JP2639320B2 - Impact type print head device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head device used for an impact type printer.

[0002]

2. Description of the Related Art FIGS. 5 to 7 are structural views showing first to third conventional examples of an impact type print head device.
Hereinafter, description will be made based on these drawings.

FIG. 5 shows a clapper-type print head device which performs printing when attracted by a magnetic force generated in a coil. The coil drive circuit 50 applies a voltage to the coil 54 according to the image signal output from the image signal generation source 52. Thus, a magnetic circuit is formed between the fixed magnetic member 56, the leaf spring 58, and the movable magnetic member 60. Then, the coil 54
, The movable magnetic member 60 is attracted in the direction of the fixed magnetic member 56. At this time, the print pin 62
An image is formed by moving in the direction of the arrow 64 and hitting the sheet 68 placed on the platen 66. Thereafter, when the voltage to the coil 54 is cut off, the print pin 62 returns to the original position by the elastic force of the leaf spring 58.

FIG. 6 shows a spring-charge type print head device in which a magnetic force of a permanent magnet is cut off by applying a voltage to a coil, and a print pin is driven by the elastic force of a leaf spring. Due to the magnetic force of the permanent magnet 70, the movable magnetic member 72,
A magnetic circuit is formed between the leaf spring 74, the permanent magnet 70, and the fixed magnetic member 76. Therefore, the movable magnetic member 7
2 is attracted to the fixed magnetic member 76. Here, the coil drive circuit 78 applies a voltage to the coil 54 according to the image signal output from the image signal generation source 52 to excite the coil 54. Then, since the magnetization direction of the coil 54 has the opposite polarity to the magnetic force of the permanent magnet 70, the permanent magnet 7
0 by canceling the magnetic force of the movable magnetic member 72.
Is separated from the fixed magnetic member 76 by the elastic force of the leaf spring 74. At this time, the print pin 80 moves in the direction of the arrow 82 and forms an image by hitting the sheet 68 placed on the platen 66. After that, the printing pin 80
When the voltage to the coil 54 is cut off, the movable magnetic member 72 returns to the original position by being attracted to the fixed magnetic member 76.

FIG. 7 shows a print head device described in Japanese Patent Application Laid-Open No. 1-275149. The same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. Coil drive circuit 5
0 applies a voltage to the coil 54 by the image signal output from the image signal generation source 52 and
Drive in the direction of. The platen 84 is made of a piezoelectric element and is driven in the direction of arrow 64 by a platen drive circuit 86 in synchronization with the print pin 62. Further, as a configuration similar to this, there is a print head device described in Japanese Patent Application Laid-Open No. 62-277564.

[0006]

However, in the print head device shown in FIGS. 5 and 6, even if the energy of the print pin is changed by changing the voltage applied to the coil, an image having a gradation is obtained. Was difficult to form. Even if an image having gradation can be formed, it is extremely difficult to obtain stable quality.

Further, the print head device shown in FIG. 7 drives the platen in synchronization with the print pins, thereby increasing the distance between the print pins and the platen as compared with the related art, thereby facilitating the insertion of paper. At the time of driving, a clear image is obtained by driving the platen so that the distance between the print pin and the platen is a predetermined distance.
Further, the print head device described in Japanese Patent Application Laid-Open No. 62-277564 is intended to secure a print density by vibrating a platen at high frequency in response to the movement of a print pin. Therefore, in these print head devices,
In any case, it is difficult to form an image with gradation.

[0008]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an impact type print head device capable of forming an image with gradation with stable quality.

[0009]

SUMMARY OF THE INVENTION A print head device according to the present invention has been made to achieve the above object, and has a platen on which a sheet is placed and a piezoelectric element is provided. A print pin facing the placed paper and having a sharpened tip, an image signal generation source that generates a multi-tone image signal, a print pin driving unit that drives the print pin based on the image signal, Platen driving means for driving the platen by expanding and contracting the piezoelectric element in synchronization with the print pin based on an image signal.

