JPS62133776A - Light emitting element driving device - Google Patents

Abstract

PURPOSE:To exceedingly reduce power consumption by detecting an information signal by use of an information signal discriminating means to change over a signal change-over means and by driving a light emitting element driving means strongly to send the information signal. CONSTITUTION:An information signal Sa which is to be transmitted is inputted in an information signal input terminal 1a and then it is inputted in a signal change-over means 5 through an information signal amplifying means 2a and an information signal modulating means 3a. Also, a control signal Sb is inputted in a control signal input terminal 1b and then it is inputted in the input terminal of the signal change-over means 5 through a control signal amplifying means 2b and a control signal modulating means 3b. An information signal discriminating means 4 is connected to the output side of the information signal amplifying means 2a so as to operate the signal change-over means according to a state of the information signal Sa. As a result, both cases of an information transmitting duration during which the signal inputted in a light emitting element driving means 6 is the information signal Sa and a link retaining duration during which that is the control signal Sb are realized according to the state of the information signal Sa.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light-emitting element drive unit used in optical communication in which information is transmitted by converting electrical information signals into optical signals using light-emitting elements such as light-emitting diodes and laser diodes. The present invention relates to a light emitting element driving device that reduces power consumption.

[Conventional technology]

A conventional light emitting element driving device maintains a link by constantly flowing a constant carrier to the light emitting element.

[Problem that the invention seeks to solve]

However, in optical communications, suppressing the driving power of the light emitting elements to the lowest possible level leads to lower power consumption and smaller size of the entire device. In particular, in communication systems that use mobile terminal equipment with an added function of transmitting optical signals into space, a low-power light emitting element driving method is desired in view of the requirement for battery life.

In view of the above points, this invention divides the period during which optical communication is performed into an information transmission period in which the original information is transmitted, and a link maintenance period in which only the maintenance of the communication link is necessary. However, the purpose of the latter is to reduce drive power by suppressing the drive to the minimum necessary to maintain the link.

[Means for solving problems]

A first aspect of the one light emitting element driving device according to the present invention includes an information signal input terminal, a control signal input terminal, a signal switching means,
It consists of a light emitting element driving means and an information signal identifying means.

A second aspect of the invention includes a control signal input terminal, a control signal light emitting element driving means, an information signal input terminal, and an information signal light emitting element driving means.

[Effect]

In the first invention, when an information signal is input by the information signal identifying means, the signal switching means is switched to strongly drive the light emitting element driving means, and when there is no information signal, the light emitting element driving means is driven weakly.

In the second invention, the information signal and the control signal are transmitted by driving separate light emitting element driving means.

〔Example〕

FIG. 1 shows an embodiment of a light emitting element driving device according to the present invention. In this figure, 1a is an information signal input terminal, and information signal Sa
is input. 1b is a control signal input terminal, and control signal sb
is input. 2a is information signal amplification means, 2b is control signal amplification means, 3a is information signal modulation means, 3b is aJ control signal modulation means, 4 is information signal identification means, and information signal Sa
Determine whether there is an input. 5 is a signal switching means which is switched by the information signal identifying means 4. 6 is a light emitting element driving means, and 7 is a light emitting element.

Next, the operation will be explained.

The information signal Sa to be transmitted is input to the information signal input terminal 1a, and the information signal amplifying means 2a and the information signal modulating means 3a
The signal is inputted to the signal switching means 5 through. Also, the control signal sb
is input to the control signal input terminal 1b, and the control signal amplifying means 2
b and is inputted to the input end of the signal switching means 5 via the control signal modulating means 3b. The information signal identifying means 4 is connected to the output side of the information signal amplifying means 2a, and operates the signal switching means 5 according to the state of the information signal Sa. As a result, depending on the state of the information signal Sa, the information transmission period in which the signal input to the light emitting element driving means 6 is the information signal Sa, and the control signal sb
〒Both cases of a certain link retention period are realized and performed.

In such a configuration, the effective value of the information signal Sa needs to be set to a sufficient value so as not to cause problems with the information to be transmitted, but the control signal sb has a smaller amount of information compared to this. Since the amount is small, the effective value can be set at a lower level. Normally, the signal switching means 5 is set to the control signal side, but when the information signal Sa is input to the information signal input terminal 1a, the information signal identifying means 4 detects this, and the signal switching means 5 switch to the information signal side. As a result, the light emitting element driving means 6 emits light with a sufficient effective value corresponding to the information signal Sa during the transmission period of the information signal Sa, and emits light with a low effective value during the period when the information signal Sa is not present.

FIG. 2 shows an example of a driving waveform of the light emitting element driving means 6. In FIG.

a is a drive waveform during the information transmission period; taking the case of telephone voice as an example, the band is usually about 4KH2, and a signal with a frequency of several 10 to several 100 KHz is used to transmit this. b is a driving waveform in the link holding section, and the purpose of link holding can be sufficiently achieved with a signal of about 100 bits/second at most.

Next, this invention will be explained in detail.

This invention can be applied to various signal transmissions such as data and images, but it is particularly effective when it is necessary to maintain a line even when not making a call, such as with a telephone. This case will be explained using the receiving system shown in FIG. In Figure 3, 11a
11b is photoelectric conversion means for information signals, 11b is photoelectric conversion means for control signals, 12a is demodulation means for information signals, 12b is demodulation means for control signals, 13a is amplification means for information signals, 13b is amplification means for control signals, 14 1 is a link opening/closing means, and 15 is an information output terminal.

