JPH01304641A - Ultrasonic image visualizer - Google Patents

Abstract

PURPOSE:To perform an image display of incident ultrasonic image by making electrons emitted from a electron emitting means reach an anode while it is controlled by the electric potential fluctuation of the electron emitting means with respect to an electron control means caused by the incidence of the ultrasonic image. CONSTITUTION:An ultrasonic wave reached an earth layer 6 excites an piezoelectric substance 2 to generate a high frequency electric signal of ultrasonic frequency. A photocathode 4 emits photoelectrons being stimulated by a light source 15, and a control grid 8 is given with a negative cutoff voltage. When the high frequency electric signal generated by the excitation of the substance 2 is at a negative half-cycle, the potential of the grid 8 is displaced to a normal direction relatively to the potential of a piezocathode 5, and the photoelectrons which was cut off are sucked by a metal bag 10 with anode potential and they reach a fluorescent screen 11 while passing through the bag 10. The electrons are converged during this time so that an incident ultrasonic image can be image displayed on the screen 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ultrasonic image visualization device that visualizes the in-plane distribution of incident ultrasonic energy.

(Prior art) In an ultrasonic device, thin pulsed ultrasonic beams are sequentially projected into the medium to be measured from a transducer array one by one, and the reflected waves are received by the same transducer array. There is a method that observes the intensity of light as changes in the brightness of a cathode ray tube. This device is designed to obtain a single cross-sectional image using at least several dozen ultrasonic beams. In such a conventional apparatus, the time required to obtain two cross-sectional images is controlled by the total number of ultrasound beams and the sound velocity of the ultrasound signal in the medium to be measured. The total number of ultrasound beams is closely related to the resolution of the obtained cross-sectional image, and cannot be reduced too much. Therefore, the time it takes to obtain one cross-sectional image is controlled by the speed of sound, and there is a drawback that it cannot be obtained in a short time. The following methods have been considered as means for eliminating such drawbacks in imaging the ultrasound reflected signals from the subject. In other words, a lens imaging system combined with water surface ripple type holography, a method using optical interferometry to observe the displacement caused by the ultrasonic wavefront passing through a thin film reflecting mirror suspended freely in water, or a method using an optical plane. There are optical methods such as viewing ultrasonic waves in trapped water using the Schlieren method. In addition, a completely computerized system uses a two-dimensional array transducer, placing the necessary electronic circuits for each transducer element that makes up the array, and finally converting the delivery data of each element into a computer. There is a method of obtaining an image of the distribution of a wave front, a wave source, or a reflection source.

(Problem to be solved by the invention) However, the disadvantage of the former group of physical methods is that although the devices are practical and exaggerated, there is no way to obtain power gain for the signal. Therefore, it is safe to say that the sensitivity is poor and it is impossible to directly see reflected waves from within the body.
The only useful image is when a metal test piece is irradiated with high-power ultrasonic waves. Although the latter electronic means can provide an appropriate power gain and II product index for the signal, it results in a bulky and bulky electronic device, and it is difficult to use as a two-dimensional array transducer. If you try to obtain a video signal directly at the coupling surface of the lens, it will take 256 pixels in view of the spatial resolution of human vision.
This requires a huge number of transducer elements such as X256=65536, which is difficult to implement. Of course, in this case, a computer for image reconstruction is not required, but C0DTV
Defects in elements, such as those that occur in cameras, immediately appear as blemishes on the image. Furthermore, even if computational holography is to be performed, 64x64=4096 transducer elements are required. It is almost impossible to carry out the procedure of amplifying and digitally converting signals with frequencies on the order of MHz through several thousand channels, and storing the signals in a storage device.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to realize an ultrasonic image visualization device that allows an ultrasonic image on an imaging plane to be directly viewed in a simple manner.

(Means for Solving the Problems) The present invention solves the above problems, in an ultrasound image visualization device that visualizes the in-plane distribution of incident ultrasound energy,
Electron emitting means in which a photoelectron radioactive material that emits electrons when stimulated by light is combined with a piezoelectric material that generates a variable potential upon incidence of an ultrasonic signal; and a resistor for lowering the electron emitting means to a ground potential in a direct current manner. an anode to which a positive voltage is applied for accelerating the electrons released from the electron emitting means to achieve a power gain of 17; and a non-signal conductive means disposed between the electron emitting means and the anode. an electronic control means that cuts off the electrons when input and emits the electrons when an ultrasonic signal is input; a fluorescent display means coated with a fluorescent paint that emits light due to the impact of the collision of the electrons; and each of the constituent parts. It is characterized by comprising a vacuum chamber for accommodating the electron emitting means, and a light source that irradiates the electron emitting means with light to cause the electron emitting means to emit electrons.

(Function) Electrons emitted from the electron emitting means by light are controlled by potential fluctuations of the electron emitting means relative to the electronic control means caused by the incidence of the ultrasonic image, and reach the anode, thereby visualizing the ultrasonic image.

The emitted electrons from the electron emitting means that emit thermoelectrons are controlled by the potential fluctuation of the modulation means caused by the electric signal generated in the piezoelectric material by the ultrasonic input, thereby visualizing the ultrasonic image.

