JPH09254482A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a dot superposition or an interdot clearance from occurring in a line feed part by counting a paper feed amount using a first and a second detecting means, then comparing these counts with a previously specified value, and calculating a line feed correction value based on the comparison results, and further, feeding the paper based on the correction value each time the line is fed. SOLUTION: When a first sensor 8 detects the tip of a paper, its detection signal is sent to a counting circuit part 13, then the counting circuit part 13 counts a pulse motor transit clock until a second sensor 12 detects the tip of the paper. Next, the counted value (c value) is sets to a comparison operating part 14 to calculate the difference between the counted value and a previously specified value (k value). In addition, a line feed correction operating part 15 corrects the value obtained by counting an initialized line feed amount (c value) in such a manner that the value is incremental, if the c value is higher than the previously specified value (k value), and on the contrary, corrects the c value in such a manner that it is decremental, if the c value is lower than the k value, in proportion to the difference. This correction amount is stored in line feed correction memory 16 and the drive of a pulse motor 18 is controlled by a motor control part 17 each time the line is fed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveying section for conveying a sheet, a first detecting section for detecting the sheet, and a sheet for conveying the sheet at a position separated by a predetermined distance on the downstream side of the sheet conveying from the first detecting section. The present invention relates to a printer that includes a second detection unit that detects and a printing unit that prints on the paper, and that prints on the paper, and particularly relates to a printer that performs highly accurate paper feed control.

[0002]

2. Description of the Related Art A conventional printer will be described with reference to FIGS.

FIG. 8 is an overall view of the thermal printer, and FIG. 9 is a schematic cross-sectional view of a paper feeding section. In the figure, 1 is a carriage and 2 is a printing head, which is driven by a belt 4 by a carriage drive motor (pulse motor) 3. Reference numeral 5 is a feed roller, 6 is a paper discharge pinch roller, 7 is a paper input pinch roller, 8 is a paper detection sensor, and 9 is a feed gear, which is connected to a paper feed motor (pulse motor) (not shown) and a reduction gear group. Then, the paper 10 is fed to the position of the platen 11 by driving the paper feed motor, and the print head 2 prints on the paper 10.

However, in the above-mentioned conventional printer, even if the paper feed motor is sent by a predetermined number of pulses, the paper feed amount of the paper varies from printer to printer due to manufacturing errors and the like, and the printing position varies. Especially when printing enlarged characters or images, gaps were seen even when the line feeds were connected. Therefore, in the conventional paper feed control, in order to prevent the occurrence of a gap at the line feed portion at the time of enlarged printing or image printing, the last few dots of the first to the previous line and the second few dots of the next line overlap. The paper feed was controlled so that it would be printed.

Further, as a means for suppressing variations in sheet feeding accuracy, there is known one disclosed in Japanese Patent Application Laid-Open No. 7-186484. In this publication, a reference roller having an outer peripheral length substantially equal to the length of one line feed of the print head and formed of a material having a small dimensional change with respect to temperature is provided so as to contact a part of the paper. The feed speed of the paper and the peripheral speed of rotation of the reference roller are made equal, and a decoding plate with a reference slit for detecting the rotation charge is coaxially provided on this reference roller, and the photo slit detects the reference slit to feed the paper. Control the amount,
Variations in the paper feed are corrected by providing a controller that controls so as to correct the error in the paper feed amount.

[0006]

However, in the above-described line feed control of dot overprinting, the density of the overprinted area becomes dark, and when the entire enlarged character or image image is viewed, the overprinted characters are overprinted. The place looks like a black streak. Therefore, even if the print quality of each line is good, the print quality of the entire image is poor.

This state (a state in which two dots are overlapped) is shown in FIG.
And shown in FIG. FIG. 10 is an explanatory diagram showing a state of a line feed portion of dot overlapping printing of enlarged characters, and FIG. 11 is an enlarged explanatory diagram showing details of a dot overlapping portion.

The print head has N dots and the number of overlapping dots is 2. 2 dots under the first line (N
-1 dot, N dot) and 2 dots above the 2nd line (1
If the density of one dot is shaded in the enlarged explanatory diagram of FIG. 11, the dot overlapping portion will be the density of halftone dots, and the overall image There was a problem that it looked like a black streak with a 2-dot line when viewed.

