To meet the growing demand for compact image sensors in the camera phone market, Sanyo Electric Co. Ltd. recently developed a megapixel CCD image sensor. According to the company, it has the smallest pixel size in the industry. “More than 90% of the new mobile phones launched in Japan have a camera function,” said Toru Watanabe, general manager of Sanyo Semiconductor’s CCD business unit.
The new CCD image sensor of Sanyo Electric has a pixel size of only 2.7 × 2.7 microns and is part of a camera module called HyperEye IGT99353M-ST. The company has started to provide samples of the module. This 100-megapixel CCD has a frame transmission rate of 7.5 frames per second and an optical diagonal dimension of 3.92 mm. The module, including the image sensor, has three plastic lenses and a mechanical shutter. It uses a multi-chip package to package an analog IC and a digital IC together to provide comprehensive camera functions. The company’s use of mechanical shutters in mobile phone camera modules is somewhat different, because shutters are rare in mobile phone camera applications, which may lead to increased costs and larger sizes.
“We want to use the shutter to prevent image blur during frame transmission,” Watanabe said. He pointed out that the device has significantly improved resolution when capturing moving objects. “Because of this frame transmission sensor structure, the sensor is significantly thinner than other format sensors, so the overall height of the module including the shutter is smaller than the height of sensor modules using other formats.” According to Sanyo Electric With a thickness of 7.6 mm, it is the smallest CCD camera module currently available.
When shooting VGA resolution video at 7.5 frames / second, its power consumption is 120 mW. At 15 frames per second, power consumption rises to nearly 160 milliwatts. Watanabe said that under the same circumstances, the power consumption of a camera module using a CMOS image sensor is about 200 milliwatts, so the CCD is very competitive in terms of power consumption. But for the entire camera module, its power consumption depends not only on the image sensor, but also on the signal processing part of the back end, but Watanabe did not make a direct comparison here.
This module uses a single 2.9V power supply, the same as Sanyo’s CIF and VGA resolution modules. Sanyo now produces CCD image sensors for camera phones, with a monthly output of 2.5 million. The company said that adding a 100-megapixel CCD image sensor will soon increase the total monthly CCD image sensor output to 3 million.