A field emission type electron emitting means emits electrons using an electric field generated based on potential fluctuations generated in a piezoelectric material by ultrasonic input, and visualizes an ultrasonic image.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of the present invention.

In the figure, reference numeral 1 denotes an image converter that converts image information generated by incident reflected ultrasonic waves into an electronic image and displays the image on a fluorescent surface. 2 is a piezoelectric material that converts mechanical imaging by an incident ultrasonic signal into an electrical signal, and an electrode 3 is provided on the front surface, and a photocathode 4 is electrically coupled to the electrode 3 to form a piezo cathode 5. There is. And # piezoelectric material 2. The electrode 3 and the cathode 4 are diced into substrate patterns, and each substrate pattern is a pixel constituting a screen. Reference numeral 6 denotes a ground layer made of a sound-transmitting conductor, which serves as an incident surface for ultrasonic signals. Reference numeral 7 denotes a resistor made of nickel chromium or the like and having a resistance value RK, which is attached to the side surface of the piezoelectric material 2 and connects the photocathode 4 and the earth layer 6 in order to return the photocathode 4 to earth. It is. Assuming that the capacitance of the piezoelectric material 2 is OK, the time constant CKR of this resistor must be sufficiently slower than one cycle of the ultrasonic frequency. For example, if CK=several tens of 1)F, RK will be several tens of Ω for fo=2~3MH2.
The above is sufficient. Reference numeral 8 denotes a control grid to which, in order to control photoelectrons emitted from the piezo cathode 5, a negative potential is applied to an extent that cuts off the electron flow when there is no input ultrasonic signal. Reference numeral 9 denotes an electron lens that focuses electrons emitted based on the ultrasonic image from the piezo cathode, and the focused electron beam passes through a metal back 10 to which an anode voltage is applied and hits the fluorescent surface 11. An image is displayed by applying an electron bombardment. Reference numeral 12 denotes a vacuum chamber that houses each of the above-mentioned parts, and 13 denotes an outer casing that houses the entire body, which is made of a material such as metal, ceramic, or glass, and the front part of the fluorescent surface 11 is transparent. It has a transparent surface 14 made of material. Reference numeral 15 denotes a light source for stimulating the photocathode 4 to emit photoelectrons. This equivalent circuit is shown in FIG.

Next, the operation of the above embodiment will be explained. The reflected ultrasound that has reached the ground layer 6 excites the piezoelectric material 2 to generate a high-frequency electrical signal at the frequency of the ultrasound. The photocathode 4 emits photoelectrons when stimulated by the light source 15, but since a negative cutoff voltage is applied to the potential of the control grid 8, the electrons pass through the control grid 8 and reach the fluorescent surface 11. I can't. Said piezoelectric material 2
During the negative half cycle of the high-frequency electric signal generated by the excitation of metal back 10
is attracted to the metal back 10 and passes through the fluorescent surface 11.
reach.

During this time, the electrons are focused by the electron lens 9 and the fluorescent surface 1
1, the incident ultrasound image is displayed faithfully.

The control grid 8 has a base pattern that matches the notches of the diced M-cut piezo cathode 5, and is arranged so that the wire of the control grid 8 is placed on top of the base score, and the pitch is approximately equal to the pitch of the first cut. If they are separated from the piezo cathode 5 by an equal distance, electron emission can be suitably controlled without interfering with the movement of electrons. Since this operation is performed using electron radiation to image the ultrasound signal, it is contained in a vacuum chamber 12.

As explained above, according to the present embodiment, an ultrasound image can be displayed as an image using a function similar to Tact Vision.

Various ways of using the apparatus of the above embodiments are possible.

Control) ~ When a signal with the same frequency as the ultrasonic signal is applied to the roll grid 8 along with a DC bias, the amplitude of the signal determines when photoelectrons pass through the control grid 8, not only the amplitude of the incident ultrasonic wave but also the phase distribution. They also become sensitive to things.

Imaging that does not require the electron lens 9 can be performed by separately performing calculation processing or image reconstruction processing using the image including the amplitude information and phase information obtained above as a hologram.

Further, images can be quickly acquired from the amplitude nine-phase images obtained above, and only the Doppler shift can be selectively imaged by performing a difference between images or a higher-order time change extraction process.

If a positive strobe pulse is applied to the control grid 8 together with a DC bias, an image of the incident ultrasonic wave is visualized in a time-selective manner only when the strobe pulse is applied. In addition, this strobe pulse is related to the timing of irradiation of the ultrasonic pulse (or burst), that is, after the ultrasonic pulse is irradiated to the target space to be examined, the strobe pulse is applied at the timing when the reflected wave at the depth of the region of interest returns. If a pulse is applied to the control grid 8, it can be used as a range gate. Fluorescent surface 1
1 with an afterglow property longer than the strobe pulse interval is effective for continuous image display.

