JP2645007B2 - Image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of forming a marking provided on a recording paper and having an edge in a direction intersecting the moving direction of the recording paper in a direction intersecting the moving direction of the recording paper. The present invention relates to an image recording apparatus which reads by a plurality of arranged photoelectric sensing elements and obtains a signal for controlling an image forming position based on a detection signal from each photoelectric sensing element.

(Prior art)

In addition to providing a marking for aligning the image forming position in the area outside the effective screen of the recording paper, a marking sensor is disposed so as to face the recording paper so as to read the marking, and the marking is moved with the movement of the recording paper. US Pat. No. 4,440,1024 discloses an image recording position control method in which marking information obtained by crossing the marking sensor position is used as a signal for controlling the image forming position on the recording paper, and the image forming position is controlled based on this signal.
And U.S. Pat. No. 4,859,984, U.S. Pat. No. 4,658,984, and the like, as well as in Japanese Patent Application Laid-Open Nos. Sho 57-124753 and Sho 57-122455.

Each of the above known examples detects the marking position on the recording paper, that is, the recording paper position in the recording paper feeding direction, based on a signal generated when the marking written on the recording paper as the recording paper moves crosses the sensor. I do it. In the detection of marking having a marking edge in a direction intersecting the moving direction of the recording paper, the detection purpose is basically achieved by detecting the marking by a single photoelectric sensor. In order to increase the detection accuracy, a sensor having a small spot diameter is usually used.

FIG. 7 is a diagram showing a configuration example of a sensor having a small spot diameter. The sensor 1 includes a light emitting laser diode 2, a light projecting lens system 3, a light receiving lens system 4, a light receiving photodiode 5, a light receiving element driving circuit 6, a light receiving element driving circuit 7, and the like. In a typical example, a beam diameter of 60 μm and a detection accuracy of ± 10 μm are realized, which is sufficient to satisfy the required accuracy of alignment in ordinary image recording.

Known examples of the marking detection means include JP-A-61-221764, JP-A-61-265506, and JP-A-61-265507.

[Problems to be solved by the invention]

The markings read by the sensor are printed on recording paper in advance, or written using the same recording system as image recording in the first step of image recording,
This marking may have partial defects. In such a case, when the marking detection is performed by the sensor 1 having a small spot diameter as shown in FIG. 7, the above-described defect is detected because the detection area of the sensor 1 is too small, and the desired marking reading information is not obtained. There was a problem that it could not be obtained.

FIG. 8 is a diagram showing an example of a marking defect that occurs when a marking used for alignment of each color is written by a multi-stylus electrostatic recording head in a color electrostatic plotter. FIG. 2A shows a state where the marking is basically correctly recorded. However, in the case of this marking, there is a gap between the dots because the diameter of the recording dot 8 is small, and if the passing position of the detection spot of the sensor overlaps this gap, a detection error may occur.
FIG. 6B shows a case where a phenomenon called abnormal discharge has occurred, in which a recording dot 8a much larger than a normal recording dot 8 size is formed. If a sensor crosses this portion 8a, a large detection error naturally occurs. FIG. 7C shows a case where a phenomenon called dot missing has occurred, in which the diameter of the recording dot 8 is remarkably reduced as in 8b, or a state in which no recording is formed as in 8c. Therefore, a detection error occurs when the sensor crosses these portions 8b and 8c. Further, FIG. 9D shows a case where dots 8d, 8e, etc., in which the peripheral portion of the dot 8 has a high density but the central portion has a low density, occur. Also in this case, a detection error occurs depending on the setting of the detection level of the sensor. Such minute defects cannot be completely eliminated even if the marking is formed by another recording method.

If the detection spot diameter of the sensor is increased, the detection error based on the above-described defect is reduced. However, when the detection spot diameter of the sensor is large, the detection accuracy is lowered, and a problem such as a change in the detection position due to a change in the base fog density or the recording density of the marking occurs, and the detection performance becomes extremely unstable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image recording apparatus having a marking reading means capable of detecting an error without any error even if the marking includes a minute defect.

[Means for solving the problem]

In order to solve the above problems and achieve the object, the image recording apparatus of the present invention is configured as follows.

(1) A marking provided on a recording sheet and having an edge in a direction intersecting with the moving direction of the recording sheet is read by a plurality of photoelectric sensing elements arranged in a direction intersecting with the moving direction of the recording sheet. An image recording apparatus that obtains a signal for controlling an image forming position based on the detection signal of the above, wherein, among the plurality of photoelectric sensing elements, a predetermined number or more of photoelectric sensing elements detect a mark, and the edge of the marking is detected. Is determined.

