LED array for emitting light of multiple wavelengths

• US 5,187,377 A
• Filed: 12/17/1991
• Issued: 02/16/1993
• Est. Priority Date: 07/15/1988
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Katoh, Masaaki
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): TRAN, MINH LOAN
• Application Number:
  US07/810,366
• Time in Patent Office: 427 Days
• Field of Search: 357/17, 357/45, 307/311, 307/317.1, 313/500, 340/762, 340/760, 362/800, 362/310, 315/192, 315/312, 315/324
• US Class Current: 257/89
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: Y10S 257/918 Light emitting regenerative switching device, e.g. light emitting scr arrays, circuitry
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An LED array comprising a substrate, a plurality of first LEDs, and a plurality of second LEDs, wherein the range of wavelengths of light from the first LEDs is different from the range of wavelengths of light from the second LEDs; the first LEDs and the second LEDs are respectively connected in series so that a current alternatively flows through the first LEDs and the second LEDs in the opposite directions; the first LEDs connected in series and the second LEDs connected in series are further connected in parallel; and the first LEDs and second LEDs are arranged in a line on the substrate.

Claims

1. An LED array for use as a light source in a contact-type linear image sensor, the LED array comprising a substrate, a pair of reflection plates, a rod lens covering the reflection plates, the reflection plates and the rod lens being mounted on the substrate, a plurality of electrodes spaced at equal intervals between the pair of reflection plates, and multiple pairs of a first LED and a second LED disposed on the respective electrodes in such a manner that the first LED and the second LED are connected in parallel, the first LED and the second LED having different ranges of wavelength, the LED pairs being connected in series wherein the first LEDs and the second LEDs are arranged in opposite directions relative to each other so that currents flow through the first LEDs and the second LEDs in opposite directions whereby either the first or the second LEDs emit light depending upon the direction of current flow.

2. An LED array according to claim 1, wherein each series of LED pairs includes a single resistance for adjusting luminance of light.

3. An LED array according to claim 1, wherein the first LEDs emit green light and the second LEDs emit red light.