JPH0872341A - Raster type recording apparatus - Google Patents

Abstract

PURPOSE: To accurately set a printing position by ensuring paper feed accuracy and eliminating cumulation by performing correction of paper feed accuracy inclusive of a fluctuation component by a method wherein a feed distance as an accuracy calculation factor is cumulated and correction is performed on the basis of the cumulation data when a correction value is calculated. CONSTITUTION: The correction frequency for correcting the feed accuracy of recording paper PS is set to once with respect to 200 pulse signals outputted from a second encoder 13. A first, encoder 12 outputs 200 pulse signals per the one line feed of the recording paper PS as a plan value and the second encoder 13 outputs one pulse signal per the 10-line feed of the recording paper PS. At first, a correction factor (m) as an initial correction value and the number of printing lines per 200 pulses of the second encoder 13 are calculated by preliminary test printing and printing raster length is measured. Objective raster length and the actual raster length are outputted to a feed accuracy operation circuit 19. The operation circuit 19 calculates feed accuracy on the basis of formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raster type recording apparatus which prints on recording paper in a raster system.

[0002]

2. Description of the Related Art Raster printers of this type, which print on recording paper by the raster method, are rapidly becoming popular in recent years because of their high printing speed and excellent image quality. However, in such a printer, it is difficult to obtain the feeding accuracy of the recording paper, so that the feeding amount of the recording paper and its printing position cannot be matched, and the printing quality is deteriorated. Therefore, conventionally, for example, as disclosed in Japanese Unexamined Patent Publication No. 5-305747, an encoder is engaged with a transport mechanism for transporting recording paper, and the encoder outputs the recording paper at a cycle corresponding to the feeding speed of the recording paper. A method is adopted in which the feed of one raster of the recording paper is grasped by counting the number of pulse signals.

In the above method, when the pulse signal from the encoder does not match the actual recording paper feed amount, the following correction is made to deal with it. That is, with respect to the number of output pulses of the encoder described above, first, the number of pulses n corresponding to one print line of the recording paper is determined, and then the print data of the image having the predetermined print length R is printed by the printer to print at this time. Measure the length R '. continue,
The conveyance accuracy p of the recording paper is calculated by the calculation (R'-R) / R, and the correction coefficient m of the output pulse of the encoder is calculated by the calculation 1 / (np). Then, the print position is determined based on the pulse number n. That is, until the number of print lines reaches a multiple of the correction coefficient m, the print position for each print line is determined every time the number of pulses of the encoder becomes n, and each time the number of print lines reaches the multiple of the correction coefficient. ,
The number of output pulses of the encoder is (n-1) or (n +
Based on 1), the printing position of the line is determined, and the deviation of the initial value that the printer has potentially is absorbed.

Further, the actual transport amount of the recording paper and the initial transport amount when the preceding print length R ′ is measured are determined by the above pulse number n for each predetermined period when the printer is operated. When the number of lines corresponding to the actual carry amount is r ′ and the number of lines corresponding to the initial carry amount is r, the calculation (r′−r) / r is performed.
Thus, the transport accuracy Δp is obtained for each predetermined period. Then, the correction accuracy Δm of the number of output pulses of the encoder for each predetermined period is obtained by calculation 1 / (nΔp), and further calculation (1 /
The above correction coefficient m is corrected to m ′ by m ′) = (1 / m) + (1 / Δm) to absorb the variation in the feed amount of the recording paper during conveyance.

[0005]

The paper feed accuracy in such a conventional raster printer is 0.1% (± 1 m).
m / 1 m), which is sufficient in normal use, but it is a multi-pass multi-color system in which multiple colors are recorded on the same recording area by repeatedly feeding and returning recording paper. It has not been sufficient for a device such as a recording device that requires high precision of paper feeding. Further, when the feeding amount of the recording paper is changed during the conveyance, the correction is performed after the change occurs, so that there is a drawback that the change in the section cannot be corrected.

Therefore, according to the present invention, the paper feed accuracy (± 0.05 mm / 1) applicable to the above-described multicolor recording apparatus is provided.
m) is ensured, and even if the feed amount of the recording paper fluctuates, the fluctuation is corrected by including the fluctuation in that section so that the accumulation is eliminated and the printing position is accurately determined.

