JP2556054B2 - Printhead driving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a method for driving a print head using a piezoelectric element as a driving source, which has a high reliability in printing and simplifies the structure. It is attached to the elastic rod and the printing wire fixed to the tip of the rod so that it is almost perpendicular to the rod, and it is attached to the frame, and the tip is tapped near the proximal end of the rod. A piezoelectric element for imparting vibration to the piezoelectric wire, and a pulse voltage having a frequency equal to the natural frequency of the vibration system consisting of the printing wire and the lever is applied to the piezoelectric element to resonate the vibration system, and the tip of the printing wire is The printing medium is tapped multiple times during one dot printing cycle.

[Industrial applications]

Wire dot printers are widely used as printers for various computer terminals and word processors.

Among them, the serial dot printer is capable of adapting to various characters, symbols, and figures because the characters and the like are formed by dots and recorded, and the application is expanding as a terminal of OA (office automation) equipment.

The print heads used in these dot printers include a print magnet type and an ink jet type.

However, each of them has advantages and disadvantages, and recently, a print head using a piezoelectric element as a drive source of a print wire is attracting attention because it can perform high-speed printing and has a simple structure.

[Conventional technology]

The print head uses, as a drive source of the print wire, a piezoelectric element that generates a vertical displacement due to a piezoelectric effect according to a voltage applied to the electrodes.

Since the amount of displacement of the piezoelectric element is very small, it is necessary to expand its operation.

For this reason, the conventional print head is constructed as shown in FIG.

In the figure, reference numeral 4 denotes a first leaf spring having a base end 4b fixed to a frame and swinging about the base end 4b.

2 is attached to the tip portion 4a of the first leaf spring 4 at the first leaf spring 4
It is a printing wire that is fixed so that it is almost at a right angle to.

Reference numeral 5 is a second leaf spring whose base end 5b is fixed to the frame body and which swings about the base end 5b as a fulcrum.

The tip portion 5a of the second leaf spring 5 projecting at a right angle is in contact with the vicinity of the fulcrum of the first leaf spring 4.

Then, the piezoelectric element 1 is mounted so that the tip portion abuts on the position close to the fulcrum of the second leaf spring 5, and the print head is configured.

When the print head configured as described above is driven, the control unit 9 sends a print signal to the drive circuit 10, and the drive circuit 10 applies a pulse voltage to the electrode of the piezoelectric element 1 based on the print signal.

The piezoelectric element 1 expands when a pulse voltage is applied,
The second leaf spring 5 swings around the base end portion 5b as a fulcrum, and the tip portion 5a of the second leaf spring 5 taps near the fulcrum of the first leaf spring 4.

As a result, the first leaf spring 4 largely swings around the base end 4b as a fulcrum, and the print wire 2 taps a print medium (not shown) to print.

[Problems to be Solved by the Invention]

The conventional print head is provided with the first and second leaf springs as described above, and the expansion amount of the piezoelectric element is expanded by the lever action of each leaf spring.

Since the lever action is adopted, the swing amount of the tip end portion of each leaf spring becomes small unless the precision of the component parts is high.

Due to this, the conventional method of driving the print head not only requires high accuracy in the components and becomes costly, but also because the print wire only taps the print medium once during one dot printing cycle, There was a problem that the printing was not clear.

The present invention was created in view of the above points, and an object of the present invention is to provide a method for driving a print head which is clear in printing, has high reliability, has a small number of components, and is low in cost.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, the elastic rod 3 having the base end portion 3b fixed to the frame body 8 and the rod 3 which is substantially perpendicular to the rod 3. And a piezoelectric element 1 attached to the frame body 8, which is attached to the frame body 8 and taps the vicinity of the base end portion 3b of the rod 3 to vibrate the rod 3.

Then, a pulse voltage having a frequency equal to the natural frequency of the vibration system consisting of the printing wire 2 and the lever 3 is applied to the piezoelectric element 1 to cause the vibration system to resonate, and the tip of the printing wire 2 becomes
The print medium is tapped multiple times during one dot printing cycle.

