JP2000296946A - Paper thickness measuring method for printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure the thickness of paper of respective levels related to the hardness of the paper. SOLUTION: This method drives a stepping motor so as to move a carriage having a recording head to a platen side, successively integrating a time difference between a pulse signal of the movement which occurs at the same period as that of a driving pulse and the driving pulse with the movement, and measures the thickness of paper by the coincidence of the obtained integral value and the setting value of time difference integration. In this method, the number of the driving pulses from the time when the recording head is brought into contact with standard level paper to the time of pressure contact, a standard characteristic curve B of the number of the driving pulses and the integral value of the time difference and a standard characteristic setting point KB on the curve B, characteristic curves A, C corresponding to the paper of respective paper levels previously, obtained normal line of a setting point KB, and the integral value of the time difference on the intersections KA, KC of a normal curve K consisting of a group of normal lines for curves A, B, C passing through the setting point KB and the curves A, C of the respective paper levels are set as the setting value of the time difference integration of the respective paper levels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a sheet thickness in a printer.

[0002]

2. Description of the Related Art In a wire dot type recording head,
In order to achieve high-speed printing, it is necessary to minimize the stroke of striking the wire. On the other hand, this recording head allows many types of paper to be printed, for example, by allowing copying via a copying material, and the distance between the recording head and the recording paper greatly fluctuates as compared with other types of printers. Therefore, this type of printer includes a mechanism for adjusting the distance between the platen and the recording head.

A paper thickness measuring method for this adjustment is described in Japanese Unexamined Patent Application Publication No. Sho. The described technology includes a stepping motor that moves a carriage on which a recording head is mounted in a direction perpendicular to a platen axis, generates a pulse signal having a period proportional to the amount of movement of the carriage, and generates a pulse signal from a preset reference position of the carriage. The stepping motor is driven, the time difference between the drive pulse and the pulse signal is sequentially calculated and integrated, and the time when the integrated value reaches a predetermined value almost coincides with the time when the recording head contacts the paper. Therefore, the number of drive pulses from the time of the reference position to the time when the predetermined time difference integrated value is reached is measured, and the paper thickness is measured based on the corresponding movement amount. .

[0004]

In the above-mentioned technology, the characteristic curves of the drive pulse and the time difference integrated value when the recording head comes into pressure contact with the sheet after the recording head comes into contact with the sheet are used as the characteristic curves relating to the hardness of the sheet. The characteristic characteristic curves are used for each of the sheets, and the time when the recording head comes into contact with the sheet is determined by using a predetermined time difference integral value common to these. However, if the slope of the characteristic curve differs depending on the type of paper, etc., particularly when the slope is gentle, the point in time when the predetermined time difference integral value is reached is longer than the point in time when the recording head actually contacts the sheet. Also quite late. Therefore, the thickness of each level of paper cannot be measured accurately.

In order to solve the above problems, the present invention relates to a characteristic curve of a drive pulse and a time difference integral value when a recording head is pressed against a sheet after the recording head is in contact with each level of the sheet. In the printer, the predetermined time difference integral value is appropriately set for each level of paper, so that the point of contact with the paper can be accurately grasped, and the thickness of each level of paper can be accurately measured. It is an object of the present invention to provide a method for measuring paper thickness.

[0006]

According to a first aspect of the present invention, a stepping motor is driven to move a carriage mounted with a recording head in a direction perpendicular to a platen axis. In a paper thickness measuring method for integrating a time difference between a pulse signal having a period proportional to a moving amount of the sheet and measuring a sheet thickness based on a moving amount up to a predetermined time difference integral set value, a standard level paper is used. On the other hand, a standard characteristic curve consisting of a characteristic curve of the number of drive pulses and the time difference integrated value when the recording head is pressed against the sheet after being in contact with the sheet, and the predetermined time difference integral set value in the standard characteristic curve. A standard characteristic set point, which is an intersection with the integrated value straight line, and a normal line at the standard characteristic set point are obtained in advance, and each of the characteristics corresponding to the paper of each paper level having different paper quality is determined. Using a curve and a normal curve passing through the standard characteristic set point and comprising a set of normals to each of the characteristic curves, the level characteristic / intersection of the normal curve and the characteristic curve of the paper level is used. The time difference integral value at the intersection of the normals is set as the time difference integral set value of the paper level relating to the point of contact.

Therefore, the time difference integral set value unique to each paper level is used, and the number of drive pulses from the time point of the reference position of the movement to the time point when the time difference integral value is reached is calculated as follows.
It is taken in as a value related to the movement amount.

