JPH09214430A - Infrared ray transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the infrared ray transmitter with an excellent transmission characteristic. SOLUTION: The infrared ray transmitter 10 is used in combination with a transmitter 2 that sends a sum signal SMIX between a signal SFM modulated by a video signal and signals LFM, RFM modulated by audio signals in terms of an infrared ray 3. The transmitter 10 is provided with an infrared ray photosensor 11 that receives the infrared ray 3 and provides an output of the sum signal SMIX, a circuit 12 with a filter characteristic to extract the signals LFM, RFM modulated by the audio signal from an output signal of the infrared ray photosensor 11 and an infrared ray emitting element 14 emitting an infrared ray 19 whose luminous intensity is controlled by the signals LFM, RFM modulated by the audio signal extracted from the circuit 12 with this filter characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared transmission device.

[0002]

2. Description of the Related Art AV equipment mainly used at home includes those which transmit video signals and audio signals by infrared rays.

FIG. 4 shows a usage state of such a device. For example, a video signal (composite color video signal) and an audio signal reproduced by the VTR 1 are supplied to an infrared transmitter 2 and converted into infrared rays 3. Sent.

In this case, for example, as shown in FIG. 5, the video signal SS has a carrier frequency of 11.5 at the sync chip.
The carrier frequency at MHZ and white peak is converted to the FM signal SFM with 13.5 MHZ. The left and right channel audio signals L and R have a carrier frequency of 2.3 MHz.
And 2.8 MHz FM signals LFM and RFM.

Then, these signals SFM, LFM and RFM are added and frequency-multiplexed, and by the addition signal SMIX, the magnitude of the current (instantaneous value) supplied to the infrared LED.
Is controlled, and the emission intensity of infrared rays is controlled according to the instantaneous value of the addition signal SFM.

When the infrared ray 3 is received by the infrared receiver 4, the original video signal SS and audio signals L and R are taken out. That is, in the receiver 4, the infrared photosensor receives the infrared light 3 to extract the signal SMIX, and the FM signals SFM, LF
M and RFM are separated, and the separated FM signals SFM and LF
The original video signal SS and audio signals L and R are demodulated from M and RFM.

Then, these signals SS, L, R are supplied to the TV receiver (monitor receiver) 5 to output images and sounds.

Therefore, according to this infrared transmission system, it is possible to reproduce the VTR 1 without connecting the VTR 1 and the receiver 5 with a cord, which is convenient. For example, when the VTR 1 is a video camera with a built-in VTR, the captured contents can be easily viewed on a large screen.

By the way, in the above environment, if the speaker device 6 or the headphone 7 having the same receiving circuit as the receiver 4 is prepared within the radiation range of the infrared rays 3, the speaker device 6 or the headphone 7 can
It is possible to listen to the audio by the audio signals L and R.
That is, the cordless speaker device 6 or the headphones 7 allows the user to listen to the sound, and the viewing position and the degree of freedom can be expanded.

However, in actuality, in order to improve the utilization efficiency of the infrared rays 3 with respect to the receiver 4, the radiation characteristics of the infrared rays 3 are given directivity, and the radiation range thereof is, for example, as shown by the solid line in FIG. It is stereoscopically about ± 30 ° around its radial axis (front axis). Therefore, even if the speaker device 6 or the headphone 7 is prepared to listen to the sound, the listening position is considerably limited.

Therefore, as a first method, the transmitter 2
In addition to the infrared LED that transmits the addition signal SMIX, another infrared LED that transmits only the FM signals LFM and RFM of the audio signals L and R is added, and the infrared radiation range of the added infrared LED is shown in FIG. As shown by the broken line in Fig. 1, a method of setting a wide angle range is considered. In other words, if you do this, by the added infrared LED,
The speaker device 6 or the headphones 7 can be used in a wider range.

