JPH06286906A - Recording paper dislocation detector - Google Patents

Abstract

PURPOSE:To detect recording paper for its lateral dislocation high accurately and in a wide range by a simple constitution. CONSTITUTION:A value of electrostatic capacity of parallel electrode plates of interposing an end part of recording paper 1 is detected by an oscillator 3 and a counter timer circuit 4. In an arithmetic part 5, this value is input and prestored in a memory 6. Based on an electrostatic capacity value respectively in the case of not providing the recording paper 1 between electrodes and in the case of returning the recording paper 1 to a reference position at familiarizing operation time, prescribed arithmetic operation is performed to calculate lateral displacement of the recording paper. As a result, by a simple constitution, the lateral dislocation of the recording paper can be detected highly accurately and further in a wide range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a paper edge of a recording paper to be transferred, and more particularly to a recording paper misregistration amount detecting device for detecting a misregistration amount of a recording paper used in a multi-pass type thermal transfer recording device. Regarding

[0002]

2. Description of the Related Art Generally, in a so-called multi-pass type thermal transfer recording apparatus in which multiple colors are transferred and recorded on a recording paper, when recording two colors, for example,
The recording paper is sent out, one page of recording is performed with the first ink film, the recording paper is rolled back after the end, and the rolled back recording paper is fed again to perform recording with the second ink film. It has become a thing. Also,
When recording in more colors, multicolor recording is performed by repeating the above-described rewinding of the recording paper and the recording operation with the ink film.

When a long recording is carried out by such a recording apparatus, a so-called skew phenomenon occurs in which the recording paper is fed in an oblique direction, and when a plurality of recording operations are carried out, the recording shifts to cause color misregistration. There was a problem that the image quality was deteriorated. Therefore, in the conventional recording apparatus, the state of the surface of the recording paper is stored, the state of the recording paper surface is detected for each recording, and the degree of correlation with the state detected at the previous recording is calculated, The reference position of the recording paper is corrected based on the calculated degree of correlation to prevent the deviation of the recorded image.

[0004]

However, the conventional recording apparatus as described above is for detecting the deviation amount in the feeding direction of the recording paper, that is, the vertical direction, and the recording paper 1 as shown in FIG. However, there is a problem that the amount of deviation in the lateral direction, that is, in the direction orthogonal to the recording paper feeding direction cannot be detected. That is, when detecting the lateral position of the recording paper 1,
A transmissive (or reflective) optical sensor 10 is arranged at an end portion of the recording paper 1, and when the output of the optical sensor 10 reaches a predetermined amount, the end portion of the recording paper 1 reaches a predetermined position. Is detected, and the detectable range of the transmissive optical sensor 10 is
Since it is the slit part of the sensor, it is very narrow, and this type of optical sensor has variations in its output characteristics (the inclination of the sensor output in the detectable range in the figure) shown in FIG. However, there is a problem in that the lateral shift amount cannot be accurately detected. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a recording paper deviation amount detecting device capable of detecting a lateral deviation of a recording paper with a high precision and a simple structure over a wide range.

[0005]

In order to solve such a problem, the present invention provides a parallel electrode plate sandwiching an end portion of a recording sheet and a detecting means for detecting the value of the electrostatic capacitance of the parallel electrode plate. And a calculating means for calculating the change in electrostatic capacitance based on the detection output of the detecting means and calculating the lateral deviation amount of the recording paper.

[0006]

The amount of lateral deviation of the recording paper is detected by the change in the electrostatic capacity of the parallel electrode plate.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a recording paper deviation amount detecting device according to the present invention, which is applied to a multi-pass type thermal transfer recording device. In the figure, 1 is a recording paper, 2 is a parallel electrode plate, and is an edge detector for detecting the end position of the recording paper 1, 3 is an oscillator such as a relaxation oscillator, 4 is a counter / timer circuit, and 5 is a calculation. Part 6 is a memory.

