JPS6437171U

JPS6437171U -

Info

Publication number: JPS6437171U
Application number: JP13144587U
Authority: JP
Priority date: 1987-08-31
Filing date: 1987-08-31
Publication date: 1989-03-06
Also published as: JPH0450695Y2

Description

[Brief explanation of the drawing]

第１図は点灯回路の一例を示す説明図、第２図
は擬似実効値変換回路の実測値と理論値とを比較
して示す曲線図である。１０……白熱電球、３０……スイツチング素子
、４０……制御回路、４１，４５……電圧検出用
抵抗、４２……擬似実効値変換回路、４３……コ
ンパレータ、４４……パルス幅変調回路、５２…
…電流制限用抵抗、５１，５３……整流用ダイオ
ード、５５……抵抗、５６，５７……コンデンサ
、５９……帰還抵抗、６０……擬似実効値取出し
用可変抵抗、６１……バランス抵抗、６３……フ
オトカプラー、７１……オシレータ、７２……基
準電圧源、７３……コンパレータ。 FIG. 1 is an explanatory diagram showing an example of a lighting circuit, and FIG. 2 is a curve diagram comparing actual measured values and theoretical values of the pseudo-effective value conversion circuit. 10... Incandescent light bulb, 30... Switching element, 40... Control circuit, 41, 45... Voltage detection resistor, 42... Pseudo-effective value conversion circuit, 43... Comparator, 44... Pulse width modulation circuit, 52...
... Current limiting resistor, 51, 53... Rectifying diode, 55... Resistor, 56, 57... Capacitor, 59... Feedback resistor, 60... Variable resistor for taking out pseudo effective value, 61... Balance resistor, 63...Photocoupler, 71...Oscillator, 72...Reference voltage source, 73...Comparator.

Claims

[Scope of Claim for Utility Model Registration] 1. Digital image processing comprising an incandescent light bulb for illuminating the original, a lighting circuit for lighting the incandescent light bulb, and an image sensor for reading image information of the original illuminated by the incandescent light bulb. In the device, the lighting circuit is connected to a power line leading to the incandescent light bulb, and lights the incandescent light bulb at 0.3k.
comprising a switching element that performs on/off control at a frequency of Hz or higher; and a control circuit that detects the lighting voltage of the incandescent lamp and controls the pulse width of the switching element to keep the lighting voltage of the incandescent lamp constant; The control circuit includes a voltage detection resistor that detects the lighting voltage of an incandescent light bulb, a pseudo effective value conversion circuit that converts the voltage detected by this voltage detection resistor into a pseudo effective value, and a pseudo effective value conversion circuit that converts the detected voltage by the voltage detection resistor into a pseudo effective value. It is characterized by comprising a comparator that generates an output that compares a value with a reference voltage and cancels out the difference, and a pulse width modulation circuit that changes the pulse width of the switching element based on the output from the comparator. Digital image processing device. 2. The pseudo-effective value conversion circuit includes a first rectifier diode that receives the detected voltage from the voltage detection resistor,
a second rectifier diode connected to the first rectifier diode via a current limiting resistor; and a smoothing circuit including a resistor and a capacitor connected to the output end of the second rectifier diode. , and a feedback resistor for feeding back the output of the smoothing circuit to the second rectifying diode. The digital image processing device according to claim 1, which is a registered utility model.