[0007]

In order to solve such a problem, the present invention performs recording on a recording sheet to be conveyed, and based on the difference between the target conveying distance of the recording sheet and the actual conveying distance. In a raster-type recording apparatus that obtains the conveyance accuracy and calculates a correction coefficient for correcting the conveyance distance from the conveyance accuracy, the correction coefficient calculated for initial correction and the conveyance distance corrected based on this correction coefficient are stored. Storage means, a transport accuracy calculation means for calculating transport accuracy from a difference between the actual transport distance in the new recording section and the transport distance stored in the storage means, and correction from the transport accuracy calculated by the transport accuracy calculation means. A correction coefficient calculation unit that calculates a coefficient and a new correction coefficient from the calculated correction coefficient and the correction coefficient stored in the storage unit, and a correction coefficient calculation unit The correction coefficient and the conveyance distance corrected based on the correction coefficient which is provided with a cumulative means for accumulating in the storage means for the conveyance distance correction and conveying precision calculation in the next recording interval.

A first encoder, which is engaged with a motor for conveying the recording paper and outputs a pulse signal corresponding to the rotation speed of the motor, and a pulse signal, which is engaged with the recording paper and corresponds to the feeding speed of the recording paper, are provided. A second encoder for outputting is provided, and the number of pulses from the first encoder, which is more accurate than the second encoder, is measured during the predetermined number of pulses from the second encoder indicating the reference number of pulses in the recording section, The measured number of pulses of the first encoder is divided by the average number of pulses based on the correction coefficient calculated by the correction coefficient calculation means, and this value is set as the actually measured transport distance. Further, the conveyance distance is not corrected in the predetermined recording section immediately after the start of recording.

[0009]

The correction coefficient calculated for initial correction and the transport distance corrected based on this correction coefficient are stored in the memory, and when the actually measured transport distance is measured in a new recording section, The transport accuracy is calculated from the difference between the transport distance stored in the memory, the correction coefficient is calculated from the transport accuracy, and a new correction coefficient is calculated from the calculated correction coefficient and the correction coefficient stored in the memory. This correction coefficient and the transport distance corrected based on this correction coefficient are accumulated in the memory for transport distance correction and transport accuracy calculation in the next recording section. Therefore, since the correction coefficient is calculated from the accumulated past data, even if the feed amount of the recording paper fluctuates, it is possible to secure the paper feed accuracy that quickly follows the fluctuation, and high-precision paper feed is required. It is possible to secure the paper feeding accuracy applicable to the multi-color recording device.

A second number indicating the number of reference pulses in the recording section
The number of pulses from the first encoder, which is more accurate than the second encoder, is measured during the predetermined number of pulses from the encoder, and the measured number of pulses from the first encoder is calculated by the correction coefficient calculation means. It is divided by the average number of pulses based on the correction coefficient, and this value is set as the actually measured transport distance. As a result, the actually measured transport distance can be accurately obtained. Further, in the predetermined recording section immediately after the start of recording, dummy recording is performed on the recording paper without correcting the transport distance. As a result, it is possible to eliminate the adverse effect of the correction based on the action of the variable element such as the environmental temperature.

[0011]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a raster type recording apparatus according to the present invention. In the figure, PS is recording paper,
Reference numeral 1 is a recording head for performing raster printing on the recording paper PS, 2 is a conveying roller for pressing the recording paper PS against the recording head 1 and conveying the recording paper PS in the direction of the arrow in the figure, 3 is a conveying roller 2
Reference numeral 11 denotes a motor for rotating and driving the motor 3, and 11 is a speed reducer for decelerating the rotation of the motor 3 and transmitting the decelerated rotation to the conveying roller 2.

Reference numeral 12 is a first element which is in contact with the motor 3 and outputs a pulse signal having a cycle corresponding to the rotation speed thereof.
The encoder 13 is directly engaged with the recording paper PS, and the recording paper P
A second encoder for generating a pulse signal having a cycle corresponding to the feed speed of S, 13R is a recording paper P of the second encoder 13.
It is an auxiliary roller for assisting engagement with S. Also,
Reference numeral 14 is a counter for counting pulse signals from the first encoder 12, 15 is a counter for counting pulse signals from the second encoder 13, and 16 is a raster signal RST described later.
A counter that counts the number of print lines (the number of conveyance distances of the recording paper PS) on the basis of the number, and a control 17 that controls the counting operation of each of the counters 14 to 16 and controls the entire recording apparatus according to the count value of each counter. It is a circuit (CPU).

Further, 18 is a memory, 19 is a conveyance accuracy calculation circuit for calculating the conveyance accuracy of the recording paper PS, and 20 is a correction coefficient m of the pulse signal output from the second encoder 13 based on the calculated conveyance accuracy. A correction coefficient calculation circuit for calculating 21, a raster signal forming circuit for generating a raster signal RST indicating movement of one raster of the recording paper PS based on the pulse signal output from the first encoder 12 and the correction coefficient m, and 22 for control This is a head driver circuit that drives the recording head 1 to print based on the control of the circuit 17.

