive circuit 70 drives the pulse motor 60 to rotate.

When the recording medium 66 is conveyed by a predetermined distance x, the main conveyance roller 64 is rotated by (x / 2πr) · 360 degrees depending on the relationship with the radius r of the main conveyance roller 64. The CPU 72 controls the pulse motor drive circuit 70,
To drive.

[0006]

However, the above-mentioned conventional example has the following drawbacks.

That is, in the above-mentioned conventional example, as to how much the recording paper 66 moves when the pulse motor 60 is rotated by a constant step, the distance from the rotation axis of the main transport roller 64 to the surface is constant r. It was decided assuming that there was.

However, the manufacturing roller has different conveyance characteristics depending on the position of the surface of the roller due to an error in a normal process. For this reason, even if the rollers are rotated by the same angle, the movement amount may differ depending on the position where the roller is conveyed with respect to the recording medium, which significantly impairs the accuracy and quality of the formed image on the recording medium. There was a possibility.

Therefore, in view of the above points, an object of the present invention is to provide a low-cost image forming apparatus configured so that an image formed on a recording medium can always be formed in high quality regardless of the conveyance characteristics of the recording medium conveying roller. To provide.

[0010]

In order to achieve such an object, an image forming apparatus according to the present invention comprises a carrying roller for carrying a recording medium, and a holding means for holding the carrying characteristics of the carrying roller. And a determination unit that determines the position of the transportation roller with respect to the recording medium, the data obtained from the determination unit, and the driving condition of the transportation roller based on the transportation characteristic data obtained from the holding unit. And a determining means for determining.

[0011]

According to the above construction of the present invention, the driving condition of the carrying roller is determined based on the data from the roller position judging means and the data from the carrying characteristic holding means. It is possible to form a high quality image without using a special transport roller.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a schematic view of a recording paper conveying system in an embodiment of the present invention. In the figure, 1 is a recording sheet, 3 is a recording head, and 5 is a main transport roller.

The recording paper 1 is moved relative to the recording head 3 by the main transport roller 5, and an image can be formed on an arbitrary position of the recording paper 1.

7 is a pulse motor, 6 is a drive belt, and 8
Is a pulley. The pulley 8 is directly connected to the rotation shaft of the main transport roller 5, and transmits the rotation of the pulse motor 7 to the main transport roller 5 via the drive belt 6. A light shielding plate (not shown) is attached to the pulley 8 and shields the photo interrupter 4 when the main transport roller 5 reaches a predetermined rotation position.

By setting the recording paper 1 in the conveyance system in a state where the main conveyance roller 5 is stopped at the rotation position where the photo interrupter 4 is shielded from light, the main conveyance roller 5 is moved during the subsequent conveyance of the recording paper. It is possible to determine on which surface the recording paper is being conveyed.

Reference numeral 10 denotes a CPU, which is a conveyance characteristic table 1
1, a pulse motor drive circuit 9 is connected.

The transport characteristics of the main transport roller 5 are recorded in advance on the transport characteristic table 11. This conveyance characteristic is such that the surface of the conveyance main roller 5 is 6 degrees every 60 degrees with reference to the position where the photo interrupter 4 is shielded from light.
It is divided into two ranges, and the goodness and badness of each transportability is held by a coefficient with the standard being 1.

FIG. 2 shows the contents of the transport characteristic table.

The CPU 10 determines the conveyance surface of the conveyance main roller 5 with respect to the recording paper 1 by calculating and recording the total rotation angle of the pulse motor 7 from the time of setting the recording paper, and referring to the conveyance characteristic table 11. Determine driving conditions such as the number of driving steps and speed of the pulse motor 7,
A command is supplied to the pulse motor drive circuit 9.

Then, the pulse motor drive circuit 9 drives the pulse motor 7 in accordance with the command supplied from the CPU 10.

FIG. 3 shows a source code in C language of a sequence for determining the number of driving steps of the pulse motor 7 executed by the CPU 10.

The step 1 in FIG. 3 is the transfer characteristic table t.
Refers to.

In step 2, the function f () is a function that returns the step number cs actually given to the pulse motor with the desired step number os as a parameter. However, one step is assumed to be once.

In step 4, s is a variable that holds the number of steps from the 0 ° phase of the main transport roller for the current recording paper, and cs is a variable that holds the number of steps actually given to the pulse motor. .

In step 5, i is a variable which is currently being calculated, and c is a variable which indicates the position of the main transport roller with respect to the current phase as an angle.

Steps 6 and 7 correct os and cs to start the calculation from 0 degrees of the current phase.

In steps 8-12, 60 degrees or 60
The step number s is added for each step, and when the target step number os is exceeded, the process proceeds to step 13.

