# US 4,395,910 A · Geometric correction circuit for ultrasonic scan display

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- Number: US 4,395,910 A
- Document ID: US4395910A
- Status: Granted
- Kind: A
- Application number: 06/189,730
- Filed: 1980-09-22
- Granted: 1983-08-02
- Earliest claimed: 1980-09-22
- Assignees: Sonometric Systems, Inc.
- Inventors: Kai E. Thomenius
- Web page: https://patentgrep.com/patent/US4395910A

## CPC

- G01S 7/52063: {Sector scan display}
- G01N 29/0627: {Cathode-ray tube displays (in general G01R13/20)}
- G01N 29/0645: {Display representation or displayed parameters, e.g. A-, B- or C-Scan}
- G01R 13/20: Cathode-ray oscilloscopes
- G01S 7/5205: {Means for monitoring or calibrating}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

Circuitry for generating a distortion-free sector display in a cathode ray tube for displaying signals from an ultrasonic transducer moving back and forth in an arcuate path. Sine and cosine beam sweep signals are developed using signals respectively representing the angular position .theta. of the transducer on its angular path (representing the sine) and 1-.theta..sup.2 /2(representing the cosine). A transducer position signal is stored on a relatively large capacitor, and a capacitor of smaller capacitance is used to generate a ramp signal in producing the sine and cosine beam sweep signals.

## Claims

### Claim 1

In ultrasonic scan and display apparatus utilizing a transducer pulsed at a relatively high frequency and which moves back and forth in an arcuate path at a relatively lower frequency, the improvement for generating a beam deflection signal to produce a sector display in a cathode ray tube comprising first capacitor means of relatively large capacitance for storing a signal related to the angular position of said transducer in said path, second capacitor means of relatively small capacitance for generating a signal producing a trace sweep of the beam in said cathode ray tube, and first gate means for coupling together and decoupling said first and second capacitor means at a rate dependent upon said transducer pulsing frequency.

### Claim 2 (depends on 1)

Apparatus according to claim 1, in which said first gate means decouples said first and second capacitor means during trace portions of the sweep of said beam in said cathode ray tube.

### Claim 3 (depends on 2)

Apparatus according to claim 2, in which said beam deflection signal produces beam deflection in the direction of an X-axis in said cathode ray tube, and including a source of unidirectional current flow coupled to said second capacitor means.

### Claim 4 (depends on 2)

Apparatus according to claim 2, in which said beam deflection signal produces beam deflection in the direction of a Y-axis in said cathode ray tube, and including a source of bidirectional current flow coupled to said second capacitor means.

### Claim 5 (depends on 1)

Apparatus according to claim 1, including third capacitor means of relatively large capacitance for storing a signal related to the angular position of said transducer in said path, fourth capacitor means of relatively small capacitance for generating a signal producing a trace sweep of the beam in said cathode ray tube in a direction generally perpendicular to the direction of the trace sweep produced by the signal from the second capacitor means, and second gate means for coupling together and decoupling said third and fourth capacitor means at a rate dependent upon said transducer pulsing frequency.

### Claim 6 (depends on 5)

Apparatus according to claim 5, in which said first gate means decouples said first and second capacitor means during trace portions of the sweep of said beam in said cathode ray tube in the direction of an X-axis in said tube, and said second gate means decouples said third and fourth capacitor means during trace portions of the sweep of said beam in said cathode ray tube in the direction of a Y-axis generally perpendicular to said X-axis.

### Claim 7 (depends on 6)

Apparatus according to claim 6, including a source of unidirectional current flow coupled to said second capacitor means, and a source of bidirectional current flow coupled to said fourth capacitor means.

### Claim 8 (depends on 7)

Apparatus according to claim 7, in which the signal stored by said third capacitor means is generally proportional to .theta., and the signal stored by said first capacitor means is generally proportional to 1-.theta..sup.2 /2.