JPH04168075A - Printer - Google Patents

Abstract

PURPOSE:To make it possible to precisely transport a sheet to a printing position by calculating the positional relationship between the center position of a photosensor and a sheet end position based on a period when an output signal from the photosensor changes, and correcting the positional relationship between a printing position and the sheet using the calculation value. CONSTITUTION:When the end of a sheet transported passes through a photosensor 11, an output signal from the photosensor 11 changes. A change period detection device 12 detects a period from the start to the end of a change in this output signal, and a position calculation device 13 divides the number of pulses corresponding to the change period by 1/2 so that the matching of a sheet end position to the center position of the photosensor is ensured by calculation. After that, a correction device 14 corrects the positional relationship between a printing position and the sheet by using as a required number of pulses a value obtained by subtracting 1/2 of the number of pulses during the change period from the number of pulses for transporting the sheet to a printing position. Subsequently, the positional relationship between the sheet and a printing position can be correctly determined, if there are variations of photosensor properties and sheet reflection factor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a printer device, and more particularly to correction of the positional relationship between a conveyed sheet and a printing position.

(Prior Art) In general, a printer device detects the leading edge position of the paper in order to determine the printing start position of the printing paper being transported, and transports the printing paper to a predetermined position based on this leading edge position.

FIG. 2 shows the main parts of a conventional printer device.

The illustrated device includes a photosensor 1, an A/D conversion section 2, a successive approximation section 3, a control section 4, a memory 5, an LF pulse motor drive circuit 6, and an LF pulse motor 7.

The photosensor 1 is made of a photocoupler or the like, and is installed on the paper conveyance path.

The A/D (analog/digital) converter 2 includes an A/D converter circuit that converts an analog signal output from the photosensor 1 into a digital signal.

The successive approximation unit 3 is a circuit that successively compares the data input from the A/D conversion unit 2 and the data input previously.

The control unit 4 calculates the relative position between the edge of the paper (not shown) and the photosensor 1 based on the output data of the successive approximation unit 3, and generates an LF pulse based on this calculation result and data stored in the memory 5. This is a control circuit that controls the motor drive circuit 6.

The memory 5 stores predetermined data for transporting the paper from the end of the paper past the photosensor 1 to a predetermined printing position.

The LP pulse motor drive circuit (hereinafter referred to as motor drive circuit) 6 is a drive control circuit that drives and controls the LF pulse motor 7 based on drive pulses from the control section 5.

The LF (line feed) pulse motor (hereinafter referred to as a motor) is a motor that rotates based on drive pulses output from the motor drive circuit 6 and conveys paper.

Next, the operation will be explained.

An analog signal A is sent from the photosensor 1, and this signal A is digitized into a digital signal B by the A/D converter 2.

The successive approximation unit 3 inputs this digital signal B and successively compares whether the current manually input data increases or decreases with respect to the previous input data, and determines whether the current input data increases or decreases. If so, a detection pulse C is output.

The control unit 4 determines that the edge of the paper has passed over the photosensor 1 while the detection pulse C is input, and when the detection pulse C is turned off, the edge of the paper has completely passed the photosensor 1. I judge that. When the control unit 4 determines that the paper has passed the photosensor 1, it outputs motor drive pulses E of a certain value preset in the memory 5 to the motor drive circuit 6.

The constant value set in the memory 5 is the photo sensor 1
The value corresponds to the number of pulses corresponding to the amount of rotation of the motor 7 necessary to convey the paper from the position to the print head section (not shown).

When a pulse F is output from the motor drive circuit 6, the motor 7 rotates by an amount of rotation corresponding to the pulse F, and conveys the paper to the print head section.

(Problems to be Solved by the Invention) As described above, in the conventional apparatus described above, a predetermined slice level is set for the output change of the photosensor 1, and when this slice level is exceeded, the paper edge position and the center of the photosensor 1 are set. It is determined that the position matches the position, and the paper is conveyed based on the result of this determination.

However, the rate of change of the output of the photosensor 1 at the time of rising or falling is not constant due to differences in the reflectance or transmittance of the paper being conveyed and variations in the sensitivity of the photosensor 1 itself.

Therefore, when the paper edge position is calculated based on signals having such different rates of change, the actual paper edge position and the calculated paper edge position may not match.

As a result, the paper is conveyed with an error in the paper edge position, and there is a problem that the predetermined printing position of the paper and the position of the print head that performs the actual printing are misaligned. Ta.

In addition, in order to correct such misalignment between the paper and the print head, the operator must change the slice level and drive amount of the motor 7 according to the paper and each printer device. In this case as well, there was a problem of poor operability.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a printer device that can accurately determine the positional relationship between paper and a printing position.

(Means for Solving the Problems) A printer device of the present invention includes a photosensor whose output signal changes when the sheet being conveyed passes the paper edge, and a photo sensor whose output signal changes from the start to the end of the change in the output signal of the photosensor. a changing period detecting means for detecting a period, a position calculating means for calculating a positional relationship between a paper edge position and a detection reference position of the photosensor based on the period detected by the changing period detecting means, and the position calculating means A correction means is provided for correcting the positional relationship between the print position and the paper based on the positional relationship calculated in .

