JPH06238966A - Serial impact printer - Google Patents

Abstract

PURPOSE:To provide an impact printer in which clear printing is obtained up to a lowermost layer of many print sheets of a set. CONSTITUTION:A carriage 5 placing a print head 2 and a carriage 10 placing a platen 7 are respectively movably supported to guide shafts 3, 4 and 8, 9, and printing is conducted while both the carriages 5, 10 are synchronously moving in the same direction. A platen 7 has protrusions opposed to dot wires, and is vibrated by a piezoelectric element in the case of printing. A guide shaft 8 for supporting the platen 7 is disposed on the same plane as that of the head 2 and the platen 7. The platen 7 does not escaped around the shaft 8 because an impact of the head 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial impact printer, and more particularly to a structure in which a print head and a platen sandwich a print sheet and move in synchronization with each other in the same direction for printing.

[0002]

2. Description of the Related Art Conventionally, impact printers have been used for printing on a large number of sets of printing papers on which pressure sensitive papers such as carbon papers are stacked. As such a device, there has been a demand for a device capable of printing on a large number (for example, about 10 sheets) of paper. However,
Printing on a large number of sheets has the following two problems. First, since printing is performed with sufficient density even on the lowermost printing paper, if the printing is performed with a strong impact force, the impacting force is too strong for the uppermost printing paper to cause perforation. Further, if the impact force is weakened for this reason, the striking force transmitted to the lower layer of the printing paper is dispersed, so that the printed characters are easily blurred.

In order to solve these problems, the inventors of the present application have considered the printer shown in FIG. That is, the print head 2 and the platen 7 are arranged to face each other with the print paper 6 sandwiched therebetween. The print head 2 and platen 7
Is supported on the guide shafts 3, 4 and 8, 9 slidably in the same direction, and printing is performed while the print head 2 and the platen 7 are synchronously moved along the print paper. By vibrating the platen 7 with a piezoelectric element at the time of impact by the print head 2, energy is applied to the printing paper of a large number of sets from both front and back sides, and clear printing is obtained over all the leaves of the paper.

[0004]

However, in the above conventional structure, since the guide shaft 8 for the platen 7 is located below the platen 7, the guide shaft 8 is attached to the platen 7 when the print head 2 impacts. Rotational force about is generated. That is, the platen 7 escapes, and as a result, the impact force is weakened, and the darkness of the characters printed on the lower layer of the printing paper of the multi-sheet set is not sufficient.

If an attempt is made to increase the rigidity of the platen in order to solve this problem, the platen itself becomes large and heavy, which leads to a high cost. Also, the power of the motor for moving the platen is required, resulting in a high cost. I will end up. Further, it is conceivable to make the guide shaft 8 supporting the platen thick, but this also increases the cost.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a serial impact dot printer having a simple structure and capable of clearly printing the lower layer characters of a multi-sheet set.

[0007]

In order to achieve this object, the present invention is directed to a print head having an impact printing element and movable along a print sheet, and a print head sandwiched between the print head and the print head. The platen, a guide shaft for movably supporting the platen in parallel with the print head, and a drive means for synchronously moving the print head and the platen in the same direction, the print head, the platen, and the The guide shafts are arranged on the same plane.

[0008]

According to the above construction, when the print head runs along the print paper, the platen disposed opposite to the print head with the print paper sandwiched between the platen and the print head is synchronized with the print head. Drive in the same direction. At the time of printing, the platen receives an impact force from the print head, but since it is arranged on the same plane as the guide shaft, no force is applied in the rotation direction around the guide shaft. That is, the impact force of the print head can be converted into energy for printing without the platen 7 escaping.

[0009]

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

The print head 2 is a so-called impact type which selectively drives a plurality of impact elements, that is, dot wires. The print head 2 is mounted on a carriage 5 and supported by a main guide shaft 3 and a sub guide shaft 4 so as to be reciprocally movable in the axial direction.

The platen 7 is mounted on the carriage 10,
The main guide shaft 8 and the sub guide shaft 9 are supported so as to be reciprocally movable in the axial direction. The main guide shaft 8 and the sub guide shaft 9 are the guide shafts 3 and 4 for the print head 2.
Parallel to.

The platen 7 has a leaf spring 19 on the carriage 10.
Is mounted so as to be able to vibrate in a direction facing the print head 2. A piezoelectric element 20 is attached between the leaf spring 11 and the carriage 10, and the piezoelectric element 20 extends its length by applying a voltage. The platen 7 can vibrate in a direction facing the print head 2 due to expansion and contraction of the piezoelectric element 12.

