JP5176227B2 - Image acquisition device using acoustic lens - Google Patents

Description

  The present invention relates to an image acquisition device, which transmits ultrasonic waves in water such as the sea, converges reflected waves from the object with an acoustic lens, and performs signal processing to turbidity and illuminance of water. The present invention relates to a video acquisition device that can acquire a video with a wide field of view regardless of the situation.

  Conventionally, various video acquisition apparatuses that acquire an underwater video are known. This type of image acquisition device, for example, by acquiring the reflected wave of the signal transmitted from the transmitter by using the receiver corresponding to the transmitter while changing its position by towing on a ship or the like, There is a video acquisition device that can acquire two-dimensional data of azimuth and depth (depth) and generate a three-dimensional video by processing the two-dimensional data in time series.

  In the video acquisition device as described above, there is a video acquisition device with various devices for the purpose of controlling the transmission direction at high speed without using a delay circuit and having a sharp directivity. doing.

JP 47-26160 A

  An image acquisition device described in Patent Document 1 includes a transmitter capable of transmitting various frequency component outputs, and an array transmitter that is driven by the transmitter and transmits sound waves having the input frequency in directions determined by the input frequency. And an acoustic lens for converging the reflected wave from the target of the sound wave emitted by the array transmitter, and the reflected wave is imaged on the receiving surface by the acoustic lens and the sound wave is transmitted from the array transmitter. A receiver having a plurality of receiving elements arranged linearly at right angles to the direction of the receiving element, and analyzing the frequency of each receiving element output of the receiver and synchronizing the frequency output with the position of the receiving element In addition, two-dimensional information of a target at a specific position is obtained by a frequency component included in the output.

  The video acquisition device described in Patent Document 1 configured as described above enables acquisition of a two-dimensional video by using a frequency sweep method as an ultrasonic transmission / reception wave and signal processing method.

  However, according to the configuration of the above-described conventional video acquisition device, there is a problem that it is impossible to acquire a 3D video in real time. In addition, if it is to be configured as a device capable of acquiring 3D video in real time, a receiver having multiple channels in the horizontal direction and the vertical direction must be prepared, resulting in an increase in cost and a huge amount of equipment. It was not possible to implement because

  Furthermore, image acquisition devices using the frequency sweep method have been put into practical use as devices that can be seen underwater even in muddy water and at night, such as underwater work that is not affected by the turbidity and illuminance of water, and monitoring for underwater security. It was not.

  Therefore, the present invention has been made in view of the above problems, and its purpose is to perform underwater visual inspection even in muddy water and at night, such as underwater work not subject to the turbidity and illuminance of water, and monitoring for underwater security. It is a main problem to provide a video acquisition device that can be inexpensively provided.

  The present invention will be described below.

  An image acquisition apparatus according to the present invention includes a transmitter that transmits ultrasonic waves having different frequencies in an azimuth direction, a fixed lens that is fixed in position, and a movable lens that can adjust a relative distance between the fixed lens and the fixed lens. And an acoustic lens that converges the reflected wave from the ultrasonic object transmitted from the transmitter, and a receiver in which a plurality of receiving elements elongated in the azimuth direction are arranged in the vertical direction, A signal processing device that performs signal processing on a reflected wave acquired from the receiver, and a display unit that displays information obtained by the signal processing device.

In the video acquisition device according to the present invention, the receiver may be curved only in the vertical direction and have a substantially C-shaped cross section perpendicular to the azimuth direction.

Further, in the image capturing apparatus according to the present invention, the transmission wave machine, and transmitting the lowest frequency at both ends of the transmitting range of the azimuth direction of transmitting the ultrasonic wave, the center from both ends of the transmitting range The frequency transmitted toward the can be increased.

  The video acquisition device according to the present invention includes a fixed lens in which the position of the acoustic lens is fixed, and a movable lens that can adjust the relative distance between the fixed lens, and thus the temperature of sound speed between water and the lens. Because the image is blurred or distorted on the imaging plane on the receiver due to the different dependence, and the frequency transmitted from the transmitter is transmitted at a different frequency in the azimuth direction, It is possible to adjust the blurring and distortion of the image on the imaging plane on the receiver due to the different dependence.

