JPH055742B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to running paper such as electrostatic recording paper in a color electrostatic recording device (however, it is not limited to paper in the strict sense, but also to films, sheets, etc.). The present invention relates to a running paper position detection device for detecting the position of paper (including the like).

BACKGROUND OF THE INVENTION In recent years, the development of color printers and plotters has progressed, and along with this, there has been a demand for color printing and images as good as color photographs. In order to obtain such good image quality, in an apparatus that obtains a color image by superimposing images of a plurality of colors, alignment of each image is an essential condition. For this reason, an apparatus has been proposed that attaches a registration mark within the effective screen of a recording medium, detects it with an optical sensor, etc., determines the position of the recording medium, and aligns each image. below,
A recording medium position detection device in a conventional color image recording device will be described.

FIG. 6 is a perspective view showing a schematic configuration of a conventional color image recording apparatus. In the figure, reference numeral 1 denotes a recording section, and the recording section 1 includes an electrostatic recording head 2 and liquid toner developers 3a to which black, cyan, magenta, and yellow liquid toners are supplied and independently set at developing positions. , 3b, 3c, and 3d. Conveying rollers 5 and 6 are provided on the upstream and downstream sides of the electrostatic recording paper 4 in the running direction with respect to the recording unit 1,
These conveyance rollers 5 and 6 move the recording paper 4 as indicated by the arrow A in the figure.
Drive in direction B. A presser roller 7 is provided above the recording head 2 to maintain contact between the recording paper 4 and the recording head 2. A mark detector 8 is provided on the lower surface side of the recording paper 4 between the developing device 3a and the recording head 2. 9 is shown as being formed on the top surface of the recording paper 4 for convenience, but it is actually formed on the bottom surface) to detect the position and generate a position signal. The mark detector 8 is connected to a recording head translation control circuit 10 for calculating the amount of deviation of the recording paper 4 in the direction perpendicular to the running direction based on the position signal from the mark detector. Recording head 2
A recording head translation device 11 for translating the recording head 2 in a direction perpendicular to the running direction of the recording paper 4 is provided at a side end of the recording paper 4 . This translation device 11 is connected to the translation control circuit 10 and controlled based on its output signal. Further, a vertical registration mark 12 (written on the top surface of the recording paper 4 for convenience in this figure) is formed on the bottom surface of the recording paper 4. This mark 12 is read by a mark detector 13, and a vertical registration mark 12 is formed on the bottom surface of the recording paper 4.
The amount of deviation in the running direction is detected.

The operation of the color image recording apparatus configured as described above will be described below.

Before the first color image is recorded, the recording paper 4 is first run in the direction of arrow A, and the electrostatic recording head 2 forms 9 and 12 latent images on the recording paper 4, respectively. These are developed by a black liquid toner developer 3a to form horizontal registration marks 9 and vertical registration marks 12. The recording paper 4 on which the horizontal registration marks 9 and the vertical registration marks 12 have been recorded is returned to its original position by reversing the conveyance rollers 5 and 6. Next, to record a black image, use the black liquid toner developer 3 again.
A is set at the development position. While the recording paper 4 is traveling in the direction of arrow A by the conveyance rollers 5 and 6,
Vertical registration mark 1 is detected by mark detectors 13 and 8.
2. Horizontal registration mark 9 is detected. A predetermined number of vertical registration marks 12 are detected by the mark detector 13.
At the same time as the black image is detected, a latent image for a black image is formed on the recording paper 4 by the electrostatic recording head 2. At this time, the mark detector 13 is configured so that the timing for energizing the recording head 2 to form a latent image is always the same number of signal pulses between the vertical registration marks.
It is controlled by the detection signal from. By doing this, even if the recording paper 4 expands or contracts due to changes in humidity, tension during running, etc., it is possible to always record on the same recording line between the vertical registration marks. Further, the mark detector 8 constantly observes the lateral registration mark 9, and sends the amount of deviation when the lateral registration mark 9 deviates from the reference position as the recording paper 4 travels to the recording head translation control circuit 10. The translation control circuit 10 calculates the amount of deviation perpendicular to the running direction of the recording paper 4, determines the amount of translational movement of the recording head 2, and outputs this signal. A signal from the translation control circuit 10 is sent to the translation device 11 to translate the recording head 2 in the direction of arrow C so that the image is always aligned with the horizontal registration mark 9.
It is controlled so that it is recorded equidistant from. In this way, a latent image is formed on the recording paper 4 by the recording head 2 while tracking the horizontal registration mark 9 and the vertical registration mark 12 recorded on the recording paper 4 by the mark detectors 8 and 13, respectively. , developer 3a
Develop it to obtain an image.