Here, the edge detecting section 2 detects the lateral deviation state of the recording paper by the change of the electrostatic capacity, as will be described later, and when the value of this electrostatic capacity is given to the oscillator 3. The oscillator 3 outputs a pulse having a cycle corresponding to the capacitance. The counter / timer circuit 4 counts the number of this pulse based on the clock signal a and outputs it to the arithmetic unit 5. The calculation unit 5 inputs the count value of this pulse and is stored in the memory 6 in advance. When the recording paper does not exist between the electrodes and when the recording paper is returned to the reference position during the smoothing operation described later, respectively. Predetermined arithmetic processing is performed based on the count value corresponding to the electrostatic capacitance value, and the lateral deviation amount b of the recording paper is output.

Next, FIG. 2 is a diagram showing a state of detection of the end portion of the recording paper. As shown in FIG. 2B, the edge detector 2
Are two metal plate electrodes (hereinafter, electrodes) 2 arranged in parallel
When the recording paper 1 is arranged so that the end portion of the recording paper 1 is inserted between the electrodes 2A and 2B, the electrostatic capacitance between the electrodes 2A and 2B becomes It changes depending on the quantity. The recording paper deviation amount detection device of the present invention is
The horizontal deviation of the recording paper is detected by utilizing this change in electrostatic capacity.

That is, the capacitance of the electrodes 2A and 2B is as shown in FIG.
As shown in (b), the electrostatic capacitances C1 of the portion where the recording paper 1 is inserted and the portion where the recording paper 1 is not inserted are
It can be divided into C2. Here, when the potential difference between the electrodes is V and the charge density is σ,

V = σt / ε 1 + σ (d−t) / ε 0 = σ {(1 / ε 1 −1 / ε 0) t + d / ε 0)} (1) It should be noted that ε0 and ε1 respectively represent the dielectric constants of the portion where the recording paper 1 is not inserted between the electrodes (that is, air) and the portion where the recording paper 1 is not inserted (that is, the recording paper 1),
d is the distance between the electrodes, and t is the thickness of the recording paper 1.

Therefore, when the length of the recording paper 1 inserted between the electrodes is x and the length of the electrodes in the longitudinal direction (that is, the recording paper feed direction) is L, the electrostatic capacitance C1 is C1. = [Sigma] L / V = xL / {(1 / [epsilon] 1-1 / [epsilon] 0) t + d / [epsilon] 0)} (2)

On the other hand, the capacitance C2 can be expressed as C2 = ε0 (x0-x) L / d (3), where x0 is the lateral direction of the electrodes (that is, the direction orthogonal to the recording paper feed direction). it can.

Therefore, the total capacitance C between the electrodes is C = C1 + C2 = [1 / {(1 / ε1-1 / ε0) t + d / ε0)}-ε0 / d] xL + ε0x0L / d (4) Become.

Therefore, the above equation (4) can be expressed as C = Kx + C0 (where K and C0 are constants) (5).

As can be seen from the equation (5), the electrodes 2A, 2
Depending on the insertion amount x of the recording paper 1 into the B, the total capacitance between the electrodes changes linearly. Therefore, as shown in FIG. 2A, if the end of the recording paper 1 is inserted between the electrodes 2A and 2B, the end position of the recording paper can be detected based on the capacitance. .

In this way, the edge of the recording paper 1 can be detected from the electrostatic capacitance between the electrodes 2A and 2B, but when the type of recording paper, that is, the material, changes its dielectric constant ε1, and It is necessary to recalculate the constant K due to the change in the thickness t of the recording paper. However, if it is possible to return the paper to a certain position due to the lateral displacement of the recording paper by a leveling operation for the recording paper feed system, etc., regardless of the type and thickness of the recording paper, Its end position can be detected.

That is, when the position where the lateral displacement can be restored by the leveling operation or the like is x, the electrostatic capacitance Cr between the electrodes at that time is
From the equation (5), Cr = Kx + C0 (6).

Next, the electrostatic capacitance Cd when the recording paper is deviated by .DELTA.x based on this position is Cd = K (x + .DELTA.x) + C0 (7).

