JPH0825699A - Raster type recording apparatus - Google Patents

Abstract

PURPOSE:To accurately determine a printing position so as to follow the fluctuations of the feed quantity of recording paper by correcting the printing position corresponding to the feed quantity of recording paper corresponding to the accuracy of a detection means to perform printing output. CONSTITUTION:The feed speed of recording paper PS is detected by an encoder 6 to be applied to a control circuit 10, a counter 11 and a correction count number operation circuit 12 as a pulse signal (b) and the rotational speed of a motor 3 is detected by an encoder 5 to be applied to the counter 11 as a pulse signal (a). During the one pulse output from the encoder 6, 20-pulse output is performed from the encoder 5. A rough printing position is determined on the basis of the pulse signal (b) and the fine adjustment of a printing position is performed on the basis of the pulse signal (a) to output an accurate printing start signal (c) to a control circuit 10. By this constitution, a printing position is accurately determined so as to follow the fluctuations of the feed quantity of recording paper. The encoder 6 may be not high in accuracy.

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, an encoder is engaged with a transport mechanism for transporting the recording paper, and the pulse signals output from the encoder in a cycle corresponding to the feeding speed of the recording paper are counted, so that one raster of the recording paper can be obtained. The method of grasping the sending of is adopted.

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 for one raster of recording paper is determined, and then print data of an image having a predetermined raster length R is printed by a printer to obtain a print raster length R ′. taking measurement. Then, the calculation (R '
-R) / R is used to obtain the conveyance accuracy p of the recording paper, and the calculation 1 / (np) is used to obtain the correction coefficient m of the output pulse of the encoder. Then, the number of rasters is counted based on the number of pulses n, and until the number of rasters reaches a multiple of the correction coefficient m, the printing position for each raster is determined every time the number of pulses of the encoder becomes n, and the number of rasters is determined. Each time the number of output pulses of the encoder reaches (n-
Based on 1) or (n + 1), the print position for one raster is determined, and the deviation of the initial value that the printer has potentially is absorbed.

Further, the actual carry amount of the recording paper and the initial carry amount when the raster length R'is measured are counted for each predetermined period during printing by the printer based on the above-mentioned pulse number n. The number of rasters is compared, and the number of rasters corresponding to the actual carry amount is r ′, and the number of rasters corresponding to the initial carry amount is r.
Then, the transport accuracy Δp for each predetermined period is obtained by the calculation (r′−r) / r. 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 / m ′) = (1 / m) +
The above-described correction coefficient m is corrected to m ′ by (1 / Δm) to absorb the variation in the feed amount of the recording paper during conveyance.

[0005]

In such a conventional raster type printer, when the feed amount of the recording paper changes during the conveyance, the correction is performed after the change occurs.
There was a drawback that the followability to fluctuations was poor. Also,
When the correction data is calculated, the calculation error component is also included in the calculation. For example, the same + direction conveyance fluctuation error is added to the + direction error of the control by the correction data including the measurement error component. However, in the worst case, there is a drawback that the printing accuracy is lowered. There is also a method of determining the printing position only by the pulse signal of the encoder, but this method has a drawback that the printing accuracy depends on the accuracy of the encoder.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to accurately follow the fluctuation of the recording paper feed amount and accurately determine the printing position.

[0007]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention is a raster type recording apparatus for performing printing on a conveyed recording paper by a raster method, and detecting the conveyance amount of the recording paper. Means, an accuracy calculation means for calculating the accuracy of the detection means in advance, a correction means for correcting the printing position of the recording paper according to the accuracy calculated by the accuracy calculation means for each detection output of the detection means, and the correction means. An output means for outputting a print start signal at the corrected print position is provided.

Further, a first encoder for generating a first pulse signal for each predetermined transport amount is provided as a detection means, a counter is provided as an output means, and the first encoder is synchronized with a motor for transporting the recording paper. The second encoder for generating the second pulse signal having a shorter cycle than the pulse signal of the above is engaged with the motor, and the correction means sets the print position according to the accuracy calculated by the accuracy calculation means each time the first pulse arrives. The corrected value is given to the counter as a counter value, and the counter counts the second pulse after the input of the first pulse and outputs the print start signal when the counted value reaches the counter value. It is the one.

Further, a timer is provided as an output means, and an oscillator for supplying a clock signal is connected to the timer,
The correction unit corrects the print position according to the accuracy calculated by the accuracy calculation unit each time the first pulse arrives, and gives this correction value to the timer as a timer value. The timer outputs the clock after the input of the first pulse. A time counting operation is performed based on the signal, and a print start signal is output according to the time up.

[0010]

When the amount of recording paper conveyed is detected by the detecting means, the printing position corresponding to the amount of recording paper conveyed is corrected according to the accuracy of the detecting means and printed out. As a result, even when the feed amount of the recording paper fluctuates during the conveyance, the recording paper can be swiftly followed to print at the correct position on the recording paper, and a highly accurate detection means is not required.

