JPH0825750A - Serial printer with sheet thickness detecting mechanism - Google Patents

Abstract

PURPOSE:To effect printing under uniform printing pressure by controlling a position of a printing head so that the distance between the printing head and a printing face of a sheet is kept constant with respect to the entire width of the sheet whose thickness in the right and left directions is different. CONSTITUTION:A serial printer with a sheet thickness detecting mechanism is provided with a printing unit 8 including a printing head 10 for printing letters on a printing sheet through an ink ribbon, etc., a sheet thickness detecting mechanism 18 for detecting the thickness of the entire width of the printing sheet when first printing is started after closing a power source switch or after setting a printing sheet, and a sheet thickness detection controlling circuit 17 for storing and controlling the thickness of the entire width of the printing sheet detected by the sheet thickness detecting mechanism 18. Also, the serial printer is provided with a printing head movement unit 53 for moving the printing head 10 so that the distance between a top end of the printing head 10 and a printing face of the printing sheet is kept constant according to the thickness of the entire width of the printing sheet stored in the sheet thickness detection controlling circuit 17, a control unit 7 for controlling the operation of the whole printer, and an operation unit 54 for operating the printer and indicating the condition of the printer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer having a paper thickness detecting mechanism, and more particularly to a serial printer having a function of controlling the distance between the print head and the printing surface of the printing paper to be kept constant over the entire width of the printing paper. Regarding serial printers.

[0002]

2. Description of the Related Art Conventionally, a serial printer with a paper thickness detecting mechanism of this type eliminates the retracting operation of the print head at the time of feeding the paper and prints the printing paper as shown in Japanese Patent Laid-Open No. 59-20692. It is an object of the present invention to provide a serial printer that does not require a metal belt to be held. FIG. 5 is a front view showing an example of a printing mechanism of this conventional serial printer with a paper thickness detecting mechanism. Referring to FIG. 5, paper thickness sensors 83 and 83 ′ for measuring the thickness of the printing paper 85 are attached to both sides of the print head 10, and the paper thickness sensors 83 and 8 provided in the printing direction are attached.
At 3 ', the thickness of the printing paper 85 is measured. When the print head 10 moves to the right, the paper thickness sensor 83 'causes the print paper 85
Measure the thickness of. The thickness of the printing paper 85 is as shown in FIG.
5B, when the change from P1 to P2 is detected, the thickness of the print head 10 is changed by the print head up-and-down mechanism 82 using a DC motor or a stepping motor when the thickness changes. The distance between the lifted printing paper 85 and the print head 10 is kept constant by the difference (P2-P1). Here, the print sheet presser 84 prevents the print sheet 85 from bending, and when the paper is fed or the thickness of the print sheet 25 is changed, the print sheet presser 8 is pressed.
In order to avoid raising 4, it is composed of a spring having a spherical portion in contact with the paper.

[0003]

This conventional serial printer with a paper thickness detecting mechanism measures the thickness of the print paper in the direction in which the print head is moving, and the measured value allows the print head to keep a constant distance from the print surface of the paper. Since the control is performed so as to maintain the distance, it is necessary to control so that the distance between the print head and the printing surface of the paper is kept constant each time the print head is moved.

[0004]

SUMMARY OF THE INVENTION A serial printer with a paper thickness detecting mechanism of the present invention comprises a printing means including a print head for printing characters on a printing paper via an ink ribbon, and after the power is turned on or after the printing paper is attached. Sheet thickness detecting means for detecting the thickness of the entire width of the printing sheet at the start of printing for the first time, storage means for storing the thickness of the entire width of the printing sheet detected by the sheet thickness detecting means, and storage in this storage means. And a moving unit that moves the print head so as to keep the distance between the front end of the print head and the print surface of the print paper constant according to the thickness of the entire width of the print paper.

Further, in the serial printer with a paper thickness detecting mechanism of the present invention, the paper thickness detecting means has a roller that rotates in contact with the printing paper, a shield plate that expands and displaces the positional displacement of the roller, and the shield plate. Displacement detecting means for detecting the displacement of the.

