JPH0776151A - Printer - Google Patents

Abstract

PURPOSE:To automatically adjust an interval between a print head and a platen to an optimum interval even when not only a thickness of a paper but also the quality of the paper and the temperature of the print head are changed. CONSTITUTION:A print head 1, a platen 2 to be rotated, an adjusting mechanism 3, a drive means 4 for driving the adjusting mechanism, a sensor 5, and a control means are provided. The adjusting mechanism 3 axially supports a guide axis 30 for guiding the print head 1 in parallel with the platen 2 through an eccentric axis 30a arranged on both ends, and allows the print head 1 to approach the platen 2 and to separate from it by the rotation of the eccentric axis for adjusting the interval between them. The sensor 5 is arranged fixedly out of a printing area adjacently to the platen 2, for detecting the printing pressure of the print head by facing the print head 1. The control means drives the drive means 4 based on a detected signal from the sensor 5 so as to adjust the interval between the print head 1 and the platen 2 in accordance with the printing pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer which is connected to, for example, a computer or a word processor and is used to print out a record.

[0002]

2. Description of the Related Art Conventionally, when printing with a printer, the user manually adjusts the distance between the print head and the platen to an appropriate distance according to the thickness of the printing paper and the like by clicking the print position adjustment. . In addition, 2-23
According to No. 410, the sensor for detecting the thickness of the paper is used to detect the thickness of the printing paper, and the distance between the print head and the platen is automatically adjusted to an appropriate distance according to the thickness of the printing paper. It was

[0003]

However, in the former printer, when the thickness and quality of paper are different,
The distance between the print head and the platen had to be manually adjusted, which was troublesome. Further, the latter printer detects the paper thickness of the print paper with a sensor and automatically adjusts the distance between the print head and the platen only in accordance with the paper thickness of the print paper. Therefore, for example, the paper quality has changed. In this case, there is a problem that the distance between the print head and the platen cannot be automatically adjusted to an appropriate distance.

Therefore, an object of the present invention is to provide a printer capable of automatically adjusting the distance between the print head and the platen to an appropriate distance not only when the thickness of the paper is changed but also when the paper quality or temperature changes. To provide.

[0005]

SUMMARY OF THE INVENTION The present invention is a printer for feeding paper between a print head and a platen for printing, and an adjusting mechanism and a adjusting mechanism for varying the distance between the print head and the platen. Drive unit, a sensor for detecting the print pressure of the print head facing the print head through the paper, and the drive unit is driven based on the detection signal from the sensor to set the distance between the print head and the platen. A control means for adjusting the printing pressure of the print head according to the degree of the printing pressure is provided.

Another feature of the present invention is that the platen is driven to rotate, and the sensor is fixedly provided adjacent to the platen outside the printing area. The platen is fixed, and the sensor is provided on a part of the platen. The adjusting mechanism pivotally supports a guide shaft that guides the print head parallel to the platen via eccentric shafts provided at both ends of the guide shaft, and rotates the eccentric shaft to move the print head toward and away from the platen. This is to make the space between the print head and the platen variable.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The present invention, as shown in FIG. 1, includes a print head 1, a platen 2, an adjusting mechanism 3, a driving means 4 for driving the adjusting mechanism, a sensor 5, and a controlling means 6 (shown in FIG. 3). ) Has. Hereinafter, they will be described in order.

The print head 1 is mounted on a carriage 11, and as shown in FIG. 1, is guided by a guide shaft 30 provided at a position opposed to the platen 2 to maintain a predetermined distance from the platen 2. , Reciprocating in parallel. The platen 2 is rotatably supported by the left and right side plates 8a and 8b, and is rotationally driven by a paper feed motor (not shown).

The adjusting mechanism 3 includes a print head 1 and a platen 2.
The distance between the guide shaft 30, the second gear 31, and the fixed guide 3 is adjusted as shown in FIGS. 1 and 2.
2 and.

The guide shaft 30 is rotatably mounted on the left and right side plates 8 via eccentric shafts 30a integrally provided at both ends thereof.
A second gear 31 is attached to the end of the right eccentric shaft 30a protruding from the right side plate 8b. The carriage 11 is slidably fitted to the guide shaft 30, and the guide piece 11a (shown in FIG. 2) at the rear end of the carriage 11 slides on the fixed guide 32 supported by the left and right side plates 8a and 8b. Received freely. Therefore, the guide shaft 30 rotates with the center of the eccentric shaft 30 a as the center of rotation, so that the carriage 11 fitted to the guide shaft 30 approaches and separates toward the platen 2 by the rotation of the guide shaft 30. As an example, the distance between the print head 1 and the platen 2 is kept at a predetermined reference position, and the print head 1 is moved toward the platen 2 by the rotation of the guide shaft 30 in one direction. The print head 1 is configured to be separated from the platen by rotation.

A ribbon cassette 7 is set behind the print head 1, and an ink ribbon 7a pulled out from the ribbon cassette 7 is inserted between the print head 1 and the platen 2.