According to a second aspect of the present invention, there is provided a method as set forth in the first aspect, wherein the standard characteristic set point and the level characteristic / normal intersection with respect to the characteristic curve at an appropriate level are replaced by a normal curve connecting the standard characteristic set point and the characteristic curve. Is used, and the time difference integral value at the level characteristic / linear intersection, which is the intersection of the straight line and the characteristic curve of the paper level, is set as the time difference integral setting value of the level related to the point of contact. It is characterized by doing. Therefore, the same operation is performed according to the operation of the first aspect.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a view showing an example of a mechanism for adjusting a gap G between a platen and a recording head in a serial printer to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a carriage for moving a recording head,
Is mounted on a guide shaft attached to a base so as to be rotatable in an eccentric state, and a gap G with the platen 4 is provided.
Is configured to be adjustable.

Reference numeral 5 denotes a stepping motor.
It is a two-phase excitation type, is driven at a period of 3.5 milliseconds, and is connected to a driven vehicle 7 of the guide shaft 3 via a reduction gear 6. It comprises a sign plate 11 attached to the shaft 8 of the stepping motor 5 with a 10 rotary encoder, and a pattern detector 12 for reading the sign pattern of the sign plate 11. The rotary encoder 10 is set to output one pulse width in synchronization with one-phase driving of the stepping motor 5, and outputs a number of pulse signals proportional to the rotation angle. Reference numeral 13 denotes a position detector for detecting a reference position in a state where the carriage 1 is most retracted, and includes, for example, a microswitch. A guide member 14 supports the other end of the carriage 1.

Reference numeral 15 denotes a control device which receives signals from the position detector 13 and the rotary encoder 10 as described later,
The stepping motor 5 is driven based on each of the signals, and the carriage 1 is moved in the direction of arrow E in the figure to control the gap G to be adjusted to a value suitable for the thickness of the recording paper.

FIG. 1 is a block diagram of a control device for measuring sheet thickness according to an embodiment of the present invention. In the figure,
Reference numeral 20 denotes a motor drive control means for controlling the rotation of the stepping motor 5, and when a loading switch (not shown) is pressed, the carriage 1 is moved backward in a direction away from the platen 4, and when a predetermined reference position is reached, a position detector 13 is provided. Receives the reference position detection signal from the controller, and sets the reference position. Next, the carriage 1 is moved in the direction of the platen 4 to bring the recording head 2 into contact with the sheet. Further, when the sheet thickness is detected, the stepping motor 5 is driven so that the gap G becomes appropriate.

[0014] 21 in the time difference detecting means detects that the change in the time difference between the period of the drive pulse period and the stepping motor 5 of the pulse signal outputted from the rotary encoder 10 has occurred, the respective time difference △ T _n Output. 22
Is a time difference integrating means, and the integrated value of each time difference ΔT _n Σ (△ T
_n ) is calculated and output to the contact determination means 23 described later.

Reference numeral 23 denotes a contact determining means, which is a time difference integrated value Σ
When (△ T _n ) coincides with the judgment level value (time difference integral setting value) specified by the integral value judgment level setting means 26 described later, a contact judgment signal is output. The corresponding contact determination signal indicates that the recording head 2 has contacted the sheet, as described later.

Reference numeral 24 denotes a sheet thickness detecting means, and the position detector 1
The pulse signal output from the rotary encoder 10 is counted from the time when the reference position detection signal is output from 3 as a starting point until the contact determination signal is output from the contact determination means 23, and based on the counted value. To calculate the thickness of the paper.

Reference numeral 25 denotes paper level specification means for specifying each paper level relating to the hardness of the paper and the like. Reference numeral 26 denotes an integral value judgment level setting means for setting a judgment level value to be compared with the integral value by the time difference integrating means 22 based on the sheet level designation by the sheet level designation means 25 and contacting the judgment level value. This is given to the judgment means 23.

The integral judgment level setting means 26 sets an appropriate judgment level value (time difference integral setting value) for each designated paper level. The paper used in the printer can be classified, for example, according to its hardness. When the recording head 2 is brought into contact with the paper to detect the thickness of the paper, a relatively soft paper such as a copy paper is pressed without difficulty when the recording head 2 comes into pressure contact with the paper. The integration value Σ (△ T _n ) of each time difference △ T _n described above gradually increases with the progress of the drive pulse. Therefore, it is desirable to set the judgment level value composed of the time difference integral value Σ (△ T _n ) relatively small for soft paper.

FIG. 3 is a diagram relating to the setting of the judgment level value in the integral value judgment level setting means 26. In the figure,
The horizontal axis is the number of drive pulses of the stepping motor 5 (equivalent to the number of output pulses of the rotary encoder 10), and the vertical axis is the time difference integrated value Σ (△ T _n ), as indicated by the solid lines indicated by A, B, and C in FIG. The broken lines shown between them indicate the characteristic curves of the number of drive pulses and the time difference integral value Σ (△ T _n ) for each level of paper, and the curve B is a standard characteristic curve for paper of standard hardness.
Curve A shows the characteristic curve of a relatively hard sheet, and curve C shows the characteristic curve of a relatively soft sheet. I is a standard time difference integral set value preset for the standard characteristic curve B. Note that the origin in the figure indicates the point in time when the recording head 2 starts to contact the sheet.

