| CCD CAMERA |
| CCD (Charged Coupled Device) Image Sensor |
| Solid-state image sensing device that converts optical signal to electronic signal. CCD is composed of photo diode arrays that produce electric charges according to strength of optical signal and the register part that transfers the electric charges to vertical and horizontal directions to read them out as signal voltage. A device that uses CCD in the register part is called CCD image sensor and is often called simply CCD. |
| Frame Storage |
| Frame storage is a system that reads out photoelectric conversion signal. It reads out only odds field line signal in one field and even line signal in the other field line. The exposure time is counted as one frame. |
| Field Storage |
| Field storage system exposes in one field period and reads out combined photoelectric conversion signals of adjacent two lines in order to compensate the reduced signal level, which becomes a half of the signal level of frame storage, resulting from a half of the exposure time of frame storage system. The system changes the combination of the two lines at each field to adopt to the interlace methods. |
| Interline Transfer CCD |
| The signal charges of photo sensors are simultaneously transferred to the vertical register at periodical timing and shifted in vertical register one by one at every horizontal period. This system reads out all of the horizontal pixels at the last stage of the vertical register. |
| Progressive Scan CCD |
| Progressive Scan CCD is an image sensor that has two readout methods; (1) Read out photoelectric converted signal equivalent to one frame signal in one field period through two independent registers for each field. (2) Read out photoelectric converted signal equivalent to one frame signal in one frame period as non-interlace signal. In ordinary CCD image sensor, two field image signals that have one field exposure timing difference are used to form one frame signal, which results in blurring. Since Progressive Scan CCD reads out picture information from all pixels in one field period, a camera that uses this CCD is effective in taking a still picture without causing blurring. |
| Effective Pixels |
| Total number of the photo diode arrays on the chip of CCD image sensor are called total number of pixels, while the number of photo diodes which contribute to the actual image signal is called effective pixel number. The periphery of a photo diode array has optical black which is the standard for the black level and this area (about 10% of the total number of pixels) is not included in the effective pixels. |
| Composite Signal |
| Signal is composed of luminance signal, sync signal, chrominance signal and burst signal (video output signal). |
| Y/C Output |
| Output format of the color picture signal, separating luminance signal (Y) and chrominance signal (C). The luminance signal contains the composite sync signal, and chrominance signal contains the color burst signal. When input into color monitor, the composite signal is separated into luminance signal and chrominance signal. This may narrow the luminance signal bandwidth. When Y/C separated signal is input, the horizontal resolution becomes better because the separating circuit for color monitor is not used. |
| Sync System |
| When picture signal must be synchronized with the external system, the sync signal of the system is supplied to a camera to synchronize with its picture signal. This is called external synchronization system. There are two external sync signals supplied from outside, composite sync signal system and HD/VD signal (Horizontal/Vertical Drive) system. The operation with internal sync signal generated in a camera irrelevant to the external signal is called internal sync system. |
| AGC (Automatic Gain Control) |
| AGC automatically controls amplifier gain to prevent the signal saturation when the input light is strong, and increases gain to the regulated level to maintain the appropriate signal level when the input light is weak. It enables to take pictures with fixed lens iris from dark to bright place within the limited range. |
| AE (Automatic Exposure) |
| Automatic exposure function detects the brightness of the photographic subject to adjust the iris of lens and shutter speed automatically. |
| Gamma Correction |
| Cathode-ray tubes generally used for TV have non-linear electric-light conversion characteristic which is expressed as Gamma = 2.2. In order that the optical input level to a camera proportions to the light emitting level from cathode-ray tubes, the picture output signal from a camera must be compensated. The Gamma compensation that is equals to 0.45 must be made for the output signal of usual CCD camera. |
| DSP (Digital Signal Processing) |
| Against the conventional analog signal processing, a camera uses digital signal processing circuit with A/D (Analog to Digital) converter to obtain picture signal. The camera provides various picture outputs including analog signal and a variety of formats of digital signal. Generally, the signal is processed in analog format from the output CCD image sensor to correlated double sample hold circuit and AGC. |
| S/N Ratio (Signal-to-noise Ratio) |
| The ratio between signal and noise, and the higher S/N value represent the less noise and higher quality picture. |
| Electric Iris |
| In order to maintain the CCD output level within a certain range regardless of the input optical level, the time to store electric charge is changed per each frame. |
| Long Term Exposure |
| Enable the high sensitivity shooting with longer electric storage time (several fields) of the CCD. This is effective for the motionless object. |
| Coaxial Transmission |
| A system which transfers video signal by one cable loading on DC power supply of camera drive. |
| Illumination |
The brightness or intensity of light falling on a surface, and the unit is lx.
| Fine |
10,000 lx., ( Cloudy sky: 1,000 lx.) |
| Indoor (with light from the outside) |
500 lx. |
| Indoor (without light from the outside) |
100 lx. |
| Dusk |
2 lx. |
| Moonlight |
0.01 lx. |
| Starlight |
0.001 lx. |
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| White Balance |
| Color reproduction adjusting function depending on the source of light. The output signal is adjusted so that the white photographic subject is correctly reproduced. If white balance is not adjusted correctly against the color temperature of the source of the light, CCD camera is not able to reproduce white color correctly. Those cameras with auto white balance function automatically adjust the white balance. |
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| LENS |
| ALC(Automatic Lens Control) |
| Automatic luminance energy adjustment, which controls the picture output in a certain range according to the change of the input luminance energy. |
| C-mount |
| One of the lens mounting systems, with 17.526mm flange back. C-mount lens is mainly used with 1/2", 1/3" CCD camera. * Flange back: the distance from the mounting a basic phase to the focal point. |
| CS-mount |
| One of the lenses mounting systems, with 12.5mm flange back. CS-mount lens is mainly used with 1/3" CCD camera, and recently CS-mount lens can be used with either C and CS mount lens by using the C-mount adapter or adjusting the flange back. |