Further, in the one disclosed in Japanese Patent Application Laid-Open No. 7-186484, the reference roller is made of a material whose dimensional change with temperature is small, and the size of the print head is 400 dp.
When i is 64 dots, the maximum length of one line is about 4.05 mm
The diameter of the reference roller having an outer circumference of about 4.05 mm is about 1.29 mm. Even with a 168-dot multi-head, the maximum length of one line is about 10.65 mm and the diameter of the reference roller is about 3.39 mm.

Therefore, the reference roller must be finished with excellent dimensional accuracy, and the cost is increased due to the construction of a mechanism for rotating the paper without slipping.

The present invention has been made in view of these points, and provides a printer equipped with a paper feeding device that can be implemented accurately and inexpensively so that no gaps are created at the line feed portion without overlapping dots at the line feed portion. The purpose is to do.

[0012]

In order to achieve the above-mentioned object, a printer according to a first aspect of the present invention comprises a transport unit for transporting a sheet, a first detection unit for detecting the sheet, and a first detection unit. In the printer that prints on the paper, the printer includes a second detection unit that detects the paper at a position separated by a predetermined distance on the downstream side of the paper conveyance, and a printing unit that prints on the paper. Counting means for counting the sheet feed amount by the detecting means and the second detecting means, comparing means for comparing the value counted by the counting means with a prescribed value defined in advance, and based on the comparison result by the comparing means. And a control unit for feeding the paper with a line feed amount obtained by adding a correction based on the line feed correction value of the correction unit for each paper feed line feed.

In the printer having the above construction, the leading edge of the paper is detected by the first detecting means and the second detecting means, and the feeding amount of the paper between them is counted by the counting means, and the counted value is defined in advance. The specified value is compared with the comparison means, the line feed correction value is calculated by the correction means based on the comparison result, and the control means feeds the paper with the line feed amount corrected by the line feed correction value, and the paper for each line feed is calculated. To feed accurately.

According to another aspect of the printer of the present invention, the transport section has a sheet input roller for inserting a sheet into the printing section and a sheet discharge roller for discharging the sheet. At least one of the first detecting means and the second detecting means is disposed between the sheet discharging roller and the sheet discharging roller.

In the printer having the above-mentioned configuration, by disposing at least one of the first detecting means and the second detecting means between the paper input roller and the paper output roller, The first detecting means or the second detecting means can also be used as a detecting means for performing the paper cueing control or a detecting means for detecting the paper END which has been conventionally used.

According to a third aspect of the present invention, the printing unit is provided so as to be movable in the horizontal direction, a plurality of transport rollers for transporting a sheet are provided in parallel with the moving direction of the printing unit, and the transport rollers are provided between the transport rollers. First detecting means and second detecting means are provided.

In the printer having the above structure, the first detecting means and the second detecting means are arranged between the conveying rollers, so that the first detecting means and the second detecting means are arranged. It does not require any space and can detect the paper at the part where the paper does not float or sag.

[0018]

DETAILED DESCRIPTION OF THE INVENTION A printer according to the present invention will be described below with reference to a first embodiment shown in the drawings. FIG. 1 is a mechanical block diagram of the printer according to the first embodiment, FIG. 2 is a schematic cross-sectional view of a paper feeding unit showing a state in which a first sensor is turned on at the leading edge of the paper, and FIG. 3 is a second sensor at the leading edge of the paper. FIG. 6 is a schematic cross-sectional view of the sheet feeding unit showing a state in which the sheet feeding unit is turned on.

In the figure, 8 is a first sensor (first paper detection sensor) which is a first detection means, 10 is a paper, 12 is a second sensor (second paper detection sensor) which is a second detection means, 13 indicates that the paper 10 is the first sensor 8 and the second sensor 12.
A counter circuit section which is a counting means for counting the number of pulses of the motor when moving between the two (states of FIG. 2 to FIG. 3), and 14 is previously defined as a value (c value) counted by the counter circuit section A comparison calculation unit for performing comparison calculation with the specified value (k value) set, 15 is a line feed correction calculation unit for correcting the line feed amount with the line feed correction value obtained by the comparison calculation unit 14, and 16 stores the line feed correction amount. A line feed correction information memory 17, which is stored in advance, causes a motor control unit to send a pulse to a paper feed motor (pulse motor) 18 for rotational driving.