As a second method, as shown in FIG. 7, the audio signals L and R obtained by the receiver 4 are
A method is considered in which the infrared light 9 is supplied to another transmitter 8 to form an infrared light 9 similar to the infrared light 3, and the infrared light 9 is transmitted to the speaker device 6 or the headphones 7. Therefore, also in the case of this method, the sound can be heard in a wider range as compared with the case of only the infrared ray 3.

[0013]

However, in the case of the first method, the closer the speaker device 6 or the headphone 7 is to the transmitter 2, the stronger the infrared light received by the speaker device 6 or the headphone 7 becomes. The closer to the device 2, the better the S / N and distortion rate of the audio signals L and R. Therefore, in order to obtain better sound quality, it is necessary to approach the transmitter 2, that is, to move away from the receiver 5.

When the speaker device 6 or the headphone 7 is located in front of the receiver 5, the speaker device 6 or the headphone 7 is located in an asymmetrical position with respect to the transmitter 2, so that a difference in sound quality occurs between the left side and the right side. Sometimes.

Further, in the case of the second method, both the infrared rays 3 and the infrared rays 9 are received depending on the position of the speaker device 6 or the headphones 7. Then, the FM signals LFM and RFM transmitted by the infrared ray 3 and the infrared ray 9 are transmitted.
Since there is usually a difference (error) in the carrier frequency between the FM signals LFM and RFM transmitted by the speaker device 6, a beat is generated due to the difference, and this causes beat noise to cause the speaker device 6 or the headphones 7 to operate. Will be heard from.

The present invention is to solve the above problems.

[0017]

Therefore, in the present invention, the addition signal of the signal modulated by the video signal and the signal modulated by the audio signal is used in combination with the transmitter for transmitting by infrared rays. And an infrared photosensor that receives the infrared light and outputs the addition signal, and a circuit having a filter characteristic that extracts a signal modulated by the audio signal from the output signal of the infrared photosensor. An infrared transmission device having an infrared light emitting element that emits infrared light whose emission intensity is controlled by a signal modulated by the audio signal extracted by the filter characteristic circuit.

Therefore, infrared rays from the transmitter are relayed by the infrared transmission device, and at this time, the audio signal is retransmitted without being returned to the baseband signal.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10 indicates a form of a circuit of an infrared transmission device according to the present invention. The infrared transmission device 10 receives infrared rays 3 from a transmitter 2 and adds them. The infrared photosensor 11 that outputs the signal SMIX and the FM signals LFM and RF of the added signal SMIX
And a bandpass amplifier 12 that selectively amplifies M. Furthermore, the infrared transmission device 10 includes a plurality of infrared LEDs 14 that output infrared rays 19 and a bandpass amplifier 1.
2 has a drive amplifier 13 for driving an infrared LED 14 by FM signals LFM and RFM. The bandpass amplifier 12 can be configured by combining a bandpass filter having an occupying band of the FM signals LFM and RFM as a pass band and an amplifier.

FIGS. 2A and 2B show one form of the appearance and structure of the infrared transmission device 10. For example, a cylindrical body 22 is formed on the upper surface of a disk-shaped base 21 made of a plastic material. It is vertically formed integrally with the table 21. A long window 23 is formed on the peripheral surface or the side surface of the cylinder 22 in the vertical direction, and a plurality of infrared LEDs 14 are vertically arranged inside the cylinder 22 so as to face the window 23.

In this case, the radiation characteristics of each infrared LED 14 are three-dimensionally centered on the radiation axis (front axis).
It has a wide angular range of about 30 ° or more, and is provided so that all radiation axes are in the same direction (parallel). Although not shown, the window 23 is provided with an optical filter that allows the infrared rays 3 to pass therethrough.

Further, a box body 24 is provided on the top of the cylindrical body 22 so as to be rotatable in a direction to be described later. In addition, for example, a circular window 25 is provided on the peripheral surface or the side surface of the box body 24.
A parabolic reflector 26 is provided on the box 24 so as to face the window 25, and the infrared photosensor 11 is provided at the focal position. In this case, the box body 24 is provided so that the direction of the central axis of the reflecting mirror 26 can be changed vertically and horizontally within a predetermined range.