In this device, the energy density ratio of the output optical image to the incident ultrasonic energy density, that is, the power gain, depends on the accelerating electric field between the anode potential (for example, about 1 to 5 kV) applied to the control grid 8 and the metal back 10. However, a mesh electrode may be provided immediately in front of the metal bag 10, and the acceleration may be caused by a voltage applied between the mesh electrode and the anode (metal bag 10). When the mesh electrode is used to accelerate electrons, if the phosphor surface 11 is a penetration type phosphor surface that allows selection of the emission color, the color can be selected by the voltage between the mesh electrode and the anode. In this case, it is possible to apply a high pressure of ultrasonic frequency to the control grid 8 and select the phase of the visible component of the incident ultrasonic wave, thereby displaying images of different phases in different colors. can.

With the configuration shown in FIG. 3, it is possible to obtain an image orthicon ultrasonic plate that converts ultrasonic input into an image and converts it into an electrical signal. In the figure, parts equivalent to those in FIG. 1 are given the same reference numerals. In the figure, 21 is a target mesh to which a 7-node voltage is applied and accelerates and collects electrons, and 22 is a substance such as cesium that accumulates the emitted electrons based on the ultrasonic image and forms a charge image. is the target to be coated. This is an image converter in which the fluorescent surface 11 of the image converter 1 shown in FIG. 1 is replaced with a target 22.

The electrons emitted from the piezo cathode 5 reach the target 22
The target 22 collides with the target 22 to emit secondary electrons.

Therefore, the target 22 is positively charged.

Reference numeral 24 denotes an electron gun that emits thermoelectrons. Since the positively charged part of the target 22 is neutralized by the electrons, the return electron beam is changed depending on the image of the target, and is sent to the electron multiplier 24 as a video signal current. is returned and amplified.

Other field meals 125. Axial magnetic field coil 26
．． It is equipped with a deflection coil 27, etc., and has essentially the same structure as a well-known image orthicon, so a description thereof will be omitted.

Other structures such as image pickup tubes such as Brambicon can also be applied.

If a strong magnetic field is applied to the image converter 1 parallel to the tube axis, the low-speed electrons will move toward the anode while drawing a circular axial path along the lines of magnetic force, making it possible to draw an ultrasonic image as it is, like a close-up image. can.

It is also possible to adopt a storage type fluorescent surface structure by using an insulating mesh for charge storage and a flood gun for illuminating in a negative manner. Further, an electron multiplier using a microchannel plate may be arranged between the control grid 8 and the fluorescent surface 11.

FIG. 4 is a diagram of another embodiment for effectively transmitting ultrasonic waves to the vinyl cathode. In the image converter 1, a window made of a plastic or glass plate that also serves as a wall of the vacuum chamber of the outer casing 1.3, into which ultrasonic waves are incident, is connected to the atmosphere, the outer casing 13, and the vacuum chamber 12 from the viewpoint of broadband operation. It is necessary to match the impedance between them, but in addition to double impedance matching, it is difficult to have the strength to withstand static pressure to maintain a vacuum, so avoid applying static pressure to the window part. It is desirable to do so.

In FIG. 4, 31a and 31b are concave lenses made of plastic, and 31C is a plastic lens 31a,
A liquid chamber lens with silicone oil in the convex lens-shaped space created by 31b, and three types of lenses are combined to form a composite lens 3.
1 is formed.

Reference numeral 32 denotes a container which has the above-mentioned composite lens 31 at its lower part and houses an image converter, and is composed of a silicone oil storage section 33 and an auxiliary vacuum chamber 34. The silicone oil storage section 33 has excellent sound transmission properties (low propagation loss),
It is made of silicon, whose speed of sound and acoustic impedance are approximately equal to that of air. The auxiliary vacuum chamber 34 is provided as a relay vacuum chamber in order to reduce the static pressure applied to the image converter 1. Since the liquid placed in the silicone oil storage section 33 is exposed to the auxiliary vacuum chamber, it is not preferable that the liquid has a high vapor pressure at room temperature. Silicone oils of low or medium molecular weight are advantageous. In this way,
The vacuum chamber of the image converter 1 is not directly exposed to atmospheric pressure, and in particular, no large static pressure is applied to the ultrasound entrance window.

The composite lens 31 may be a zone plate type lens, or may simply be a thick plastic concave lens. Furthermore, when performing holography without using a lens, or when it is desired to completely separate the lens from the container 32 and attach it externally, or to make it replaceable, the synthetic lens 31 shown in FIG. 4 can be replaced with a planar thick plate. When used, the ultrasonic waves are essentially coupled to the incident surface of the piezo cathode without causing image distortion.The plate material should be of sufficient strength and have acoustic properties similar to those of water or oil, such as Polymethylpentene and the like are preferred.

In the case of FIG. 4, the surface of the silicone oil is directly exposed to the auxiliary vacuum chamber, but a structure in which the silicone oil is sealed in a chamber partitioned by a thin film may also be used. This example is the fifth example.
As shown in the figure. In the figure, parts equivalent to those in FIG. 4 are given the same reference numerals.

In the figure, reference numeral 35 denotes a bellows made of a flexible thin film, and by moving the bellows 35 back and forth, the piezo cathode 5 is moved up and down, thereby changing the distance on the optical axis and adjusting the focus.

