JPH0419945B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a differential amplitude expansion mechanism.

Conventionally, the mechanical displacement generated by a drive source is magnified and transmitted by two levers, and the couple differentially transmitted by these two levers is applied to a movable member.
There is a differential amplitude expansion mechanism for obtaining displacement with expanded amplitude.

FIG. 1 is a side view showing a conventional differential amplitude amplifying mechanism, and shows an example where the mechanism is applied to a printing element of a dot type printer. In the figure, a piezoelectric body 2 whose one end is fixed to a metal mounting member 1 is a driving source.
When a driving voltage is applied to the electrodes (not shown) of the piezoelectric body 2, the piezoelectric body 2 expands and causes dimensional distortion, and this dimensional distortion is transmitted to the metal through the first and third metal coupling members 3 and 5. the first and second movable members 7 of
and 8, giving mechanical displacements in the directions indicated by dashed arrows A and B, respectively. The lower ends of the first and second movable parts 7 and 8 are respectively connected to the first movable parts 7 and 8.
It is connected to the mounting member 1 via second and fourth metal coupling members 4 and 6 at a location spaced apart from the third coupling members 3 and 5 by a predetermined distance.
When mechanical displacements in the directions of dashed arrows A and B are transmitted to the first and second movable members 7 and 8, respectively, the second and fourth coupling members 4 and 6 bend, and the second and fourth coupling members 4 and 6 bend in response. A rotational moment is generated in the first and second movable members 7 and 8, resulting in an enlarged displacement in the directions indicated by dashed arrows C and D at the upper ends of the first and second movable members 7 and 8, respectively. . One ends of fifth and sixth coupling members 9 and 10 made of metal plates are fixed to the upper ends of the first and second movable members 7 and 8, respectively. Parts 9 and 1
0 is connected to a third movable member 11 made of metal. Displacements in the directions of dashed arrows C and D are transmitted to the third movable member 11 via the fifth and sixth coupling members 9 and 10, respectively.
Since these two displacements are in opposite directions, the third
The movable member 11 receives a couple of differential displacements, and causes an enlarged displacement in the direction indicated by the dashed arrow E at its tip end. Third movable member 11
A wire 12 for dot printing is attached to the tip of the wire 12, and each time the drive source, that is, the piezoelectric body 2 generates dimensional distortion, it moves in the direction of the broken line arrow E to print dots.

In such a conventional differential amplitude expansion mechanism, excessive bending stress is applied to the fifth and sixth coupling members 9 and 10 during operation, for example, during dot printing. For this reason, especially when applied to a printing element of a device that operates repeatedly many times, for example, a dot type printer, the magnitude of the repeatedly applied stress exceeds the fatigue limit, causing the fifth and sixth connecting members 9
and No. 10 have the disadvantage of being susceptible to breakage.

The object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a differential amplitude swing which reduces the bending stress acting on a pair of plate-shaped coupling members that transmit a pair of opposite displacements more than before, thereby preventing breakage and breakage. The purpose is to provide an enlargement mechanism.

The mechanism of the present invention includes a columnar driving member whose one end is fixed to a mounting member and whose other end generates displacement in a predetermined direction, and two connecting members whose one ends are spaced apart from each other by a predetermined distance. are connected to the drive member via one of the coupling members and to the mounting member via the other, each of which produces an angular displacement in opposite directions in response to the displacement transmitted via the one coupling member. first and second movable members; one end of each is connected to the other end of the first and second movable members, and the plate-shaped first and second movable members are configured to transmit the angular displacements in opposite directions, respectively. a second coupling member; and a second coupling member whose one end is connected to the respective other ends of the first and second coupling members and which produces rotational movement in response to the mutually opposite angular displacements transmitted through the two coupling members. and a thin rod-shaped wire whose one end is joined to the other end of the third movable member, and whose joint part transmits force in a direction tangential to the central axis in response to the rotational movement. In the differential amplitude amplification mechanism, the first and second coupling members are arranged such that the intersection of two center lines assumed in the direction of transmission of the angular displacement on each plate surface of the first and second coupling members is located at the junction point of the wire. It is characterized in that the distance between the tangent line and the extension line is zero in practice.

