JPS62140854A - Ultrasonic image recording head - Google Patents

Abstract

PURPOSE:To obtain an ultrasonic image recording head of good energy efficiency capable of high-speed printing, by providing an ultrasonic energy generation element of such a construction as that piezoelectric ceramics layers and electrode layers are alternately laminated and a common electrode is connected to the every other electrode layer, a multi-step horn connected to the element, and a wire connected to the tip end of the horn. CONSTITUTION:A laminated body 1 consisting of piezoelectric ceramics layers and electrode layers is actuated by a resonance frequency ranging from 100kHz to approximately 2-3MHz. A two-step horn 2 is varied in cross section, i.e. from 19.6mm<2> to 3.93mm<2> in a first step horn and from 3.14mm<2> to 0.62mm<2> in a second step horn. Each horn is so designed as to have the step positioned at 1/4 a wave length lambda of the ultrasonic generated from the piezoelectric ceramics 1 and have a length of 1/2 lambda. The two-step horn can enlarge 25 times the displacement generated in the piezoelectric ceramics 1. A heat conductive layer 3 in an ink retention body 6 is a good conductive layer of low volume resistivity and in close contact with a pyrogenic insulating ink layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultrasonic image recording head used for printing and image recording.

(Prior art and its problems) The conventional ultrasonic recording method, as described in Japanese Patent Laid-Open No. 48-31944, uses an ultrasonic transducer that is placed at a position where it does not touch the surface of a heat-sensitive material when it is at rest (not in operation). A configuration is disclosed in which the ultrasonic transducers are arranged at minute intervals to reduce contact wear between the ultrasonic transducers and the surface of the heat-sensitive material.

In such a recording method, when the vibrator is selectively operated to cause ultrasonic vibration, the vibrator and the heat-sensitive material are brought into contact only at the peak of the amplitude to transmit ultrasonic energy and print. However, this technique increases the amplitude of the ultrasonic transducer due to the presence of a small gap and records only at the peak of the amplitude, resulting in poor energy efficiency. If the interval is not maintained accurately and constant, the peak of the interpupillary distance of the ultrasonic sensor will not be able to transmit ultrasonic energy to the heat-sensitive material with good reproducibility. Further, in actual printing, high frequencies are used, which consumes a considerable amount of power, and the amount of heat generated by the ultrasonic wave generation source is also large, which is impractical.

Furthermore, in order to use ultrasonic energy efficiently, there is a method of concentrating the energy using a horn, but if this is done with only one horn, the concentration of ultrasonic energy is insufficient, and two Impedance matching with the sickle medium cannot be achieved and clear recording results cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to improve the drawbacks of the conventional ultrasonic technology, efficiently concentrate ultrasonic energy to generate an ink meniscus, and sweep a recording device for printing.

(Means for Solving the Problems) The present invention provides an ultrasonic wave generator characterized in that piezoelectric ceramic layers and electrode layers are alternately laminated, and each electrode layer is provided with a common electrically connected wire at every other layer. This is an image recording head.

(Function) The ultrasonic energy generating element employing a laminated structure has a large amount of displacement and can be driven at low voltage. The generated ultrasonic energy is concentrated by a multi-stage horn. As a result, the displacement generated at the end of the horn due to ultrasonic vibration is further magnified.

Theoretically, the displacement magnification rate of one stage of horn heating is determined by the cross-sectional area ratio between the input end and the terminal end of the horn. In the present invention, since two or more stages of horns are stacked and used, the displacement magnification rate of the entire horn can be expressed as the product of the displacement magnification rates of the horns in each stage. As a result, the ultrasound energy is more efficiently focused.

This ultrasonic energy is transmitted to the ink holder through a wire whose length is designed to resonate at an integral multiple of the 1/2 wavelength, and the ink meniscus generated due to the loss of ultrasonic propagation inside the ink holder is It will increase. That is, the efficiency of image recording throughout the apparatus is significantly improved.

(Example) Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of an ultrasonic recording device according to the present invention. In the figure, numeral 1 is a laminate of, for example, a zircon-lead titanate-based or niobic acid-based piezoelectric ceramic and an electrode layer. This is operated at a resonant frequency of about 100 KHz to several MHz. Dimensions are 5ff x 51fl+ and height 9
It will be around H. However, the thickness of the ceramic layer is preferably about 115 pm, and the number of laminated layers and the height of the laminated body are adjusted according to the desired resonant frequency. Titanium chromium alloy is used, and the cross-sectional area of the first step horn changes from 19.6- to 3,93-, and the second step horn changes from 3.14- to 0,62-. It's a shame.

The position of the step in each horn is located at a length of 2, which is the wavelength λ of the ultrasonic wave generated by the piezoelectric ceramic 1, and each horn is designed to have a length of pseudo λ. The changes occurring in the piezoelectric ceramic 1 due to this two-stage horn are magnified 25 times.

The thermally conductive layer 3 in the ink holder 6 is a highly conductive layer with low volume resistivity υ, and the highly thermally insulating ink Ii! Closely connected to 34. The high heat insulating ink layer 4 has a high volume resistivity, and the ink used for this layer does not reduce the volume resistivity of the high heat insulating ink layer 4 and is viscous enough to be transferred to a recording medium at about several tens of degrees Celsius. There is no particular restriction on the viscosity as long as it is not too low and the viscosity decreases to a level at which transfer is not sufficient at over 100°C. The recording medium is not particularly limited and may be a plain paper OHP sheet.

The recording head according to the present invention basically has the above-mentioned configuration, but the characteristics of the horn will now be further described. Table 1 shows the tip of the piezoelectric element, the tip of the single-stage horn, the tip of the double-stage horn, and
Table 1 shows the equivalent mass tip displacement and kinetic energy of each wire having a length designed to resonate at an integral multiple of the wavelength of the wire.

First, an ink meniscus occurs instead of ghee. When attempting to print while moving the recording head at a rate of about 10 inertia/see, the input signal should have a pulse width of about 10 seconds, the applied voltage should be an impulse signal with a peak value of 7 V, and this should be output at 150 KHz. Gate transmission. During this time, only the heads with two-stage horns have verifiable records.

Further, even if the piezoelectric multilayer element 1 is continuously driven, the temperature of the piezoelectric multilayer element 1 only rises to about 35° C., which is an unprecedentedly low amount of heat generation.

That is, the combination of the piezoelectric laminated element and the two-stage step horn enables efficient thermal transfer recording using ultrasonic waves.

(Effects of the Invention) As described above, the present invention makes it possible to efficiently concentrate ultrasonic energy using a small amount of human power, thereby making it possible to improve the printing device's performance compared to the conventional thermal transfer type printing device that uses ultrasonic waves. Thus, an energy-efficient ultrasonic image recording head capable of high-speed printing can be obtained. Furthermore, since there are fewer component parts, it can also be made smaller.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the head for ultrasound imaging according to the present invention. 1... Piezoelectric multilayer ceramic element, 2-2 step horn, 3... Heat conduction jV&, 4... High heat insulating ink layer, 5... Recording medium, 6... Ink holder. ,′・−゛pa＼

Claims (1)

[Claims] An ultrasonic energy generating element having a structure in which piezoelectric ceramic layers and electrode layers are alternately laminated and each electrode layer is connected to a common electrode at every other layer, a multistage horn connected to the element, and a tip of the horn. An ultrasonic image recording head comprising: a wire connected to the ultrasonic image recording head;