Since the image converter 1 according to the present invention irradiates light with a light source 15 to activate the photocathode 4, it is housed in a shield case except for the fluorescent surface 11 to avoid interference with light or electromagnetic waves. is preferred. Furthermore, since the piezo cathode 5 also senses sounds and vibrations at frequencies lower than ultrasonic waves, it is desirable to provide a shield against sounds and vibrations. Shielding against light and electromagnetic waves is the first priority.
A conductive thin film is deposited on the entire outside of the outer casing 13 of the image converter 1 shown in the figure and the container 32 shown in FIG. 4 by a method such as plating or vacuum deposition. The acoustic shield can be installed by adding a cushion to the mechanism to absorb vibrations.

Figure 6 is a structural diagram showing an example of coupling with an acoustic surface wave instead of the image converter for bulk waves or longitudinal waves in liquid as described above, (a) is a structural diagram of an image converter, and (b) is a piezoelectric 5 is an enlarged view of the cathode 5. FIG. In the figure, the first
Parts equivalent to those in the figure are given the same reference numerals. In the diagram, 4
0 is an acoustic surface wave (hereinafter referred to as SΔW) transducer disposed on the circumference of the piezoelectric material 2 to generate a surface wave running from left to right in the figure by ultrasonic input, and 41 is a SAW transducer 40. It is also a sound absorbing material placed on the circumference that absorbs the surface waves arriving from the surface. 42 is piezoelectric material 2 and antimony cesium l1l (about 1000 people)
III! of carbon or nichrome provided between the photocathode 45 of II (about 50 to 100 people) Earthlitan layer.

The photocathode 4 emits photoelectrons due to the light from the LED light source 15, and is cut off by the control grid 8. When a signal is input to the SAW transducer 40 arranged on the circumference, an acoustic surface wave is generated, and the acoustic wave runs from left to right in the figure. Since the piezoelectric material 2 is not diced, it generates an electrical signal based on the acoustic wave as the acoustic wave passes through it, and photoelectrons are generated when the control grid 8 becomes positive relative to the potential of the otocathode 7 in the negative half cycle. passes through the control grid 8 and reaches the anode, making the fluorescent surface glow, and the electrical signal input to the SAW transducer 40 is visualized through the ultrasonic surface wave.

In the above embodiment, the cathode for emitting electrons uses photoemission by a photocathode, and is of a cathode drive type as is clear from the equivalent circuit of FIG. The embodiment shown in FIG. 7 is of a control grid drive type using a thermionic emission type cathode. In the figure, parts equivalent to those in FIG. 1 are given the same reference numerals. In the figure, 101 is a filament that emits thermoelectrons when heated, and 102 is an electrode that receives an electric signal generated based on an ultrasonic signal input to the piezoelectric material 2 with the piezoelectric material 2 in between. Reference numeral 103 denotes a focusing electrode for focusing the electron beam emitted from the filament 101 according to a principle to be explained later, and is supplied with a voltage of -8V.The focusing electrodes 102 are arranged in parallel as shown in (b). 104 is an anode to which +1.2 kV" is applied to attract the electron beam, and a fluorescent material 105 is coated on the electron beam collision surface.

Before explaining the operation of the above embodiment, the principle of operation of the above apparatus will be explained with reference to FIG. In the figure, parts that operate in the same way as the parts in FIG. 7 are given the same reference numerals.

(A) The figure shows the principle of modulation.
1.2kV”, filament 101 “’o v”
"'-8V" is applied to the focusing electrode 103, and the modulation electrode 1
02 represents the equipotential line when "'-5V" is applied. When the voltage of the modulation electrode 102 is 15cm, the equipotential line of OV passes through the front of the filament 101 (OV),
The cathode is surrounded by a negative potential and is in a cut-off state, with no electrons being emitted. (B) Figure shows the state of focusing. As shown in (B), when the voltage of the modulation electrode 102 is changed from '-5V' to 'ov', 0■
The equipotential line passes through the back side of the filament 101 as shown in the figure (B), and the area around the filament 101 becomes a positive potential, electrons are emitted, and an electron beam flows toward the anode 104. time, upper and lower focusing electrodes 10
When a suitable negative voltage 9, for example "-8", is applied to 3, the electron beam reaches the surface of the anode 104 in a focused state perpendicular to the equipotential lines. Figure (c) is an easy-to-understand diagram that summarizes the states of figure (a) and figure (mouth) in three dimensions. The modulation electrode 102 is thus divided, and an electron beam reaches the anode 104 from the Ov portion, and no electron beam is generated from the II 5 V II portion.

In FIG. 7, -8 is applied to the focusing electrode 103 similarly to FIG.
V", filament 101 has "o v", 7/-t
'1olcG and t'1.2kV' are applied. The electrode 102 is similar to the focusing electrode shown in FIG.
An appropriate negative voltage is applied to , and when no ultrasonic signal is input, it is cut off. When the ultrasonic signal is input, an electric signal is generated in the piezoelectric material 2, and during the period of the positive potential, the voltage shown in Fig. 8 is The electron beam reaches anode 104 as shown. Each of the electron beams illuminates the fluorescent material 105 of the anode 104 at a position corresponding to the cell that generated the electron beam. Therefore, the image formed by the ultrasonic waves incident on the array transducer formed by the elements as a whole appears as a visible WI image on the anode side. An equivalent circuit of this device is shown in FIG. 7/-Fl 04-"+1.2k as shown
V' is fiflat 101, and O■'' is added.