The characteristic curves are obtained, for example, by appropriately classifying various levels of paper according to its hardness, setting each representative paper in a printer, and driving the stepping motor 5 to determine the number of drive pulses and the time difference. The integral value Σ (△ T _n ) is actually measured and obtained. As shown in the drawing, the slope of the curve becomes gentler as the paper is softer.

The curve K passes through the intersection of the standard characteristic curve B and the integral line representing the standard time difference integral set value I, and has a normal to each of the characteristic curves A, B, C, etc. It is a line curve. The normal curve K and each characteristic curve A, B, C
Intersections K _A , K _B , and K _C represent the respective judgment level values set by the integral value judgment level setting means 26 and the respective drive pulse numbers.

When the standard characteristic curve B is expressed by the equation, y = f (x), where x is the horizontal axis and y is the vertical axis, an appropriate coefficient for each level, for example, coefficient a1 or coefficient a2 Is multiplied by the above equation to obtain each characteristic curve A or B, the equation of the tangent at each of the intersections K _A and K _C is
_B is obtained in a similar manner. That is, each characteristic curve A or C
Is a time difference with respect to the standard characteristic curve B.
The value obtained by dividing the T _n with coefficients a1 or coefficients a2 △ _T n / a1 or △ _T becomes n / a2.

Therefore, the time difference integral value Σ (△ T _n ) for the standard characteristic curve B and the time difference integral value Σ (△ T _n / a1) or Σ (△ T _n / a2) for each of the characteristic curves A and C are:
It can be regarded as an equivalent level value as an integral value judgment level. Each of the intersection points K _A , K _B , K forming the respective time difference integrated values
_Since the coordinate of _C is defined for each tangent line related to each coefficient a1 or a2, it can be defined by each normal line at each coordinate. Therefore, the normal curve K is created by a combination of these normals.
In the figure, each paper characteristic indicated by a broken line is set according to the above.

Next, the operation of the above-configured apparatus will be described. FIG. 4 is a flowchart showing the operation of the control device 15. In the following description, each value (△ T _n / a1) or (△ T _n / a2) relating to the time difference is referred to as a value (△
T _n ).

When the paper level is designated by the paper level designation means 25, the integrated value determination level setting means 26 determines the time difference integral set value of the paper level from these characteristics A, B, C, etc. _K ) is specified (S1). When paper is loaded and a loading switch (not shown) is pressed (step S2), the stepping motor 5 is driven to rotate forward by the motor drive control means 20, and the carriage 1 is moved to substantially the center of the print area (step S2). S3). The carriage 1 is continuously driven in the reverse direction,
Is moved toward the position detector 13 (S4). When a position detection signal is output from the position detector 13 (S5), the stepping motor 5 stops (S6).

Subsequently, the stepping motor 5 is driven to rotate forward at a predetermined rotation speed, and the carriage 1 is moved to the platen 4.
(S7), and a pulse signal is generated from the rotary encoder 10 at the same time. Since the rotation of the stepping motor 5 tends to be uneven at the beginning of the movement of the carriage 1, the detection and the like are executed after this is stabilized.

FIG. 5 is a waveform diagram of signals related to the operation of the control device 15. Referring to FIG. 3, the load acting on the stepping motor 5 is substantially constant until the recording head 2 comes into contact with the sheet. Therefore, the period T of each pulse signal output from the rotary encoder 10 and the period of the driving pulse signal T
Is equal to When a difference occurs in each of the periods, the time difference detecting means 21 detects a time difference ΔT between the signals (S8).

The time difference integrating means 22 sequentially calculates the time difference integrated value Σ (△ T _n ) (where n is the number of occurrences of the time difference ΔT) (S9). Time difference until reaching the relevant contact ΔT
Does not occur, the time difference integrated value Σ (△ T _n ) becomes 0. When the recording head 2 starts to contact the sheet, the load is applied to the carriage 1 and the period of the pulse signal of the rotary encoder 10 becomes longer, so that a time difference ΔT is generated, and the time difference integrated value Σ (ΔT _n ) gradually increases.

The time difference integrated value Σ
(△ T _n ) is compared with the time difference integral set value T _K (S
10) If they match (S11), the sheet thickness detecting means 24
As a result, the paper thickness corresponding to the number of drive pulses up to the time difference integrated value Σ (△ T _n ) is detected (S1).
2). The motor drive control means 20 includes a paper thickness detection means 24
, The movement of the carriage 1 is stopped (S13).

Since the stop position is a position adjusted by using an appropriate judgment level value for the paper level, the gap G between the recording head 2 and the platen 4 is a value adapted to the paper level.

