JPH0243779A - Micro-displacement magnifying mechanism temperature compensation device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is for compensating for negative linear expansion due to temperature rise of the piezoelectric element in a minute displacement magnification mechanism using a piezoelectric element that expands and contracts when a voltage is applied. The present invention relates to a temperature compensation device.

(Prior Art) Conventionally, in a minute displacement magnification mechanism 51 as shown in FIG. 7 used in a printer head, for example, a piezoelectric element 52 is used.
When the displacement of There was a problem in that the displacement finally expanded due to the change, that is, the displacement of the printing wire 53, was not stable.

Therefore, in order to solve the above problem, conventionally, a material with a low coefficient of thermal expansion, such as an invar alloy, is used for the frame 54 of the micro displacement amplifying mechanism 51, and a thermal expansion member 55 with a high coefficient of thermal expansion is used in contact with the piezoelectric element 52. By using this, when the temperature of the piezoelectric element 52 increases, the temperature of the temperature compensating member 55 increases by receiving heat transferred from the piezoelectric element 52,
By causing the temperature compensation member 55 to undergo positive linear expansion, f
f-Line expansion 1 between the frame side and the piezoelectric element side due to the negative line rfJ clothes of the piezoelectric cord 52 itself due to the upper back of the electric cord 52
A temperature compensating means is employed to compensate for the difference & to equalize the amount of thermal expansion on the frame 54 side and the thermal expansion (2) on the j1 electric element side (piezoelectric element 524 temperature compensating member 55).

(Problems to be Solved by the Invention) J. In the conventional minute displacement magnifying mechanism 51, for example, the situation shown in FIG.
, a similar temperature sensor B is attached to the temperature compensation member 55, and a similar temperature sensor C is attached to the frame 54, and the room temperature is 2.
When the respective temperatures were measured when the piezoelectric system element 52 was continuously driven at 0 degrees, data as shown in FIG. 9 were obtained.

As shown in FIG. 9 above, the drive start 30 of the piezoelectric system 52
In a second, the temperature 11 of the piezoelectric cord 52 itself reached 60 degrees, but the temperature T2G of the temperature compensating member 55, the temperature T3 of the frame 54 rose only to 26.5 degrees.

Similarly, after 360 seconds, the temperature T1 reached 68 degrees, but the surface temperature T2 rose only to 35 degrees, and the temperature T3 rose only to 33 degrees.

That is, in the case of the conventional temperature compensating means, the heat conduction between the temperature compensating member 55 and the frame 54 due to the heat generated by the FF cable 52 is not uniformly conducted, and a 4-degree gradient occurs. Therefore,
There was a problem in that a difference occurred in the amount of thermal expansion between the frame side and the piezoelectric element side, resulting in incorrect temperature compensation.

Therefore, in the present invention, a heating element is attached to the temperature compensation member, the temperature compensation member is heated in response to the temperature rise of the piezoelectric element, and the temperature compensation member is provided with a positive line # corresponding to the negative line expansion of the piezoelectric element, The technical problem to be solved is to control the temperature so that the amount of thermal expansion on the frame side and the piezoelectric element side are equalized by swelling.

(Means for Solving the Problem) The technical means for solving the above problem consists of a piezoelectric element that expands and contracts by the application of an electric current, a frame that fixes the piezoelectric element at one end in the expansion and contraction direction, and a frame that fixes the piezoelectric element at one end in the expansion and contraction direction. a movable member connected to the other end in the expansion/contraction direction of the piezoelectric cable f, and a movable member connected to the other end of the piezoelectric cable f in the direction of expansion and contraction; A temperature compensating device in a minute displacement amplifying mechanism, which includes a temperature compensating member for compensating for linear expansion of the piezoelectric element due to changes in its own temperature and changes in ambient temperature, comprises: the piezoelectric element, the temperature compensating member; A temperature sensor that detects each mL of the temperature and outputs an electric signal corresponding to each detected temperature, and a temperature compensation member that is arranged to allow heat transfer, and when the required main force is supplied. A heating element that generates heat and causes the temperature compensating member to undergo positive linear expansion, and an electrical signal corresponding to each of the detected temperatures output from the temperature sensor are input, and the amount of negative linear expansion of the piezoelectric element is inputted. At the same time, calculate the amount of positive linear expansion of the temperature compensation member to compensate for this amount of negative linear expansion, and set the temperature of the temperature compensation member to a temperature corresponding to this amount of positive linear expansion. and temperature control means for supplying the necessary power to the heat generating element.