[Action]

As described above, the present invention is provided with a single elastic lever that performs a lever movement of a one-stage configuration, and strikes near the base of the lever,
The displacement of the tip of the printing wire is increased by resonating the hammer.

Therefore, since the number of parts is small and the lever does not need to be highly accurate, the cost of the drive means for the print head is low.

On the other hand, a relatively heavy printing wire is attached to the tip of the rod to increase the distance between the fulcrum of the rod and the tip of the printing wire, causing the tip to resonate and be displaced greatly, so the printing medium is tapped. The energy to do is great. Also,
Since it resonates, the print wire taps the print medium multiple times during one dot printing cycle.

 Therefore, the printing becomes clear and the reliability of the printing improves.

〔Example〕

The present invention will be specifically described below with reference to the drawings.
The same reference numerals indicate the same objects throughout the drawings. First
FIG. 2 is a configuration diagram showing a method of driving the print head of the present invention, and FIG. 2 is a diagram showing a resonance state of the print wire.

In FIG. 1, reference numeral 3 designates a lever having an elastic property in which the base end portion 3b is fixed to the frame body 8 (fixed portion 7a) and swings around the base end portion 3b as a fulcrum.

Reference numeral 2 denotes a printing wire fixed to the tip of the rod 3 so as to be substantially perpendicular to the rod 3.

Reference numeral 1 denotes a piezoelectric element which is attached to the frame body 8 and which vibrates the rod 3 by tapping the vicinity (a tapping portion 7b shown in the drawing) of the tip end to the base end 3b of the rod 3.

When the print head having the above-described structure is driven, the control unit 9 sends a print signal to the drive circuit 10, and the drive circuit 10 applies a pulse voltage to the electrodes of the piezoelectric element 1 based on the print signal. There is.

At this time, the pulse frequency applied to the piezoelectric element 1 is the frequency sent from the oscillator 11 that is equal to the natural frequency of the vibration system of the print wire 2 and the lever 3.

Thus, a pulse voltage having a frequency equal to the natural frequency of the resonance system composed of the printing wire 2 and the lever 3 is applied to the piezoelectric element 1, and the tip end of the piezoelectric element 1 is the base end 3b of the rod 3.
This vibrating system resonates because it strikes in the vicinity. Therefore, the amount of displacement of the tip of the print wire 2 increases, and the tip of the print wire 2 strikes the print medium.

At this time, as shown in FIG. 2, since it resonates at every 1-dot printing cycle, the tip of the printing wire 2 taps the print medium a plurality of times during the 1-dot printing cycle to perform printing.

〔The invention's effect〕

Since the present invention is configured as described above, it has the effects described below.

The vibrating system consisting of the printing wire with a large mass at the tip and the lever resonates, causing the printing wire to move during one dot printing cycle.
Since the printing medium is struck multiple times, the sharpness of printing is ensured and the reliability of printing is improved.

Further, since the number of constituent parts is small, the cost is low.

[Brief description of drawings]

 FIG. 1 is a configuration diagram showing a method of driving a print head of the present invention, and FIG. 2 is a diagram showing a resonance state of a print wire. FIG. 3 is a side view of a conventional print head. In the figure, 1 is a piezoelectric element, 2 is a printing wire, 3 is a lever, 4 is a first leaf spring, 5 is a second leaf spring, 8 is a frame, 9 is a control unit, 10 is a drive circuit, and 11 is an oscillator. Shown respectively.

Claims (1)

(57) [Claims] 1. An elastic rod (3) having a base (3b) fixed to a frame (8) and a tip of the rod (3) so as to be substantially perpendicular to the rod (3). Is attached to the frame (8) and the printing wire (2) fixed to the section, and the tip end of the rod (3) taps the vicinity of the base end (3b) of the rod (3), A piezoelectric element (1) for imparting vibration is applied to the piezoelectric element (1) with a pulse voltage having a frequency equal to the natural frequency of a vibration system including the print wire (2) and the rod (3). Then, the vibration system is caused to resonate, and the tip of the print wire (2) taps the print medium a plurality of times during one dot printing cycle.