JPH106607A - Method for discriminating kind of printing sheet in serial printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the kind of a printing sheet correctly by judging the kind of the printing sheet by judging whether the difference in the approach quantity of a print head is more than or equal to a prescribed value or not when the change quantity of pulse frequency associated with the change of the distance of a pair of magnetic substances exceeds the first and second standard values by the approach to a printing sheet. SOLUTION: During non-printing, the distance between a magnetic coil sensor 5 and a magnetic piece is kept constant, the pulse frequency from an LC oscillating circuit 15 connected to the sensor 5 changes when a ribbon protector contacts a printing sheet. A count circuit 13 counts the pulse from the circuit 15 and outputs the count value to a control part 11. The control part 11 compares the value with a standard value and judges whether the difference is a prescribed value or not, and judges whether the change quantity of the pulse frequency exceeds the first and second standard values. When the quantity exceeds both standard values, the difference in the approach quantity of a print head at that time is calculated, and the kind of the printing sheet is judged by judging whether the difference is more than or equal to a prescribed valued or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the type of printing paper in a serial printer having an automatic paper thickness detection sensor, and more particularly to a method for determining single paper and copy paper.

[0002]

2. Description of the Related Art Conventionally, as an automatic paper thickness detection method for automatically detecting the thickness of a print paper, a pair of ferrite cores of ferromagnetic material are provided near a print head to change the distance between the print head and the print paper. There is also a pair of ferrite cores in which the distance between them is changed. In this method, a winding is applied to one ferrite core, and a change in inductance according to the distance between the ferrite cores is pulse-converted using an LC oscillation circuit. When the interval between the print head and the print paper is reduced and the print head comes into contact with the print paper, the frequency of the pulse output from the LC oscillation circuit changes. When the change in pulse frequency exceeds a certain amount,
It is determined that the print head has hit the print sheet, and the print head is separated from the sheet by a predetermined amount from that position to make the interval between the print head and the sheet constant.

If the printing paper is copying paper, the printing speed must be lower than the normal printing speed. Therefore, it is necessary to determine whether the set printing paper is single paper or copying paper. This determination was made by detecting the paper thickness. That is, if the paper thickness detected by the automatic paper thickness detection is equal to or less than the reference thickness, the sheet is determined to be a single sheet, and if the thickness is equal to or greater than the reference thickness, it is determined to be a copy sheet. When it is determined that the paper is a single sheet, the printing speed is set to the normal speed, and when it is determined that the paper is a copy paper, the printing speed is set to a printing speed lower than the normal speed and the impact force is increased to perform printing.

[0004]

However, in the above-described conventional method for determining the type of printing paper, the distinction between a single sheet and a copy sheet is made based on the sheet thickness. Is determined. In addition, since printing is performed at a speed lower than the normal printing speed irrespective of the single sheet, there is a problem that the throughput cannot be improved.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for determining the type of printing paper inserted between a printing head and a platen. The distance between the magnetic materials changes, and the inductance output output from the pair of magnetic materials is converted into a pulse output. When the print head approaches the printing paper, the amount of change in the frequency of the pulse exceeds the first reference value. Is determined, and if it is determined that the pulse frequency has exceeded the threshold value, the approach amount of the print head when the threshold value is exceeded is stored. If the pulse frequency variation exceeds the first reference value, the pulse frequency variation is determined. It is determined whether or not the second reference value has been exceeded. If the second reference value has been exceeded, the approach amount of the print head when the second reference value has been exceeded is stored, and when the change amount of the pulse frequency exceeds the first reference value. Of print head approaching The difference between the approach of the print head when the amount of change in pulse frequency exceeds the second reference value and discriminates the type of printing paper by determining whether more than a predetermined.

According to the present invention having the above configuration, it is determined whether or not the amount of change in the pulse frequency due to the approach of the print head and the printing paper exceeds the first reference value and the second reference value larger than the first reference value. I do. When both the reference values are exceeded, the difference between the approach amounts of the print head at the time when both reference values are exceeded is calculated, and the type of the printing paper is determined based on whether or not the difference is equal to or more than a predetermined value.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. Elements common to the drawings are assigned the same reference numerals. FIG. 1 is a flowchart showing the operation of the embodiment of the present invention, FIG. 2 is an explanatory diagram showing an automatic paper thickness detection mechanism of the embodiment, and FIG. 3 is a block diagram showing the embodiment. First, an automatic paper thickness detection mechanism according to the embodiment will be described with reference to FIG.