When the element (piezoelectric material 2) vibrates due to the incidence of the ultrasonic signal, the potential of the modulation electrode 102 changes.

This is equivalent to inputting the high frequency signal generated by the element to the control grid in the vacuum tube of the equivalent circuit shown in FIG. A negative bias "'-vq" is added to the control grid in advance so that it is cut off at the time of input.

Therefore, current flows during the positive period of the input signal, and the ultrasonic signal is visualized at the anode 104 by the fluorescent substance 105.

In this type of device, the following modifications can be considered.

(i) Although the focusing electrode 103 is made of a thin metal plate as shown in FIG. 7(b), it may be a mesh electrode made of wire.
1 and the piezoelectric material 2 can be optimized by setting the relative position H relationship of the three components to a node.

(ii) By applying a DC magnetic field in the vertical direction in FIG. 7, the spot of the electron beam of each cell displayed by the fluorescent material 105 of the anode 104 can be narrowed down.

(iii) Vacuum container or outer casing of the device, method of introducing ultrasonic waves, installation of a preliminary vacuum chamber, use of lenses, acousto-optical structure, electro-optical structure of the array itself, etc. as shown in Figures 2 to 6. All of the structural devices etc. described above can also be used in the embodiments described above.

(iv) Regarding pulse operation, RF burst operation, or CW decoding operation, in this case, a strobe pulse or RF burst may be superimposed on the angular bias of the focusing electrode 103 (corresponding to the control grid).

Next, FIGS. 10 to 13 show an embodiment in which a flat type image tube in the form of a two-dimensional cold cathode triode array using a field emission type cold cathode is applied. In each figure, parts equivalent to those in FIG. 1 are given the same reference numerals. In the figure, 201 is a cathode gate layer including a gate metal that operates as a cathode and a control grid; 202 is an acoustic matching layer that matches the acoustic impedance between the incident ultrasonic signal and the piezoelectric material 2;
03 is an anode that attracts electrons using high voltage and displays an image. In FIG. 11, which is an enlarged view of the cathode gate layer 201, 204 is an insulator separating each element of the array transducer, 205 is an electrode of the piezoelectric material 2, and the lower part of the piezoelectric material 2 is connected by a conductor Wr1206. Ru.

FIG. 12 is an enlarged view of the X section of the cathode gate layer 201 surrounded by a dashed line. In the figure, 207 is a conical microchip that operates as a power grid that causes electrons to be emitted by electric discharge, and 208 is a gate that operates as a control grid that applies a positive voltage to cause microchip 207 to emit electrons by field emission. It's metal.

Reference numeral 209 denotes an insulating layer that insulates between the electrode 205 and the gate metal 208. A hole is made in the insulating layer 209 and the microchip 207 attached to the electrode 205 is passed through it.

The operation of the embodiment configured as described above will be explained. The overall structure is as shown in FIG. 10, and is roughly divided into a lower ultrasonic incidence section and an upper display section, with the space between them located in a vacuum chamber. The structure of the vacuum chamber is similar to that shown in FIG. In the ultrasonic incidence section, the incident ultrasonic signal passes through the acoustic matching layer 20
2 to excite the piezoelectric material 2. Acoustic matching layer 202
It has two layers, with a glass plate placed on top of a polystyrene plate. In FIG. 11, which is an enlarged view of the ultrasound incidence part,
The piezoelectric material 2 is placed between the electrodes 205 1. : Generates an electrical signal, and the upper electrode is given a positive and negative varying potential with respect to the lower electrode.

Each element is separated by an insulator 204, and the upper electrode is grounded to the lower electrode by a resistor made laterally of the piezoelectric material 2 by a method such as plating, vapor deposition, or sputtering. In FIG. 12, which is an enlarged view of the cathode gate layer 201, the microchip 207 is attached to the electrode 205, and the gate metal 208 and the electrode 205 are connected to each other.
The voltage applied between them causes a discharge due to the conical tip effect of the microchip 207.

The tip of the conical shape is sharp, and since the gate metal 208 is close, electron emission occurs at a relatively low voltage (approximately 40 V). The piezoelectric substance 2 is excited by the incidence of the ultrasonic signal, and in the negative half cycle of the voltage applied to the electrode 205, ie, the microchip 207, the potential of the microchip 207 becomes more negative than that of the gate metal 208. relatively gate metal 2
08 is more positive than the microchip 207, electron emission occurs. These electrons reach the anode 203 through the hole in the gate metal 208. The anode 203 is very close to the cathode gate layer 201 and the image on the gate metal 208 reaches the 7 node 203 as it is. FIG. 13 is an enlarged view of the anode 203. Glass transparent surface 14
A phosphor is coated on the inner surface of the metal back 10 to form the fluorescent surface 11, and a light-shielding black porous aluminum layer 210 is provided further inside the metal back 10 to block light from the inner surface to the fluorescent surface 11. .

