Circuit for adjusting luminous energy of light-emitting element and optical device using same
AssigneeRohm Co., Ltd.
InventorsHideki Tawarayama, Yoshitaka Koharagi
Life of this patent
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Abstract
Luminous energy of a light-emitting element in an optical device is adjusted to a desired level by a light adjusting circuit including a light-receiving element adapted to detect the level of luminous energy of light emitted from the light-emitting element, an up/down counter circuit for counting clock signals up or down according to the level detected by the light-receiving element, and a current adjusting circuit for resetting the current intensity supplied to the light-emitting element according to output data from the up/down counter circuit.
Claims10
A light adjusting circuit for adjusting luminous energy of a light-emitting element;
- said light adjusting circuit comprising:
- a light-receiving element which detects level of luminous energy of light emitted from said light-emitting element;
- a plurality of up/down counter circuits each for counting clock signals up or down according to said detected level of luminous energy,
- a memory device connected to receive and store data outputted from said counter circuits;
- and
- a plurality of current adjusting circuits each for selecting one of a plurality of current intensity values according to data received from said memory device and supplying a current with said selected current intensity value through an associated one of a plurality of constant current sources to said light-emitting element.
An optical device comprising:
- a light-emitting element;
- a light-receiving element which detects level of luminous energy of light emitted from said light-emitting element;
- a plurality of up/down counter circuits each for counting clock signal up or down according to said detected level of luminous energy;
- a memory device connected to receive and store data outputted from said counter circuits;
- and
- a plurality of current adjusting circuits each for selecting one of a plurality of current intensity values according to data received from said memory device and supplying a current with said selected current intensity value through an associated one of a plurality of constant current sources to said light-emitting element, whereby current passed through said light-emitting element is adjusted.
Dependencies are inferred from the claim text.