JPH0532003A - Paper thickness detection controller - Google Patents

Abstract

(57) [Summary] [Configuration] The maximum stroke C toward the platen side of the print head is required to calculate the thickness B of the paper. The number of pulses sent to the stepping motor until the head comes into contact with the platen is stored as the maximum stroke C until the head comes into contact with the platen.
The thickness B of the paper is obtained by subtracting the motor pulse number A sent from the initial position until the print head contacts the paper. [Effect] By measuring the distance from the initial position of the print head to the platen, that is, the maximum stroke C, it is possible to eliminate the influence of variations in the processing accuracy and assembly accuracy of the printer mechanism when obtaining the paper thickness. it can.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer having an automatic paper thickness adjusting mechanism.

[0002]

2. Description of the Related Art In a conventional apparatus, as described in Japanese Patent Laid-Open No. 63-281872, a stepping motor moves a print head toward a print sheet placed on a platen, and the print head comes into contact with the print sheet. The amount of increase / decrease of feedback pulse caused by stepping motor step out at that time is detected by a slit detection element, etc., and the absolute thickness of the printing paper is judged by the number of feedback pulses from the initial position of the print head to the position where it abuts the paper. But
The initial position of the print head is not constant due to variations in the processing and assembly accuracy of the printing device mechanism, and even if the paper thickness is the same, the number of feedback pulses from the initial position of the print head to the contact with the paper fluctuates. However, there is a problem that the paper thickness cannot be calculated correctly.

[0003]

In the above-mentioned prior art, the number of feedback pulses from the initial position of the print head used for calculating the paper thickness to the position where it abuts the paper depends on the accuracy of processing and assembling of the printer mechanism. There is a problem in that the tolerance cannot be taken into consideration and the correct paper thickness cannot be calculated.

An object of the present invention is to bring the print head into contact with the platen from the initial position in the absence of paper in advance and to store the number of pulses sent to the stepping motor up to that time in the storage unit. By calculating the paper thickness from the number of pulses from the position to the contact with the paper, it is possible to eliminate the influence of variations in the machining and assembly accuracy of the mechanical section, and to accurately calculate the paper thickness. To supply.

[0005]

SUMMARY OF THE INVENTION In the automatic paper thickness adjustment control of a printing apparatus, the above object is to store the number of pulses until the print head is moved from the initial position to the platen side in the absence of paper in advance and abuts against the platen. This is achieved by providing a mode of operation in which the part is stored.

That is, if the distance from the initial position of the print head to the platen is C, the distance from the initial position of the print head to contact the paper is A, and the thickness of the paper is B, the thickness of the paper is B = C-A. The value of C varies from device to device due to variations in processing and assembly precision of the printing device mechanism. Therefore, in order to determine the value of C,
There is provided an operation mode in which the stepping motor is rotated from the initial position until the print head comes into contact with the platen when there is no paper in the initializing operation when the power is turned on or when there is no switch, and the pulse number at that time is stored as C. If the value of C is required at the time of initialization when the power is turned on, if the switch moves the print head to the platen side at each initialization, the value of C is held even when the power is off, and then this operation mode is performed. Held up. If the value of C is obtained, the stepping motor is rotated from the initial position until the print head comes into contact with the paper at the time of automatic paper thickness adjustment, and the pulse number at that time is subtracted from the value of C to obtain the paper thickness B. You can ask.

[0007]

According to the present invention, the print head is moved to the initial position in the direction perpendicular to the platen during the initialization operation when the power is turned on. After that, the print head is moved to the platen side, and the number of pulses of the stepping motor until the print head contacts the platen is counted and stored in the storage unit,
Again, move the print head to the initial position. Whether or not the print head comes into contact with the platen is determined by step-out detection due to an input change of an encoder pulse linked with the rotation of the stepping motor or an input change of a pressure sensor mounted near the print head. The distance from the initial position of the print head to the platen is calculated in this way by converting the number of pulses, and when the value is C, the number of pulses A from the initial position to the contact of the print head with the paper is adjusted during automatic paper thickness adjustment. The paper thickness B can be obtained by counting and subtracting A from C. The value of C is stored in the storage unit each time the power is turned on.