In FIG. 2, a print head 1 for printing is mounted on a carriage 2, and the carriage 2 is slidably fitted on a shaft 3. The shaft 3 is rotatable by a stepping motor described later, and the print head 1 approaches or separates from the platen 4 as the shaft 3 rotates. A magnetic coil sensor 5 is fixed to the carriage 2, and a ribbon protector 6 is mounted below the magnetic coil sensor 5. A magnetic piece 8 is fixed to the ribbon protector 6 via a mounting member 7. At the time of non-printing (in a state where no printing paper is loaded), the interval between the magnetic coil sensor 5 and the magnetic piece 8 is kept constant. The printing paper 9 is mounted between the ribbon protector 6 and the platen 4.

In FIG. 3, a control unit 11 controls the entire operation of the printer, is constituted by a microcomputer or the like, and has a storage function, a calculation function, and a comparison function. A motor driver 12 and a counter circuit 13 are connected to the control unit 11. The motor driver 12 is the control unit 1
The stepping motor 14 is driven by the command of 1. The stepping motor 14 is a motor for rotating the shaft 3 shown in FIG. The count circuit 13 is an LC oscillation circuit 1
5 and the LC oscillation circuit 15 is connected to the magnetic coil sensor 5.
It is connected to the. The LC oscillation circuit 15 is a circuit that converts the inductance output of the magnetic coil sensor 5 into a pulse and outputs the pulse to the count circuit 13.

FIG. 4 is a block diagram showing details of the counter circuit according to the embodiment. In the figure, a counter circuit 1
Reference numeral 3 comprises two timer counters 13a and 13b. The timer counter 13a generates a phase switching cycle of the stepping motor 14 for moving the print head 1 in the direction of the platen 4 and a time for sampling a pulse output from the LC oscillation circuit 15, and a clock (CLK) of the timer counter 13a. The terminal has a clock signal CLK-P
However, the gate (GATE1) terminal has a gate signal GA
The control unit 1 shown in FIG.
1 respectively. Timer counter 13a
Signal IPT-P output from the output (OUT) terminal of
Is input to the motor driver 12 and the timer counter 13b through the inverter 16.

The timer counter 13b includes the LC oscillation circuit 1
The pulse output from the counter 5 is counted, and the signal IPT-P output from the timer counter 13a is input to the gate (GATE2) terminal. This timer counter 1
3b is connected to the controller 11 shown in FIG. 3, and the count result of the timer counter 13b is output to the controller 11. The count values of both timer counters 13a and 13b can be set arbitrarily. When the gate terminal is "1" and the count is started, the output (OUT) terminal becomes "0" at the same time.
It is used in a mode in which the output terminal changes from "0" to "1" at the end of counting.

Next, the operation of this embodiment will be described mainly with reference to the flowchart of FIG. 1 and the timing chart of FIG. FIG. 5 is a timing chart showing the operation of the counter circuit. The signals a to e shown in FIG. 4 show the waveforms (a) to (e) shown in FIG.

The frequency of the pulse output from the LC oscillation circuit 15 does not change until the ribbon protector 6 contacts the printing paper 9, but changes when the ribbon protector 6 contacts the printing paper 9. The frequency of the pulse before the change is assumed to be f, and this value f is stored in the control unit 11 in advance.

A printing paper 9 is mounted between the ribbon protector 6 and the platen 4, and the control unit 11
, The stepping motor 14 is driven.
Thus, the shaft 3 shown in FIG. 2 rotates, and the carriage 2 starts to approach the printing paper 9.

