JPS63297055A - Dot impact printing head - Google Patents

Abstract

PURPOSE:To obtain a dot impact printing head capable of printing at high speed and having a large adjusting range, by a method wherein a voltage is applied to a piezoelectric actuator to press a printing hammer toward a drive mechanism after the printing hammer separate from attracting surfaces of the drive mechanism and perform an impact-printing. CONSTITUTION:With the electric supply to demagnetizing coils 6a, 6b, a printing hammer 3 is released from attracting surfaces of yokes 4a, 4b to perform an impact-printing through an ink ribbon. In thin case, because of the high spring constant of the printing hammer 3, the printing hammer 3 cannot return to the attracting surfaces of the yokes 4a, 4b even when the conduction to the demagnetizing coils 6a, 6b is brought to a stop. Then, a voltage is applied to a piezoelectric actuator 7 simultaneously with the stop of the supply to the demagnetizing coils 6a, 6b. The piezoelectric actuator 7 is driven, whereby the lower end part of the printing hammer 3 is pressed toward a plate spring presser 2. On the contrary, the upper end part of the printing hammer 3 is pressed toward the yokes 4a, 4b, thereby being again attracted to the attracting surfaces of the yokes 4a, 4b to be in waiting state for a next printing command.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a dot impact printer.
In particular, the present invention relates to a dot impact print head that is capable of high-speed printing and has a wide i-alignment range.

[Prior Art] A print head used in a spring-type dot impact printer generally includes a printing hammer made of a leaf spring with a hammer pin fixed to one end, a drive mechanism that drives the printing hammer, and a drive mechanism that drives these printing hammers. It is composed of a supporting body that supports it.

The drive mechanism described above is composed of a pair of yokes installed in parallel with a permanent magnet sandwiched between them, and a degaussing coil wound around each yoke.When the degaussing coil is not energized, the permanent magnet acts. When the printing hammer is attracted to the yoke side and the degaussing coil is energized, the magnetic force of the permanent magnet is canceled out, and the printing hammer is struck against the ink ribbon to print.

In order to increase the printing speed in such a dot impact printer, it is necessary to (1) make the area around the hammer pin of the printing hammer lighter, or (2) increase the spring constant of the leaf spring that makes up the printing hammer.

[Problem to be Solved by the Invention 1] By the way, in the method (2) of lightening the area around the hammer pin described above, the printing hammer must be made thin and small. It was not possible to form a magnetic path that would allow sufficient magnetic flux to flow, and an auxiliary yoke had to be installed to increase the amount of magnetic flux.

Moreover, there were naturally limits to how much the upper end of the printing hammer could be made light, and there were also limits to how high the printing speed could be increased.

On the other hand, method (■) in which the spring constant is increased increases the natural frequency, making it possible to print at higher speeds;
For this purpose, a high-performance permanent magnet and an auxiliary yoke are required. Moreover, since the spring constant is high, it is difficult to secure a sufficient gap between the printing hammer and the yoke (yoke gap). For this reason, there are drawbacks such as damage to the ink ribbon due to catching between the ink ribbon and the printing hammer pin, and uneven print density due to the narrow taX range.

The present invention was made against this background, and aims to provide a dot impact print head that is capable of high-speed printing and has a wide 111 area.

Means for Solving Problem E J In order to solve the above problem, the present invention provides a printing hammer made of a plate spring to which a hammer pin is fixed at one end, a driver groove for driving the printing hammer, and a drive groove for driving the printing hammer, a support for supporting a printing hammer and a drive mechanism; provided on the support;
The printing apparatus includes a piezoelectric actuator that presses the printing hammer in the direction of the driving isotochi.

[Effect 1 The above as well! According to Sei, the printing hammer is sucked by the drive mechanism! After impact printing is performed away from surface 7, voltage is applied to the piezoelectric actuator and the leaf spring (printing hammer) is pushed in the direction of the drive fi6W, thereby attracting the upper end of the printing hammer to the surface again @ for the next printing. Be prepared for orders.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing the configuration of a print head according to an embodiment of the present invention.

In the figure, 1 is a support for the LT-arm. A printing hammer 3 made of a leaf spring is vertically fixed to the leg portion of the support 1 by a leaf spring holder 2.

Further, at the upper end of the support 1, a seeker 4a and a permanent magnet 5 are provided.
, yoke 4b are stacked, and the yoke 4 at 4b attracts the upper end of the printing hammer 3.