Further, when the operation for obtaining the distance C from the initial position of the print head to the platen is performed by the switch, the print head is moved to the initial position in the direction perpendicular to the platen by pressing or switching the switch. After that, the print head is moved to the platen side, the number of pulses of the stepping motor until the print head contacts the platen is counted and stored in the storage unit, and the print head is moved to the initial position again. The value of C stored here is retained even when the power is turned off, and is kept stored until the switch performs this operation again.

[0009]

[Embodiment] As one embodiment of the present invention, it is detected that the print head comes into contact with a platen or a sheet by a change in a detection pulse from an encoder that works in conjunction with a stepping motor that moves the print head to the platen side. A method for calculating the thickness of the paper by
Further, the case where the contact of the print head with the platen or the sheet is detected by the change in the signal level of the pressure sensor will be described with reference to FIGS.

FIG. 1 shows an outline of an automatic paper thickness adjusting mechanism section. The print head moves left and right in the axial direction of the eccentric support rail 3 to perform printing. The eccentric support rail 3 is interlocked with the stepping motor 5, and the eccentric support rail 3 is rotated by the rotation of the stepping motor 5.
Also rotates, and the paper surface gap 8 between the print head 1 and the paper 7 placed on the platen 2 can be changed. The encoder 4 is attached to the shaft of the stepping motor 5, and the photosensor 6 can read the change in the light from the slit due to the rotation of the encoder, and the movement amount of the print head 1 with respect to the paper can be known.

FIG. 2 is a block diagram of the control unit of the printing apparatus. The control unit 9 receives data from the upper host via the interface 13. When the control section 9 prints the data when it receives the data that triggers printing, it drives the carrier motor 10 that should move the print head 1 in the positive or negative direction. If the received data is a sheet suction trigger, the control unit 9 sucks the sheet, and therefore the sheet conveyance motor 1
Drive 1 When inhaling to a predetermined position, the control unit 9 drives the stepping motor 5 to adjust the head gap to keep the distance between the print head 1 and the paper 7 constant. When the head gap is adjusted, the repetitive pulse from the encoder is passed from the I / O sensor 12 to the control unit 9, and the thickness of the paper is calculated from the result.

A method of calculating the sheet thickness will be described with reference to FIGS. 3 and 4. When a pulse is sent to rotate the stepping motor 5, the output of the encoder 4 is detected by the sensor 6 along with the rotation of the stepping motor 5, and when it is rotating at a constant speed, the pulse period of the detected waveform is almost It becomes a constant T. When the head 1 comes into contact with the paper 7, the rotation of the stepping motor is hindered and the cycle of the detection pulse from the encoder is disturbed.
It is considered that the print head is in contact with the paper when the cycle at that time is T'or more. The maximum stroke C for moving the print head 1 in the vertical direction with respect to the paper 7 is obtained, and the pulse number A sent to the stepping motor is subtracted from C until the period of the detection pulse from the encoder becomes T'or more. B is required.

FIG. 5 shows an example in which the maximum stroke C is obtained during the initialization operation when the power is turned on. When the printer is initialized when the power is turned on, the print head is moved to the initial position (stopper position). A counter for obtaining the maximum stroke C is initialized. In order to move the print head to the platen side, the stepping motor is driven by one pulse, and the counter for obtaining C is updated. This operation is repeated until the print head comes into contact with the platen. When the print head comes into contact with the platen, the driving of the motor is stopped and the value of the counter is stored in the storage unit as the maximum stroke. When performing this operation, it is necessary to remove the paper,
The value of C is obtained every time the power is turned on.