  The image acquisition device according to the present invention transmits ultrasonic waves having different frequencies in the azimuth direction, converges reflected waves from the object with an acoustic lens, and a plurality of receiving elements that are elongated in the azimuth direction are arranged in the vertical direction. Since the reflected wave is received by the receiver having a substantially C-shaped cross section perpendicular to the azimuth direction and the received signal is processed, the image acquisition device can be manufactured at low cost and the image With the acquisition device fixed at a fixed point, it is possible to view underwater even in muddy water and at night, such as underwater work that is not affected by underwater turbidity and illuminance, monitoring for underwater security.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the drawings. The following embodiments do not limit the invention according to each claim, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. .

  FIG. 1 is a schematic diagram illustrating a configuration of a video acquisition device according to the present embodiment, FIG. 2 is a perspective view illustrating a receiver 40 that configures the video acquisition device according to the present embodiment, and FIG. FIG. 4 is a cross-sectional view showing a cross section of the acoustic lens 30 and the wave receiver 40 constituting the video acquisition device according to the present embodiment. FIG. FIG. 5 is a diagram illustrating a display method of the display unit 60 of the video acquisition device according to the present embodiment.

  As shown in FIG. 1, the image acquisition device 1 according to the present embodiment includes a transmitter 10 that transmits ultrasonic waves 11 having different frequencies in the azimuth direction X, and an ultrasonic wave transmitted from the transmitter 10. The acoustic lens 30 for converging the reflected wave 21 from the 11 objects 20 and a cross section orthogonal to the azimuth direction X have a substantially C-shaped shape, and a plurality of receiving elements 41 elongated in the azimuth direction X are provided in the vertical direction. An arrayed receiver 40, a signal processing device 50 that performs signal processing on the reflected wave 21 acquired from the receiver 40, and a display means 60 that displays information obtained by the signal processing device 50 are provided. Yes.

  The ultrasonic wave 11 transmitted from the transmitter 10 transmits the lowest frequency at both ends of the azimuth direction X in FIG. 1, and gradually increases along the azimuth direction X toward the center of the azimuth direction. Sound waves are being transmitted. Therefore, the highest frequency is transmitted at substantially the center positions at both ends in the azimuth direction X.

  Moreover, as shown in FIG. 1, the ultrasonic wave 11 transmitted from the transmitter 10 is transmitted as a fan-shaped fan beam. Furthermore, the ultrasonic wave 11 has a frequency of 20 k to 2 MHz. In this way, when ultrasonic waves are used as a transmission signal, the ultrasonic waves are longer in wavelength and stronger in directivity than light, so they are not scattered in muddy water and have low illuminance such as at night. However, since it is not absorbed, it is less attenuated in the liquid and can propagate far away. For this reason, it can be used as a transmission signal of the image acquisition device even in muddy water or at night.

  The ultrasonic wave 11 transmitted from the transmitter 10 is reflected by the underwater object 20 to generate a reflected wave 21. The reflected wave 21 is converged by using the acoustic lens 30, decomposed in the vertical direction Y, and converged on the imaging surface 40 a of the receiver 40.

  Here, as shown in FIG. 2 and FIG. 3, the receiver 40 has a substantially C-shaped cross section orthogonal to the azimuth direction X. The receiving elements 41 elongated in the azimuth direction X are arranged in the vertical direction. Note that the receiver 40 according to the present embodiment is configured as a receiver 40 having 64 receiving elements 41 arranged in the vertical direction and 64 channels in the vertical direction.

  Further, as shown in FIG. 3, the acoustic lens 30 includes a fixed lens 31 and a movable lens 32. The movable lens 32 is configured to be able to move to an arbitrary position between the fixed lens 31 and the imaging surface 40a of the receiver 40, and the relative distance between the fixed lens 31 and the movable lens 32 is set. It can be adjusted. As described above, since the relative distance between the fixed lens 31 and the movable lens 32 is installed so as to be adjustable, the temperature dependency of the sound speed between the water and the lens is different by appropriately adjusting the position according to the frequency. Adjustment of image blur and distortion on the imaging surface 40a on the receiver 40, and the frequency transmitted from the transmitter 10 are transmitted at different frequencies in the azimuth direction X. It is possible to adjust the blurring and distortion of the image on the imaging surface 40a on the wave receiver 40 due to the different dependency. The acoustic lens 30 is made of acrylic resin for both the fixed lens 31 and the movable lens 32.

  Furthermore, as shown in FIG. 3, the fixed lens 31 is formed as a concave lens having concave portions on both sides, and the movable lens 32 is a concave lens having a convex portion centered on the incident side (fixed lens 31 side) surface. The surface on the radiation side (receiver 40 side) is formed as a concave lens having an annular convex portion at the peripheral edge.