An optical filter (not shown) that allows the infrared rays 19 to pass therethrough is provided at the front of the reflecting mirror 26. Further, for example, the bandpass amplifier 12 is provided inside the base 21, and a power supply circuit necessary for operating the circuits 11 to 14, for example, a battery (not shown) is provided.

In such a structure, when the infrared transmission device 10 is used, it is arranged as shown in FIG. 3, for example. That is, the infrared photo sensor 11 is the transmitter 2
The orientations of the infrared transmission device 10 and the reflecting mirror 26 are set so that the infrared rays 3 from the infrared rays are received and the infrared rays 19 from the infrared LEDs 14 are received by the speaker device 6 or the headphones 7.

Then, the infrared ray 3 from the transmitter 2 is received by the receiver 4 to extract the video signal SS and the audio signals L and R, and the signals SS, L and R are supplied to the receiver 5.

At this time, a part of the infrared rays 3 is received by the infrared photosensor 11, and the addition signal SMIX is output from the infrared photosensor 11, and this signal SMIX is output.
Among them, the FM signals LFM and RFM are selected and amplified by the bandpass amplifier 12, and the addition signal (LFM + RFM) of the FM signals LFM and RFM is supplied to the drive amplifier 13.
Then, in the drive amplifier 13, the infrared LED 1
The magnitude (instantaneous value) of the drive current supplied to 4 is controlled by the addition signal (LFM + RFM) from the bandpass amplifier 12, and the emission intensity of the infrared ray 19 from the infrared LED 14 follows the instantaneous value of the signal (LFM + RFM). Controlled.

Then, the infrared rays 19 are transmitted to the speaker device 6
Alternatively, since it is received by the headphone 7, the audio signal L,
You can hear the voice from R.

In this way, according to the infrared transmission device 10, the infrared rays 3 from the transmitter 2 are relayed and supplied to the speaker device 6 or the headphones 7, so that the existing speaker device 6 can be used in a wider range. Alternatively, headphones 7 can be used.

In this case, in particular, according to the infrared transmission device 10 described above, the infrared transmission device 10 is connected to the image receiving device 5.
If you place it near the
The light reception level of the is increased and the sound quality is improved, and the screen also looks large, and the image shift between the screen and the sound quality when the viewing position is changed is reduced. Further, the usable range of the speaker device 6 or the headphones 7 can be set as a range centered on the receiver 5. Furthermore, the speaker device 6 or the headphones 7
Is located in front of the receiver 5, the infrared transmission device 1
Since the position is symmetrical with respect to 0, there is no difference in sound quality between the left side and the right side.

The FM signals LFM and RFM transmitted by the infrared ray 19 are added signals SMI when the infrared ray 3 is received.
The signals separated from X, the signals LFM and RFM transmitted by the infrared ray 3 and the signal LFM transmitted by the infrared ray 19,
There is no deviation in the carrier frequency from the RFM. Therefore, the speaker device 6 or the headphones 7
However, even if both the infrared rays 3 and the infrared rays 19 are received, no beat is generated due to the shift of the carrier frequency, and no beat noise is heard.

Further, by providing a reflecting mirror 26 to the infrared photo sensor 11, the infrared photo sensor 1
Since the light receiving sensitivity of 1 can be increased,
It is possible to improve the S / N and the distortion rate of the audio signals L and R transmitted by. In addition, the reflecting mirror 26
Also acts as a light shielding plate, so that it is possible to prevent the infrared rays 19 sent from the infrared LED 14 from being received by the infrared photosensor 11 and causing oscillation.

Further, as shown in FIG. 1, since the circuit structure is simple and no special parts are required,
Cost can be reduced. When the device 1 is an audio device, the infrared ray 3 from the transmitter 2 can be relayed by the infrared transmission device 10 and transmitted to the speaker device 6 or the headphone 7. Therefore, the speaker device 6 or the headphone 7 can be transmitted. The range in which 7 can be used cordlessly can be expanded.