The electrons reaching the anode 203 pass through the light-shielding black porous aluminum layer 210 and the metal back 10 to the fluorescent surface 1.
1 and visualize the incident ultrasound image.

An equivalent circuit of the above device is shown in FIG. As is clear from the figure, this device operates as a triode vacuum tube consisting of a microchip 207 as a cathode, a gate metal 208 as a control grid, and an anode 203. The gate metal 208 is grounded or given a DC bias, and operates based on the potential difference between the potential generated by the piezoelectric material 2 and the potential of the gate metal 208.

A resistance value R8 of the resistor 7 is a resistance necessary to form a ground return for the microchip 207.

The time constant RsC between this resistance Rs and the capacitance C of the upper and lower electrodes 205@ of the piezoelectric material 2 is made to be sufficiently slow from the ultrasonic frequency and appear sufficiently short for mechanical vibrations and artifacts. For example, if the time constant is several μs to several tens of μs, R3 is almost nonexistent for MHz band ultrasound.
It exhibits a sufficient shunt effect for a microphone-like region (several kHz or less).

A method for manufacturing the ultrasonic wave incidence section shown in FIG. 11 will be described. Acoustic matching layer 2
A conductor is uniformly applied to the glass plate 02 to serve as a ground-side electrode, and a polarized piezoelectric material 2 (piezoelectric ceramic plate) with an electrode, which has been pre-drilled or grooved in countless numbers, is placed on top of the conductor in a cold manner. Adhere by pressure welding method etc. Thereafter, 5 iOz is applied to the top plane part of the element by CVD method or the like, excluding the hole or groove part, and a metal layer such as Nb (niobium) is also applied by the same method. Next, a hole in the gate metal 208 is made by photo-etching, and the Si plate is placed in the hole using the hole to receive the hole.
Etch the O2 layer until it touches the Ni electrode directly below it. Thereafter, a conical microchip 207 is formed by vacuum evaporation. At this time, the hole in the gate metal 208 just acts as a mask, but if you do not want the gate metal 208 to thicken, use a vapor deposition mask using the same mask button used to make the hole in the gate metal 208 by photo-etching. Just create and use it.

Thereafter, it is assembled so as to face the anode 203 to form a "vacuum tube", and finally a polyretin plate of the acoustic matching layer 202 is applied.

In the above-mentioned field emission type device, an image tube structure of an electric field focusing type or a magnetic field focusing type may be used instead of the proximity type. Alternatively, another mesh electrode may be inserted between the anode 203 and the cathode gate layer 201 to form a tetrode structure, and the imaging function may be turned on/off by this second gate. This can be used as a range gate when imaging echoes caused by pulsed ultrasonic irradiation, and allows selective imaging in the depth direction. Furthermore, in the example, in order to avoid lateral coupling of the piezoelectric material, an example was described in which the piezoelectric material was cut into elements to create a two-dimensional array. It can be used in combination with a triode having a chip type field emission cathode or an array of tetrodes with an additional mesh electrode inserted.

In order to increase the sensitivity, it is better that the gap between the hole diameter of the gate metal 208 and the size of the microchip 207 is small. In addition, it is important to use a piezoelectric material with a large glue constant and to sufficiently match the acoustic impedance.For this purpose, the piezoelectric material should be crystal, LiNbO3, LiNbO3, etc. rather than PZT.
Lf TaO3゜ZnO, PVDF, P (VD
F-TrFE).

P (VDCN) or the like is preferable, and if a narrower band is acceptable, the voltage obtained can be increased by making it resonate sharply. On the other hand, single crystal is considered to be more advantageous than ceramic in terms of the material's vacuum resistance, residual gas release properties, etc.

(Effects of the Invention) As explained in detail above, the present invention has different electron emission methods, such as those that use photoelectrons, those that use thermoelectrons, and those that use electrons by field emission. Electron emission is controlled and displayed using ultrasonic signals, and ultrasonic images can be visualized easily and in a relatively simple manner, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIG.
The equivalent circuit of the device shown in the figure, FIG. 3 is a diagram of an application example of an image orthicon type ultrasound imaging tube using the device of FIG. 1, and FIG. 5 is a diagram of another embodiment of the device shown in FIG. 4, FIG. 6 is a diagram of an embodiment using ultrasonic surface waves, and FIG. 7 is a diagram of a second embodiment of the present invention.
8 is an explanatory diagram of the principle of the device shown in FIG. 7, FIG. 9 is an equivalent circuit diagram of the device shown in FIG. 7, FIG. 10 is a diagram of the third embodiment of the present invention, and FIG. FIG. 12 is an enlarged view of the cathode gate layer, FIG. 13 is an enlarged view of the anode, and FIG. 14 is an equivalent circuit diagram of the device shown in FIG. 1... Image converter 2... Piezoelectric material 3.
...Electrode 4...Photocathode 5
... Piezo cathode 6... Earth layer 7...
・Resistance element 8...Control grid 9...
・Electronic lens 10... Metal back 11... Fluorescent surface 12... Vacuum chamber 15... Light source 2
2...Target 23...Electron gun 31...
Synthetic lens 32... Container 33... Silicone oil storage section 34... Auxiliary vacuum chamber 35... Bellows 4
0...SAW transducer 41...Earth litane layer 101...Filament 102...Modulation electrode 103...Focusing electrode 104
... Anode 201 ... Cathode gate layer 202 ... Acoustic matching layer 203 ... Anode 20
4... Insulator 205... Electrode 206...
Conductor layer 207...Microchip 208...
・Gate metal 209... Insulating layer 210... Black porous aluminum layer for light shielding Patent applicant Yokogawa Medical Systems Co., Ltd. Figure 3 B4i Wat pipe Figure 8 (A) Ov equipotential line conflict) Figure 9 Figure 11 Figure 12 Figure 13 Figure 14