FIG. 6 is an example in which the maximum stroke C is obtained only when the switch is switched. If the switch is not switched, normal processing is continued, but when the switch is switched, the operation of the flow of FIG. 5 is performed. Then, the maximum stroke C is obtained. In this case, the value of C needs to be held even when the power is turned off.

In the above embodiment, the print head is a platen,
Alternatively, whether or not the sheet comes into contact with the sheet is checked by the change in the pulse from the encoder, but it is also possible to use a pressure sensor as shown in FIGS. 7 and 8. The schematic configuration is the one in which the encoder 4 and the photosensor 6 are removed from FIG.
Instead, as shown in FIG. 1, the pressure sensor 21 is attached to the tip or all of the print head 1. The configuration of the control unit is shown in FIG.
Is the same as. Whether the print head comes into contact with the platen or the paper is determined by the change in the signal level of the pressure sensor. If the number of pulses sent to the stepping motor is counted until the signal level of the pressure sensor changes, the sheet thickness can be calculated as described above.

[0016]

According to the present invention, the distance from the initial position of the print head used to calculate the thickness of the paper to the platen, that is, the maximum stroke C of the print head to the platen is actually measured and stored. Therefore, it is possible to eliminate the influence on the maximum stroke C due to variations in the accuracy of processing and assembling of the printing device mechanism, and it is possible to accurately calculate the thickness of the paper.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an automatic gap adjusting mechanism according to an embodiment of the present invention.

FIG. 2 is a control block diagram of the present invention.

FIG. 3 is an explanatory diagram of a step-out detection method (encoder pulse).

FIG. 4 is an explanatory diagram of a paper thickness calculation method (encoder pulse).

FIG. 5 is a flowchart for obtaining the maximum stroke (at power-on).

FIG. 6 is a flowchart for finding the maximum stroke (switch switching).

FIG. 7 is an explanatory diagram of a step-out detection method (pressure sensor).

FIG. 8 is an explanatory diagram of a paper thickness calculation method (pressure sensor).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Print head, 2 ... Platen, 3 ... Eccentric support rail, 4 ... Encoder, 5 ... Stepping motor, 6 ... Photo sensor, 7 ... Paper, 8 ... Paper gap, 9 ... Control part, 10 ... Carrier motor, 11 ... Paper transport motor, 1
2 ... I / O sensor, 21 ... pressure sensor.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location G01B 21/08 101 (72) Inventor Mamoru Gokita 4-3 Kanda Surugadai, Chiyoda-ku, Tokyo Hitachi Techno Engineering Within the corporation

Claims (2)

[Claims] 1. A print head, a drive unit for moving the print head in a direction perpendicular to the paper transport direction, a print paper transport unit, a control unit for editing print data sent from a host, a paper surface and the print. In a printer having an automatic paper thickness adjusting mechanism section for automatically adjusting a gap with a head and a control section capable of detecting or calculating the paper thickness at the time of automatic paper thickness adjusting, the automatic paper thickness adjusting mechanism is provided. Part, using a stepping motor and an encoder, the number of pulses sent to the stepping motor, the difference between the number of feedback pulses from the encoder, or detects a step out of the motor by a change in the cycle of the feedback pulse from the encoder, The number of pulses until the out-of-step is detected is stored in advance by moving the full stroke without the paper, and from that pulse number By subtracting the number of pulses sent to the stepping motor until the loss of synchronism detection during automatic paper thickness adjustment, the paper thickness detection control apparatus and calculates the thickness of the sheet. 2. The automatic paper thickness adjusting mechanism using the stepping motor and pressure sensor as means for measuring a gap from the paper surface of the print head according to claim 1, wherein the paper is fully loaded without paper. The number of pulses sent to the stepping motor until the signal level of the pressure sensor changes by the stroke movement is stored, and the number of pulses until the signal level of the pressure sensor changes during automatic paper thickness adjustment from that number of pulses. A paper thickness detection control device that calculates the paper thickness by subtracting.