With the above configuration, the pulse motor transfer clock is sent to the counting circuit section 13 and the motor control section 16, and when the first sensor 8 detects the leading edge of the sheet 10 (FIG. 2), the signal is It is sent to the counting circuit unit 13, and then the second sensor 12 detects the leading edge of the paper 10 (FIG. 3).
The counting circuit unit 13 counts the pulse motor transfer clock. The counted value (c value) is compared by the comparison calculation unit 14
And the difference from the specified value (k value) specified in advance is calculated, and the line feed correction calculation unit 15 defines a value (c value) in which the default line feed amount is counted according to the difference. When the value is larger than the specified value (k value), it is corrected positively, and the counted value (c value) is the specified value (k value) that is specified in advance.
When it is smaller, it is corrected negatively. This correction amount is stored in the line feed correction information memory 16, and the motor control unit 17 stores each line feed.
The drive of the pulse motor 18 is controlled by.

The first embodiment of the actual control state will be described below. FIG. 4 is a flowchart, which will be described with reference to FIGS. 1, 2, 3, and 5.

In the flowchart of FIG. 4, first, when the print start is turned on (S1), the paper feed motor 18 is driven (S2), the feed roller 5 rotates, and the paper pinch roller 7 feeds the paper 10. To be paper. Next, as shown in FIG. 2, when the first sensor 8 is turned on at the leading edge of the sheet 10 (S3), the counting circuit unit 13 starts counting (4). Then, as shown in FIG. 3, when the second sensor 12 is turned on at the leading edge of the sheet 10 (S5), the counting circuit unit 13 is activated.
Ends counting (S6).

In the paper feeding of the printer shown in the figure, one pulse is fed to the paper feeding motor 18 by 1/800 inch. Here, the specified count value is specified and set to 577 pulses (k value).

It is assumed that the value counted by the counting circuit unit 13 is 581 pulses (c value). The count value (c value) is sent to the comparison calculation unit 14 to be compared and calculated (S
7), 581 pulses (C value) -5 in the line feed correction calculation unit 15
77 pulses (k value) = 4 pulses (s value) are sent, and the line feed correction calculation unit 15 performs the correction calculation of the following equation 1 (S).
8).

[0025]

[Equation 1]

Here, the ideal line feed value (r value),
The printing head used here is a 168-dot multi-head. As shown in FIG. 5, this head has a dot pitch of 0.0635 mm and a dot size of 0.04 mm.
It is 8 × 0.09 mm. The ideal line feed amount at the dot pitch is an enlarged character that feeds at all dots, 0.0635 mm x N for image printing, that is, 0.0635 mm x 1
It becomes 68 dots. Here, the prescribed value (k value) of line feed is prescribed and set to 336 pulses (r value). Therefore, the line feed correction value (h value) is 4 pulses (s value) × 336 pulses (r value) / 577 pulses (k value) = 2.33.

However, the line feed correction value (h value) is used to correct the pulse of the paper feed motor 18 and must be an integer.
And This is because the ideal line feed value (r value) is ideal for the corrected line feed amount, but in reality, even if the line feed amount is corrected, the feed amount of one pulse of the paper feed motor 18 remains unchanged. Further, if the space between the previous line (first line) and the next line (second line) is opened more than the state shown in FIG. 5, the generation of a gap in the printed state will be visually recognized. Therefore, the line feed amount after correction is set to satisfy the following conditions.

When the dot pitch is P, the number of line feed dots is N, and the feed amount of one pulse of the paper feed motor 18 is L, P × N ≧ corrected line feed amount ≧ P × N-L.

In this embodiment, the paper feed motor 1
1 pulse feed of 8 is 1/800 inch feed (0.03
175 mm), the dot spacing 0.0 shown in FIG.
Larger than 155 mm, maximum 0.01625 mm (about 1
(/ 33 dots) will overlap.

However, in actual printing, the gap is very conspicuous because it appears as a streak (gap) on a white background (paper) during printing of black or color, but a slight overlap (0.01625 mm or less). Is not a level at which it is recognized as a streak in the visually printed state, and is a level at which there is no problem in the overall printing quality.

Further, in the present embodiment, the one-pulse feed of the paper feed motor 18 is 1/800 inch feed, which overlaps. However, naturally, if the one-pulse feed of the paper feed motor 18 is 1/1900 inch feed, Correction is possible within the range of 5 to FIG.