Claims (40)

[Claims] (1) In an ultrasonic image visualization device that visualizes the in-plane distribution of incident ultrasonic energy, a photoelectron radioactive material that emits electrons when stimulated by light is combined with a piezoelectric material that generates a fluctuating potential when an ultrasonic signal is incident. An electron emitting means, a conductive means using a resistor for lowering the electron emitting means to a ground potential in a direct current manner, and applying a positive voltage for accelerating the electrons emitted from the electron emitting means to obtain a power gain. an electronic control means disposed between the electron emitting means and the anode to cut off the electrons when no signal is input and to emit the electrons when an ultrasonic signal is input; and an impact of the collision of the electrons. The present invention is characterized by comprising: a fluorescent display means coated with a fluorescent paint that emits light by a fluorescent paint, a vacuum chamber that houses each of the constituent parts, and a light source that irradiates the electron emitting means with light to emit electrons. Ultrasonic image visualization device. (2) An ultrasonic image visualization device that visualizes the in-plane distribution of incident ultrasonic energy includes an electron emission means that is heated and emits thermoelectrons, and a power gain that is achieved by accelerating the electrons emitted from the electron emission means. an anode to which a positive voltage is applied to obtain a positive voltage, a focusing means for deforming an equipotential surface generated between the electron emitting means and the anode so as to focus the electron beam on the anode surface, and the electron emitting means. a piezoelectric material that is excited by an incident ultrasonic signal to generate an electric signal and provides a fluctuating potential to the modulation means; and a fluorescent paint that emits light due to the impact of the collision of the electrons. An ultrasonic image visualization device comprising a coated fluorescent display means and a vacuum chamber that accommodates each of the components. (3) The ultrasonic image visualization apparatus according to claim 1, wherein the electron emitting means are arranged two-dimensionally in a grid pattern. (4) The ultrasonic image visualization apparatus according to claim 3, further comprising electromagnetic or electrostatic electron focusing means between the electronic control means and the anode. (5) The ultrasonic image visualization apparatus according to claim 4, wherein a direct current bias that cuts off electrons is supplied to the electronic control means when no ultrasonic signal is input. (6) Visualize the amplitude-phase image by applying a DC bias and a high-frequency signal with the same frequency as the frequency of the incident ultrasound to the electronic control means to make it sensitive to the phase distribution in addition to the amplitude distribution of the incident ultrasound. The ultrasonic image visualization device according to claim 1, characterized in that: (7) The ultrasound image visualization apparatus according to claim 2 or 6, wherein the amplitude-phase image is visualized as a hologram by performing separate calculation processing or image reconstruction calculation processing. (8) The ultrasound image visualization apparatus according to claim 7, wherein the amplitude-phase image is subjected to time change extraction processing to visualize Doppler shifts of image components. (9) The ultrasonic image according to claim 2 or 3, wherein a direct current bias and a strobe positive pulse are applied to the electronic control means, and the incident ultrasonic image is visualized in a time-selective manner only at the time of application of the positive pulse. Visualization device. (10) A strobe positive pulse is applied to the electronic control means in relation to the timing of irradiation of the ultrasonic pulse wave or burst wave to be irradiated to the target space to be examined so as to serve as a range gate for defining the depth of the region of interest. 4. The ultrasonic image visualization apparatus according to claim 2, wherein a range gate is used to visualize a region of interest having a depth determined by the range gate. (11) The electronic control means is a mesh having an electron passing portion that coincides with the mesh of the base of the electron emission means, and the distance from the electron emission means is approximately equal to the size of the mesh of the mesh. The ultrasonic image visualization device according to claim 2 or 3, characterized in that: (12) The ultrasonic image visualization device according to claim 3, further comprising a mesh disposed in front of the fluorescent surface for accelerating electrons by applying a positive voltage. (13) According to claim 2 or 12, the fluorescent surface has a multilayered structure in which the fluorescent agents each have a different color, and the fluorescent surface develops multiple colors as the accelerating voltage changes. Ultrasonic image visualization device. (14) The ultrasonic device according to claim 13, characterized in that images of different phases are displayed in different colors by applying a DC bias and a high frequency signal of the frequency of the incident ultrasonic wave to the electronic control means to select the phase. Sound wave image visualization device. (15) The ultrasonic wave according to claim 2, 9 or 10, comprising a fluorescent surface using a fluorescent agent having an afterglow property longer than the time interval between strobe pulses applied to the electronic control means. Image visualization device. (16) The ultrasonic imaging visualization device according to claim 2 or 3, characterized in that it has a fluorescent surface and a nearby structure that accumulates a pattern of electron distribution. (17) The ultrasonic image visualization