In the above description of FIG. 3, the normal curve K
Is a curved line, but a straight line may be used instead. In this case, the standard characteristic set point (intersection K _B ) and a characteristic curve of an appropriate level, for example, an intersection K _C with respect to the characteristic C are connected by a straight line, and each value at the intersection of the straight line and the characteristic curve indicated by the broken line is obtained. the time difference integration setting value of the respective paper levels may be set as (this referred to as T _M). Since each time difference integral set value T _M generally approximates each integral determination set value T _K when the normal curve K is used, the gap G is set to a value approximated to the former.

Each of the above-mentioned integral judgment set values _TM is determined by the integral value judgment level setting means 26 based on the specification of the paper level.
Moving the time difference integration but set value T _K is assumed to be specified, the carriage 1 platen 4 side by the stepping motor 5 sheets of appropriate levels is mounted in the sheet level from the characteristics A, B, C, etc. by At this time, the slope (ΔT / T) of the tangent line for each pulse period T is calculated, and this is combined to obtain the characteristic curve, which is compared with the standard characteristic curve to calculate the slope coefficient for the standard characteristic curve. seeking multiplier may be determined the time difference integration setting value T _K in the same manner as described above.

[0033]

According to the first aspect of the present invention, the standard characteristic of the number of drive pulses and the time difference integrated value when the recording head is pressed against the paper of the standard level after the recording head comes into contact with the paper. Curve, a standard characteristic set point in the standard characteristic curve and a normal line at the standard characteristic set point are determined in advance, and the characteristic curve corresponding to paper of each paper level having a different paper quality, and passing through the standard characteristic set point and The time difference integral value at the level characteristic / normal line intersection, which is the intersection of the normal curve composed of a set of normals to each characteristic curve and the characteristic curve of the paper level, is converted to the paper level related to the point of contact. , The time of the contact is properly determined for each sheet level, and the sheet thickness is accurately measured. Therefore, the gap G between the recording head and the platen is set appropriately for each paper level.

According to the second aspect of the present invention, a normal curve connecting the standard characteristic set point and the level characteristic / normal intersection with respect to the characteristic curve at an appropriate level is replaced with a normal curve. A straight line connecting the two is used, and the level characteristic / intersection of the line and the characteristic curve of the paper level is used.
Since the time difference integral value at the straight line intersection is the time difference integral setting value of the level relating to the point of contact, the time difference integral setting value approximates the time difference integral setting value obtained using the normal curve. Thus, the same effect as in claim 1 can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device for measuring a sheet thickness according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a mechanism for adjusting a gap between a platen and a recording head according to the present invention.

FIG. 3 is a diagram relating to setting of a judgment level value in an integral value judgment level setting means.

FIG. 4 is a flowchart illustrating an operation of the control device.

FIG. 5 is a waveform diagram of signals related to the operation of the control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotary encoder 13 Position detector 15 Control device 20 Motor drive control means 21 Time difference detection means 22 Time difference integration means 23 Contact determination means 24 Paper thickness detection means 25 Paper level designation means 26 Integration value determination level setting means

Claims (2)

[Claims] A stepping motor for moving a carriage on which a recording head is mounted in a direction perpendicular to a platen axis, generating a pulse signal having a cycle proportional to the amount of movement of the carriage, and stepping from a preset reference position of the carriage. A sheet thickness measuring method for driving a motor, sequentially calculating and integrating the time difference between the drive pulse and the pulse signal, and measuring the sheet thickness based on the amount of movement until reaching a predetermined time difference integration set value. A standard characteristic curve consisting of a characteristic curve of the number of drive pulses and the time difference integrated value when the recording head is pressed against the paper after the recording head comes into contact with the standard level paper relating to the hardness of the paper. A standard characteristic set point consisting of an intersection of the standard characteristic curve with an integral line representing the predetermined time difference integral set value, and a normal line at the standard characteristic set point Are determined in advance, and using the characteristic curves corresponding to the respective paper levels having different paper qualities, and a normal curve passing through the standard characteristic set point and including a set of normals to the respective characteristic curves, The time difference integral value at the intersection of the level characteristic and the normal line, which is the intersection of the normal curve and the characteristic curve of the paper level, is set as the time difference integral set value of the paper level, and the sheet thickness in the printer. Measuring method. 2. A straight line connecting the standard characteristic set point and the level characteristic / normal line intersection with respect to the characteristic curve at an appropriate level instead of a normal curve connecting the standard characteristic set point and the characteristic curve at an appropriate level. The time difference integral value at the level characteristic / linear intersection, which is the intersection of the characteristic curve and the characteristic curve of the paper level, is set as the time difference integral setting value of the paper level related to the point of contact. Item 2. A method for measuring a sheet thickness in the printer according to Item 1.