(Function) According to the temperature compensator for a minute displacement magnifying mechanism configured as described above,
The temperature detector detects the temperature of the piezoelectric element while a voltage is applied and the piezoelectric element is driven, and outputs an electric signal corresponding to the detected temperature to the temperature control means. When the temperature control means receives the electric signal, it calculates the amount of negative linear expansion of the piezoelectric element, and also calculates the amount of positive linear expansion of the temperature compensation member to compensate for this amount of negative linear expansion, thereby performing temperature compensation. The necessary power to heat the member to a temperature corresponding to this positive linear expansion W& amount is outputted to the heating element. As a result, the temperature compensating member is heated to a temperature corresponding to the above-mentioned positive linear expansion amount, and is linearly expanded until it compensates for the negative linear expansion of the piezoelectric element, so that the thermal expansion amount on the frame side and the piezoelectric element side is The difference is converged to zero, and the displacement of the minute displacement magnifying mechanism is always controlled to be constant regardless of temperature changes of the piezoelectric element.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 1, which is a perspective view of a minute displacement magnifying mechanism 1 used in a printer head, etc., it extends in the longitudinal direction when a DC voltage is applied, and returns to its original state when the voltage is removed. A piezoelectric element 2 such as a laminated piezoelectric ceramic is attached to a base part 6 via a temperature compensating member 5 at one end surface in the direction of expansion and contraction. On the other hand, a frame 4 made of, for example, a super invar alloy with a predetermined thickness
is formed into a substantially U-shape mainly consisting of the base portion 6 and first and second support portions 7.8 formed on both sides of the base portion 6.

An interlock F9 is fixed to the other end of the piezoelectric element 2 in the direction of expansion and contraction.

Between the upper surface of one side of the interlocking element 9 and the upper end surface of the first support section 7 of the frame 4, there are elastically deformable first and second hinge sections 1.
0.11, the first tilting body 12 is formed to be tiltable.6, between the loose side upper surface of the interlocking element 9 and the upper end surface of the second support part 8 of the frame 4, Elastically deformable third
, the second tilting body 15 is formed to be tiltable via a fourth hinge portion 13.14.

A leaf spring 16.17 is fixed at its base to the tip of the first and second inner tilting bodies 12.15, and a wire to which the printing wire 3 is attached is attached to the tip of each of these machine springs 16.17. A support arm 18 is fixed.

When the piezoelectric cord 2 extends in the longitudinal direction by applying a DC voltage, the first and second inner tilting bodies 12°15 move to the second,
They are each tilted outward using the fourth hinge portions 11 and 14 as a fulcrum. As a result, the leaf spring 16 on the first tilting body 12 side is pulled, and the leaf spring 17 on the second tilting body 15 side is pushed out, so that the wire support 7-m 18 is
The printing wire 3 guided by the printing wire 3 is tilted in a direction in which it curves to the printing position.

The temperature compensating member 5 inserted between the piezoelectric cord 2 and the base portion 6 of the frame 4 is made of, for example, Al5O12 material, and its A7 rate E is E=7. lX10K
9/am2FIll rate α is α-23,8x 10'/'C1 Specific heat C is c = 0.215 cal/9/'C density q is q = 2.71 'j/Cm3 and external dimensions are 3 .4x 4.4x 4.9 (height) (about 14j mm).

On the other hand, the linear expansion amount α of the piezoelectric element 2 is α=−6,OX 10′/′C1, and the external dimensions are 3×3×18 (height) (unit layer).

In addition, the frame 4 uses super invar alloy,
(The Young's modulus E of
Tonatteru.

As shown in FIG. 2, a resistance heating element 21 is attached in a U-shape to the temperature compensating member 5 of the minute displacement magnification mechanism 1 configured as described above, and as shown in FIG. To,
A very thin temperature sensor 22 is attached to the piezoelectric cord 2, a similar temperature sensor 23 to the temperature compensation member 5, and a similar temperature sensor 24 to the frame 4. -V resistance heating element 21, temperature detectors 22, 23, 24, respectively (
As shown in the electrical control circuit block diagram of FIG. 4, it is connected to a temperature control circuit (temperature control means) 25.

The temperature control circuit 25 receives an electric signal corresponding to the temperature of the piezoelectric element 2 outputted from the temperature detector 22 and the temperature detector 23.
After inputting the electric signal corresponding to the temperature of the temperature compensation member 5 outputted from the temperature detector 24 and the electric signal corresponding to the temperature of the frame 4 outputted from the temperature detector 24 and recognizing the temperature of the piezoelectric cable 2, the above recognition is performed. Calculate the amount of negative linear expansion IM corresponding to the temperature. Historically, the temperature control circuit 25 uses a temperature compensating member 5 to compensate for the difference in expansion caused by the negative linear expansion of the piezoelectric element 2 and the positive linear expansion of the frame 4 due to the temperature rise of the frame 4.
After calculating the required temperature of the temperature compensating member 5 to cause positive linear expansion of the temperature compensating member 5 and calculating the electric power required to heat the temperature compensating member 5 to the above required temperature, By supplying the heating power to the resistance heating element 21, the heating element 21 generates heat, and the temperature of the temperature compensation member 5 is raised to the temperature g: above, thereby converging the expansion difference to zero. It is something that makes you

As shown in the cross-sectional view of FIG. 5, the resistance heating element 21 is
A film-like resistance heating material 31 made of, for example, nickel-chromium (Ni-Cr) is used for the core, and a film made of, for example, tantanium oxide (Ti) is used to protect and insulate this resistance heating material 31.
The insulating coating 32 formed in Q2) is formed. This insulating coating 32 includes a first layer insulating coating 32Δ adhered to the surface of the temperature compensating member 5, and a second layer insulating coating 32 on the outside.
It consists of B. Incidentally, FIG. 6 is a developed view of the resistance heating element 21.