apparatus according to claim 3, further comprising a microchannel type electron multiplier at an intermediate portion between the electron emitting means and the fluorescent surface. (18) A target that accumulates charges at the position of a fluorescent surface, an electron gun that scans the target with an electron beam, and means for focusing and deflecting the electron beam, and changes in the amount of electrons returning from the target. The ultrasound image visualization device according to claim 1, wherein the ultrasound image visualization device outputs the ultrasound image as an electric signal. (19) The ultrasonic image visualization device according to claim 3, wherein the ultrasonic image visualization device is placed in a strong magnetic field and causes the emitted electron beam from the electron emitting means to travel straight. (20) Ultrasonic image visualization according to claim 2 or 3, further comprising a lens imaging type or zone plate imaging type acousto-optic system for imaging the incident ultrasound signal on the electron emitting means. Device. (21) An ultrasonic image visualization device characterized in that the device according to claim 1 or 2 is housed in a sealed chamber as a means for eliminating a pressure difference between atmospheric pressure and a vacuum chamber in the electron emitting means. (22) A sound-transmitting thick plate is used in the ultrasonic entrance window of the sealed chamber as a means of eliminating the differential pressure between atmospheric pressure and vacuum applied to the electron emission means, and an image is formed at the position of the electron emission means outside. Claim 21 further comprising an acousto-optic means for
The ultrasonic image visualization device described. (23) Claim 21, characterized in that the sealed chamber serving as a means for eliminating the differential pressure between atmospheric pressure and vacuum applied to the electron emitting means is filled with a liquid that is excellent in sound transmission and has a small vapor pressure even at room temperature. Or the ultrasound image visualization device according to 22. (24) Ultrasonic image visualization according to claim 21, 22 or 23, characterized in that a sealed chamber made of a flexible membrane is provided as means for eliminating the differential pressure between atmospheric pressure and vacuum applied to the electron emitting means. Device. (25) The ultrasonic image visualization apparatus according to claim 24, further comprising an acousto-optical focus adjustment means for changing the length on the optical axis of the sealed chamber made of flexible material. (26) The ultrasonic image visualization device according to claim 2, 3, 18 or 21, characterized in that it is covered with a shielding means against light and electromagnetic waves. (27) The ultrasonic image visualization device according to claim 2, 3, 18 or 21, further comprising means for protecting against sound and vibration. (28) The ultrasonic image visualization device according to claim 2 or 3, comprising an acoustic surface wave transducer provided on the circumference of the electron emitting means and a sound absorbing material also provided on the circumference. (29) Claim 28, characterized in that a resistive earth return layer is provided on one continuous and smooth plate of piezoelectric material, and the electron emitting means is provided with a photoelectron emitting material coated on the resistive earth return layer. The ultrasonic image visualization device described. (30) The ultrasonic image visualization device according to claim 2, further comprising a permanent magnet or an electromagnet for applying a perpendicular magnetic field to the electron beam traveling direction of the device. (31) The ultrasonic image visualization device according to claim 2, wherein a plate grid-like electrode is used as the focusing means. (32) The ultrasonic image visualization device according to claim 2, wherein a spring cam-shaped electrode is used as the focusing means. (33) The ultrasonic image visualization device according to claim 2, wherein a mesh electrode is used as the focusing means. (34) In an ultrasonic image visualization device that visualizes the internal distribution of incident ultrasonic energy, a microchip that functions as a conical cold cathode to emit field electrons and ultrasonic waves generated by the incident ultrasonic image are used. a piezoelectric material that converts the microchip into an electrical signal; an electronic control means that controls the electrons emitted from the microchip based on the electrical signal; 1. An ultrasonic image visualization device comprising: an anode having a fluorescent surface; and a vacuum chamber accommodating each of the constituent parts. (35) The ultrasonic image visualization device according to claim 34, wherein the electrodes of the piezoelectric material are connected by a resistor. (36) The ultrasonic image visualization device according to claim 34, wherein the piezoelectric material is diced for the purpose of avoiding lateral coupling. (37) Lithium niobate with a large g constant (
LiNbO_3), polyvinylidene fluoride (PVDF),
Vinylidene fluoride-trifluoroethylene copolymer (P(VDF)
-TrFE)) or vinylidene cyanide-vinyl acetate copolymer (P(VDCN-VAC)). (38) The ultrasonic image visualization device according to claim 34, characterized in that a light-shielding layer is provided on the fluorescent surface. (39) Claim 34, characterized in that the electron emitting means, the electronic control means, and the anode having a fluorescent surface are provided in close proximity, so that the electrons emitted from the electron emitting means are directly imaged. Ultrasonic image visualization device. (40) The ultrasonic image visualization apparatus according to claim 34, wherein the electrons emitted from the electron emitting means are focused by an electron focusing means and imaged on a fluorescent surface on an anode.