The dynamic range of the new DPM sensors ensures outstanding highlight handling performance - with exposures in excess of 600% being comfortably managed. Other 1000 pixel sensors barely exceed half that figure. The result is that high charge packets (that must be stored in the sensor electrodes) and which are caused by highlights, can be easily handled.

When it comes to camera sensitivity, the benefits of the DPM sensor technology are also distinct. Due to the relatively large pixel size (window size) of the 2/3 inch DPM sensor, when compared to other current sensors, the sensitivity of the new BTS concept is the same as its 2/3 inch competitors (2000 lux at f8) - but without the need to use on-chip micro lenses.

This means that with DPM technology, camera sensitivity is linear across the full range of camera lens f-stops. So maximum sensitivity and resolution are assured when they are most needed.

Frame Transfer sensors give the added assurance of absolutely no lag or smear. So dynamic resolution is optimum under all operating conditions, giving clean and clear pictures for slow or stop motion VT playback, or in standard panning shots.

In addition, a horizontal reverse scan mode is featured, so shots through mirrors can be made without external effects units being necessary.

For tomorrow's television and also today's, the unique switching capability of the new BTS DPM sensors represents a considerable technological achievement. An achievement that is made possible by using Frame Transfer techniques. Ones which have already been proven in use, in the existing range of BTS cameras. From compact portables, through to studio and EFP/Triax units, and on into the future with the 2.2 million pixels sensor for the BTS High Definition camera. But why Frame Transfer? The answer to which type of sensor meets needs best can be found by looking at critical factors affecting sensor performance - and thus picture quality.

Smear - eliminate or simply reduce it?
Other types of sensor have an intermediate store that permits fast transfer of image charges via a vertical shift register, into the store. This helps reduce smear.
The nature of the Frame Transfer concept however, means that smear is not just reduced - it simply does not exist.

The FT sensor construction is based around an image section, a storage area (intermediate store) and horizontal output shift register(s). The image pixels in the image section are used for integration, capture of the image, and for moving the charge packets quickly downwards into the storage area.

The problem of smear occurs during the vertical transfer of picture information - charge packets - from the image area of the sensor, using vertical shift registers, to the horizontal shift register. During this period there is a continual build-up of photo charge, with leakage of incoming light into the vertical shift registers. The result of this leakage is that electrons are generated.

Since the time taken to move one complete image down the vertical shift register to the horizontal shift register is governed by the clock frequency, vertical smear is caused by the leakage of electrons as they are shifted down the vertical register.

When the picture contains highlights, this phenonemon is particularly evident. With a vertical trail running from top to bottom of the complete picture. The Frame Transfer CCD with its 10-year garanteed shutter, is the only true solution to the smear problem. The Frame Transfer sensor moves charge packets rapidly from the image region to the storage region, during a small part of the internal vertical blanking. Without the shutter, some smear would still occur. With it, it can't. Because it is timed to operate during the shift of charge packets. Thus preventing any light from contaminating the next picture.

Other sensor technologies involve moving the charge packets, during the vertical blanking period, into adjoining shift registers next to the image pixels, and then on into the field memory. Due to this field memory, the vertical transfer rate can be considerably speeded up, and is not limited to field rate frequencies.

The result is that smear can be reduced to a claimed -116 dB. But not eliminated completely. Reducing exposure times down to say 1/2000 second, with the associated shortening of integration times, and smear increases again. By a factor of 40, or +32 dB at 1/2000 second and +26 dB at 1/1000 second.

A further problem is caused by having shift registers in the light path next to the image pixels. With FT technology on the other hand, pixels are also used to transport the image, so pixels and windows can be relatively larger without gaps between them for shift registers. The result, better performance under all conditions.

Dynamic resolution - to lag or not to lag
TV is about moving pictures and not static test patterns. The dynamic resolution of a sensor is therefore critical.
Assuming that a sensor has sufficient pixels to resolve the highest frequency for a TV standard under static conditions, what reduces this response under dynamic conditions? Lag.

In Frame Transfer sensors, 100% of the charge in the image pixels is moved to the storage area. So lag is not possible. And dynamic resolution is maximised, providing clean clear film-like pictures.

With other sensors, lag is present, because the charge transfer between the pixels and the vertical shift register is incomplete. This is caused by a small number of electrons accumulated in the image pixels, being left behind after transfer. The amount of lag, therefore being determined by the efficiency of the transfer.

High sensitivity - across all f-stops
The increasing requirement for cameras to perform as multi-role units (with potential outside broadcast lighting problems) requires that sensors maintain high sensitivity under all conditions.

Some sensor designs feature micro lenses located above the sensor pixels. These are intended to focus more of the available light onto the sensitive area, which would otherwise be wasted on non-sensitive shift register elements. On these sensors, shift registers are located with the pixels in the image capture region of the device.

Micro lenses however, can cause problems. These include non-linear sensitivity, a fall-off in resolution plus flare and halos which are the result of irregularties on the surface of sensors with micro lenses.

As the camera lens iris is closed, using higher f-stops, the light falling onto the sensor will be more parallel and the micro lenses will focus more light onto the pixels, as intended. When the camera lens is wide open however, the light falling onto the micro lenses will not be parallel, and thus all available light will not be focussed onto the pixels.

In other words, sensors with micro lenses are least sensitive when the camera lens is wide open - so when maximum sensitivity is needed, it is not available.

BTS Frame Transfer sensor technology guarantees high sensitivity and does not rely on micro lenses on the surface of the sensor. With the FT sensors, efficient conversion of light input to an electrical output is determined by a number of factors such as internal capacitance and size of actual pixel windows.

The result of BTS sensor technology is a sensor that offers the highest linear sensitivity performance.

The increasing acceptance and use of widescreen television, means without question that the new DPM Dynamic Pixel Management sensors plus the new LDK 10 and LDK 10P (portable) cameras from BTS are going to be playing a leading role.

Needless to say, however, BTS is committed to offering continuing support for our current camera products such as the LDK 9, LDK 9P and LDK 93. This commitment is demonstrated by the availability of wide screen sensors for these cameras too.

With the 1/2 inch wide screen sensor. The first EDTV image sensor that is switchable electronically between 4:3 and 16:9 aspect ratios. Fully meeting EDTV requirements and at the same time offering a cost effective implementation of that performance in SDTV cameras.

BTS 1/2 inch wide screen sensors, giving a proven performance that's characterised by a high dynamic range. And because you are dealing with a Frame Transfer sensor - absolutely no smear and no lag. Whether you are committed to the cameras of today or are planning a commitment to the cameras of tomorrow, BTS sensor technology makes the commitment to go with you.

When you want to switch from 4:3 to 16:9, BTS cameras and FT sensors will switch with you.