In the conventional raster printer, the second encoder 13 is used to correct the conveyance accuracy of the recording paper PS.
It is determined whether or not the number of recorded rasters matches the predetermined value for each pulse number (predetermined section) defined in 1., and if they do not match, a new correction value is calculated according to the difference and correction is performed. I am trying. Since such a conventional device reflects the measured value in a predetermined section on the conveyance of the next predetermined section, it is not possible to make a correction in consideration of the change in the section where the conveyance distance has changed. In addition, there is a drawback that the accuracy deteriorates in proportion to the length of the predetermined section. For this reason,
In the apparatus of this embodiment, the transport distance (design value and actual measurement value) as the accuracy calculation factor is accumulated, and when the correction value is calculated, the correction is performed based on this accumulated data.

That is, in the apparatus of this embodiment, first, the recording paper PS
The correction frequency for correcting the conveyance accuracy of 1 is set to once for 200 pulse signals output from the second encoder 13. Then, as design values, the first encoder 12 outputs 20 pulse signals per one line conveyance of the recording paper PS, and the second encoder 13 outputs one pulse signal per ten lines conveyance of the recording paper PS. I shall.

In such an apparatus according to the present invention, first, the correction count m as the initial correction value and the second
The number of print lines per 200 pulses of the encoder 13 is calculated. Here, an image having a predetermined raster length is printed and the print raster length (1 line) is measured. In this case, assuming that the place to be printed as "1000" mm as the raster length is "1001" mm, the control circuit 17 causes the target raster length and the actual raster length (note that the target raster length and the actual raster length are shown by symbols R and R'in FIG. 1). , R, r'indicate the number of rasters) are output to the transport accuracy calculation circuit 19. Arithmetic circuit 19
Calculates the conveyance accuracy p based on the equation (1). That is, p = (1001-1000) / 1000 = 1/1000 (1)

In this way, the conveyance accuracy p by the test printing is calculated and sent to the correction coefficient calculation circuit 20. The correction coefficient calculation circuit 20 obtains the correction coefficient m based on the equation (2). m = 1 / np (where n is the number of pulses of the first encoder 12) = 1 / (20 × (1/1000)) = 50 (2) As a result, the correction coefficient for correcting the transport distance of the recording paper PS “50” is required as m. The value of the calculated correction coefficient is appropriately stored in a register (not shown) in the correction coefficient calculation circuit 20 or the memory 18, and is also given to the raster signal forming circuit 21.

The correction coefficient "50" is the same as the correction coefficient m in the prior art, and the print interval is corrected by n ± 1 in the print lines in multiples of "50", and the print interval is set in the other print lines. Means n. That is, in the above-mentioned case, 19 pulses are set between the 49th line and the 50th line, and 100, 150, ...
Similarly, in the line, there are 19 pulses. Then, the raster signal RST based on such a correction coefficient is output from the raster signal generation circuit 21. When the recording paper PS is conveyed, the control circuit 17 drives the driver circuit 22 in synchronization with this raster signal to cause the recording head 1 to record. In this case, the average number of pulses output from the first encoder 12 per line is calculated by the control circuit 17 by the equation (3). That is, the average pulse number = (20 × 49 + 19 × 1) /50=19.98 (3)

Further, in order to obtain the correlation between the first encoder 12 and the second encoder 13 in this test print n, the number of pulses of the first encoder 12 and the second encoder 13 is counted. Then, assuming that these values are 320003 pulses and 1600 pulses, respectively, the control circuit 1
7 obtains the ratio of the pulse numbers of the first encoder 12 and the second encoder 13 by the equation (4). 320003/1600 = 200/1 (4)

Next, the control circuit 17 calculates the number of reference print lines, that is, the number of print lines for every 200 pulses of the second encoder 13 based on the equation (5), and the reference number of print lines and the above-mentioned number. The correction frequency is stored in the memory 18. Reference print line number = (200 × 200) /19.98=2002.002 (line) (5) Thus, the reference print line number and the correction frequency are stored in the memory 18, and the transport accuracy is based on the stored values. By performing the initial correction of the above, the initial conveyance deviation that the apparatus potentially has can be absorbed.