With the above, the setting of the correction amount is completed (S
9), for each line feed, two pulses are added to the set line feed value (r value) for correction line feed.

In the above embodiment, the count value (c value)
Is greater than the specified count value (k value), the counted value (c value) is the specified count value (h
If it is smaller than (value), it means that the paper has been fed too far.
The (s value) of (c value)-(k value) = (s value) becomes negative, and the above contents are corrected to be negative. This correction amount is stored in the line feed correction information memory 16 and is corrected for each achievement.

The embodiment described above is an example,
It is not limited to this. For example, in the above-described embodiment, the counting circuit unit 13 counts the number of pulses of the paper feed motor 18. The time from when the first sensor 8 detects the leading edge of the paper 10 until when the second sensor 12 detects it. May be This makes it possible to improve the accuracy of the comparison calculation unit 14 of the above-described embodiment.

For example, the counting circuit unit 13 of the above embodiment
It is assumed that the value counted in 581 pulses (c value) is actually 581.9 pulses. In this case, 0.9 pulses are truncated in the pulse count. There is no problem if the paper feed motor 18 feeds one pulse of 1/1200 inch or 1/1600 inch.
On the contrary, if the 1 pulse feed such as 1/400 inch feed becomes coarse, the influence of this error becomes large. In that case μse
The accuracy can be improved without any problem by counting and performing comparison calculation in the time of c unit.

In addition, the paper cue control, which is conventionally performed by using either the first sensor 8 or the second sensor 12, is performed on the paper E.
It may also be used as a sensor used for ND detection. For that purpose, it is preferable that the first sensor 8 and the second sensor 12 are provided between the paper input pinch roller 7 and the paper output pinch roller 6.

If the first sensor 8 and the second sensor 12 are provided outside the paper input pinch roller 7 and the paper output pinch roller 6, the paper cue control and the paper END are performed at that position.
It cannot be used also as a sensor used for detection.
In the paper cue control, the paper 10 may be set at the entrance of the paper entry pinch roller 7 at the start of printing, and cannot be used as a paper cue control sensor.
Further, the case where the second sensor 12 is provided on the downstream side in the paper transport direction with respect to the paper discharge pinch roller 6. It cannot be used for detecting the sheet END at that position. Paper EN
This is because the D sensor has to detect the distance until just before the paper 10 is separated from the paper discharge pinch roller 6 after the paper END is detected, and recognize the end of the printing range.

Therefore, by providing the first sensor 8 and the second sensor 12 between the paper input pinch roller 7 and the paper output pinch roller 6, the first sensor 8 or the second sensor 12 is conventionally implemented. It can also be used as a sensor used for paper cueing control and paper END detection.

The first sensor 8 and the second sensor 12 are
The paper detection sensor is not limited to this because the paper detection accuracy is required for its function, but it is optimal to use a photo sensor. This is because when a mechanical sensor is used, the accuracy of line feed correction decreases due to the variation of the sensor itself, and therefore the variation of the sensor itself is suppressed and the precision of line feed correction is improved by using the photosensor.

Further, the first sensor 8 and the second sensor 12
As shown in FIG. 7, a plurality of feed rollers 5a and 5b are provided in the moving direction of the carriage 1.
Or between the feed roller 5b and the feed roller 5c. This is because the photo sensor is a transmissive type, and the detection member (paper 10) is provided between the reflector and the sensor.
This is because there is a reflection type that allows the light to pass through and is detected, and in this case, it cannot be arranged directly below the feed rollers 5a, 5b, 5c.

Therefore, the first sensor 8 and the second sensor 12
Is provided between the feed roller 5a and the feed roller 5b or between the feed roller 5b and the feed roller 5c, the restriction on the sensor mounting space is relaxed, and the type of sensor is not limited.

On the outside of the feed rollers 5a, 5b, and 5c (on the left side of the feed roller 5a and the right side of the feed roller 5c in FIG. 7), the edge of the sheet is lifted or loosened in the sheet width direction, so that the position of the sheet 10 is increased. Cannot be detected stably. Therefore, the feed rollers 5a, 5b, 5
By arranging the sensor between c, the type of the sensor is not limited, and since the feed rollers press the both sides of the sheet 10, the sheet can be surely detected.

