JPS6433976A - Light output changing circuit - Google Patents

Light output changing circuit

Info

Publication number
JPS6433976A
JPS6433976A JP19082387A JP19082387A JPS6433976A JP S6433976 A JPS6433976 A JP S6433976A JP 19082387 A JP19082387 A JP 19082387A JP 19082387 A JP19082387 A JP 19082387A JP S6433976 A JPS6433976 A JP S6433976A
Authority
JP
Grant status
Application
Patent type
Prior art keywords
control circuit
circuit
current
driving
rom
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP19082387A
Inventor
Kyoji Sakamura
Original Assignee
Nec Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING STIMULATED EMISSION
    • H01S5/00Semiconductor lasers
    • H01S5/06Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/062Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
    • H01S5/06209Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in single-section lasers

Abstract

PURPOSE:To enable the adjustment of light emitting quantity of a photo element without using a variable resistor or many switches, and realize a small-sized device, by providing a control circuit with an ROM capable of writing and erasing to adjust an output current. CONSTITUTION:A light output changing circuit is provided with a photo element 1, a driving circuit 2 to drive the photo element 1 in accordance with an input signal, and a control circuit 5 to vary the driving capability of the driving circuit 2. The control circuit 5 is provided with a ROM 10 capable of writing and erasing to adjust an output current. For example, the control circuit 5 is constituted of a current source circuit 6, constant current source 9 and the ROM 10. When it is assumed that the capability of a transistor 7 is equal to that of transistors Q1-Qm, the mirror ratio becomes integral multiples of 1, 2, 3, 4... according to whether memory element M1-Mn-1 are in the state of electrical continuity or not, as the result of current mirror effect. Therefore the output current of the control circuit 5 changes, so that the light emission intensity can be changed by adjusting the driving current of the photo element 1.
JP19082387A 1987-07-29 1987-07-29 Light output changing circuit Pending JPS6433976A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP19082387A JPS6433976A (en) 1987-07-29 1987-07-29 Light output changing circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP19082387A JPS6433976A (en) 1987-07-29 1987-07-29 Light output changing circuit

Publications (1)

Publication Number Publication Date
JPS6433976A true true JPS6433976A (en) 1989-02-03

Family

ID=16264354

Family Applications (1)

Application Number Title Priority Date Filing Date
JP19082387A Pending JPS6433976A (en) 1987-07-29 1987-07-29 Light output changing circuit

Country Status (1)

Country Link
JP (1) JPS6433976A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0311832A (en) * 1989-06-08 1991-01-21 Mitsubishi Electric Corp Optical transmitter
JPH04209582A (en) * 1990-12-04 1992-07-30 Mitsubishi Electric Corp Light emitting element driving circuit
EP0678982A2 (en) * 1994-04-22 1995-10-25 Canon Kabushiki Kaisha Semiconductor light emitting element driving circuit

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0311832A (en) * 1989-06-08 1991-01-21 Mitsubishi Electric Corp Optical transmitter
JPH04209582A (en) * 1990-12-04 1992-07-30 Mitsubishi Electric Corp Light emitting element driving circuit
EP0678982A2 (en) * 1994-04-22 1995-10-25 Canon Kabushiki Kaisha Semiconductor light emitting element driving circuit
EP0678982A3 (en) * 1994-04-22 1996-03-06 Canon Kk Semiconductor light emitting element driving circuit.
US5739717A (en) * 1994-04-22 1998-04-14 Canon Kabushiki Kaisha Semiconductor light emitting element driving circuit
EP0905900A1 (en) * 1994-04-22 1999-03-31 Canon Kabushiki Kaisha Driving circuit for light emitting diode

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