Luminance-adjustable ophthalmoscope dimming circuit

Abstract

The invention provides a luminance-adjustable ophthalmoscope dimming circuit comprising a dimming key, a DC (Direct Current) power supply, an inverter, a dimming controller and a pulse width modulation integrated circuit; the dimming key outputs a luminance adjusting signal to the dimming controller; the dimming controller outputs one dimming pulse signal with a duty ratio corresponding to that of the luminance regulating signal to the pulse width modulation integrated circuit; the pulse width modulation integrated circuit outputs a driving pulse signal with corresponding duty ratio to the inverter according to the dimming pulse signal; and the inverter outputs an AC (Alternating Current) voltage according to the driving pulse signal and the received DC power supply to drive a ophthalmoscope light source to emit light having corresponding luminance. The luminance of the light emitted from the ophthalmoscope light source varies with the specific duty ratio of the driving pulse signal output by the pulse width modulation integrated circuit, that is to say,, the light source with larger duty ratio is higher in luminance; and thus, by outputting the luminance adjusting signals with different duty ratios by the dimming key; therefore, the luminance of the light source can be adjusted.

Description

technical field [0001] The invention relates to a medical examination instrument, in particular to an ophthalmoscope dimming circuit with adjustable illuminance. Background technique [0002] An ophthalmoscope is an instrument used to check the fundus for hemorrhage, retinal breaks and other fundus lesions. The structure of the eye generally includes a shell, a power supply, a light source 1, a focusing system, and a variable eyepiece 6. The power supply generally uses an inverter to convert the DC power output from the battery into an AC power supply with a constant duty cycle. Such as figure 1 , 2 As shown, the light source 1 mainly adopts an incandescent lamp or a halogen lamp, and the condenser lens 2, the rotating diaphragm disk 3, and the objective lens 4 in the concentrating system are sequentially arranged along the main optical path of the light source, and a turning reflector 5 is arranged at the end of the concentrating system, variable The eyepiece 6 is locate...

AI Technical Summary

Problems solved by technology

[0003] However, the illuminance of the light source of the existing ophthalmoscope is generally single and fixed, such as 20LX, and the current maximum illuminance is 80LX. The illuminance is still obviously low, and it is far from meeting the requirements of modern medicine.

Due to the difference in vision of users, or the absence of darkrooms in community health stations and township hospitals, the ophthalmoscope with 80LX illumination is obviously insufficient, making doctors and other users unable to make correct judgments

[0004] Moreover, users usually use ophthalmoscopes in different environments, but when the ambient brightness is high, they only need to use ophthalmoscopes with low illuminance, and when the ambient brightness is low, they need to use ophthalmoscopes with high illuminance. The level of illumination also affects the selection of illumination parameters

The existing single-illuminance ophthalmoscope obviously restricts the improvement of the convenience of use

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