In the temperature compensator for a minute displacement magnifying mechanism configured as described above, the resistance heating material 31 of the flush resistance heating element 21 has a thickness of 2 micrometers, a width of 2 mm, and a length of 12 mm.
．． 2 mm, and when this is heated with a DC power supply of 3 pols 1 to 1, the temperature rise of the temperature compensating member 5 can be calculated as Sl as follows, assuming that the heat loss due to thermal conduction is zero.

First, the resistance value 1 or [Ω1 of the resistance heating material 31 is determined from the following equation.

R=ρ, L/S where ρ is the volume resistivity of the resistance heating material 31 [μΩ-cm]
L is the length of the resistance heating material 31 [ml] S is the cross-sectional area of the resistance heating material 31 [ml].

- In the above equation, ρ-112x 10"" l = 12.
2x 10-”, S-2x 2 x 10 = 4
Substituting each of x 10-3 and calculating J1, R=
3.42 [Ω].

Next, when a DC voltage of 3 volts is applied to the resistance heating material 31 to generate heat, the light heat ΦH [cal
Calculate F using the following formula.

H = 0.24X E2/R where E is the voltage applied to the resistance heating material 31, in this case E = 3 volts, R is the resistance value of the resistance heating material 31,
In this case R=3.42 ohms.

When calculating by substituting each value into the above formula, H = 0
．． 632 [cal roar.

Next, based on the amount of heat generated by the resistance heating material 31 (1), the temperature of the temperature compensating member 5 per second is increased by 4. t [℃] is 9
Calculate using the following formula.

t-to(/CQV where C is the specific heat of the temperature compensation member 5 [cat/sF/''
C]q is the density [g/cm3] of the temperature compensation member 5.

V l; is the volume [cIR3] of the temperature compensating member 5.

In the above formula, c=0.215. q=2.71, V=
When calculated by substituting each of 73.3 x 10-3, t becomes 14.8 ['CI, and the temperature compensation member 5 has an upper temperature limit of 15°C per second.

(Effects of the Invention) As described above, according to the present invention, the piezoelectric element of the minute displacement magnification mechanism repeats expansion and contraction operations, and the negative linear expansion of the piezoelectric element that occurs in the process of rising temperature is suppressed by the heating action of the heating element. Since compensation can be performed by controlling the positive linear expansion of the temperature compensating member, the thermal expansion on the frame side and the piezoelectric element side are equal, and the displacement of the minute displacement magnification mechanism is always stabilized regardless of the temperature rise of the piezoelectric element. It has the effect of being able to.

[Brief explanation of the drawing]

Fig. 1 is a perspective external view of a minute displacement magnifying mechanism according to an embodiment of the present invention, Fig. 2 is a perspective external view of a resistance heating element stretched to a temperature compensating member, and Fig. 3 is a temperature detector and a resistance heating element. The installation of the body is shown in the figure, Figure 4 is a block diagram of the upper air control circuit, Figure 5 is a sectional view of the resistance heating element, Figure 6 is an exploded view of the resistance heating element, and Figure 7 is a diagram of the conventional minute displacement magnification mechanism. A front view, FIG. 8 is a four-dimensional diagram of a temperature detector for measuring the temperature of each part of the minute displacement magnification mechanism, and FIG. 9 is a diagram of temperature measurement data by the temperature detector. 1... Minute displacement magnifying mechanism 2... Piezoelectric element 4... Frame 5... Temperature compensation member... Resistance heating element 24... Temperature detector 25... Temperature control circuit

Claims (1)

[Scope of Claims] A piezoelectric element that expands and contracts when a voltage is applied, a frame that fixes the piezoelectric element at one end in the expansion and contraction direction, a movable member connected to the other end of the piezoelectric element in the expansion and contraction direction, and the piezoelectric element Provided between one end and the frame, or between the other end of the piezoelectric element and the movable member, to compensate for linear expansion of the piezoelectric element due to changes in temperature of the piezoelectric element itself and changes in ambient temperature. a temperature detector that detects the respective temperatures of the piezoelectric element and the temperature compensation member and outputs an electric signal corresponding to each detected temperature; a heating element that is attached to the temperature compensating member in a heat-transferable manner and generates heat when the required electric power is supplied to cause the temperature compensating member to undergo positive linear expansion; Electric signals corresponding to each detected temperature are input, and the amount of negative linear expansion of the piezoelectric element is calculated, and the amount of positive linear expansion of the compensation member is calculated to compensate for this amount of negative linear expansion. , a temperature control means for supplying the heating element with the necessary power to bring the temperature of the temperature compensating member to a temperature corresponding to the amount of positive linear expansion. Compensation device.