When the recording of the black image is completed, the recording paper 4 is pulled back to its original position, and then the cyan liquid toner developer 3b is set to the developing position, and the running state of the recording paper 4 is adjusted to the horizontal registration mark 9 and the vertical registration mark 9. While monitoring the registration marks 12 by tracking them with mark detectors 8 and 13, a latent image is formed by the recording head 2, and a cyan image is developed by the developer 3b. A similar operation is performed sequentially for the magenta and yellow liquid developers 3c and 3d, and finally a full-color image in which four colors are superimposed is obtained.

FIG. 7 is a diagram showing a schematic configuration of the mark detector 8 for tracking the horizontal registration mark 9 in the above apparatus. In this mark detector 8, light from a light source 14 is collected by a condenser lens 15, and illuminates the horizontal registration mark 9 on the recording paper 4 traveling in the direction of the arrow. The light collected on the horizontal registration mark 9 is reflected and sent to the light-to-digital converter 17 through the condenser lens 16, which converts the light into a digital signal proportional to the intensity of the light reflected from the recording paper 4. Occur.

As shown in FIG. 8, the optical-digital converter 17 includes a photodiode 18 whose photocurrent changes depending on the amount of incident light, an operational amplifier 19 that converts the photocurrent of the photodiode 18 into voltage, and an operational amplifier 19.
It has an analog/digital converter 20 that converts the output voltage of the converter into a digital signal. An example of the relationship between the photocurrent of the photodiode 18 and the amount of incident light is shown in FIG. As seen in FIG. 9, the amount of incident light changes depending on the proportion of the horizontal registration mark 9 in the area detected by the photodiode 18. In other words, as shown in FIGS. 10a, b, c, and d, the amount of light entering the photodiode 18 changes depending on which position in the detection area 21 of the photodiode 18 the horizontal registration mark 9 passes. , the amount of deviation of the lateral registration mark 9 can be detected from this amount of change.

The vertical registration mark 12 is composed of a large number of marks formed at regular intervals in the running direction of the recording paper 4, and the mark detector 13 is formed by a mark detector 9.
Similarly, it receives reflected light from the registration mark 12 and generates an output signal corresponding to the amount of incident light. In this case, when the part without the vertical registration mark 12 passes through the detection area of the mark detector 13, the amount of reflected light is large, but when the marked part passes, the amount of reflected light decreases rapidly, so this sudden output The mark position in the running direction of the recording paper 4 can be detected by the decrease.

Problems to be Solved by the Invention However, according to the above configuration, in order to measure the lateral deviation in the running direction of the recording paper and the position (moving speed) in the running direction, the horizontal registration mark 9 and the vertical registration mark are used, respectively. 12 types of registration marks are used, and two mark detectors corresponding to each registration mark must be used. For this reason, there are problems in that the circuit of the recording paper position detection device becomes expensive, and the space occupied by the registration mark within the width of the recording paper increases, reducing the area in which an image can be recorded.

The present invention solves the above conventional problems,
By a low-cost, simple method, and without using much of the effective recording area, it is possible to record the sideways of paper such as recording paper (not limited to paper in the strict sense, but also includes films, sheets, etc.) while it is running. It is an object of the present invention to provide a position detection device for running paper that can detect the position in the direction and lengthwise direction.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a rectangular shape on one edge of the running paper so as to have sides at regular intervals in the running direction and sides perpendicular and parallel to the running direction. A photoelectric conversion means having a rectangular detection area with sides perpendicular and parallel to the running direction of the running paper receives the reflected light. The apparatus is configured to detect the amount of lateral deviation of the registration marks and the pitch between each registration mark from a change in a signal output from a single photoelectric conversion means.