The driving means 4 is for driving the adjusting mechanism 3, and as shown in FIG.
It is composed of a drive shaft 41, a pinion gear 42, and a first gear 43.

The drive motor 40 is fixedly provided inside the right side plate 8b, and a pinion gear 42 is attached to the tip of the drive shaft 41 protruding from the right side plate 8b. The pinion gear 42 meshes with the first gear 43, and the first gear meshes with the second gear 32.

The sensor 5 is provided with the print head 1 via the paper P.
The print pressure of the print head 1 is detected in the opposite direction. As shown in FIG. 1, the sensor 5 is provided adjacent to the platen 2 on the left side of the printing area and is fixed to the tip of a bracket 5a fixed to the left side plate 8a.

As shown in FIG. 3, the control circuit constituting the control means 6 calculates the optimum distance between the print head 1 and the platen 2 based on the detection signal of the printing pressure detected by the sensor 5, The rotation of the drive motor 40 is controlled via the motor drive circuit 40a.

As another embodiment of the present invention, the platen is not limited to a rotatable platen but may be a fixed type. In this case, the sensor may be provided on a part of the platen. The location of the sensor may be anywhere on the platen as long as it faces the print head.

Further, the structure of the driving means is not limited to the above, for example, the first gear 43 may be omitted, and other means for rotationally driving the guide shaft 30 may be appropriately used.

Further, when printing on the sensor, either when the paper and the ink ribbon are set, when only the paper is set, or when neither the paper nor the ink ribbon is set. In some cases.

Next, the operation of the present invention will be described with reference to FIGS.
Will be described with reference to.

First, when the sheet P is wound around the platen 2, the printing pressure is detected by the sensor 5 prior to the printing operation. That is, the print head 1 is moved to a position outside the print area (for example, the home position), and printing is performed on the sensor 5. The pressure applied to the sensor 5 is converted into a current / voltage, and the detection signal thereof is sent to the control circuit 6. The control circuit 6 calculates the optimum distance between the print head 1 and the platen 2 based on the supplied detection signal, and sends the motor drive signal to the motor drive circuit 40a. Drive motor 4
0 is rotationally driven by being controlled by the motor drive circuit 40a, and the eccentric shafts 30a provided at both ends of the guide shaft 30 are driven via the drive shaft 41, the pinion gear 42, the first gear 43, and the second gear 31. Rotate. The rotation of the eccentric shaft 30a causes the guide shaft 30 to rotate about the center of the eccentric shaft, so that the guide shaft 30 approaches the platen 2.
The print head 1 is moved so that the print head 1 and the platen 2 are separated from each other and the distance between them is optimized.

After that, the print head 1 is moved into the print area and printing is performed in accordance with the normal printing operation.
The print head 1 and the platen 2 adjusted as described above are kept at a good distance, and good quality printing is performed.

The above-described printing pressure detection operation may be performed in the first line every time the page is changed, or may be performed in each half page or in each line. If the printing operation continues, the temperature of the print head rises and the printing conditions change. Therefore, if the timing of print pressure detection is determined in consideration of this, the gap between the print head 1 and the platen 2 is always optimized. It is possible to automatically adjust and print at various intervals.

When a sensor is provided in the print area, the print pressure may be detected in the first line of each page, and the line feed may be performed. The ink ribbon may be removed from the printing position when the printing pressure is detected.

The present invention can be implemented in a dot matrix type impact printer. Further, it is possible to simultaneously inspect whether or not the print pin is damaged from the print pressure detection data.

[0026]

As described above, according to the present invention,
The sensor detects the printing pressure of the print head and the distance between the print head and the platen is automatically adjusted based on this detection signal, so even if the paper thickness, paper quality, print head temperature, etc. change Printing can be performed by always automatically adjusting the distance between the head and the platen to the optimum distance, which is a remarkable effect in improving the printing quality.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a block diagram of a drive circuit of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 print head 2 platen 3 adjusting mechanism 30 guide shaft 30a eccentric shaft 4 driving means 5 sensor 6 control means

Claims (4)

[Claims] 1. A printer for feeding a sheet between a print head and a platen for printing, an adjusting mechanism for varying a distance between the print head and the platen, and a drive for driving the adjusting mechanism. Means, a sensor that faces the print head through the paper and detects the printing pressure of the print head, and the drive means is driven based on a detection signal from the sensor to drive the print head and the platen. And a control unit that adjusts the interval according to the degree of the printing pressure of the print head. 2. The printer according to claim 1, wherein the platen is driven to rotate, and the sensor is fixedly provided outside the printing area adjacent to the platen. 3. The printer according to claim 1, wherein the platen is fixed, and the sensor is provided on a part of the platen. 4. The adjusting mechanism according to claim 1, wherein the adjusting mechanism pivotally supports guide shafts for guiding the print head in parallel with the platen via eccentric shafts provided at both ends thereof. A printer characterized in that the print head is brought into contact with and separated from the platen by rotation of the eccentric shaft to make a distance between the print head and the platen variable.