Device and method for controlling brightness of radio terminal
US6281640A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 8, 2000 |
| Grant date | Aug 28, 2001 |
| Priority date | — |
| Expiry date | Jun 8, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D30/70
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A device for controlling brightness of a radio terminal. In the brightness control device, a photometer measures brightness of an incident light to generate an electric signal depending on the brightness. A light emitting device emits a light, and a power supply provides a power supply voltage to the light emitting device in response to a control signal. A controller measures brightness while the light emitting device is turned on/off, using the photometer, and generates the control signal for enabling the power supply to provide the power supply voltage to the light emitting device according to a brightness difference during light-on and light-off of the light emitting device. The controller comprises a switch for switching a signal output from let the photometer to either a first input node or a second input node of a comparator; the comparator for generating a signal corresponding to a difference between the signals received at the first and second input nodes thereof; and a pulse density modulation (PDM) signal generator for generating a PDM signal for the signal output from the comparator as the control signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.