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

FIGS. 2a and 2b are a partial perspective view and a characteristic diagram, respectively, for explaining the principle of the present invention. In Figure a, points P1 and P2 on the center line of the plate surface of the fifth coupling member 9 are the joint points of the third movable member 11 and the first movable member 7 and the fifth coupling member 7, respectively. This point is assumed to be the intersection of this cross section and the center line of the plate surface, assuming a cross section passing through the edge of. Similarly, points P3 and P4 on the center line of the plate surface of the sixth coupling member 10 pass through the joining edges of the third movable member 11 and the second movable member 8 and the sixth coupling member 10, respectively. This point is assumed to be the intersection of the cross section and the center line of the plate surface. Point P6 is the fifth
and the intersection of two straight lines extending from the center lines of the respective plate surfaces of the sixth coupling members 9 and 10. Furthermore, point P
Reference numeral 5 indicates the attachment point of the wire 12 in FIG. 1 (not shown in FIG. 2a). 1st and 2nd
from the movable members 7 and 8 of the dashed arrow C, respectively.
When the displacement in the direction indicated by and D is transmitted, this displacement is transmitted to the third movable member 11 via the fifth and sixth coupling members 9 and 10, and is transmitted to the point P5.
gives a displacement to the wire attached to the When the wire performs impact printing in response to this, a reaction force in the direction shown by the broken line arrow G acts from the wire to the point P5. In response to this reaction force, tensile stress and compressive stress act on the fifth and sixth coupling members 9 and 10, respectively, to maintain balance with the reaction force. That is, at this time, the tensile stress and compressive stress acting on the fifth and sixth connecting members 9 and 10, respectively, have a resultant force at point P6 as shown by the broken line arrow F.
, that is, parallel to and opposite to the dashed arrow G, the magnitude becomes equal to the reaction force. Furthermore, if the distance d between the broken line arrows F and G is not zero, a couple moment is generated by the reaction force and the counterbalancing force, and the fifth and sixth Connecting members 9 and 10
Bending stress acts on each. If the distance d is zero, the above-mentioned coupled moment will not occur, so
No bending stress acts on the fifth and sixth coupling members 9 and 10.

Note that for the following explanation, points P1 to P6
Determine two-dimensional coordinates in a plane containing With the point P1 as the origin, the abscissa x is parallel to and in the same direction as the dashed arrow F, and the ordinate y is perpendicular to the abscissa and above. The position of the point is expressed in horizontal and vertical coordinates x and y in millimeters (mm).
It is expressed as a pair (x, y). Further, the fifth and sixth coupling members 9 and 10 have a thickness t and a width W.

Figure 3b shows the distance d for one design example in figure a.
The relationship between and stress σ is shown. In this design example, point P1
is selected as the origin, so P1=(0,0), P2=(-
3.7, 12.9), P3 = (-2.3, 2.0), P5 = (-3.0,
−8.6), and the abscissa x4 of P4=x4, 11.1),
By changing the distance d, that is, the arm of the couple, the relationship between the distance and the maximum stress σ acting on the fifth and sixth coupling members 9 and 10 was determined by simulation. , and the plus and minus signs attached to the distance d indicate the magnitude of the ordinate of the point P6 with respect to the ordinate of the point P5. The fifth and sixth coupling members 9 and 10 have a plate thickness t=0.3 mm and a width W=2 mm.
The magnitude of the reaction force is 15 Newtons. When the distance d is near zero, the above-mentioned bending stress hardly acts and tensile or compressive stress acts, whereas as the absolute value of the distance d increases, the bending stress increases, Therefore, the stress σ increases. In this design example, the fifth and sixth coupling members 9 and 1
When using steel with a fatigue limit of about 40 kg/mm ² as the material for the 0, the absolute value of the distance d must be designed to be 5 mm or less to prevent breakage. Of course, the upper and lower limits of the distance d that do not cause destruction vary depending on how each of the above numerical values is selected, but an increase in bending stress as the absolute value of the distance d increases is unavoidable. In the mechanism of the present invention, by configuring the distance d to be substantially zero, almost no bending stress acts on the fifth and sixth coupling members 9 and 10, thereby preventing breakage and breakage. .