According to the present invention, with the above-described configuration, the amount of light incident on the photoelectric conversion means through the rectangular detection area is reduced when the portions (white portions) between the registration marks arranged at intervals pass through the rectangular detection area. is a large constant quantity,
Next, when the leading edge of the registration mark approaches the rectangular detection area, the amount of light decreases rapidly, and then becomes a small constant amount while the registration mark passes through the entire range of the rectangular detection area in the running direction. Afterwards, when the rear edge of the registration mark approaches the rectangular detection area, the light intensity increases rapidly, and when the registration mark passes, the light intensity returns to the original large constant intensity, and therefore the output signal of this photoelectric conversion means The position (velocity) of the running paper in the running direction is detected by detecting a sudden change in the value, and the amount of horizontal deviation of the registration mark is determined by the output value when the output signal reaches a low constant value. It is possible to detect the amount of displacement in the lateral direction of the running paper.

Embodiments The present invention will now be described in more detail with reference to embodiments of the drawings.

FIG. 1 is a schematic perspective view showing a color image recording apparatus using a position detection device according to an embodiment of the present invention. In addition, in the figure, the same reference numerals are used for the same parts as in the conventional one shown in FIG. 6, and detailed description thereof will be omitted.

Similarly to the color image recording apparatus shown in FIG. 6, the color image recording apparatus shown in FIG. 1 has conveyance rollers 5 and 6 for moving the recording paper 4 in the A direction or the B direction, and the recording section 1 is provided between them. The recording section 1 includes an electrostatic recording head 2 and a presser roller 7 for forming a latent image, a liquid developer 3a to which liquid toner of multiple colors is supplied, respectively.
3b, 3c, and 3d are provided, and a recording head translation device 11 is connected to the recording head 2.

A registration mark detector 23 is arranged below the recording paper 4 between the recording head 2 and the liquid developer 3a. This registration mark detector 23 detects the position of a registration mark 24 formed on the bottom surface of the recording paper 4 (in this figure, the registration mark 24 is written on the top surface of the recording paper for convenience).
The output signal is sent to the position detection circuit 25. The position detection circuit 25 calculates the amount of deviation in the direction perpendicular to the running direction of the recording paper 4 and the pitch (travel speed) between the registration marks 24 from the signal of the registration mark detector 23, and uses information regarding the amount of deviation to translate the recording head. It outputs to the control circuit 26, and also sends information regarding the pitch to the recording timing control circuit 27. The recording head translation control circuit 26 controls the translation device 11 based on the input shift amount information. The recording timing control circuit 27 determines the recording timing for each line of image information recording based on the input pitch information, and controls the head drive circuit 28.
A predetermined number of lines are recorded between registration marks.

The registration mark 24 is different from the conventional one and is formed only on one side of the recording paper 4, as shown in FIG. ) and are arranged at appropriate intervals (pitch P) in the running direction. As shown in FIG. 2, the registration mark detector 23 includes a light source 30 that illuminates the registration mark forming portion of the recording paper 4, a condensing lens 31, and a rectangular opening 3 for making the mark detection area quadrilateral.
It consists of a light shielding plate 32 equipped with 2A, a condensing lens 33 that condenses the reflected light from the recording paper, and a photoelectric conversion section 34. This rectangular opening 32A is arranged so that its sides are parallel and perpendicular to the running direction of the recording paper, as shown in FIG. The end side 24A in the running direction is positioned so as to pass approximately in the middle of the opening 32A. Note that if the light-receiving surface of the photoelectric conversion section 34 is rectangular like the opening 32A, there is no need to provide the light shielding plate 32 in the optical path, and the sides of the rectangular light-receiving surface of the photoelectric exchange section 34 are used for recording. They may be arranged parallel to and perpendicular to the paper running direction. For the photoelectric conversion section 34, a photodiode whose photocurrent changes depending on the amount of incident light is used, and a PIN photodiode, for example, which has particularly good photoresponsiveness is most suitable.

