Digital signal transmission system having conversion means for reducing the light emission time of a light emitting diode

• US 4,912,524 A
• Filed: 11/30/1987
• Issued: 03/27/1990
• Est. Priority Date: 12/17/1986
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takeuchi, Tosifumi, Nagai, Yutaka, Nakamura, Masafumi
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): PASCAL, LESLIE C
• Application Number:
  US07/126,506
• Time in Patent Office: 848 Days
• Field of Search: 455/601, 455/608, 455/609, 455/610, 455/612, 455/617, 455/618, 455/619, 375/22, 307/265, 307/266, 328/58
• US Class Current: 398/106
• CPC Class Codes: G11B 20/10009 Improvement or modification of read or write signals
• CPC Class Codes: G11B 7/0045 Recording G11B7/006, G11B7/0065 take precedence
• CPC Class Codes: H04B 10/502 LED transmitters
• CPC Class Codes: H04B 10/5055 using a pre-coder
• CPC Class Codes: H04B 10/508 Pulse generation, e.g. generation of solitons
• CPC Class Codes: H04B 10/541 Digital intensity or amplitude modulation
• CPC Class Codes: H04L 25/493 by transition coding, i.e. the time-position or direction of a transition being encoded before transmission

Abstract

The invention relates to a system to transmit digital signals reproduced from a compact disk player, a digital audio tape recorder or the like. In order to increase the S/N ratio of transmission of the digital signals, the occurrence probability of data to be transmitted is made low and light emission time of a light emission element is made small, and the peak value of emission is increased corresponding to the above reduction. As a result, the S/N ratio can be increased in the same transmission band as that in the prior art. In order to reduce the occurrence probability of data, a method of generating pulses at the leading edge and the trailing edge of a pulse signal or a method of compressing data is provided.

Claims

1. A digital signal transmission system including a light emission element for transmitting digital signals by light, comprising:

means for converting modulated data into pulse data having a plurality of pulses each having a pulse width of T seconds and corresponding to a leading edge or a trailing edge of said modulated data, wherein said modulated data maintains a level "1" and a level "0" for a duration of at least 2T seconds with respect to a data transmission rate of 1/T (bit/seconds) of the code converting means;

wherein the light emission element emits light in response to the pulse data; and

receiving means for subjecting said light emitted by the light emission element to a second order differentiation, converting the differentiated data into binary signals by prescribed slice level and for demodulating the binary signals.