JPH0373467B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to impact print heads, particularly impact print heads used in dot impact printers.

Conventionally, impact print heads have been used as print heads for dot impact printers, which perform printing operations by utilizing dimensional distortion caused by piezoelectric transverse effects of piezoelectric or electrostrictive ceramics.

Figures 1a and 1b are perspective and side views, respectively, of a conventional impact print head. The printing head shown in FIG. 1A has a plurality of printing units 1 arranged and attached to one end of a head base 2, and a wire 11 fixed to the end of each printing unit 1 is provided at the other end of the mounting member 2. The wires are arranged by passing through guide holes of the wire alignment member 21 and aligning them. Each printing unit 1 has piezoelectric plates 41 and 42 on both sides of a conductive electrode plate 50, as shown in FIG.
is fixed to one end of the piezoelectric vibrator, and conductor electrode plates 51 and 52 are fixed to both outer surfaces of the piezoelectric vibrator.
It is constructed by attaching and fixing a wire 11 for printing dots. Electrode plates 51 and 52 are connected to one of a pair of conductive wires 6 via metal attachment member 2, and electrode plate 50 is connected to the other conductive wire 6. The piezoelectric plates 41 and 42 have been polarized in advance, and when a driving voltage is applied between the electrode plates 51 and 52 and the electrode plate 50 via the conductive wire 6, the piezoelectric plates 41 and 42 are polarized due to the piezoelectric transverse effect. The piezoelectric plate 42 contracts and causes a strain in the direction of the broken line arrow A, and the piezoelectric plate 42 expands and causes a strain in the direction of the broken line arrow B. Along with this, the piezoelectric vibrator is bent, and the wire 11 is bent as indicated by the broken line arrow C.
The printing operation is performed by moving in the direction of and placing dots on the printing surface.

Conventional impact print heads such as those described above have disadvantages of large size and high power consumption. That is, the printing unit 1 used in the conventional impact printing head is
Printing is performed by generating dimensional distortion in the piezoelectric body using the piezoelectric transverse effect, but the resulting distortion is smaller in the piezoelectric transverse effect than in the case of the piezoelectric longitudinal effect (about 1/3 times the Poisson's ratio). times), so in order to store the specified mechanical energy, it is necessary to have a large volume (the square of Poisson's number, which is approximately 9 times the volume), and the electromechanical coupling coefficient is small, so in order to obtain the specified strain. requires large driving power (approximately 5 times as much power). In a conventional impact printing head equipped with a plurality of printing units 1 that utilize such a piezoelectric transverse effect, each printing unit 1 is large in size as described above, and each printing unit 1 does not allow printing by other printing units during printing operation. They must be arranged with sufficient distance from each other so as not to come into contact with the printing unit 1, and an increase in the size of the printing unit is unavoidable.

SUMMARY OF THE INVENTION An object of the present invention is to provide an impact print head which eliminates the above-mentioned drawbacks and which is compact and consumes less power.

The print head of the present invention includes a piezoelectric body that generates dimensional strain due to the piezoelectric longitudinal effect, a transmission mechanism that transmits the dimensional strain to generate displacement in a predetermined direction, and one end of which is fixed to a predetermined location of the transmission mechanism. a plurality of printing units each having a thin rod-shaped wire member that performs a printing operation in accordance with the displacement; and at least one of the printing units provided with a guide hole through which a tip end of each wire member of the printing unit can slide. and the wire members of the printing units divided into two groups each having a predetermined number of wire members are arranged at a predetermined angle of inclination to each other, and each tip is passed through the guide hole one by one. Each set of printing units forms two printing unit blocks stacked in the thickness direction, and the gap between the two printing units corresponds to the thickness of the printing unit. The head stand has a holding member for holding the printing units of both blocks alternately inserted and arranged in an overlapping manner at a larger area than the printing unit.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 2 and FIGS. 3a and 3b are a side view, a top view, and a side view, respectively, showing an embodiment of the present invention. FIG. 2 shows an example of the configuration of the printing unit used in this embodiment. The piezoelectric body 4, which is a driving source for printing operation, has a plurality of internal electrodes 42 provided in parallel to each other at predetermined intervals within a piezoelectric material 41, and a pair of external electrodes (not shown) are provided on the sides of the piezoelectric body 4.
, and every other internal electrode 42 is alternately connected to one and the other of a pair of external electrodes.
When a driving voltage is applied between the external electrodes, this voltage is applied between the internal electrodes 42, and the piezoelectric body 4 is expanded due to the piezoelectric longitudinal effect, causing dimensional distortion. This piezoelectric body 4
The lower end of the piezoelectric body 4 is fixed to the mounting member 3.
The upper end of the first and second
is connected to movable members 5 and 7 of. The lower ends of the first and second movable members 5 and 7 are further connected to the mounting member 3 via a plate-shaped coupling member.
The mounting member 3 is integrally formed of metal with the movable members 5 and 7, and is provided with a screw hole 12 for passing a screw when it is assembled into a print head. One ends of first and second transmission members 8 and 9 made of metal plates are fixed to the upper ends of the first and second movable members 5 and 7, respectively. The other end of 9 is attached and fixed to a predetermined location of a third movable member 10 made of metal. A printing wire 11 is attached and fixed to the tip of the third movable member 10. When the dimensional strain that occurs when a driving voltage is applied to the piezoelectric body 4 is transmitted to the first and second movable members 5 and 7, both act as levers, so the dashed arrows D and D are shown at their upper ends, respectively. A displacement in the direction of E is produced. These two mutually opposite displacements are transferred to the third movable member 10 via the first and second transmission members 8 and 9.
is transmitted to give rotational moment. Along with this, the wire 11 moves in the direction of the broken line arrow F to perform a printing operation. In this way, the piezoelectric body 4 of the piezoelectric longitudinal effect type
By using this as a driving source, it is possible to realize a printing unit that is smaller and consumes less power than conventional print heads.