The printing pin is driven by the printing pin driving means to apply an impact force to the paper placed on the platen via an ink ribbon, and the platen is applied to the platen driving means. When driven, the image signal extends in a direction approaching the print pin as the density of the image signal increases. Further, the “platen including a piezoelectric element” as used herein also includes a “platen made of a piezoelectric element” in which a piezoelectric element is integrated with a platen.

[0011]

The image signal source outputs multi-gradation image signals to the print pin driving means and the platen driving means. Then, the printing pin driving means drives the printing pins based on the image signal, and gives an impact force to the paper placed on the platen via the ink ribbon. At this time, the platen driving means also extends the platen via the piezoelectric element in a direction approaching the print pins as the density of the image signal increases. That is, the interval between the print pin and the platen is
It becomes shorter as the density of the image signal increases. Further, since the tip of the print pin is sharp, the area where the tip of the print pin contacts the paper increases as the distance between the print pin and the platen becomes shorter. Therefore, by finely adjusting the interval between the print pin and the platen by the piezoelectric element, an image with gradation can be obtained.

[0012]

FIG. 1 is a configuration diagram showing one embodiment of a print head device according to the present invention. Hereinafter, description will be made with reference to this drawing. However, the same parts as those in FIG.

The print head device of this embodiment has a platen 10 comprising a piezoelectric element and a paper 68 placed on the surface.
A print pin 12 facing the paper 68 placed on the platen 10 and having a sharpened tip 12a (see FIG. 3);
Image signal generating source 14 for generating multi-tone image signal S
And a print pin driving means 16 for driving the print pins 12 based on the image signal S, and a platen drive circuit 18 as a platen drive means for driving the platen 10 in synchronization with the print pins 12 based on the image signal S. I have.

The printing pins 12 are driven by the printing pin driving means 16 to apply an impact force to the paper 68 placed on the platen 10 via an ink ribbon (not shown).
The platen 10 is driven by a platen drive circuit 18 to expand and contract in the same direction as the print pin 12 (arrow 64) and to approach the print pin 12 as the density of the image signal S increases (see FIG. Extends to arrow 20).

The printing pin driving means 16 is of a clapper type comprising a coil driving circuit 50, a coil 54, a fixed magnetic member 56, a leaf spring 58 and a movable magnetic member 60.

The coil driving circuit 50 includes the image signal generating source 1
When the image signal S from 4 has an image, a predetermined drive pulse voltage is applied to the coil 54. The presence of an image means that the image signal S has 16 gradations from "0" (non-printing state) to "15" (highest density printing), and the image signal S ranges from "1" to "15". There is an image.

When a predetermined voltage is applied to the coil 54,
The movable magnetic member 60,
A magnetic circuit is formed between the leaf spring 58 and the fixed magnetic member 56. Thereby, the movable magnetic member 60 is attracted to the fixed magnetic member 56, and the print pin 12 fixed to the movable magnetic member 60 moves in the direction of arrow 64. The amount of movement of the print pin 12 at this time is determined by the distance between the movable magnetic member 60 and the fixed magnetic member 56, and the movable magnetic member 60 comes into contact with the fixed magnetic member 56 during the maximum movement.

The platen driving circuit 18 applies a driving pulse voltage to the platen 10 while changing the driving pulse voltage in synchronization with the coil driving circuit 50 and in accordance with the image signal S. Since the platen 10 is made of a piezoelectric element, it extends in the direction of the arrow 20 according to the magnitude of the drive pulse voltage applied from the platen drive circuit 18.

As shown in FIG. 3, the printing pin 12 has
2a is processed into a conical shape, and the interval between the printing pin 12 and the platen 10 when the printing pin 12 protrudes is adjusted to the interval at which the leading end 12a of the printing pin 12 barely reaches the paper 68.

FIGS. 4A and 4B are explanatory diagrams showing the relationship between the platen driving pulse voltage and the formed image. FIG. 4A shows the platen driving pulse voltage, FIG. 4B shows the platen displacement, and FIG.
(C) shows the formed dot. When forming dots of the minimum density, only the print pins 12 are driven without driving the platen 10. If the platen drive voltage is sequentially increased as the density of the image signal S increases, the extension amount of the piezoelectric element increases in accordance with the voltage, so that the contact area between the paper 68 and the tip 12a of the print pin 12 changes, and The size can be changed.