Further, although a thermal printer has been described in the present embodiment, the invention is not limited to this, and an ink jet printer may be used.

[0044]

According to the printer of the first aspect, the leading edge of the paper is detected by the first detecting means and the second detecting means, and the feeding amount of the paper in the meantime is counted by the counting means. The comparison means compares with a specified value specified in advance, the line feed correction value is calculated by the correction means based on the comparison result, and the control means feeds the paper with the line feed amount corrected by the line feed correction value. It is possible to accurately feed the paper for each line feed regardless of the paper feed error of the transport unit.

In particular, when printing enlarged characters or images, there is no gap in the line feed and it is not necessary to forcibly print the line feed with a plurality of overlapping dots.
It is possible to improve the printing quality without the overlapping portions being seen as black streaks.

In the printer according to the second aspect, at least one of the first detecting means and the second detecting means is arranged between the sheet input roller and the sheet discharge roller. The first detecting means or the second detecting means can be used also as the detecting means for performing the paper cueing control or the detecting means for detecting the paper END that has been used conventionally, and prevent an increase in the number of parts. You can

In the printer according to the third aspect, since the first detecting means and the second detecting means are arranged between the conveying rollers, the first detecting means and the second detecting means are arranged. It is possible to achieve space saving without requiring a space therefor, and moreover, since it is possible to detect the paper at a portion where the paper does not float or slack, it is possible to improve the paper detection accuracy.

[Brief description of drawings]

FIG. 1 is a mechanism block diagram showing an embodiment of a printer of the present invention.

FIG. 2 is a schematic cross-sectional view of a sheet feeding unit (conveying unit) showing a state in which a first sensor is turned on at the leading edge of the sheet.

FIG. 3 is a schematic cross-sectional view of a sheet feeding unit (conveying unit) showing a state in which a second sensor is turned on at the leading edge of the sheet.

FIG. 4 is a flowchart illustrating the operation of the printer of the present invention.

FIG. 5 is an explanatory diagram showing a first example of a line feed correction control state.

FIG. 6 is an explanatory diagram showing a second example of a line feed correction control state.

FIG. 7 is a perspective view of the thermal printer with a platen removed to explain the mounting positions of the first and second sensors.

FIG. 8 is a perspective view of a conventional thermal printer.

FIG. 9 is a schematic cross-sectional view of a paper feeding unit.

FIG. 10 is an explanatory diagram showing a conventional dot overlapping printing state of enlarged characters.

11 is an enlarged explanatory diagram showing details of a dot overlap printing portion of FIG.

FIG. 12 is an explanatory diagram showing an example of a conventional line feed control state.

[Explanation of Codes] 1 Carriage 2 Printing Head 5 Feed Roller 6 Paper Ejection Pinch Roller 7 Paper Input Pinch Roller 8 First Sensor (Paper Detection Sensor) 10 Paper 12 Second Sensor (Paper Detection Sensor) 13 Counting Circuit Section 14 Comparison Calculation Unit 15 Linefeed Correction Calculation Unit 16 Linefeed Correction Information Memory 17 Motor Control Unit 18 Paper Feed Motor (Pulse Motor)

Claims (3)

[Claims] 1. A conveying unit for conveying a sheet, a first detecting unit for detecting the sheet, and a second detecting unit for detecting the sheet at a position separated by a predetermined distance on the downstream side of the sheet conveying from the first detecting unit. And a printing unit that prints on the paper, and in a printer that prints on the paper, a counting unit that counts the feed amount of the paper by the first detection unit and the second detection unit, Comparing means for comparing the value counted by the counting means with a prescribed value defined in advance, correction means for calculating a line feed correction value based on the comparison result by the comparing means, A printer comprising: a control unit that feeds a sheet with a line feed amount corrected by a line feed correction value. 2. The conveying section has a sheet input roller for inserting a sheet into the printing section, and a sheet discharge roller for discharging the sheet, and the sheet input roller and the sheet discharge roller. The printer according to claim 1, wherein at least one of the first detecting means and the second detecting means is disposed between the printer and the printer. 3. The printing unit is provided so as to be movable in the horizontal direction, and a plurality of carrying rollers for carrying the paper are provided in parallel with the moving direction of the printing unit, and the first detecting means and the carrying unit are provided between the carrying rollers. The printer according to claim 1, further comprising a second detection unit.