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High Speed Image Capture for Mechanical Analysis

IP.com Disclosure Number: IPCOM000080397D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 63K

Publishing Venue

IBM

Related People

Mayes, JE: AUTHOR [+2]

Abstract

Design, development and testing of mechanical devices requires equipment to visually display performance in slow motion for analysis of operation. High-speed movies have slow turn-around times, are difficult to synchronize, and are not useful for error trapping.

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High Speed Image Capture for Mechanical Analysis

Design, development and testing of mechanical devices requires equipment to visually display performance in slow motion for analysis of operation. High- speed movies have slow turn-around times, are difficult to synchronize, and are not useful for error trapping.

The components of an improved system are shown in Fig. 1. A photodiode array camera 1 can serve as the image sensing device, as well as arrays of charge-coupled devices or so-called "bucket-brigade" devices. The photodiode array consists of a rectangular matrix of diodes, Fig. 2, on which the image is focused, for example, a 50 x 50 matrix array. The matrix is read out to obtain the 2500 analog "bits" which represent an image.

The specially constructed array is capable of reading out 50 lines in parallel to achieve a frame rate of 20,000 per second. This rate compares favorably with high-speed motion-picture photography, which typically achieves 16,000 frames per second. Having achieved the high frame rate, the 50 parallel video signals are amplified and converted to digital information by the analog-to-digital converter 3. The video signals can now be stored digitally in a random-access digital storage device 4, for later reconstruction and playback in slow motion. The digital storage has a capacity of 80 frames, for example.

In playback mode, one frame of information is read out to the playback register 5. This information is converted to an analog signal by the digital-to- analog converter 6 and displayed on a display device 7. Each frame is played back a selected number of times depending on the slow-motion effect desired. Since the system is all electronic, a wide variety of record and playback features can be provided through the control logic 8. Start of the record cycle can be synchronized to the motion being observed via a related electrical signal from the device being observed or through a variety of motion-sensing transducers, either of which applies a signal to the sync line 9.

Although economic considerations could limit the high-speed storage, control logic 8 can allow the operator to delay the start of record and vary the time between successive frames, to take maximum advantage of the limited storage for observation of selected portions of a motion cycle in detail. In some cases, it may be necessary to provide a strobe light 10 to "stop" the movement of a fast moving part, or to provide sufficient illumination for the camera. The strobe is triggered at record time by the control logic. For longer cycle, slower moving parts, it is desirable to provide a high volume, lower cost storage such as tape or disk 11.

Fig. 2 is a fragmentary illustration of the photodiode array in the camera 1. The array consists of a silicon chip containing a 50 x 50 matrix of photodiodes 12-1 to 12-2500 (only a few of which are shown) and a parallel shift register 13. Capacitors 18-1 to 18-2500 are connected in parallel with respec...