As can be seen from the equation (4), since all constants related to the material and thickness of the recording paper are included in the constant K, from the equations (6) and (7), Δx = ( Cd-Cr) x / (Cr-C0) (8), and the movement amount .DELTA.x from the reference position can be obtained regardless of the material and thickness of the recording paper. It should be noted that C0 represents the electrostatic capacity when no recording paper is inserted between the electrodes 2A and 2B. In fact, C0 also contains stray capacitance, but this is irrelevant to the position x.

Therefore, as a procedure for detecting the lateral shift amount of the recording paper 1, firstly, as a first procedure, the recording paper 1 has electrodes 2A,
The capacitance C0 when not inserted between 2B is measured and stored. Next, as a second procedure, a leveling operation or the like is performed to correct the recording paper to the reference position, and the electrostatic capacitance Cr at that time is measured and stored. Finally, as the third procedure, when it is desired to detect the amount of deviation of the recording paper, the electrostatic capacitance Cd at that time is measured, and Δx is calculated by the equation (8).

Next, FIG. 3 is a circuit diagram showing the configuration of the oscillator (relaxation oscillator) 3 for detecting the amount of deviation of the recording paper 1. Here, the unknown capacitance Cx in the figure corresponds to the capacitance of the deviation detection unit 2, that is, the electrodes 2A and 2B. In this case, the oscillation cycle T of the oscillator 3 is T = 2CxR1log2 (9). Therefore, by measuring the cycle T, the unknown capacitance Cx
Can be asked.

Since the oscillator 3 oscillates as a square wave with a duty of 50%, its output can be directly connected to a digital circuit, and the oscillation period T can be measured more accurately by counting a large number of waves. Moreover, since it is not a voltage level measurement, it is not affected by noise.

As described above, in this embodiment, the change in the electrostatic capacitance between the electrodes 2A and 2B due to the insertion of the recording paper 1 is calculated based on the oscillation period T of the oscillator 3, and the recording paper is based on this. The horizontal deviation of 1 can be detected with high accuracy and in a wide range. Note that other techniques may be used instead of the oscillator 3 as long as the capacitance can be detected. In addition, in the present embodiment, an example in which the lateral deviation of the recording paper is detected in the multi-pass type thermal transfer recording device has been described, but the present invention is not limited to this, and any device can be used as long as it is a device for transferring the recording paper. Can also be applied to.

[0025]

As described above, according to the present invention,
Since the edges of the recording paper are sandwiched by the parallel electrode plates and the amount of horizontal displacement of the recording paper is detected by the change in the capacitance of the parallel electrode plates, the horizontal displacement of the recording paper is highly accurate and wide range with a simple configuration. Can be detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a recording paper deviation amount detection device according to the present invention.

FIG. 2 is a diagram showing a lateral deviation detection state of recording paper in the above apparatus.

FIG. 3 is a circuit diagram showing an example of an oscillator constituting the above device.

FIG. 4 is a diagram showing a detection state of a recording paper lateral deviation in a conventional apparatus.

FIG. 5 is a diagram showing an output characteristic of a photo sensor that detects an edge portion of a recording sheet in a conventional apparatus.

[Explanation of symbols]

 1 Recording Paper 2 Edge Detection Unit (Parallel Electrode Plate) 3 Oscillator (Detection Unit) 4 Counter / Timer Circuit (Detection Unit) 5 Calculation Unit (Calculation Unit) 6 Memory

Claims (1)

[Claims] 1. A recording paper misalignment amount detection device for detecting the amount of misalignment of the recording paper by detecting the edge of the recording paper being transferred, comprising: a parallel electrode plate sandwiching the end of the recording paper; and a parallel electrode. A detection means for detecting the capacitance value of the plate; and a calculation means for calculating the change in the capacitance on the basis of the detection output of the detection means to calculate the lateral displacement amount of the recording paper. A recording paper misalignment amount detection device.