Further, a first encoder for periodically generating a first pulse signal for each predetermined carry amount is provided as the detection means, and the counter as the output means is synchronized with the motor after the input of the first pulse. The second pulse is counted, and when the count value reaches the counter value that is the correction value, the print start signal is output. As a result, the print position on the recording paper can be accurately determined with a simple configuration.

Further, a timer is provided as an output means, and after the input of the first pulse, the timer measures the timer value, which is a correction value, based on the clock signal, and outputs a print start signal in response to the time-up. To do. As a result, if the resolution of the clock signal is set to a high value, it is possible to immediately follow the conveyance variation of the recording paper and print at the correct position.

[0013]

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
A motor 4 for rotationally driving the motor 4 is a speed reducer that decelerates the rotation of the motor 3 and transmits the decelerated rotation to the transport roller 2.

Reference numeral 5 denotes a recording paper PS which is engaged with the motor 3.
The encoder 6 generates a pulse signal a having a cycle corresponding to the feeding speed, 6 is an encoder that is directly engaged with the recording paper PS to be conveyed, and generates the pulse signal b having a cycle corresponding to the conveyance speed, and 7 is an encoder 6. It is an auxiliary roller for assisting engagement with the recording paper PS.

Reference numeral 8 is a head driver circuit for driving the recording head 1, 9 is a memory for storing accuracy information of the encoder 6, and 10 is a control circuit for controlling the above-mentioned respective parts. In addition, 11 is a recording paper PS for the control circuit 10.
Is a counter for outputting a print start signal c to the counter 6, and 12 is a correction count number calculation circuit for calculating the correction count number given to the counter 11 according to the accuracy of the encoder 6.

Next, the operation of the recording apparatus configured as described above will be described. The rotation output of the motor 3 rotating at a constant speed is decelerated at a constant rate by the speed reducer 4. The recording paper PS is transported in the direction of the arrow in the figure by the rotation of the transport roller 2 which is interlocked with the deceleration rotation output of the speed reducer 4. On the other hand, the transport speed of the recording paper PS is detected by the encoder 6 and given to the control circuit 10, the counter 11 and the correction counter number calculation circuit 12 as a pulse signal b. Further, the rotation speed of the motor 3 is detected by the encoder 5 and given to the counter 11 as a pulse signal a.

Here, as a design value, 20 pulses are output from the encoder 5 during one pulse output from the encoder 6. Further, in order to obtain the conveyance accuracy of the recording paper PS, print data of an image having a predetermined raster length is printed by the printer and the print raster length is measured. At this time, the accuracy data of the encoder 6 is calculated based on the output pulse signals from the encoder 5 and the encoder 6 which are measured at the same time, and the correction count number calculation circuit 12 is preliminarily calculated.
Have been given to.

In this case, the correction count number calculation circuit 12
When the pulse signal b is input from the encoder 6, calculates a correction count number according to the accuracy of the encoder 6 and gives it to the counter 11. When the pulse signal b is input from the encoder, the counter 11 counts the correction count number given from the correction count number calculation circuit 12 based on the pulse signal a from the encoder 5, and when the count is completed, the control circuit 10 starts printing. The signal c is transmitted. Upon receiving the print start signal c, the control circuit 10 immediately controls the head driver circuit 8 to drive the recording head 1. As a result, one raster (one line) is recorded on the recording paper PS.

By the way, in the conventional raster type recording apparatus, when the printing position of the recording paper PS is determined, when the feed amount of the recording paper PS fluctuates during the conveyance, the fluctuation occurs and then the correction is performed to determine the printing position. Therefore, there is a problem that the followability to fluctuations is poor. There is also a method of determining the printing position only by the pulse signal of the encoder 6, but in this method, the printing accuracy depends on the accuracy of the encoder,
An expensive and highly accurate encoder is required to determine an accurate print position.

Therefore, in this embodiment, the rough print position is determined based on the pulse signal b from the encoder 6, and the print position is finely adjusted based on the pulse signal a from the encoder 5 to obtain an accurate print start signal c. Can be output to the control circuit 10. As a result, the recording paper PS
Even when the feeding amount of the sheet fluctuates during the conveyance, it can quickly follow the printing and print at the correct position on the recording paper PS, and the encoder 6 is not required to be particularly accurate. Further, since the reference of the printing position is determined by the pulse signal b from the encoder 6, even if an error occurs in the pulse signal a from the encoder 5, it is possible to prevent the accumulation thereof. That is, even if an error occurs in the pulse signal a due to the fluctuation of the carrier system during the printing of a certain raster, the pulse signal b from the encoder 6 is input to newly generate the pulse signal a during the printing of the next raster. Since the error is counted, the previous error is never accumulated.