However, the number of reference print lines for every 200 pulses of the second encoder 13 which has been initially corrected is "2002.
“002” changes when the conveyance of the recording paper PS changes due to temperature change or the like. Therefore, in the apparatus of this embodiment, in addition to the above-described initial correction, the dynamic correction described below is performed. FIG. 2 is a diagram showing a situation of the above-mentioned dynamic correction, and the dynamic correction operation will be specifically described with reference to FIGS. 2 and 1. That is, first, in the section immediately after the operation start time (time point in FIG. 2) of the recording paper conveyance system of the apparatus, the environmental temperature may be significantly different from the time when the initial correction value is calculated. In the section, the correction data in the current environment is not calculated and the variation is directly added to the printing. Further, since the error in the measurement data for correction is large, it is not possible to stably convey the recording paper. Therefore, in the device of this embodiment, in the section,
Only the number of pulses from the first encoder 12 with respect to the number of pulses of the second encoder 13 is counted, and dummy recording (only the recording sheet conveying operation) is performed to record dummy data (non-printing data) on the recording sheet PS. .

Now, the dummy recording section is set to 2 for carrying accuracy correction.
If the number of intervals, that is, 400 pulses of the second encoder 13 is allocated and the number of pulses from the first encoder 12 is “79960” during that period, the control circuit 17 causes the recording line of 400 pulses of the second encoder 13 per 400 pulses. The number of pulses is calculated by the equation (6) using the average pulse number of the first encoder 12 stored in the memory 18, and the transport accuracy calculation circuit 1
Output to 9. 99960 / 19.998 = 4002.002 (6) In this case, the carrying accuracy calculation circuit 19 calculates the carrying accuracy Δp by the expression (7). Δp = (4002.002−2002.0002 × 2) /2002.002×2=−2.002/4004.004 (7) When the correction coefficient Δm is calculated by the correction coefficient calculation circuit 20 using this accuracy Δp, It becomes like Formula (8). Δm = 1 / (20 × (−2.002 / 4004.004)) = − 100.00 (8)

The sign of the correction coefficient Δm indicates whether the recording paper PS extends (n + 1) or contracts (n-1). That is, as the control direction, when Δm is positive, (n−
1), when Δm is negative, (n + 1) is used. A new correction coefficient m ′ is obtained from the correction coefficient Δm thus obtained and the correction coefficient m at the time of initial correction. That is, 1 / m ′ = 1 / m + 1 / Δm = 1/50 + 1 / −100 m ′ = 100 (9), and this correction coefficient m ′ calculated during dummy recording is not shown in the correction coefficient calculation circuit 20. It is stored in the register, the memory 18, etc. and is used as a correction value in the processing of the next recording section.

That is, when the dummy recording is finished and the recording operation is started at the time point of FIG. 2, the raster signal RST according to the correction value calculated by the equation (9) becomes the raster signal forming circuit 21.
The recording operation is performed in synchronism with this, and at the first correction point shown at the time of FIG. 2, the average pulse number of one line of the first encoder 12 is calculated by the control circuit 17 based on the equation (10). It is calculated. Average pulse number = (20 × 99 + 19 × 1) /100=19.99 (10) If the pulse number from the first encoder 12 is “39980” in the meantime, the second encoder 13
The number of recording lines per 200 pulses of is calculated as 39980 / 19.99 = 2000.000 (11), which is sent to the conveyance accuracy calculation circuit 19 and the conveyance accuracy Δp is calculated.

In this case, the conveyance accuracy Δp is Δp = (− 2.002+ (2000.000−2002.002)) / 4004.004 + 2002.002 = −4.004 / 6006.006 (12). When the correction coefficient calculation circuit 20 calculates the correction coefficient Δm using this accuracy Δp, Δm = 1 / (20 × (−4.004 / 6006.006)) = − 75.000 (13).

A new correction coefficient m ′ is calculated by the correction coefficient calculation circuit 20 based on the correction coefficient Δm thus obtained and the correction coefficient m obtained at the end of the dummy recording. That is, 1 / m ′ = 1 / m + 1 / Δm = 1/100 + 1 / −75.000 m ′ = − 300 (14), and the correction coefficient m ′ is the register in the correction coefficient calculation circuit 20 or the memory 18 or the like. It is stored in the memory and is used to correct the next recording section starting from the time point.

Next, at the second correction point shown in FIG. 2, the average pulse number of one line of the first encoder 12 is the average pulse number = (20 × 299 + 21 × 1) /300=20.003 (15 ) Is required. During that time (between time points), the number of pulses from the first encoder 12 is “3997”.
If it is “0”, the number of recording lines per 200 pulses of the second encoder 13 is 39970 / 20.003 = 1998.200 (16).