Further, in the serial printer with a paper thickness detecting mechanism of the present invention, the displacement detecting means includes a light emitting means and a light receiving means for detecting the displacement of the shielding plate.

[0007]

Next, the present invention will be described with reference to the drawings. Referring to FIG. 1 which is a block diagram showing an embodiment of the present invention, a serial printer with a paper thickness detecting mechanism of this embodiment includes a printing unit 8 including a print head 10 for printing characters on a printing paper via an ink ribbon. And a sheet thickness detecting mechanism 18 for detecting the thickness of the entire width of the printing sheet at the beginning of printing after the power is turned on or after the printing sheet is attached, and the total thickness of the printing sheet detected by the sheet thickness detecting mechanism 18 is stored. In order to keep the distance between the tip of the print head 10 and the printing surface of the printing paper constant according to the paper thickness detection control circuit 17 to be controlled and the thickness of the printing paper full width stored in the paper thickness detection control circuit 17. A print head moving unit 53 that moves the print head 10, a control unit 7 that controls the operation of the entire printer,
Operation unit 54 for operating the printer and displaying the printer status
Composed of and.

The control section 7 includes a main control circuit 1 for controlling the operation of the entire printer, a read-only program storage circuit 2 for storing a control program, and a print data receiving circuit 5 for receiving print data through an interface line 6.
And a work memory circuit 3 for temporarily storing the received print data and a read-only character pattern data memory circuit 4
Composed of and. The printing unit 8 includes a print head 10 that prints characters on a print sheet via an ink ribbon, a print head drive circuit 9 that drives the print head 10 according to character pattern data, and the print sheet in a vertical direction with respect to a print surface. A paper feed motor 12 to be moved, a paper feed motor drive circuit 11 to drive the same, a ribbon feed motor 14 to run a fixed amount of an ink ribbon during a printing operation, a ribbon feed motor drive circuit 13 to drive the same, and a print head. A print head horizontal feed motor 16 for moving the print head 10 to the left and right with respect to the print surface of the paper, a print head horizontal feed motor control circuit 15 for controlling this, and a paper attachment storage circuit 21 for storing that the paper has been attached, It is composed of a power-on storage circuit 22 for storing that the power is turned on. The print head moving unit 53 includes a print head vertical movement mechanism 20 that moves the print head 10 a distance from the paper printing surface, and a print head vertical movement control circuit 19 that controls the print head vertical movement mechanism 20. The operation unit 54 includes an operation panel 24 that operates the printer and displays the printer status, and an operation panel control circuit 23 that controls the operation panel 24.

FIG. 2 is a front view of the serial printer with a paper thickness detecting mechanism of this embodiment shown in FIG. 1, and FIG. 3 is FIG.
FIG. 3 is a block diagram showing the relationship of the components of the serial printer with paper thickness detection mechanism of this embodiment shown in FIG. In this embodiment, a case where three sheets are stacked and the right side portion of each sheet has a different length will be described. Referring to FIGS. 2 and 3 together with FIG. 1, the printing unit 8 of the serial printer with the paper thickness detection mechanism of this embodiment guides the print head 10, the ink ribbon 26, and the printing papers 61, 62 and 63. A paper guide 27, a ribbon case 40, a roller 38 for assisting the running of the ink ribbon, a ribbon feed motor 14,
A carrier unit 34 in which these are incorporated, a timing belt 35 fixed thereto, a print head traverse motor 16 and a pulley 36 for moving the carrier unit 34 via the timing belt 35, and a guide for supporting the carrier unit 34. Support guide shafts 43 and 44, a paper feed roller 37 for moving the print sheets 61, 62 and 63 in the vertical direction, a motor drive circuit 46 for driving the print head transverse feed motor 16, and a motor control circuit for this control circuit. A print head lateral feed motor control circuit 15 including a print head 51, a paper feed motor drive circuit 11, a ribbon feed motor drive circuit 13, and a print head drive circuit 9
The power-on storage circuit 22, the paper non-sensor 42 for detecting the presence / absence of the printing papers 61, 62, and 63, the output indicating that the printing paper is attached, and the memory is erased after the paper thickness detection operation is completed. It is composed of a sheet attachment storage circuit 21. The print head moving unit 53 includes print paper 61,
A printhead vertical movement mechanism 20 having a movement motor 39 for moving the position of the printhead 10 with respect to 62 and 63.
And a movement amount determination circuit 49 for determining the movement amount of the print head 10 based on the content read from the paper thickness detection control circuit 17, and a movement motor drive circuit for driving a movement motor 39 for moving the position of the print head 10 based on the result. And 50.