As shown in FIG. 5A, a clock signal CLK-P is input to the timer counter 13a.
The control unit 11 sets Tm as the sample time in the timer counter 13a (step 1), and sets "1" to the gate terminal of the timer counter 13a as shown in FIG. 5B (step 2). Timer counter 1
The sample time Tm set in 3a is a phase switching cycle of the stepping motor 14. When "1" is set to the gate terminal, the timer counter 13a starts counting, and the output signal IPT-P of the timer counter 13a.
Becomes “0” (FIG. 5C). Timer counter 13a
Becomes "0", the gate terminal of the timer counter 13b opens (FIG. 5 (d)).
The timer counter 13b starts counting pulses (FIG. 5 (e)) output from the LC oscillation circuit 15.

When the timer counter 13a finishes counting, its output signal IPT-P changes from "0" to "1" (step 3), and the gate signal of the timer counter 13b changes from "1" to "0". (Step 4). As a result, the counting operation of the timer counter 13b also ends. Count value f counted by timer counter 13b
m is sent to the control unit 11. Next, the timer counter 13a
The gate signal (GATE-P) is set to "0" to mask the input of the clock signal (CLK-P) of the timer counter 13a.

In the control unit 11, the received count value f
m is compared with a reference value f stored in advance, and it is determined whether or not the difference (fm-f) becomes a predetermined value Δf1 (step 5). Here, the reference value f is the frequency of the pulse before the change as described above, and the predetermined value Δf1 is the amount of change in the frequency for detecting the change point of the pulse frequency from the LC oscillation circuit 15, and It is remembered.
This will be described with reference to FIG.

FIG. 6 is a graph showing the relationship between the frequency of the pulse output from the LC oscillation circuit 15 and the amount of approach of the print head to the platen. The vertical axis represents the frequency, and the horizontal axis represents the amount of approach to the platen. Is shown. The solid line shows the case of copy paper, and the dotted line shows the case of single paper. Here, both copy paper and single paper have the same thickness. (The same thickness is
As shown in FIG. 7, the thickness in a state where the copy paper 9a is pressed to eliminate the intermediate gap 18 is equal to the thickness of the single paper 9b. FIG. 7 is an explanatory diagram showing a state in which the printing paper is pressed. 3) The frequency does not change until the ribbon protector 6 comes into contact with the sheet, whether it is a copy sheet or a single sheet. However, when comparing the copy paper 9a and the single paper 9b, the ribbon protector 6 comes into contact with the paper first with the copy paper 9a. This is because there is a gap in the middle of the copy paper 9a, so that the thickness before pressing is thicker than single paper,
The ribbon protector 6 comes into contact early. Therefore, as shown in FIG. 6, the frequency change appears on the copy paper before the single paper. The predetermined value Δf1 is set to an arbitrary value when the frequency starts to change. In the example of FIG. 6, the predetermined value Δf1 is the point A1 in the case of copy paper,
In the case of a single sheet, the point is A2.

In step 5, if the difference between the count value fm and the reference value f does not reach the predetermined value Δf1, the phase of the stepping motor 14 is switched (step 6), and the count value of the timer counter 13b is cleared (step 6). 7). Then, returning to step 1, the operation of starting the timer counter at the stepping motor phase switching cycle Tm is repeated.

When the difference between the count value fm and the reference value f has reached the predetermined value Δf1, the control section 11 stores the frequency change points (points A1 and A2 shown in FIG. 6) (step 8). The positions of the points A1 and A2 are specified, for example, by counting clocks with a counter (not shown) in the control unit 11. Then, the control unit 11 sets the stepping motor phase switching period Tm as a sample time in the timer counter 13a (step 9), and clears the timer counter 13b (step 10). Further, the phase of the stepping motor 14 is switched (step 11), "1" of the gate terminal of the timer counter 13a is set (step 12), and the timer counters 13a and 13b are started. Thereby, the timer counter 13b counts the pulse frequency in the cycle Tm.

When the timer counter 13a finishes counting, its output signal IPT-P changes from "0" to "1" (step 13), and the gate signal of the timer counter 13b changes from "1" to "0". (Step 14).
As a result, the counting operation of the timer counter 13b also ends. The count value fm counted by the timer counter 13b is sent to the control unit 11. Next, the timer counter 13
The gate signal (GATE-P) of "a" is set to "0" to mask the input of the clock signal (CLK-P) of the timer counter 13a.

