News Column

Patent Issued for Photodetector Circuit

September 3, 2014

By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventors Tabuchi, Yoshihisa (Gifu-ken, JP); Nagata, Yasunori (Gifu-ken, JP), filed on December 13, 2012, was published online on August 19, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8809762 is assigned to Semiconductor Components Industries, LLC (Phoenix, AZ).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Conventionally, various cameras are provided with a vibration compensation function. The vibration compensation is achieved by moving the lens in accordance with camera movement to thereby obtain an image in which vibrations are compensated for. In order to execute this vibration compensation, the lens must be driven appropriately, and this requires accurate detection of the lens position.

"For detecting positions of various components, there has been provided an arrangement in which a magnet is mounted on the target component and a Hall element for detecting this magnet is used. A Hall element is also being used for detecting a lens position."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "Technical Problem

"However, a Hall element is relatively costly. Moreover, for applications such as cameras in cell phones and smartphones where space reduction is required, or special device shapes are desired by users, it may not be possible to sufficiently satisfy such requirements or desires when a Hall element is used. It is therefore necessary to consider alternative detection methods. For example, one alternative detection method may be an optical detection method, in which a photodetector such as a photo-reflector or a photo-interrupter may be used. A photo-reflector is a device in which light emitted from a photodiode is reflected off a target and the reflected light is detected using a phototransistor. By configuring such that the received light amount at the phototransistor varies depending on lens position, the position of the lens can be detected.

"In such a photo-reflector, since outputs are influenced by factors such as element deterioration over time, changes in the power supply voltage, and temperature changes, corrections addressing those influences are desired.

"Solution to Problem

"The present invention provides a photodetector circuit for detecting light from a photodiode using a phototransistor. The photodetector circuit comprises: a communication unit that receives, at the time of startup, set data concerning a detected current; a comparison unit for comparing the set data received by the communication unit with the detected current; and an adjustment unit for adjusting a current of the phototransistor so that the detected current matches the set data. The photodetector circuit performs control at the time of startup so that the current that flows through the phototransistor matches the set data.

"Advantageous Effects of Invention

"According to the present invention, the current that flows through the phototransistor can be adjusted at the time of startup, and it is thereby possible to address factors such as element deterioration."

URL and more information on this patent, see: Tabuchi, Yoshihisa; Nagata, Yasunori. Photodetector Circuit. U.S. Patent Number 8809762, filed December 13, 2012, and published online on August 19, 2014. Patent URL:

Keywords for this news article include: Electronics, Phototransistors, Semiconductor Components Industries LLC.

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Source: Electronics Newsweekly

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