The sheet thickness detecting mechanism 18 amplifies the movement of the roller 29 via a fulcrum 28 and a sufficiently heavy roller 29 which moves while rolling on the surfaces of the printing sheets 61, 62 and 63 in accordance with the movement of the carrier unit 34. Tell, and
A shield plate 30 for blocking the light of the light emitting lamp 31 with respect to the optical sensor 32, and a roller retracting lever 33 for moving the roller 29 toward the print head 10 side of the paper guide 27 by forcibly moving the shield plate 30. And a lever moving motor 41 for moving the motor, and a lever moving motor drive circuit 52 for driving the motor. Further, the paper thickness detection control circuit 17 detects the output of the optical sensor 32 in the paper thickness detection mechanism 18 by an optical sensor output detection circuit 45.
An optical sensor output storage circuit 47 for storing the output of the optical sensor output detection circuit 45 with respect to the rotation control amount of the print head traverse motor 16 and a read circuit 48 for reading the contents of the storage circuit 47.

FIG. 4 is a flow chart showing the flow of processing at the start of printing in this embodiment. The operation of this embodiment will be described with reference to FIG. 4 together with FIG. 2 and FIG. At the start of printing, it is confirmed whether the power-on storage circuit 22 stores the fact that the power is turned on (step S1), and if stored, the process of step S3 is performed. If you don't remember
It is confirmed whether the sheet attachment storage circuit 21 stores that the sheet is attached (step S2), and if it is stored, the process of step S3 is performed. If it is not stored, the process of S6 is performed. In step S3, the thickness information of the print sheet is stored in the optical sensor output storage circuit 47 for the entire width of the print sheet in the left-right direction (step S).
3). After that, the power-on storage circuit 22 is erased (step S4) and the sheet mounting memory circuit 21 is erased (step S5), and the process of step S6 is performed. In step S6, printing is performed while controlling the distance between the print head 10 and the printing papers 61, 62, and 63 to be constant according to the thickness information of the printing paper stored in the optical sensor output storage circuit 47.

Next, the operation of step S3 will be described. The lever moving motor 41 is driven counterclockwise by an appropriate amount, and the roller pull-in lever 33 attached to the tip of this rotary shaft.
The roller 29 guided by the roller is extended until it freely contacts the printing paper. The print head traverse motor 16 is driven to correlate the output of the optical sensor 32 when the roller 29 moves while rolling on the surface of the paper with the output of the motor control circuit 51 via the optical sensor output detection circuit 45, and the print head It is stored in the optical sensor output storage circuit 47 as an optical sensor output value with respect to the motor shaft rotation amount of the lateral feed motor 16. This operation is repeated for the entire width of the paper in the left-right direction, and is stored in the optical sensor output storage circuit 47 as thickness information of the paper. After this,
The lever moving motor 41 is driven clockwise by an appropriate amount to draw the roller 29 closer to the print head 10 side than the paper guide 27 so that the print paper does not hit the roller 29 during the printing operation.

Next, the operation of step S6 will be described. Characters are printed by the print head traverse motor 16 and the print head 10 based on the print data. At this time, the reading circuit 48 reads the optical sensor output value stored in the optical sensor output storage circuit 47 corresponding to the motor shaft rotation amount of the print head lateral feed motor 16 controlled by the motor control circuit 51. This is converted into a shaft rotation amount of the moving motor 39 by the moving amount determination circuit 49, and the moving motor 3 is passed through the moving motor drive circuit 50.
Drive 9 As a result, the print head 10 and the print paper 6
The distance from each of the parts 1, 62 and 63 is kept constant.