  As shown in FIG. 3, the acoustic lens 30 forms the reflected wave 21 as an acoustic image divided in the vertical direction Y of the imaging surface 40 a of the receiver 40. In this manner, the sound pressure of the reflected wave 21 is acquired as a received signal at an arbitrary channel of the wave receiving element 41 arranged on the imaging surface 40a.

  Accordingly, the reflected wave 21 resolved in the vertical direction Y by the acoustic lens 30 is received by the wave receiving element 41 corresponding to an arbitrary channel arranged on the imaging surface 40a, so that the object 20 in the vertical direction Y is received. Position information can be obtained.

  Next, with reference to FIG. 4, signal processing in the signal processing device 50 of the video acquisition device 1 according to the present embodiment will be described.

  As shown in FIG. 4, the received signal acquired by each receiving element 41 of the receiver 40 is subjected to information processing by FFT (Fast Fourier Transform) in the signal processing device 50 for each channel. With this information processing, the processing results 51a, 51b, and 51c can be obtained for each channel. And by this processing result 51a, 51b, 51c, the change of the sound pressure P can be observed in the frequency band where the reflected wave 21 from the object exists, and the frequency transmitted from the transmitter 10 and the object By comparing the frequency of the reflected wave 21 reflected from the object 20, position information in the azimuth direction X of the object 20 can be obtained. Therefore, the position information in the azimuth direction of the object can be obtained from the level of the frequency f of the received signal and the change in the sound pressure P. Further, as described above, the position information in the vertical direction of the object can be obtained from the position in the vertical direction of each channel.

  By displaying the position information of the object obtained in this way in the vertical direction for each channel, it is possible to obtain an image 61 on the display means 60 as shown in FIG.

  In the present embodiment, the wave receiver 40 has been described as the wave receiver 40 having 64 channels on the imaging surface 40a. However, the number of channels depends on the shape of the object to be imaged and the required resolution. It can be changed as appropriate. In this case, the number of channels can be easily changed by increasing / decreasing the number of wave receiving elements 41 arranged on the image plane 40a.

  Furthermore, by performing continuous imaging using the video acquisition device 1, a time axis can be given to the imaging, and a three-dimensional image such as a moving image can be captured. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The image acquisition device 1 configured in this way can perform underwater visual observation even in muddy water and at night, such as underwater work not subject to the turbidity and illuminance of water, and monitoring for underwater security.

It is the schematic which shows the structure of the image | video acquisition apparatus which concerns on this embodiment. It is a perspective view which shows the receiver 40 which comprises the image | video acquisition apparatus which concerns on this embodiment. It is sectional drawing which shows the cross section of the acoustic lens 30 and the receiver 40 which comprise the image | video acquisition apparatus which concerns on this embodiment. It is the schematic which shows the processing method of the signal processing apparatus 50 in the image | video acquisition apparatus which concerns on this embodiment. It is a figure which shows the display method of the display means 60 of the video acquisition apparatus which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image acquisition device, 10 Transmitter, 11 Ultrasonic wave, 20 Object, 21 Reflected wave, 30 Acoustic lens, 31 Fixed lens, 32 Movable lens, 40 Receiver, 40a Imaging surface, 41 Receiver element, 50 Signal processing device, 60 display means, 61 imaging, X azimuth direction, Y vertical direction

Claims (3)

A transmitter for transmitting ultrasonic waves having different frequencies in the azimuth direction;
A fixed lens having a fixed position and a movable lens capable of adjusting a relative distance between the fixed lens and a reflected wave from an ultrasonic wave object transmitted from the transmitter are converged. An acoustic lens,
A receiver in which a plurality of receiving elements elongated in the azimuth direction are arranged in the vertical direction;
A signal processing device for signal processing the reflected wave acquired from the receiver;
A video acquisition device comprising: display means for displaying information obtained by the signal processing device. The video acquisition device according to claim 1,
The video receiver is characterized in that the receiver is curved only in a vertical direction, and has a substantially C-shaped cross section perpendicular to the azimuth direction. In the video acquisition device according to claim 1 or 2,
The feed wave machine, wherein to transmit the lowest frequency at both ends of the transmitting range of the azimuth direction of transmitting ultrasonic waves, that both ends frequency transmitting toward the center from the transmitting range increases A video acquisition device characterized by the above.

Images