In this case, the conveyance accuracy Δp is Δp = (− 4.004+ (1998.200−2002.002)) / 6006.006 + 2002.002 = −7.806 / 8008.008 (17), and this accuracy Δp When the correction coefficient Δm is calculated using, Δm = 1 / (20 × (−7.806 / 8008.008)) = − 51.294 (18).

A new correction coefficient m'is obtained from the correction coefficient Δm thus obtained and the correction coefficient m obtained at the previous correction. That is, the correction coefficient is 1 / m ′ = 1 / m + 1 / Δm = 1 / −300 + 1 / −51.294 m ′ = − 62 (19), and the processing of the next recording section starting from the time point of FIG. 2 is performed. It is used for correction of. By repeating such a calculation operation for each recording section, it is possible to perform an accurate correction for a variation in the conveyance of the recording paper PS.

[0030]

As described above, according to the present invention, the correction coefficient calculated for initial correction and the transport distance corrected based on this correction coefficient are stored in the memory, and the actually measured transport is performed in a new recording section. When the distance is measured, the transport accuracy is calculated from the difference between the measured transport distance and the transport distance stored in the memory, the correction coefficient is calculated from the transport accuracy, and the calculated correction coefficient and the memory are stored in the memory. A new correction coefficient is obtained from the corrected correction coefficient, and the correction coefficient and the transport distance corrected based on the correction coefficient are accumulated in the memory for the transport distance correction and the transport accuracy calculation in the next recording section. Therefore, the correction coefficient is calculated based on the accumulated past data, and therefore even if the feed amount of the recording paper fluctuates, the paper feed accuracy that quickly follows the fluctuation can be secured. Together, it can also be ensured applicable paper feeding precision for multicolor recording apparatus requiring high paper feeding precision.

The second number indicating the number of reference pulses in the recording section
The number of pulses from the first encoder, which is more accurate than the second encoder, is measured during the predetermined number of pulses from the encoder, and the measured number of pulses from the first encoder is calculated by the correction coefficient calculation means. The measured number of pulses is divided by the average number of pulses based on the correction coefficient, and this value is set as the actually measured conveying distance. Therefore, the actually measured conveying distance can be accurately obtained. Further, since the dummy recording is performed on the recording paper without correcting the transport distance in the predetermined recording section immediately after the start of recording, it is possible to eliminate the adverse effect of the correction due to the change in the environmental temperature and the error in the measurement data. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a raster type recording apparatus according to the present invention.

FIG. 2 is an explanatory diagram for explaining a paper feeding correction operation in the above apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording head, 3 ... Motor, 11 ... Reducer, 12 ... 1st encoder, 13 ... 2nd encoder, 14-16 ... Counter, 17 ... Control circuit, 18 ... Memory, 19 ... Conveyance accuracy arithmetic circuit, 20 ... Correction coefficient calculation circuit, 21 ... Raster signal generation circuit, PS ... Recording paper.

Claims (3)

[Claims] 1. A correction coefficient for performing recording on a conveyed recording sheet, obtaining a conveying accuracy based on a difference between a target conveying distance of the recording sheet and an actual conveying distance, and correcting the conveying distance from the conveying accuracy. In a raster type recording apparatus for calculating, the storage means for storing the correction coefficient calculated for initial correction and the transport distance corrected based on this correction coefficient, and the actual transport distance in the new recording section and the storage Transport accuracy calculation means for calculating the transport accuracy from the difference between the transport distance stored in the means, a correction coefficient calculated from the transport accuracy calculated by the transport accuracy calculation means, and the calculated correction coefficient and the storage means. A correction coefficient calculation means for calculating a new correction coefficient from the correction coefficient stored in, a correction coefficient calculated by the correction coefficient calculation means, and a correction coefficient based on the correction coefficient. Further comprising a cumulative means for accumulating in the storage unit the corrected conveying distance for the conveying distance correction and conveying precision calculation in the next recording interval Te raster-type recording apparatus according to claim. 2. The raster type recording apparatus according to claim 1, wherein a first encoder that is engaged with a motor that conveys the recording paper and that outputs a pulse signal according to the rotation speed of the motor is engaged with the recording paper. A second encoder for outputting a pulse signal corresponding to the feeding speed of the recording sheet, and having a higher accuracy than the second encoder during a predetermined pulse number from the second encoder indicating the reference pulse number of the recording section. The number of pulses from the first encoder is measured, the measured number of pulses of the first encoder is divided by the average number of pulses based on the correction coefficient calculated by the correction coefficient calculating means, and this value is measured. A raster type recording device characterized by being defined as a distance. 3. The raster recording apparatus according to claim 1, wherein the transport distance is not corrected in a predetermined recording section immediately after the start of recording.