In the control unit 11, the received count value f
m is compared with a reference value f stored in advance, and it is determined whether or not the difference (fm−f) is equal to a predetermined value Δf2 (step 15). Here, the predetermined value Δf2 is set to
a is the change in frequency for detecting a state in which the gap is completely eliminated by pressing, and as shown in FIG. 6, Δf2>
The relationship is Δf1. The predetermined value Δf2 is stored in the control unit 11 in advance.

If the difference between the count value fm and the reference value f does not become Δf2, the process returns to step 9 and repeats the counting operation until the difference between the count value fm and the reference value f becomes Δf2. When the difference between the count value fm and the reference value f becomes Δf2, the control unit 1 determines the frequency change point (point B) at that time.
1 (step 16). As shown in FIG. 6, the changing point B is the same in the case of a copy sheet and the case of a single sheet, and the point B is stored in the control unit 11 as a count value.

Next, the control unit 11 determines the difference (C) between the value of the point A stored in step 8 and the value of the point B stored in step 16.
= BA) (step 17). In the case of the copy paper 9a, the difference C1 is calculated by B-A1, and in the case of a single sheet, the difference C2 is calculated by B-A2. Then, it is determined whether the calculated value is larger or smaller than a certain reference value n (step 18). Here, the reference value n is the copy paper 9a.
And a value for discriminating the single sheet 9b from each other.
It is set to an intermediate value between 1 and C2. This reference value n is also stored in the control unit 11 in advance. If the difference between the value at point A and the value at point B is greater than n, it is determined that the sheet is a copy sheet, and if it is smaller, it is determined that the sheet is a single sheet (steps 19 and 20).

If it is determined that the sheet is a copy sheet, the control unit 11 sets a print speed and a head drive time according to the copy sheet (step 21).
1 sets a normal printing speed and a head drive time (step 22). Thus, the operation of discriminating the copy sheet and the single sheet is completed.

In the above embodiment, the timer counter 1
Although the sampling time Tm counted in 3a is set as the phase switching cycle of the stepping motor 14, the sampling time Tm does not always have to be set as this phase switching cycle. However, setting the sampling time Tm as the phase switching cycle of the stepping motor 14 has the effect of saving circuits and control.

[0027]

As described in detail above, according to the present invention, by detecting a change in the frequency of the pulse output from the automatic paper thickness detecting mechanism, whether the printing paper is copy paper or single paper is determined. This makes it possible to discriminate, and even if the single sheet is a thick sheet, the single sheet is discriminated as a single sheet and printing can be performed at a normal speed, so that the printing throughput can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an operation of an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an automatic paper thickness detection mechanism according to the embodiment;

FIG. 3 is a block diagram showing an embodiment.

FIG. 4 is a block diagram illustrating a counter circuit according to the embodiment;

FIG. 5 is a timing chart showing the operation of the counter circuit.

FIG. 6 is a graph showing a relationship between a frequency and an approach amount to a platen.

FIG. 7 is an explanatory diagram illustrating a pressed state of printing paper.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Print head 4 Platen 5 Magnetic coil sensor 6 Ribbon protector 9 Printing paper 11 Control part 13 Count circuit 13a, 13b Timer counter 14 Stepping motor 15 LC oscillation circuit

Claims (2)

[Claims] In a method for determining the type of printing paper inserted between a printhead and a platen, the distance between a pair of magnetic bodies changes due to the proximity of the printing head and the printing paper. The output inductance output is converted into a pulse output, and it is determined whether or not the amount of change in the frequency of the pulse has exceeded the first reference value due to the approach of the print head and the printing paper. When the pulse frequency change exceeds the first reference value, it is determined whether the pulse frequency change exceeds the second reference value. If it is determined that the distance exceeds the first reference value, the approach amount of the print head and the amount of change of the pulse frequency when the pulse frequency change exceeds the first reference value are stored. 2
A print paper type discrimination method for a serial printer, wherein the type of print paper is determined based on whether or not a difference from the approach amount of the print head when the reference value exceeds a predetermined value is exceeded. 2. An approach amount of the print head when the variation amount of the pulse frequency exceeds the first reference value, and a change of the print head when the variation amount of the pulse frequency exceeds the first reference value. 2. The method according to claim 1, wherein the approach amount is calculated by counting a clock from the time when the pulse frequency starts to change.