FIG. 2 is a configuration diagram showing another embodiment of the print head device according to the present invention. Hereinafter, description will be made with reference to this drawing. However, the same parts as those in FIG. 1 and FIG.

The printing pin driving means 30 is of a spring charge type comprising a coil driving circuit 78, a coil 54, a fixed magnetic member 76, a leaf spring 74, a movable magnetic member 72 and a permanent magnet 70. The coil drive circuit 78 applies a predetermined drive pulse voltage to the coil 54 when the image signal S from the image signal source 14 has an image.

In the initial state, a magnetic circuit is formed between the movable magnetic member 72, the leaf spring 74, the permanent magnet 70, and the fixed magnetic member 76 by the magnetic force of the permanent magnet 70. Therefore, the movable magnetic member 72 is attracted to the fixed magnetic member 76. Here, when a predetermined drive pulse voltage is applied to the coil 54 from the coil drive circuit 78, a magnetic flux of the coil 54 is generated in a direction opposite to a magnetic flux of the permanent magnet 70. Then, as the magnetic force of the magnetic circuit weakens, the movable magnetic member 72 is separated from the fixed magnetic member 76 by the elastic force of the leaf spring 74. At this time, the print pin 32 fixed to the movable magnetic member 72 moves in the direction of the arrow 34. The amount of movement of the print pin 32 is within the range of elastic deformation of the leaf spring 74, but since the amount of movement of the movable magnetic member 72 is regulated by the guide 36, a constant amount of movement can always be obtained.

The platen driving circuit 18 is a coil driving means 3
The drive pulse voltage is applied to the platen 10 while changing the drive pulse voltage in synchronization with 0 and according to the image signal S generated by the image signal generation source 14. The platen 10 is composed of a piezoelectric element, and extends in the direction of the arrow 20 according to the magnitude of the drive pulse voltage applied from the platen drive circuit 18. The tip of the print pin 32 is also the tip 12a of the print pin 12 shown in FIG.
Like, it is conical. Therefore, the magnetic head device of the present embodiment also has the same operation and effect as the magnetic head device of FIG.

[0025]

According to the print head device of the present invention,
By driving the printing pins by the printing pin driving means and finely adjusting the interval between the printing pins and the platen by the platen driving means, it is possible to finely change the contact area between the sharp tip of the printing pin and the paper. As a result, an image with stable gradation can be formed.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing another embodiment of the present invention.

FIG. 3 is a partially enlarged view showing a tip of a print pin of the magnetic head device according to the present invention.

4A and 4B are explanatory diagrams showing the operation of the magnetic head device according to the present invention, wherein FIG. 4A is a waveform diagram showing a platen driving pulse voltage, and FIG. 4B is a schematic diagram showing a platen displacement. It is a top view showing the dot on which 4 (C) was formed.

FIG. 5 is a configuration diagram showing a first conventional example.

FIG. 6 is a configuration diagram showing a second conventional example.

FIG. 7 is a configuration diagram showing a third conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Platen (piezoelectric element) 12, 32 Printing pin 12a Tip of printing pin 14 Image signal generating source 16, 30 Printing pin driving means 18 Platen driving circuit (Platen driving means) 68 Paper S Image signal

Claims (3)

(57) [Claims] 1. A platen on which a sheet is placed and a piezoelectric element is provided, a print pin opposed to the sheet placed on the platen and having a sharpened tip, and a multi-tone image signal is generated. An image signal generation source, a printing pin driving unit that drives the printing pin based on the image signal, and a platen driving unit that drives the platen by expanding and contracting the piezoelectric element in synchronization with the printing pin based on the image signal The printing pin is driven by the printing pin driving means,
An impact force is applied to the paper placed on the platen via an ink ribbon, and the platen is driven by the platen driving unit,
An impact-type print head device, wherein the image signal extends in a direction approaching the print pin as the density of the image signal increases. 2. The impact type print head device according to claim 1, wherein said print pin driving means is of a clapper type. 3. The impact type print head device according to claim 1, wherein said print pin driving means is of a spring charge type.