Next, the operation of detecting the registration mark 24 by the registration mark detector 23 will be explained. FIG. 4 shows an example of the output signal of the registration mark detector 23. In FIG. 3a, while the blank area between the registration marks 24 passes through the opening 32A of the registration mark detector 23, that is, the detection area, the photocurrent exhibits a high constant value, and the tip side 24B of the registration mark 24 When approaching the detection area 32A, the photocurrent decreases rapidly. When this tip side 24B passes the detection area 32A, the detection area 32A is located at the registration mark 24.
Since the photocurrent remains partially occluded, the photocurrent is a constant low value. Then register mark 24
When the rear end side 24C approaches the detection area 32A, the photocurrent increases rapidly. Thus, as shown in FIG. 4, the output signal of the registration mark detector 23 has a waveform having a falling part, a constant output part, and a rising part during the mark detection period. Here, the signal waveform 35 in which the magnitude of the output current in the constant output part is I ₁
If, however, the recording paper passes through the regular position (the registration mark 24 passes through the position shown in FIG. 3a), then the registration mark 2
4 is displaced to the left in the running direction of the recording paper (the case shown in FIG. 3b), the magnitude of the output current in the constant output section decreases as shown by I ₂ .
This is because the area through which the registration mark 24 passes within the mark detection area 32A increases. Note that if the registration mark 24 is displaced to the right in the running direction of the recording paper 4, the output during this period will increase compared to the normal position. Therefore,
By comparing the output current value of the constant output section with a certain specified value, the amount of deviation in the direction perpendicular to the running direction of the recording paper 4 is detected, and this operation is carried out by the detection circuit 25 in FIG. There is. Also, by comparing the falling part or the rising part of the output signal waveform in FIG. 4 with a certain detection level, the registration mark 20
By detecting each registration mark 24 one by one at this point, the pitch of the registration mark (travel speed) can be determined. ) can be detected. This pitch detection operation is also performed by the detection circuit 25.

FIG. 5 shows a specific example of the detection circuit 25 that detects the amount of deviation of the recording paper and the pitch P of the registration mark from the output from the photoelectric conversion section 34. Fifth
In the figure, a photocurrent from a photodiode forming a photoelectric conversion section 34 is converted into a voltage by an operational amplifier 40, amplified, and converted into a digital signal by an analog/digital converter 41.
This digital signal is sent to the programmable counter 4
latch 4 actuated by an output trigger from 2
3 and is used as information indicating the amount of deviation. Note that the count time by the counter 42 may be set in advance so that the constant output portion of the signal waveform shown in FIG. 4 can be output. Further, the output of the operational amplifier 40 is inputted to the counter 44 as a counter clear signal and to the latch 45 as a trigger signal. As a result, the latch 45 outputs a count signal indicating the pitch P of the registration mark 24. In this way, information regarding the amount of deviation of the recording paper and the mark pitch can be obtained using a single registration mark detector.

Regarding mark pitch detection, in detection using a fixed detection level, if the registration mark 24 is misaligned in the direction perpendicular to the running direction, the waveform during the mark detection period will be different from that in the normal position. Accurate detection is not possible. but,
Since this error is minute, there is usually no problem. If necessary, the output values of the constant output part I ₁ , I ₂
By changing the detection level depending on the size of the registration mark, it is possible to accurately detect the pitch of the registration mark.

Next, the operation of the color image recording apparatus shown in FIG. 1 equipped with the position detecting device having the above structure will be briefly explained.

Before the first color image is recorded, the recording paper 4 is first run in the direction of arrow A, and the electrostatic recording head 2 forms latent images of the registration marks 24 on the recording paper 4. These are developed by the black liquid toner developer 3a to form registration marks 24. After recording the registration marks, the recording paper 4 is pulled back to its original position by reversing the conveyance rollers 5 and 6. Next, in order to record a black image, the black liquid toner developing device 3a is again set at the developing position. As the recording paper 4 travels in the direction of arrow A by the conveyance rollers 5 and 6, the registration mark 24 is detected by the registration mark detector 23, and its output signal is sent to the detection circuit 2.
At the same time, a latent image for a black image is formed on the recording paper 4 by the electrostatic recording head 2. At this time, the detection circuit 25 detects the pitch of the registration mark 24 on the running recording paper according to the procedure described above, and sends the information to the recording timing control circuit 27. The recording timing control circuit 27 controls the head drive circuit 28 so that recording is performed between each pitch of the registration mark using the same number of signal pulses. By doing this, the recording paper 4 is exposed to humidity changes,
Even if the registration marks 24 are expanded or contracted due to tension during running, the same recording line can always be recorded between the registration marks 24. Furthermore, the detection circuit 25 sends information regarding the amount of deviation in the direction perpendicular to the running direction of the recording paper 4 to the recording head translation control circuit 26. Translation control circuit 2
6 determines the amount of translational movement of the recording head 2 according to the amount of deviation in the direction perpendicular to the running direction of the recording paper 4;
The recording head 2 is translated in the direction of arrow C by controlling the translation device 11, and the image is always aligned with the registration mark 2.
Record at a position equidistant from 4. In this way, by tracking the running state of the recording paper 4 with the registration mark 24 recorded thereon by the registration mark detector 23, a latent image is formed on the recording paper 4 by the recording head 2 while being constantly monitored, and the latent image is formed by the developing device. 3a to obtain an image.