FIG. 3 is a side view showing the first embodiment of the present invention. The mechanism shown in FIG. 2 is constructed so that the distance d in FIG. 2a is zero. That is, the first
and the shape of the second movable members 17 and 18 and the joining angle of the fifth and sixth joining members 9 and 10,
The imaginary plane obtained by extending the plate surface of the wire 12 and the imaginary line obtained by extending the axis of the wire 12 intersect at one point R. Therefore, the configuration is such that the distance d in FIG. Almost no bending stress acts on and 10, and breakage does not occur even if repeated operations are performed.

FIG. 4 is a side view showing a second embodiment of the invention. The mechanism of this embodiment also has a configuration such that the distance d in FIG. This is different from the example case. That is, by changing the shapes of the first and second movable members 27 and 28, displacement in the directions indicated by broken line arrows A and B is transmitted, and this is transmitted to the first and second movable members 27 and 28 via the fifth and sixth coupling members 9 and 10. When the force is transmitted to the movable member 21 of No. 3, a displacement is obtained in a direction parallel to the directions of broken line arrows A and B, as shown by broken line arrow E. In the first example,
As shown in FIG. 3, the direction of displacement transmitted from the piezoelectric body 2 and the direction of displacement transmitted to the third movable member 11 are orthogonal to each other, and between these two directions of displacement, The angle can be made to a desired size by appropriately changing the shapes of the first and second movable members. In this case as well, the configuration can be made so that the distance d in FIG. 2a becomes zero,
Therefore, it is clear that breaking and breaking can be prevented by not subjecting the fifth and sixth coupling members to excessive bending stress.

As is clear from the above explanation, the present invention has a differential amplitude type that reduces the bending stress acting on the plate-shaped coupling surfaces that transmit a pair of opposite displacements, and prevents breakage and failure. This has the effect of realizing an enlargement mechanism, and the effect is particularly significant when applied to equipment that requires a large number of repeated operations.

[Brief explanation of drawings]

FIG. 1 is a side view showing a conventional differential amplitude amplifying mechanism, FIGS. 2 a and b are a partial perspective view and a characteristic diagram for explaining the principle of the present invention, respectively, and FIGS. FIG. 3 is a side view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Mounting member, 2... Piezoelectric body, 3... First coupling member, 4... Second coupling member, 5... Third coupling member, 6... Fourth coupling member, 7, 17,2
7...First movable member, 8, 18, 28... Second
movable member, 9... fifth coupling member, 10... sixth coupling member, 11, 21... third movable member,
12...Wire.

Claims (1)

[Scope of Claims] 1. A column-shaped driving member whose one end is fixed to a mounting member and whose other end generates displacement in a predetermined direction, and two connections whose respective one ends are spaced apart from each other by a predetermined distance. connected to the driving member through one of the members and to the mounting member through the other, each of which produces opposite angular displacements in response to the displacement transmitted through one of the coupling members; first and second movable members; one end of each is connected to the other end of the first and second movable members, and the plate-shaped first and second movable members are configured to transmit the angular displacements in opposite directions to each other; a second coupling member, one end of which is connected to the other end of each of the first and second coupling members to produce rotational movement in response to the opposite angular displacements transmitted through the two; a third movable member; and a thin rod-shaped wire whose one end is joined to the other end of the third movable member, and whose joint part transmits force in a direction tangential to the central axis in response to the rotational movement. In the differential amplitude amplification mechanism, the first and second coupling members are connected at the intersection of two center lines assumed in the transmission direction of the angular displacement on each plate surface thereof and at the junction point of the wire. A differential amplitude amplifying mechanism characterized in that the distance between the tangential line and the extension line of the tangent line is substantially zero.