A method using a combination of a light emitting lamp 31 and an optical sensor 32 is used for detecting the displacement of the shield plate 30 of the sheet thickness detecting mechanism 18 of this embodiment. For this displacement detection, a hall element or a condenser is used. It can also be realized depending on the method used.

[0015]

As described above, according to the present invention,
The print head detects the total thickness of the print paper, stores the thickness, and keeps the distance between the tip of the print head and the print surface of the print paper constant according to the stored full width of the print paper. By moving the, it is possible to print with a uniform printing pressure on the entire width of the printing paper having different thicknesses in the left-right direction.

Further, the thickness of the printing paper is measured at the start of printing for the first time after the power is turned on or after the paper is attached, and thereafter, the distance between the printing head and the printing surface of the printing paper is kept constant based on the measurement result. Since the control is performed, it is not necessary to control the distance between the print head and the printing surface of the paper each time the print head is moved, and it is possible to prevent the print processing speed from decreasing when printing a large amount and continuously.

Further, since the distance between the print head and the print surface of the print paper is kept constant, there is a problem that the print paper is caught in the print head and jams the paper, or abnormal wear or breakage of the dot pin pushed out from the tip of the print head. Can be prevented.

[Brief description of drawings]

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

FIG. 2 is a front view showing a printing unit of this embodiment.

FIG. 3 is a block diagram showing the relation of each part of this embodiment.

FIG. 4 is a flowchart showing an operation at the start of printing in this embodiment.

FIG. 5 is a front view showing an example of a printing mechanism of a conventional serial printer with a paper thickness detecting mechanism.

[Explanation of symbols]

 1 main control circuit 2 program memory circuit 3 working memory circuit 4 character pattern data memory circuit 5 print data receiving circuit 6 interface line 7 control unit 8 printing unit 9 print head drive circuit 10 print head 11 paper feed motor drive circuit 12 paper feed Motor 13 Ribbon feed motor drive circuit 14 Ribbon feed motor 15 Print head horizontal feed motor control circuit 16 Print head horizontal feed motor 17 Paper thickness detection control circuit 18 Paper thickness detection mechanism 19 Print head vertical movement control circuit 20 Print head vertical movement mechanism 21 Paper mounting memory circuit 22 Power-on memory circuit 23 Operation panel control circuit 24 Operation panel 25 Data bus 26 Ink ribbon 27 Paper guide 28 Support point 29 Roller 30 Shield plate 31 Light emitting lamp 32 Optical sensor 33 Roller retracting lever 34 Carrier unit 5 Timing Belt 36 Pulley 37 Paper Feed Roller 38 Roller 39 Moving Motor 40 Ribbon Case 41 Lever Moving Motor 42 Paperless Sensor 43 Support Guide Shaft 44 Support Guide Shaft 45 Optical Sensor Output Detection Circuit 46 Motor Drive Circuit 47 Optical Sensor Output Memory Circuit 48 Readout circuit 49 Movement amount determination circuit 50 Movement motor drive circuit 51 Motor control circuit 52 Lever movement motor drive circuit 53 Print head movement unit 54 Operation unit 61 First printing sheet 62 Second printing sheet 63 Third printing sheet

Claims (3)

[Claims] 1. A printing means including a print head for printing characters on a printing paper via an ink ribbon, and detecting the thickness of the entire width of the printing paper at the start of printing for the first time after power is turned on or after the printing paper is attached. Paper thickness detecting means, storage means for storing the thickness of the printing paper full width detected by the paper thickness detecting means, and the print head according to the thickness of the printing paper full width stored in the storage means. A serial printer with a paper thickness detecting mechanism, comprising: a moving unit that moves the print head so that a distance between the front end of the print sheet and the print surface of the print sheet is kept constant. 2. The paper thickness detecting means includes a roller that rotates in contact with the print paper, a shield plate that expands and displaces the positional displacement of the roller, and a displacement detection means that detects the displacement of the shield plate. The serial printer with a paper thickness detection mechanism according to claim 1. 3. The serial printer with a paper thickness detecting mechanism according to claim 2, wherein the displacement detecting means includes a light emitting means and a light receiving means for detecting the displacement of the shielding plate.