The guide shafts 8 and 9 for supporting the carriage 10 of the platen 7 are arranged on the same plane as the print head 2 and the platen 7, as shown in FIG. The main guide shaft 8 has eccentric shaft portions 8a at both ends thereof, and both eccentric shaft portions 8
It is supported by the frame of the printer at a. By rotating a lever 8b fixed to the end of one of the eccentric shaft portions 8a, the carriage 10 is moved in the direction of approaching and separating from the print head 2, and the distance between the platen 7 and the print head 2 is set to the paper thickness. It can be adjusted accordingly. In order to enable the above movement of the carriage 10, the carriage 10
Is an elongated hole 10a having an opening penetrating the sub guide shaft 9 opened rearward. The interval adjustment operation may be performed by decelerating the rotation of the motor by a gear train instead of the lever. It is advantageous to move the platen 7 to adjust the gap because the load is smaller than that to move the print head 2.

As shown in FIG. 3, the platen 7 has a protrusion 7a that protrudes so as to face the dot wire 2a of the print head 2. The protrusion 7a has a top portion having a width slightly wider than the diameter of the wire so that it can easily face the wire 2a. When printing, the printing paper is sandwiched between the wire 2a and the protrusion 7a, so that the impact force is concentrated on a small area without being dispersed. As a result, even when printing is performed on a large number of sets of copy-type printing paper, clear printing can be performed over the entire leaves of the printing paper.

At the positions where the print head 2 and the platen 7 face each other, the carriages 5 and 10 are moored to the timing belts 11 and 12, respectively. The timing belts 11 and 12 are stretched between drive pulleys 14 and 15 of the same diameter fixed to a drive shaft 13 extending in a direction orthogonal to the main guide shafts 3 and 8 and pulleys (not shown) corresponding to the drive pulleys 14 and 15, respectively. ing. As a result, the print head 2 and the platen 7 can be moved in the same direction while facing each other. The drive shaft 13 is connected to a drive mechanism from a motor (not shown).

The printing paper 6 includes a printing head 2 and a platen 7.
Rollers 16 and 17 are provided above and below, respectively, so as to be fed in the vertical direction through the space.
The ink ribbon 18 is sent between the print head 2 and the print paper 6 by a known mechanism.

The operation of the printer configured as described above will be described. Print head 2 mounted on carriage 5
Moves along the front surface of the printing paper 6, and in synchronization with this, the platen 7 mounted on the carriage 10 also moves along the back surface of the printing paper 6. At the time of this movement, the dot wire 2a of the print head 2 impacts the print paper 6, and at the same time, a voltage is applied to the piezoelectric element 20 to vibrate the platen 7 toward the print head 2. The platen 7 may be advanced only once in synchronization with the impact of the dot wire 2a, but may be vibrated multiple times in a high cycle.

At the time of the impact, the printing paper 6 is sandwiched by a large pressure in a small area between the tip of each printing wire and the projection 7a on the platen 7. Further, since the main guide shaft 8 is arranged on the same surface of the print head 2 and the platen 7, the platen 7 is affected by the impact force.
Therefore, no rotational force around the main guide shaft 8 is generated. Therefore, there is little escape of the platen 7. Therefore,
The impact force and the vibration motion are effectively used as energy for printing, and are concentrated in a small area without being dispersed. As a result, it is possible to clearly print even the lowermost layer on a large number of sets of printing paper.

When the printing of one line is completed, the printing paper 6 is fed by the rollers 16 and 17 for a predetermined length.

[0020]

As is apparent from the above description, in the serial impact printer of the present invention, since the guide shaft on the platen side is arranged on the same surface of the print head and the platen, impact at the time of printing The platen does not generate rotational force around the guide axis due to the force. Thereby, the escape of the platen is reduced by a simple method, and good dark printing can be obtained even in the lowermost layer of the printing paper of the multi-sheet set.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a serial impact printer according to an embodiment of the present invention.

FIG. 2 is a side view.

FIG. 3 is an enlarged plan view of main parts of a print head and a platen.

FIG. 4 is a side view of a conventional printer.

[Explanation of symbols]

 2 printing head 6 printing paper 7 platen 8 guide shaft 20 piezoelectric element

Claims (5)

[Claims] 1. A print head having an impact printing element, which is movable along a print sheet, a platen disposed opposite to the print head with the print sheet interposed therebetween, and the platen is movable in parallel with the print head. And a guide shaft for supporting the print head and the platen in the same direction in synchronization with each other, and the print head, the platen and the guide shaft are arranged on the same plane. Impact printer. 2. The serial impact printer according to claim 1, further comprising a vibrating unit that vibrates the platen when the print head impacts the platen. 3. The serial impact printer according to claim 1, wherein the platen has a protrusion that projects toward the impact element. 4. The serial impact printer according to claim 1, further comprising an interval adjusting unit that moves the platen toward and away from the print head to adjust an interval between the platen and the print head. 5. The distance adjusting means according to claim 4, wherein the spacing adjusting means comprises an eccentric shaft portion provided at both ends of the guide shaft, and an operating means for rotating the guide shaft about the eccentric shaft portion. Serial printer to do.