In step 13, the remaining step number c is obtained.

At step 14, the correction of the transport characteristic table T is added to the remaining number of steps c to obtain the actual step cs.
And the return value cs is returned in step 15.

As described in the present embodiment, the main conveyance roller 5 is divided into six phases every 60 degrees, and each phase has a conveyance characteristic table having an independent value, which is a reference for shielding the photo interrupter 4 from light. High accuracy by determining the position of the main transport roller 5 from the position and deciding how many steps the pulse motor should actually rotate when it is desired to rotate the main transport roller 5 by the desired number of steps. The recording paper can be transported.

FIG. 4 is a flow chart showing the control procedure in this embodiment.

First, in steps S1 and S2, the current phase I and the roller position P during the phase, and the phase J after the conveyance and the roller position R during the phase are calculated.

In step S3, the transport characteristic table t
The corrected actual rotation step number is calculated using [0] to t [5]. Here, in the typical case where the target number of rotation steps is less than 360 degrees and J is larger than I,

[0035]

[Equation 1]

It is calculated by

When the target number of rotation steps is less than 360 degrees and J is smaller than I,

[0038]

[Equation 2]

If the number of steps is 360 degrees or more, and if the surplus obtained by dividing the target number of rotation steps A by 360 degrees is B, then J> I

[0040]

[Equation 3]

When J <I

[0042]

[Equation 4]

When J = I

[0044]

[Equation 5]

It is calculated by

Another embodiment of the present invention will be described below with reference to the related drawings.

Embodiment 2 In the embodiment described above, the actual number of steps is obtained by multiplying the number of steps for each phase by the coefficient of the transfer characteristic table, but the present invention is not limited to such a form. .

For example, it is possible to judge the position of the main transport roller 5 and use the values in the transport characteristic table to change the speed curve of the pulse motor so that a desired transport speed can be actually obtained.

In this case, assuming that the current phase is i and the position of the main transport roller in phase i is c in the above-described embodiment, the first c step is to obtain a desired speed at the i-phase value t [of the transport characteristic table. i], and the correction value is changed every 60 steps until it is rotated by the desired number of steps. The transport speed in this case is shown in FIG.

As a result, more accurate speed control is possible.

Embodiment 3 Also, in the above-mentioned embodiment, in order to determine the position of the roller with respect to the recording medium, the roller is set to a predetermined position by the sensor at the time of setting the recording medium on the roller, and thereafter the pulse to the pulse motor is pulsed. The number is controlled by the CPU, but the number is not limited to this.

For example, it is possible to directly connect a rotary encoder to the shaft of the transport roller so that the output waveform from the rotary encoder changes depending on the position of the transport roller with respect to the recording paper.

Embodiment 4 Also, in the above-mentioned embodiment, the main conveyance roller 5
It is also possible to attach a different magnetic tape 24 for each phase on the side surface (see FIG. 6) and to provide the magnetic head 23 (see FIG. 6) on the recording paper side of the main transport roller 5.

If the recording data of the magnetic tape for each phase is changed so that the output signal from the magnetic head 23 is different for each phase, the magnetic head 23
It is possible to determine the carrier characteristic table to be used by the output signal from the.

[0055]

As described above, according to the present invention, since the driving condition of the transport roller is determined from the data of the transport roller position and the transport characteristic data, the roller manufacturing cost can be increased with high accuracy. It is possible to convey recording paper and form high-precision and high-quality images.

[Brief description of drawings]

FIG. 1 is a diagram showing a recording paper conveyance system in an embodiment of the present invention.

FIG. 2 is a diagram showing contents of a transport characteristic table according to the present embodiment.

FIG. 3 is a diagram showing a drive step determination sequence of a pulse motor.

FIG. 4 is a flowchart showing a control procedure of this embodiment.

FIG. 5 is a diagram showing a transport speed in another example of the present invention.

FIG. 6 is a diagram showing another embodiment of the present invention.

FIG. 7 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 1 Recording Paper 3 Recording Head 4 Photointerrupter 5 Main Conveyor Roller 6 Drive Belt 7 Pulse Motor 8 Pulley 9 Pulse Motor Drive Circuit 10 CPU 11 Conveyance Characteristic Table 23 Magnetic Head 24 Magnetic Tape

Claims (1)

[Claims] 1. A carrying roller for carrying a recording medium, a holding means for holding the carrying characteristics of the carrying roller, a judging means for judging the position of the carrying roller with respect to a recording medium, and the judging means. An image forming apparatus comprising: a determination unit that determines a driving condition of the transport roller based on the data obtained from the data and the transport characteristic data obtained from the holding unit.