(2) A marking provided on the recording paper and having an edge in a direction intersecting with the moving direction of the recording paper is read by a plurality of photoelectric detecting elements arranged in a direction intersecting with the moving direction of the recording paper. An image recording apparatus for obtaining a signal for controlling the image forming position based on the detection signal of the above, wherein an average value of the detection signals of the marking length and / or the distance between the markings from the plurality of photoelectric detection elements is obtained, and based on the average value To determine the marking length and / or the distance between the markings.

(3) A marking provided on the recording paper and having an edge in a direction intersecting with the moving direction of the recording paper is read by a plurality of photoelectric sensing elements arranged in a direction intersecting with the moving direction of the recording paper. An image recording apparatus that obtains a signal for controlling the image forming position based on the detection signal of the above, obtains the most frequent value of the detection signal of the marking length and / or the distance between the markings from the plurality of photoelectric detection elements, Is configured to determine the marking length and / or the distance between the markings based on

[Action]

The following effects are exhibited by taking such means. That is, even if a minute defect is included in the marking, the influence is removed from the detected marking information, so that the marking can be correctly detected, and the detection area of the applied photoelectric detection element is sufficiently small. Can improve the detection accuracy,
Detection can be performed without being affected by fluctuations in the recording density of base fog or marking.

〔Example〕

FIG. 1 is a configuration diagram of an image recording apparatus recording system showing an embodiment in which the present invention is applied to an electrostatic color plotter.

Reference numeral 10 denotes an electrostatic recording paper supply roll, and a recording paper holding cylinder 10b including a forward / reverse rotatable drum or the like having a drive shaft 10a.
One end of the electrostatic recording paper 11 is fixedly wound.
The other end of the electrostatic recording paper 11 is guided by guide rollers 12a, 12b, 12c, guided to a pair of upper and lower feed rollers 13a, 13b, and is extended in a recording path. Then, the multi-stylus electrostatic recording head 14 can be moved by a known means in a direction perpendicular to the recording surface of the recording paper 11 so that color electrostatic recording is performed on the expanded recording paper 11. A pressure roller 15 as a back electrode is disposed to face the rear side of the recording paper 11. Developing / fixing heads 16a to 16d are arranged in a recording path downstream of the recording head 14. The head 16a is black, the head 16b is cyan, the head 16c is magenta, the head
Reference numeral 16d is for developing each color of yellow, and each of the heads 16a to 16d is selectively driven and controlled to an active state and an inactive state by appropriate means (not shown). The recording head 14 is a Japanese Patent Publication No. 51-44.
The developing / fixing heads 16a to 16d are already known from, for example, Japanese Patent Publication No. 777, and the like. On the upstream side of the recording head 14, a marking sensor 17 is arranged.

FIG. 2 is a diagram showing a schematic configuration of the marking sensor 17. As shown in FIG. 2, a pair of marking sensors 17a and 17b are provided on marking papers 18a and 18b, which are recorded simultaneously or prior to the image recording of the first color, in the area outside the effective screen on both the left and right sides of the recording paper 11. The light-emitting element 21a and the photoelectric conversion element 22a, and the light-emitting element 21b and the photoelectric conversion element 22b are respectively formed as a pair so that they can be read photoelectrically. Although not shown in FIG. 2, the marking sensors 17a and 17b can be independently detected for each unit information in the X direction intersecting the moving direction Y of the recording paper 11 indicated by the arrow. , A plurality of photoelectric sensing elements are arranged. Thus, the marking information of each detecting element obtained by the markings 18a and 18b crossing the positions of the marking sensors 17a and 17b as the recording paper 11 moves is extracted as a plurality of digital detection signals. The plurality of digital detection signals are subjected to signal processing based on a predetermined criterion as described later to detect and remove abnormal information, and become signals for image forming position alignment with respect to the recording paper 11.

Next, the operation of the thus configured image forming apparatus of the present embodiment will be described. In the following description, a case where the markings 18a and 18b are recorded prior to image recording will be described. Recording paper 11 pulled out from electrostatic recording paper roller 10
Passes through the guide rollers 12a and 12b, is pressed against the recording head 14 by the pressure contact roller 15, and
a, Move to the feed rollers 13a, 13b. In this movement process, first, the recording head 14 records the electrostatic latent images of the markings 18a and 18b at predetermined intervals at regular intervals as shown in FIG. The latent image is visualized by the developing / fixing head 16a. After recording the markings 18a and 18b by the desired recording size in this manner, the recording paper 11 is once rewound by the recording paper supply roller 10.