(Function) In the apparatus of the present invention, when the edge of the paper being conveyed passes the photosensor, the output signal of the photosensor changes.

The change period detection means detects the period from the start to the end of this output signal change, and the position calculation means calculates the positional relationship between the paper edge position and the detection reference position of the photosensor based on this period. For example, the position calculation means calculates that the paper edge position matches the center position of the photosensor by dividing the number of pulses corresponding to the period by 1/2.

Then, the correction means corrects the positional relationship between the printing position and the paper by, for example, subtracting 1/2 of the number of pulses within the change period from the number of pulses for transporting the paper to the printing position. This is done by setting the required number of pulses.

Therefore, even if there are variations in photosensor characteristics, paper reflectance, etc., the positional relationship between the paper edge position and the center position of the photosensor can always be accurately calculated, and as a result, the positional relationship between the paper and the printing position can also be calculated accurately. can be determined accurately.

(Embodiments) Hereinafter, the printer device of the present invention will be explained in detail using the embodiments shown in the drawings.

FIG. 1 is a block diagram showing a printer device of the present invention.

The device shown in the figure includes a photosensor 11 and a change period detection means 1.
2, a position calculation means 13, a correction means 14, an LF pulse motor drive circuit 15, and an LF pulse motor 16.

As shown in FIG. 4, which will be described later, the photosensor 11 is
This is an optical sensor that is installed on the paper conveyance path and detects transmitted light or reflected light from the paper.

The change period detection means 12 has a function of detecting a period from the start to the end of change in the output signal of the photosensor 11.

The position calculation means 13 has a function of calculating the positional relationship between the paper edge position and the center position, which is the detection reference position of the photosensor 11, based on the period detected by the change period detection means 12.

The correction unit 14 has a function of correcting the positional relationship between the print position and the paper based on the positional relationship calculated by the position calculation unit 13.

LF pulse motor drive circuit (hereinafter referred to as motor drive circuit) 15 and LF pulse motor (hereinafter referred to as motor)
Reference numeral 16 denotes a circuit that drives and controls the motor 16 based on a signal from the correction means 14, and a motor that rotates based on a drive pulse output from the motor drive circuit 15 and conveys the paper.

Next, a specific configuration of the printer device of the present invention will be explained.

FIG. 3 is a block diagram showing a specific configuration of the printer device shown in FIG. 1.

In the figure, the change period detecting means 12 includes the A/D converter 1
7, a successive approximation section 18, and a counter 19.

The position calculation means 13 includes a calculation section 21 in the control section 2o and a
/2 divider 22.

The correction unit 14 includes a correction unit 23 of the control unit 20 and a subtracter 2.
4 and a memory 25.

The A/D converter 17 converts the analog signal A from the photosensor 11 into a digital signal B as in the conventional case.
This is a D conversion circuit.

The successive approximation unit 18 includes three or more stages of buffers, and has an A/D
The input numerical value from the conversion unit 17 is compared with previous input data and subsequent input data, and the value is increased or increased in the input data. is a circuit that outputs an enable signal C during the period of increase or decrease if the decrease continues.

The counter 19 is a counting circuit that counts the number of motor drive pulses D output from a control section, which will be described later, while an enable signal C is being input.

The control unit 20 is composed of a processor, etc., and determines the paper edge position and the photo sensor 1 based on the output signal F of the 1/2 divider 22.
It has a calculation section 21 that calculates the positional relationship with the center position of 1 and a correction section 23 that will be described later.

The 1/2 divider 22 is a divider that inputs the count data E output from the counter 19 and outputs 1/2 of the value.

The memory 25 stores theoretical value data G of the motor drive pulse D required to transport the paper from the center position of the photosensor 11 to the print head section.

The subtracter 24 divides the theoretical value data G from the memory 25 and 1/
This circuit inputs the signal F output from the divider 22 and subtracts these values.

The correction unit 23 has a function of correcting the positional relationship between the printing position and the paper based on the subtraction value data H output from the subtractor 24.

Further, FIG. 4 shows the structure of the main parts of the printer device.

In the figure, 26 is a sheet of paper, and this sheet of paper 26 is configured to be conveyed on a conveyance path 27 by a feed roller 28a.

The photosensor 11 is provided on the lower surface side of the conveyance path 27,
It is configured to detect the conveyance state of the paper 26.

Further, a platen 29 is provided in front of the sheet 26 in the transport direction, and is connected to the drive shaft of the motor 16 via a drive belt 30. The platen 29 is provided with a feed roller 2 for conveying the paper along the platen 29.
8b are rotatably installed in contact with each other. Further, above the platen 29, a print head 31 for printing on the paper 26 is provided.

Next, the operation of the printer device having the above configuration will be explained.