The operation of the main part of the apparatus of this embodiment will be described more specifically below with reference to the timing chart of FIG. First, the number of pulse signals detected by the encoder 5 is 30
It is assumed that the conveyance distance of the recording paper PS is 1,000 mm as a design value and the actual measurement value is 1,001 mm for 50,000 sheets.

Here, the number of pulses when the recording paper PS is conveyed by 1,000 mm is corrected as x1 based on the following equation. That is, x1 = 300,000 × 1000/10001 = 299,700

When the number of pulse signals b from the encoder 6 is actually measured when the recording paper PS is conveyed, if the number is 15,750, the recording paper PS is 1,0.
The number of pulses x2 from the encoder 6 when transported by 00 mm is calculated based on the following equation. That is, x2 = 15,750 × 299,700 / 300,000 = 15,734.3

Assuming that one raster is printed by one pulse output from the encoder 6, the feed amount x3 of the recording paper PS at this time is x3 = 1,000 / 15,734.3 = 0. 0.0356 (mm) = 63.56 (μm). Then, each data calculated in this way is stored in the memory 9, and the control circuit 10 reads each data from the memory 9 and supplies the data to the correction count number calculation circuit 11 as necessary.

FIG. 3 (a) shows the timing of such a pulse signal b output from the encoder 6. On the other hand, FIG. 3B is a timing showing the design value of the pulse signal a from the encoder 5, which has a recording paper feed amount of 3.18 μm per pulse. Here, if the design value of the feed amount of the recording paper PS by the pulse signal b from the encoder 6 is 63.5 μm, the recording paper PS
As shown in FIG. 3 (c), the actual feed amount of the sheet shifts by 0.06 (63.56−63.50) μm for each raster printing.

This deviation is 1.62 (0.06 ×) when the 28th raster (28th raster) is printed.
27) .mu.m, which is more than half the recording paper feed amount of 3.18 .mu.m due to the pulse of the encoder 5 shown in FIG. Such a deviation is caused by the correction count number calculation circuit 1
2 is detected by calculating each of the above-mentioned data given from the control circuit 10 based on the pulse signal b from the encoder 6. Therefore, initially, the counter value “20” is set to the counter 11 in synchronization with the pulse signal b from the encoder 6.
In this case, the correction count number calculation circuit 12, which outputs the print start signal c after the 20th pulse of the pulse signal a from the counter 11, outputs the pulse signal corresponding to the previous 27th raster (27th raster) printing. At the rising edge of b, the counter value "19" is set in the counter 11.

As a result, the counter value "19" is the pulse signal a from the encoder 5 after the detection of the pulse signal b.
For example, the counter 11 is subtracted in synchronism with the above, and when the counter value becomes “0”, the print start signal c is output to the control circuit 10 and the 28th raster is printed.
After that, the counter value "1" is displayed in the counter 11.
9 ”is continuously given and thereafter the error is (3.18+
When 1.62) μm or more, the counter value “18” is given to the counter 11. Thus, when the printing error becomes equal to or higher than the resolution of the encoder 5, a new counter value is sequentially set in the counter 11, so that the error is immediately corrected and printed out.

Next, FIG. 2 is a block diagram showing a second embodiment of the present invention. As shown in FIG. 2, this second embodiment device omits the encoder 5, the counter 11, and the correction count number calculation circuit 12 for detecting the rotation speed of the motor 3 from the above first embodiment device, Instead of oscillator 13,
A timer 14 and a correction timer number calculation circuit 15 are provided.

The apparatus of the second embodiment is an example of the case where the conveying speed of the recording paper PS is assumed to be constant, and if the conveying speed of the recording paper PS is constant, the pulse signal b output from the encoder 6 is used. It is possible to control the amount of deviation from the time and print at an accurate position. FIG. 4 is a timing chart of the second embodiment apparatus that manages the amount of deviation of the encoder 6 from the pulse signal b by time. FIG. 4 (a) is a pulse signal b, and FIG. 4 (b), (c) are , A clock signal CLK output from the oscillator 13 and a print start signal c output from the timer 14, respectively.

Similar to the first embodiment, the second embodiment also stores in the memory 9 the data concerning the accuracy such as the design value and the actual measurement value of the pulse signal b output from the encoder 6 in advance. This is read by the control circuit 10 and given to the correction timer number calculation circuit 15. The recording paper PS is conveyed to the correction timer number calculation circuit 15 as shown in FIG.
Each time the pulse signal b from the encoder 6 shown in (1) rises, the deviation amount from the design value is calculated, the calculation result is set as the timer value in the timer 14, and the timer is started.

When the timer 14 is started and started, the timer value from the correction timer number calculation circuit 15 is set as shown in FIG.
The clock signal CLK from the oscillator 13 shown in FIG.
It is output to the control circuit 10 at the timing shown in (c). In this way, the printing position can be finely adjusted by the timer 14, and printing can be performed at a more accurate position by increasing the speed of the clock signal CLK.