The rewound recording paper 11 is then pulled out again to color-record the cyan component of the first color. At this time, the heads 16a, 16c, and 16d are in an inactive state, and only the head 16b is in an active state. And image recording is a marking sensor
It starts when the first marking has passed the positions 17a and 17b. The cyan images are marked one after the other 18a, 18b
The writing position is controlled by the signal that detects the. When the recording for one screen is completed, the recording paper 11 is rewound to the recording paper supply roller 10 again. The recording is performed by repeating the same process for the other color images.

As described above, in the case of color recording, the above-described electrostatic color recording process is repeated for each color by the amount of color coloring. That is, the color image is obtained by performing the overcoating three or four times. At this time, if the markings 18a and 18b do not have a defect and are correctly detected, no deviation occurs in the formation position of the image of each color.

FIG. 3 is a diagram showing the correspondence between the marking sensor 17a and the marking 18a. As shown in the drawing, the marking sensor 17a has a plurality of photoelectric conversion elements a to m arranged in a direction intersecting with the moving direction of the recording paper 11 indicated by an arrow. Such an element array type sensor is generally known as a linear image sensor and is easily available. On the other hand, the marking 18a has its edge E extending in a direction intersecting the traveling direction of the recording paper 11, but microscopically, an enlarged dot x and a missing dot y, y 'due to abnormal discharge are microscopically shown. It is present at the edge E. As a matter of course, it is necessary to detect the portion indicated by E as the marking edge.

When the recording paper moves in the direction of the arrow, first, the portion of the abnormal discharge dot x is detected by the photoelectric conversion elements g, h, i to generate a signal. When the recording paper is further fed and the edge E to be detected passes through the sensor section, the photoelectric conversion elements a, c, d, e, f, g, h, i, j, k, and m generate signals, No signal is generated because there is a missing recording dot y, y 'in the marking portion corresponding to the photoelectric conversion element b, l. Therefore, in the example of FIG. 3, it is sufficient to determine that the marking edge E has passed when, for example, four or more of the m photoelectric receiving elements have detected the marking. In general terms, it can be defined that edge passing is determined based on detection signals obtained from n of the N photoelectric receiving elements. Here, N ≧ 2 and N ≧ n> 1 are integers. The value of n is determined from the size of the defect occurring in the marking and the size of the photoelectric conversion element.For example, a marking created by an electrostatic recording device having a recording density of 16 dot / mm is converted to a 16 dot / mm photoelectric conversion. When the detection is performed by the sensors in the element row, it is preferable that at least n is 3 to 5 or more in order to prevent a detection error at the dot due to abnormal discharge. However, there is a danger that a plurality of abnormal dots will be scanned as N increases, so when N is increased, it is necessary to increase n.

By the way, by arranging the photoelectric conversion elements separately,
Waste of detecting one minute defect by a plurality of photoelectric conversion elements can be eliminated, determination processing can be simplified, and the number of photoelectric conversion elements can be reduced.

FIG. 4 is a view showing the embodiment, in which the elements are arranged at a pitch three times the element size of the photoelectric conversion elements. For this reason,
One abnormal discharge dot x is scanned by only one photoelectric conversion element c '. Therefore, the same effect as in the case of FIG. 3 can be obtained, and at the time of the determination condition N ′ ≧ n ′> 1, n ′ for determining the edge passing can be set to 2-3. Accordingly, N 'can be reduced.

In the embodiment shown in FIGS. 3 and 4, an example is shown in which the present method is applied to a detection request for detecting the edge of the marking.
For detecting the distance between markings, a different criterion and processing method than the edge detection can be applied.

FIG. 5 is a diagram showing an example of determination / processing suitable for length measurement based on a marking position in the recording paper feed direction. The photoelectric conversion element row 17a is the same as the example in FIG. 3, and the markings 181 and 182 show the vicinity of the front edge and the rear edge of each marking. Now, it is assumed that the distance X between both edges E1 and E2 is measured. The number of recording dots read from the signal obtained by each photoelectric sensing element scanning the marking is X in the six elements a, b, d, f, k, and m.
In the case of the four elements c, e, j and l, there are X-1 pieces, and in the case of the three elements g, h and i, there are X + 1 pieces. Based on these detection signals,
The number of signals finally obtained is X. The processing method will be described.