[0033]

According to the present invention, the existing speaker device or headphones can be used in a wider range. Then, in this case, if the infrared transmission device is placed near the receiver, for example, when the receiver approaches the receiver, the infrared reception level increases and the sound quality is improved,
The screen also looks large, and the image shift between the screen and the sound quality when the viewing position is changed is reduced. Further, the usable range of the speaker device or the headphones can be set to a range centered on the receiver.

Further, when the speaker device or the headphone is located in front of the image receiver 5, the position is symmetrical with respect to the infrared transmission device, so that there is no difference in sound quality between the left side and the right side. Further, there is no deviation in carrier frequency between the signal transmitted by the retransmitted infrared ray and the signal transmitted by the original infrared ray. Therefore, the speaker device or headphones
Even if both the retransmitted infrared light and the original infrared light are received, a beat due to the carrier frequency shift is not generated, and beat noise is not heard.

Further, by providing a reflecting mirror for the infrared photo sensor, the light receiving sensitivity of the infrared photo sensor can be increased, so that the S / N and distortion rate of the audio signal transmitted by infrared rays are improved. can do. Further, since the reflecting mirror also functions as a light shielding plate, it is possible to prevent the infrared rays transmitted from the infrared LED from being received by the infrared photosensor and causing oscillation.

Further, the circuit structure is simple and
Since no special component is required, the cost can be reduced. When the device of the signal source is an audio device, infrared rays from the transmitter can be relayed by an infrared transmission device and transmitted to a speaker device or headphones. Therefore, the speaker device or headphones can be used cordlessly. The range that can be done can be expanded.

[Brief description of drawings]

FIG. 1 is a system diagram showing one embodiment of the present invention.

FIG. 2 is an external view showing one embodiment of the present invention.

FIG. 3 is a diagram showing a usage state of one embodiment of the present invention.

FIG. 4 is a diagram showing one form of a usage state of the device so far.

FIG. 5 is a frequency spectrum diagram of signals transmitted and received.

FIG. 6 is a diagram showing directional characteristics of a transmitter.

FIG. 7 is a diagram showing one form of a usage state of the apparatus so far.

[Explanation of symbols]

10 ... Infrared transmission device, 11 ... Infrared photo sensor,
12 ... Band pass amplifier, 13 ... Drive amplifier, 14
… Infrared LED, 26… Reflector

Claims (5)

[Claims] 1. An infrared type transmission device used in combination with a transmission device for transmitting, by infrared rays, an addition signal of a signal modulated by a video signal and a signal modulated by an audio signal, said infrared ray transmitting device. An infrared photosensor that receives the light and outputs the addition signal, a circuit having a filter characteristic that extracts a signal modulated by the audio signal from the output signal of the infrared photosensor, and the audio that is extracted by the circuit having the filter characteristic. An infrared transmission device comprising: an infrared light emitting element which emits infrared light whose emission intensity is controlled by a signal modulated by the signal. 2. The infrared type transmission device according to claim 1, wherein the signal modulated by the video signal is an FM signal, the signal modulated by the audio signal is an FM signal, and the FM signal by the audio signal is used. The signals are an FM signal modulated by an audio signal of the left channel and an FM signal modulated by an audio signal of the right channel, and in the addition signal, an FM signal of the video signal and an FM signal of the audio signal. Is an infrared transmission device that is frequency-multiplexed. 3. The infrared transmission device according to claim 2, further comprising a light shielding means for preventing the infrared light transmitted from the infrared light emitting element from being received by the infrared photosensor. 4. The infrared transmission device according to claim 3, wherein the light shielding means is a parabolic reflector, and the infrared photosensor is provided at a focal position thereof. 5. The infrared transmission device according to claim 4, wherein the angle between the center axis of light reception of the infrared photosensor and the center axis of radiation of the infrared light emitting element can be changed. .