When the recording of the black image is completed, the recording paper 4 is pulled back to its original position, and then the cyan liquid toner developer 3b is set to the developing position, and the running state of the recording paper 4 is checked so that the registration mark 24 is aligned with the registration mark. A latent image is formed by the recording head 2 while being tracked and monitored by the detector 23, and a cyan image is developed by the developer 3b. Similar behavior with magenta,
The process is performed sequentially for the yellow liquid developing devices 3c and 3b, and finally a full-color image in which four colors are superimposed is obtained.

Effects of the Invention As is clear from the above description, the present invention provides a rectangular shape having one edge of the running paper whose position is to be detected at a constant interval in the running direction and having sides perpendicular and parallel to the running direction. form a registration mark,
The registration mark is irradiated with a light source and the reflected light is received by a photoelectric conversion means having a rectangular detection area with sides perpendicular and parallel to the running direction of the paper. The waveform of the output signal from the conversion means when passing the registration mark, that is, the output signal during the mark detection period, has a falling part, a constant output part, and a rising part. By comparing the timing with the detection level and measuring the timing for each registration mark, it is possible to detect the pitch between the registration marks. Also, by detecting the output signal of the constant output part, the horizontal direction of the registration mark can be detected. It is possible to detect the amount of deviation, that is, the amount of deviation in the lateral direction of the running paper, and as a result, there is no need for two rows of registration marks as in the past, and the surface of the running paper can be used more widely and effectively. Moreover, compared to the case where two mark detectors are used, the apparatus can be simplified and the cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a color image recording device equipped with a position detection device according to an embodiment of the present invention, and FIG. 2 is a side view schematically showing the configuration of a registration mark detector of the device shown in FIG. , FIG. 3 is a plan view illustrating the positional relationship between the mark detection area of the registration mark detector and the registration marks, FIG. 4 is an output waveform diagram of the registration mark detector, and FIG. 6 is a schematic perspective view of a conventional color image recording device, FIG. 7 is a schematic side view of the mark detector of the device shown in FIG. 6, and FIG. 8 is an electric circuit diagram showing a specific example of the detection circuit. Figure 7 is an electrical circuit diagram of the light-to-digital converter of the mark detector, Figure 9 is a graph showing the relationship between the photodiode's power generation current and the amount of incident light, and Figure 10 is the photodiode in the device shown in Figure 6. FIG. 3 is a plan view showing the positional relationship between the photodetection area and the horizontal registration mark. 1... Recording section, 2... Electrostatic recording head, 3a,
3b, 3c, 3d...Developer, 4...Recording paper,
5, 6...Conveyance roller, 7...Press roller, 23
... Registration mark detector, 24 ... Registration mark, 25 ... Detection circuit, 30 ... Light source, 32A
...Aperture, 32... Light shielding plate, 34... Photoelectric conversion section.

Claims (1)

[Claims] 1. Rectangular registration marks formed on one edge of the running paper at regular intervals in the running direction and having sides perpendicular and parallel to the running direction;
A single photoelectric sensor that has a light source that illuminates this registration mark and a rectangular detection area with sides perpendicular and parallel to the running direction of the running paper, and that receives reflected light from the running paper and generates an electrical signal. a converting means, and a change in the output value of the photoelectric converting means due to a change in brightness when the registration mark passes through the detection area, and a change in the output value of the photoelectric converting means that is constant while the registration mark is passing through the registration mark. A position detecting device for running paper, comprising a detection circuit for detecting the amount of lateral deviation and the pitch between each registration mark.