3a and 3b show an impact print head constructed by incorporating a plurality (13 in this embodiment) of the printing units shown in FIG. 2. A plurality of printing units are divided into two sets (in this embodiment, they are divided into six and seven units), and the printing units for each set are stacked on the head stand 72 to form an attached printing unit block. . A first alignment member 73 is provided at one end of the head stand 72 to guide the wires 11 to the printing surface.
A guide hole is provided through which the slider can slide. In this embodiment, in addition to the first alignment member 73, second and third alignment members 74 are used to prevent the wire 11 from generating unnecessary vibrations and coming into contact with each other and causing erroneous printing during the printing operation. and 75 are provided.
If unnecessary vibrations of the wire 11 can be prevented by appropriately selecting the dimensions of the wire 11, the printing speed, etc., the alignment members 74 and 75 can be omitted. The alignment members 74 and 75 are also provided with guide holes through which the wires 11 are passed.

When assembling the printing unit of each block into the head stand 72, since the distance between the tips of the wires 11 is quite narrow compared to the thickness of the printing unit, it is necessary to assemble the printing unit next to the mounting member 3 of the printing unit, as shown in Figure b. They are arranged radially with an inclination angle between them in the thickness direction. That is, the guide holes of the alignment members 73, 74, and 75 are provided so as to guide the wire 11 radially toward the print surface, and the screw holes 76 are provided between the head stand 72 and the mounting member 3 of the lowermost print head.
A spacer 78 with a screw hole through which the screw 79 is passed and a screw hole through which the screw 79 is passed is inserted, and a spacer 77 with a screw hole through which the screw 76 is passed is inserted between each printing unit. The printing units are arranged radially, and the screws 76 are inserted into the screw holes 12 and spacers 77 and 78 shown in FIG.
At the same time, pass the screw 79 through the screw hole of the spacer 78 and the screw hole provided in the head stand 72, and tighten the nut at the upper end to hold each set of printing units. A printing unit is held on a head stand 72. The arrangement of the two sets of printing unit blocks is as shown in Figure a.
A center line approximately parallel to the wire 11 is assumed and symmetry is provided on both sides with respect to this. By arranging it in this way, the mounting member 3 of each block
Two sets of block printing units are inserted alternately at a location where the gap between them is wider than the thickness of the mounting member 3, thereby reducing the width of the printing unit.

In this embodiment, by using a piezoelectric longitudinal effect type piezoelectric material 4 as a driving source, the printing unit is made smaller and consumes less power than the conventional printing unit. Furthermore, by dividing multiple printing units into two sets of blocks and stacking them, the height of the printing head can be shortened, and
Parts of the printing units of the two sets of blocks are inserted alternately to shorten the width of the print head, and extra empty space is eliminated as much as possible to make the volume occupied by the print head smaller than before.

Note that the structures of the printing unit, head stand 72, etc. of this embodiment are not limited to this. A piezoelectric longitudinal effect type piezoelectric body is used as a drive source, and the shape and interconnection of the mechanism that transmits the generated dimensions to the wire are changed as appropriate, or the shape of the head stand and the installation method of two sets of printing unit blocks are changed. It is easy to make appropriate changes, and it is clear that the same effects as in this embodiment can be obtained even in this case.

As is clear from the above description, the present invention has the effect of realizing an impact print head that is smaller and consumes less power than the conventional one, and this effect is particularly significant when applied to a case where the number of wires is large.

[Brief explanation of drawings]

1A and 1B are a perspective view and a side view, respectively, showing a conventional impact printing head, and FIGS. 2A and 3B are a side view, a top view, and a side view, respectively, showing an embodiment of the present invention. be. 3... Mounting member, 4... Piezoelectric body, 5, 7, 10
...Movable member, 8, 9...Transmission member, 11...Wire, 72...Head stand, 73-75...Alignment member, 77, 78...Spacer, 76, 79...Screw.

Claims (1)

[Claims] 1. A piezoelectric body that generates dimensional strain due to a piezoelectric longitudinal effect, a transmission mechanism that transmits the dimensional strain and generates displacement in a predetermined direction, and one end of which is fixed to a predetermined location of the transmission mechanism. a plurality of printing units each having a thin rod-shaped wire member that performs a printing operation in accordance with the displacement; and at least one of the printing units provided with a guide hole through which a tip end of each wire member of the printing unit can slide. and the wire members of the printing units divided into two groups each having a predetermined number of wire members are arranged at a predetermined angle of inclination to each other, and each tip is passed through the guide hole one by one. Each set of printing units forms two printing unit blocks stacked in the thickness direction, and the gap between the two printing units corresponds to the thickness of the printing unit. 1. An impact printing head characterized by comprising a head stand having a holding member for alternately inserting and overlapping the printing units of both blocks and holding them at a larger area than the impact printing head.