In this embodiment, the pulse output from the encoder 6 is one pulse for one raster, but it may be one pulse for a plurality of rasters. That is, in this case, for each raster during one pulse, the encoder 5
The number of pulses from 20 is set to 20 or the timer value set in the timer 14 is set in raster units for positioning. As a result, the resolution of the encoder can be lowered. Further, the number of pulses of the encoder 6 can be set to a plurality of pulses for one raster. That is, in this case, a counter for counting the pulses from the encoder 6 is required. After counting the number of conveyances of one raster by this counter, the print position between the pulses is obtained, and the encoder 5 corresponding to that position is obtained. Pulse or the timer 14 to finely adjust the print position. As a result, the followability of printing with respect to changes in the feed amount of the recording paper PS is improved.

The counter 11, the timer 14, the correction count number calculation circuit 12, the correction timer number calculation circuit 15 and the like used in the respective embodiments may be constituted by electric circuits or may be CPUs. . A pulse motor may be used instead of the encoder 5. Also, the encoder 6
Can be anything that detects the feeding of the chart paper,
Therefore, a mark such as a photo coupler may be used to read the mark on the recording paper. Further, in each embodiment, the feeding amount of the recording paper PS is maintained as it is and the printing timing of the recording head 1 is adjusted to determine the accurate printing position on the recording paper PS, but the printing timing is constant. The motor driver circuit shown by the broken line in FIGS. 1 and 2 may be controlled to adjust the feed amount of the recording paper PS.

[0034]

As described above, according to the present invention, when the detection amount of the recording paper is detected by the detection means, the printing position corresponding to the conveyance amount of the recording paper is determined according to the accuracy of the detection means. Since it is corrected and printed out, even if the feed amount of the recording paper fluctuates during its conveyance, it can quickly follow this and always print out at the correct position on the recording paper. Does not require high-precision detecting means.

Further, a first encoder for periodically generating a first pulse signal for each predetermined carry amount is provided as the detection means, and the counter as the output means is synchronized with the motor after the input of the first pulse. Since the second pulse is counted and the print start signal is output when the count value reaches the counter value which is the correction value, the print position on the recording paper can be accurately determined with a simple configuration. Also,
Since the timer is provided as the output means, the timer performs the time counting operation for the timer value which is the correction value based on the clock signal after the input of the first pulse, and outputs the print start signal in response to the time-up. If the resolution of the clock signal is set high, it is possible to immediately follow fluctuations in the recording paper conveyance and print at the correct position.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a second embodiment of the device.

FIG. 3 is a timing chart of the first embodiment device.

FIG. 4 is a timing chart of the second embodiment device.

[Explanation of symbols]

1 ... Recording head, 3 ... Motor, 5, 6 ... Encoder, 1
0 ... Control circuit, 11 ... Counter, 12 ... Correction count number calculation circuit, 13 ... Oscillator, 14 ... Timer, 15 ... Correction timer number calculation circuit, PS ... Recording paper, a, b ... Pulse signal,
c ... Print start signal, CLK ... Clock signal.

Claims (3)

[Claims] 1. A raster-type recording apparatus for performing printing on a conveyed recording paper by a raster method, and a detection means for detecting the conveyance amount of the recording paper, and an accuracy calculation means for calculating the accuracy of the detection means in advance. A correction unit for correcting the print position on the recording paper according to the accuracy calculated by the accuracy calculation unit for each detection output of the detection unit, and a print start signal is output at the print position corrected by the correction unit. A raster recording apparatus comprising: an output unit. 2. The raster type recording apparatus according to claim 1, wherein the detecting unit is a first unit for each predetermined transport amount of the recording sheet.
A first encoder for generating a pulse signal, a counter as the output means, and a second pulse signal having a shorter cycle than the first pulse signal in synchronization with a motor for conveying the recording paper. The second encoder is engaged with the motor, and the correction means corrects the print position according to the accuracy calculated by the accuracy calculation means at each arrival of the first pulse, and the correction value is a counter value. The raster type, wherein the counter counts the second pulse after the input of the first pulse and outputs the print start signal when the count value reaches the counter value. Recording device. 3. The raster type recording apparatus according to claim 1, wherein the detection unit includes an encoder that generates a pulse signal for each predetermined conveyance amount of the recording sheet, and the output unit includes a timer. An oscillator for supplying a clock signal is connected to the timer, and the correction means corrects the print position according to the accuracy calculated by the accuracy calculation means at each arrival of the pulse, and uses the correction value as a timer value for the timer. The raster type recording apparatus, wherein the timer performs a time counting operation based on a clock signal after the input of the pulse and outputs the print start signal in response to time-up.