FIG. 5 is a time chart showing the operation of each part of the printer device, and A-H are output signals A-H of each part shown in FIG.
It corresponds to

First, the motor 16 is driven by outputting a motor drive pulse D from the control section 20. This results in
The feed roller 28a is driven by a drive mechanism (not shown) and conveys the paper 26 in the direction of the arrow (see FIG. 4).

Also, in synchronization with the motor drive pulse D, the photo sensor 11
The output of is sampled, and successive approximation is performed in the successive approximation section 18.

When the leading edge of the sheet 26 being conveyed touches the photosensor 11, the output signal of the photosensor 11 changes. Then, when the leading edge of the paper 26 passes over the photosensor 11, the successive approximation section 18 detects a change in the sensor output and outputs an enable signal C to the counter 19 (time 1+ in FIG. 5).

As a result, the counter 19 starts counting the number of motor drive pulses D.

Thereafter, when the leading edge of the paper 26 completely passes over the photosensor 11 as the paper 26 is conveyed, the output of the photosensor 11 becomes a constant value. The successive approximation unit 18 detects this and turns off the enable signal C at time t2), and as a result, the counter 19 finishes counting the number of motor drive pulses D.

Count data E from counter 19 is 1/2 divider 2
2 is divided into 1/2, and this division data F is sent to subtracter 2.
4 is input.

That is, the number of pulses counted during time ts""t2 is a value corresponding to the amount of paper conveyance at the position before and after the leading edge of the paper 26 passes the photosensor 11, and is the drive amount of the motor 16.

This value is determined by the reflectance of the paper 26 and the photo sensor 11.
The value differs depending on the sensitivity. However, this value (
The position of the paper 26 corresponding to 1/2 of the paper conveyance amount is the case where the leading edge of the paper 26 always coincides with the center position of the photosensor 11 regardless of the number of pulses during the change period. Therefore, by reducing the number of pulses during the change period to 1/2, it is possible to calculate an accurate positional relationship between the center position of the sensor and the paper.

FIG. 6 shows the relationship between the number of pulses and the paper 26.

That is, if the number of pulses counted during the output change period of the photosensor 11 is 2a, then the leading edge of the paper 26 will always coincide with the center position of the photosensor 11 at a value a that is 1/2 of that number.

When the correction unit 23 of the control unit 20 detects that the enable signal C is turned off, it outputs the motor drive pulse D as much as necessary for the printing start part of the paper 26 to reach the print head 31, and
The paper 26 is conveyed to a predetermined position by driving the F-pulse motor 16.

That is, to explain this using FIG. 6, the drive pulse outputted by the correction unit 23 is calculated based on the theoretical value data G-(number of drive pulses in the change period 2a/2·a) stored in the memory 25.
) is subtracted (=value H of the output data of the subtracter 24).

In the above embodiment, as a correction of the positional relationship between the paper 26 and the print position, the leading edge of the paper 26 where printing starts is corrected, but with the same configuration, the trailing edge of the paper 26 and the printing end position are corrected. It is also possible to correct the positional relationship with.

Further, in the above embodiment, the number of pulses during the change period of the output of the photosensor 11 is set to 172 to detect the coincidence between the leading edge of the paper 26 and the center position of the photosensor 11, but this division value is only 1/2. Of course, it differs depending on the characteristics of the photosensor 11, etc.

(Effects of the Invention) As described above in detail, according to the present invention, the positional relationship between the center position of the photosensor and the paper edge position is calculated based on the output signal change period of the photosensor, and this calculated value is calculated. Since the positional relationship between the printing position and the paper is corrected using the above-described method, the paper can be accurately transported to the printing position regardless of the characteristics of the photosensor, the reflectance of the paper, and the like.

Therefore, there is no need for the operator to adjust the paper and printing position for each printer device or paper, and operability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of the printer device of the present invention, and FIG.
The figure is a block diagram of a conventional printer device, FIG. 3 is a block diagram showing a specific configuration of the device of the present invention, FIG. 4 is a perspective view showing the structure of the main part of the device of the present invention, and FIG. 5 is a block diagram of the device of the present invention. The operation time chart of each part of the apparatus, FIG. 6 is an explanatory diagram of paper conveyance in the apparatus of the present invention. DESCRIPTION OF SYMBOLS 11... Photo sensor, 12... Change period detection means, 13... Position calculation means, 14... Correction means. 11: Photosensor Block diagram of the device of the present invention Fig. 1 Block diagram of the conventional device Fig. 2 Specific block diagram of the i5 device of the present invention Fig. 3

Claims (1)

[Scope of Claims] A photosensor whose output signal changes when the sheet of paper being conveyed passes the edge of the sheet; a change period detection means for detecting a period from the start to the end of the change in the output signal of the photosensor; a position calculation means for calculating the positional relationship between the paper edge position and the detection reference position of the photosensor based on the period detected by the change period detection means; A printer apparatus comprising: a correction means for correcting a position and a positional relationship between the paper and the paper.