The yokes 4a and 4b have degaussing coils Ga and G.
b is wound. This is yoke 4 a, 4
This is to release the printing hammer 3 that is attracted to b.
When energized, the magnetic flux produced by the permanent magnet 5 is canceled out, and the printing hammer 3 is released. This results in
The upper end of the printing hammer 3 moves to the open position shown by the two-dot chain line in the figure, and the hammer pin 3a fixed to the upper end of the printing hammer 3 hits an ink ribbon (not shown).

The above configuration is the same as the conventional one, but in the embodiment of the present invention,
The printing hammer 3 has a sufficiently high spring constant in order to enable high-speed printing as described later, and a U-shaped groove 1a is formed in the center of the bottom of the support 1. A piezoelectric actuator 7 is fitted into this groove 1a, and one surface of the piezoelectric actuator 7 is in contact with a surface near the lower end of the printing hammer 3. Then, a gap t<2t1 is formed at the lower part of the pressing surface of the leaf spring holder 2, and as shown in Fig. 8 is made.In addition, the above-mentioned yokes 4a and 4b
, the permanent magnet 5, and the degaussing coils 6n, 6b constitute a drive mechanism for the printing hammer 3.

In this configuration, the degaussing coil 6 at 6 b
When a current is applied to the yoke 4 at 4, the printing hammer 3
rR1 is released from the suction surface b, and impact printing is performed via the ink ribbon.

In this case, since the spring constant of the printing hammer 3 is high, the printing hammer 3 cannot return to the attraction surface of the yoke 4 at 4 b even if the degaussing coils 6 a and 6 b are de-energized. At the same time as stopping the power supply to the degaussing coil 6 at 6 b, voltage is applied to the piezoelectric actuator tough. This makes the piezoelectric actuator tough! l!
lJ, the lower end of the printing hammer 3 is in the direction of the leaf spring holder 2, and conversely, the upper end of the printing hammer 3 is in the direction of the yoke 4a,
4b, and the upper end of the printing hammer 3 is again attracted to the attraction surfaces of the yokes 4a and 4b. In this way, it enters a waiting state for the next print command.

FIG. 3 is a graph showing a comparison of spring characteristics when voltage is applied to the piezoelectric actuator tough and when voltage is not applied.

In the figure, the horizontal axis indicates the yoke gap X%R glaze force F. Also, the solid line curve #a (A) shows the relationship between the yoke gear knob and the suction force F, and the broken line curve #a (B) shows the relationship between the yoke gear knob and the suction force F.
As can be seen from Figure 1, which shows the spring characteristics of the printing hammer 3 without the piezoelectric actuator 7, the attraction force F is:
As the yoke gap X becomes smaller, 2. It increases rapidly and X<X.

At this time, the printing hammer 3 is attracted by overcoming the leaf spring. However, when X>X+, the printing hammer 3 cannot be attracted.

The dashed line M (c) in the figure shows the spring characteristics when a voltage is applied to the piezoelectric actuator 7. In this case, as is clear from the figure, the suction force F always overcomes the leaf spring and can attract the printing hammer 3. This is because the yoke gap X is reduced by applying a voltage to the piezoelectric 7 cutieta.

[Effects of the Invention] As explained above, the present invention incorporates a piezoelectric actuator in the surface of the plate spring mounting surface that constitutes the printing hammer, and
When the printing hammer is attracted, the piezoelectric seven-mouth and one-actor are driven to contract the yoke ear, so that the following effects can be achieved.

(i) The yoke gap under normal conditions (when no voltage is applied to the piezoelectric actuator) can be widened. This can prevent the ink ribbon from getting caught with the hammer pin. Furthermore, since the range of adjustment of the position of the printing hammer is widened, it is possible to perform high-quality printing with less uneven printing.

(ii) A printing hammer with a high spring constant can be made. Thereby, printing speed can be increased.

[Brief explanation of the drawing]

Figure 1 shows a print head according to an embodiment of the present invention, and is a perspective view of the piezoelectric actuator in an extended state. Figure 2 is a perspective view of the main part of the same piezoelectric actuator in a contracted state. Figure fjS3 shows the yoke gap and suction force. , and is a graph showing the relationship with leaf spring characteristics. 1... Support body, 3... Printing hammer, 3
a...Hammer pin, 4a, 4b...Yoke, 5...Permanent magnet, G a, G b...
...Demagnetizing coil (4 at 4 b, 5
．． 6a, 6! > is the drive mechanism), 7... is the piezoelectric actuator, 8... is the gap.

Claims (1)

[Claims] a printing hammer made of a leaf spring with a hammer pin fixed to one end; a drive mechanism for driving the printing hammer; a support for supporting the printing hammer and the drive mechanism; A dot impact print head comprising: a piezoelectric actuator that presses in the direction of the drive mechanism.