One processing method is to employ an average value. Assuming that the detection signal of each element is Xp and the number of detection elements is P, the calculated average value is = (X1 + X2 +... + Xp) / P. In the example of FIG. 5, X- (1/13) Which is very close to the value X to be obtained. The obtained result may be rounded to the nearest decimal point.

Another processing method is to employ the most frequent data. In the example of FIG. 5, X..., X−1... 4, X + 1.

Which processing method is better should be determined based on the nature of the defect in the mark image. For example, under recording conditions where abnormal discharge occurs but dot dropout does not occur, it is appropriate to use the most frequent data, and if abnormal discharge and dot dropout occur in the same way, the average The value method or the most frequent data method may be used. Furthermore, when the number of abnormal recording locations is extremely large, it can be said that the average value method is suitable.

In the method of measuring the dimensions and pitch of the marking in the recording paper feed direction described above, the average value or the maximum frequency data of the plurality of detected length information is adopted, so that the marking edges E1 and E2 are detected by the sensors. Even in the case of detecting a marking inclined with respect to the arrangement direction of the photoelectric conversion elements 17a, the measurement can be performed without any trouble. A measurement method for measuring the length from the positions of two edges E1 and E2 by applying the edge detection method shown in FIGS. 3 and 4 to the measurement of the dimensions and pitch of the marking in the recording paper feed direction shown in FIG. It is possible. However, when the marking edge E detects a marking that is inclined with respect to the array direction of the photoelectric conversion elements of the sensor, the edge detection method cannot be applied. In this regard, it can be said that the detection method of FIG. 5 is excellent.

FIG. 6 shows a marking M composed of a non-parallel edge pattern.
M ′ is provided at both ends in the width direction of the recording paper 11, and the photoelectric conversion elements S1,
An example in which this method is applied to a measurement for detecting the length of S2, S3 and S1 ', S2', S3 'crossing the marking M, M' and detecting expansion and contraction of the recording paper 11 in the width direction will be described. FIG. That is, a plurality of photoelectric conversion elements S1, S2, S3 and S1 ', S are crossed over the non-parallel edge pattern of the two markings M, M'.
2 'and S3' are arranged so as to cross each other at a predetermined distance in the recording paper feed direction, and each of the photoelectric conversion elements facing the two patterns is specified, and S1 and S1 ', S2 and S
A plurality of combinations of 2 ', S3 and S3' are made. When the pattern of the markings M and M 'is normal without any defect, S1
Each photoelectric conversion so that the sum of the lengths of the markings crossed by S1 'and S1', the sum of the lengths of the markings crossed by S2 and S2 ', and the sum of the lengths of the markings crossed by S3 and S3' are all equal. Position the elements S1, S2, S3 and S1 ', S2', S3 ', and perform processing to detect and remove an abnormal value from the sum of the pattern lengths detected by the photoelectric conversion elements of each set, and perform the processing in the recording paper width direction. Dimensional change information is obtained.

Since the sum of the lengths of the markings obtained after the end of the marking scan changes according to the dimensional change in the width direction of the recording paper, it is used as the dimensional change information of the recording paper 11 in the width direction. When a minute defect occurs in the marking, a change occurs in the dimensional sum obtained from the combination of the photoelectric sensors, and a detection error occurs. In this embodiment, abnormal data removal processing is performed to eliminate this detection error. As the processing method, the method of calculating the average value of each data described in FIG. Can be applied.

By the way, in each of the above-described embodiments, an example is shown in which a marking sensor in which a plurality of photoelectric conversion elements are arranged is used.
It is very convenient to use a so-called linear image sensor array as the marking sensor. When a linear image sensor array is used, not only can a marking having an edge crossing the feed direction of the recording paper 11 be detected, but also a recording paper edge parallel to the recording paper feed direction, Line-shaped marking detection can be detected by the same linear image sensor array. That is, a sensor bit for detecting a marking having an edge crossing the feeding direction of the recording paper 11 is designated, and the linear image sensor array is periodically electrically scanned so as to be parallel to the feeding direction of the recording paper 11. It is only necessary to detect the position of a line or an edge and read the information of the marking in the direction crossing the recording paper feed direction by a periodic signal from a specific designated bit.

Note that the present invention is not limited to the above embodiment,
Of course, various modifications can be made without departing from the spirit of the present invention.

〔The invention's effect〕

According to the present invention, it is possible to provide an image recording apparatus having the following effects.