Next, the operation will be explained.

In FIG. 3, a photoelectric conversion means 11b for control signals, a demodulation means 12b for control signals, and an amplification means 13b for control signals.
During the information transmission period and the link holding period, the control signal receiving system obtains a reception output for the signal light from the light emitting element 7 driven by the light emitting element driving means 6 shown in FIG. The signal is input to the opening/closing means 14 as a link opening/closing signal. Also, during the information transmission period, the information signal receiving system consisting of the information signal photoelectric conversion means 11a, the information signal demodulation means 12a, and the information signal amplification means 13a receives and outputs information signal light from the transmission system during the information transmission period. issue. The link opening/closing means 14 has an information signal receiving system and an information output terminal 1.
5, and is configured to close between the information signal amplifying means 13a and the information output end 15 when the link opening/closing signal is input. As a result, the communication link is maintained regardless of the presence or absence of the information signal light.

The link opening/closing means 14 functions similarly to a hook switch used to open/close a communication link in an ordinary telephone. In the case of a telephone, it is necessary to keep the hook switch closed regardless of whether a call is being made or not, but according to this invention, for the purpose of simply maintaining a communication link, the hook switch is required for information transmission. Since the driving of the light emitting section is suppressed to a level lower than the effective value, the power consumption of the light emitting section is reduced.

FIG. 4 shows a second embodiment of the light emitting element driving device according to the present invention. Compared to FIG. 1, two light emitting element driving means are provided, 6a for information signals and 6b for control signals,
Correspondingly, a light emitting element 7a for information signals and a light emitting element 7b for control signals are provided, thereby eliminating the need for the signal switching means 5. In this configuration, the information signal light emitting element driving means 6a is driven only when the information signal Sa is present, but the control signal light emitting element driving means 6b is always driven. By having a two-system circuit configuration in this way, circuit control such as signal switching becomes unnecessary.

FIG. 5 shows the operating state of the light emitting element driving means, where C is the drive waveform of the information signal light emitting element 7a, and d is the drive waveform of the control signal light emitting element 7b.

Further, regarding the usage example, that is, the receiving system, the modification shown in FIG. 3 can be considered.

In FIG. 6, the photoelectric conversion section 11 is used in common for control signals and information signals, and the information signal demodulation means 12a can extract only the portion corresponding to the information signal from the photoelectrically converted signal light. It is configured as follows.

FIG. 7 shows an example of the configuration of the information signal identification means 4, in which the information signal input from the identification means input terminal 16 is converted into a DC voltage by the rectifier 17. The comparator 18 determines whether or not this voltage exceeds a threshold level that serves as a reference for the presence or absence of an information signal, and the result is sent to the identification means output terminal 19.
is output to.

Needless to say, the identification means output terminal 19 becomes an input to the signal switching means 5 (FIG. 1).

In addition, in the configuration example shown in Part 2, since various methods can be adopted as a modulation method when converting an electrical signal as information into an optical signal, the modulation means, demodulation means, and amplification means may be changed as necessary. It is sufficient to incorporate it into the configuration, and it is not an essential component for implementing the present invention.

〔Effect of the invention〕

As explained above, the first invention of the light emitting element driving device according to the present invention detects that the information signal is input by the information signal identifying means, switches the signal switching means, and strongly drives the light emitting element driving means. When the information signal is not input, the light emitting element driving means is driven weakly and only the control signal is sent.
Power consumption can be significantly reduced compared to the conventional method in which the light emitting element driving means is uniformly and strongly driven.

Further, the second invention has the advantage that the entire configuration can be simplified since no cutting means is required.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the light emitting device driving device according to the present invention, FIG. 2 is a diagram showing driving waveforms of the light emitting device in FIG. 1, and FIG. FIG. 4 is a block diagram showing an example of the use of the first invention, FIG. 4 is a block diagram showing the configuration of an embodiment of the second invention of the light emitting element driving device according to the invention, and FIG. A diagram showing driving waveforms of a light emitting element, FIG. 6 is a block diagram showing an example of use of the second invention,
FIG. 7 is a block diagram showing an example of the configuration of the information signal identifying means. In the figure, 1a is an information signal input terminal, 1b is a control signal input terminal,
2a is information signal amplification means, 2b is control signal amplification means, 3
a is an information signal modulation means, 3b is a control signal modulation means, 4 is an information signal identification means, 5 is a signal switching means, 6 is a light emitting element driving means, 6a is a light emitting element driving means for information signals, and 6b is a light emission for control signals. Element driving means, 7 is a light emitting element, 7a is a light emitting element for information signals, and 7b is a light emitting element for control signals. Figure 1 Figure 2 Figure 1 Time Figure 3 Figure 4 Figure 5 Figure 1 Figure 6 Figure 7

Claims (2)

[Claims] (1) An information signal input terminal to which an information signal is applied, a control signal input terminal to which a control signal is applied, a signal switching means for switching between the information signal input terminal and the control signal input terminal, and this signal a light emitting element drive means which is switched and connected to the information signal input terminal and the control signal input terminal by a switching means; and when an information signal is input to the information signal input terminal, the signal switching means is connected to the information signal input terminal. 1. A light emitting element driving device comprising: information signal identifying means. (2) a control signal input terminal to which a control signal is applied; a control signal light emitting element driving means operated by the control signal;
A light emitting element driving device comprising: an information signal input terminal to which an information signal is applied; and information signal light emitting element driving means operated by the information signal.