LIGHT-EMITTING ELEMENT DRIVING DEVICE, SEMICONDUCTOR DEVICE, LIGHT-EMITTING DEVICE, AND LIQUID CRYSTAL DISPLAY DEVICE

• Main Authors: TATEISHI TETSUO, MURAMATSU TAISUKE
• Format: Patent
• Language: English; Japanese
• Published: 22.03.2019
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

To provide a light-emitting element driving device capable of contributing to narrower pulses of light emission in a constant current LED driver with a dimming function.SOLUTION: An LED driver 1 comprises a constant current circuit CC for supplying a constant current to a light-emitting unit LL composed of an LED, a main transistor M1 inserted in series between the light-emitting unit and the constant current circuit, an auxiliary transistor M2 connected to a node ND between the constant current circuit and the main transistor, and a control circuit 10. The LED driver subjects the light-emitting unit to pulse light emission by pulse-driving the main transistor on the basis of a brightness setting signal from an external circuit 2. The control circuit applies a current to the constant current circuit via the auxiliary transistor by turning on the auxiliary transistor before turning on the main transistor, and turns off the auxiliary transistor at the same time when turning on the main transistor.SELECTED DRAWING: Figure 1 【課題】調光機能付き定電流ＬＥＤドライバにおける発光の狭パルス化に寄与する発光素子駆動装置を提供する。【解決手段】ＬＥＤドライバ１は、ＬＥＤから成る発光部ＬＬに定電流を供給するための定電流回路ＣＣと、発光部及び定電流回路間に直列に挿入された主トランジスタＭ１と、定電流回路及び主トランジスタ間のノードＮＤに接続された副トランジスタＭ２と、制御回路１０とを備え、外部回路２からの輝度設定信号に基づき主トランジスタをパルス駆動させて発光部をパルス発光させる。制御回路は、主トランジスタをターンオンする前に副トランジスタをオンにして副トランジスタ経由で定電流回路に電流を流し、主トランジスタをターンオンすると同時に副トランジスタをターンオフする。【選択図】図１