(A) According to the first invention, basically, each photoelectric conversion element is configured to be capable of independently detecting a marking, so that each piece of marking detection information can be determined separately. In addition, among the plurality of photoelectric detection elements, the configuration is such that the edge of the marking is determined based on the detection of the marking by a predetermined number or more of the photoelectric detection elements, and thus the marking includes a minute defect or the like. However, accurate marking detection can be performed without erroneous detection.

(B) According to the second invention, basically, similarly to (a), each piece of marking detection information can be sorted and determined. In addition, since the average value of the detection signals of the marking length and the distance between the markings from the plurality of photoelectric sensing elements is obtained, and the marking length and / or the distance between the markings are determined based on the average value, (a In the same way as in (1), even if the marking contains micro defects, accurate marking detection can be performed without erroneous detection. In addition to detecting the marking edge, it also detects the marking length or the distance between markings As a result, more accurate detection of marking information is possible.

(C) According to the third invention, basically, similarly to (a), each piece of marking detection information can be classified and determined. Moreover, the most frequent value of the detection signal of the marking length and / or the distance between the markings from the plurality of photoelectric detection elements is obtained,
Since the configuration is such that the marking length and / or the distance between the markings are determined based on the most frequent value, even if the marking contains a minute defect or the like, there is no erroneous detection and accurate detection as in the case of (b). In addition to performing marking detection,
In particular, since not only the detection of the marking edge but also the length of the marking or the distance between the markings can be detected, more accurate detection of the marking information is possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a recording system of an image recording apparatus showing a first embodiment in which the present invention is applied to an electrostatic color plotter. FIG. 2 is a diagram showing a schematic configuration of a marking sensor of the embodiment.
FIG. 4 is a diagram for explaining the operation of the embodiment, FIG. 4 is a diagram showing a second embodiment of the present invention, and is a diagram showing an example in which photoelectric conversion elements are arranged separately.
FIG. 5 is a diagram showing a third embodiment of the present invention, showing an example of application to length measurement based on a marking position in the recording paper feed direction, and FIG. 6 is a diagram showing a fourth embodiment of the present invention. FIG. 9 is a diagram illustrating an example of application to measurement of expansion and contraction in the width direction of a recording sheet by using a marking including a non-parallel edge pattern and a photoelectric conversion element. 7 and 8 are views showing a conventional technique, FIG. 7 is a view showing a configuration example of a sensor having a small spot diameter, and FIG. 8 is a view showing an example of marking failure. 10: electrostatic recording paper supply roll, 11: electrostatic recording paper, 12a, 12b,
12c: guide roller, 13a, 13b: feed roller, 14: multi-stylus electrostatic recording head, 15: pressure roller, 16a to 16d
... Developing / fixing head, 17, 17a, 17b ... Marking sensor, 18a, 18b ... Marking, 21a, 21b ... Light emitting element, 22a, 22
b: photoelectric conversion elements, M, M ': markings made of non-parallel edge patterns, S1, S2, S3 and S1', S2 ', S3': photoelectric conversion elements.

Claims (3)

(57) [Claims] A plurality of photoelectric detection elements arranged on the recording paper and having an edge in a direction intersecting a moving direction of the recording paper, the markings being read in a direction intersecting the moving direction of the recording paper; An image recording apparatus that obtains a signal for controlling an image forming position based on a detection signal from an element, wherein the marking is performed by detecting a mark by a predetermined number or more of a predetermined number of photoelectric detection elements among the plurality of photoelectric detection elements. An image recording apparatus characterized in that it is configured to determine an edge of the image. 2. A method according to claim 1, wherein a plurality of markings provided on the recording paper and having an edge in a direction intersecting the moving direction of the recording paper are read by a plurality of photoelectric sensing elements arranged in a direction intersecting the moving direction of the recording paper. An image recording apparatus for obtaining a signal for controlling an image forming position based on a detection signal from an element, wherein an average value of detection signals of the marking length and / or the distance between the markings from the plurality of photoelectric detection elements is obtained, and the average value is obtained. An image recording apparatus characterized in that a marking length and / or a distance between markings are determined based on the following. 3. A plurality of photoelectric detection elements arranged on a recording sheet and having an edge in a direction intersecting with the moving direction of the recording paper are read by a plurality of photoelectric detecting elements arranged in a direction intersecting with the moving direction of the recording paper. An image recording apparatus for obtaining a signal for controlling an image forming position based on a detection signal from an element, wherein a most frequent value of a detection signal of a marking length and / or a distance between markings from the plurality of photoelectric detection elements is obtained. An image recording apparatus configured to determine a marking length and / or a distance between markings based on a frequency value.