JPH04334200A - On-vehicle stereo reproducing device - Google Patents

Abstract

PURPOSE:To obtain a proper sound field in response to a seated position. CONSTITUTION:A seated position is detected by an encoder 18. A head position arithmetic operation circuit 16 calculates a position of a head based on the seated position. A control signal arithmetic operation circuit 14 outputs a delay control signal and an amplitude control signal based on the position of the head. A sound field adjustment circuit 12 delays a music signal based on the delay control signal and adjusts the sound volume based on the amplitude control signal. Thus, a proper sound field is reproduced in response to the seated position.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle stereo system, and particularly to sound field correction thereof.

0002

2. Description of the Related Art Some stereo reproduction apparatuses are used by being mounted in a car. This makes it possible to listen to musical tones stored on CDs, tapes, etc., FM broadcasts, etc. in the vehicle interior.

[0003] Incidentally, the interior of a vehicle is a special sound field space compared to a normal interior. In addition, since the driver's seat is on the right side, the driver is not seated in the center with respect to the left and right speakers. As a result, when the musical sounds emitted from the left and right speakers reach the driver's ears, the volume, phase, etc. of the sounds will be different between the right and left speakers.

[0004] The volume can be adjusted using a balance volume provided in the stereo playback device. However, the phase difference cannot be adjusted. Therefore, a stereo playback device is sometimes provided with a sound field adjustment circuit. This sound field adjustment circuit generates a reverse phase difference, etc. based on a phase difference, etc. that will occur in advance. This makes it possible to eliminate the phase difference between the left and right sides when musical sounds reach the driver's ears.

[0005]

[Problems to be Solved by the Invention] However, conventional in-vehicle stereo systems have the following problems. In conventional sound field correction, correction is performed assuming that the listener is sitting in a predetermined seat position. However, in many modern cars, the seat position, etc., can be changed, so the seat position, etc., is not necessarily constant. For this reason, a problem has arisen in that appropriate sound field correction cannot be obtained depending on the seat position or the like. In particular, in a small space such as a vehicle interior, changes in the sound field due to changes in location are even more pronounced.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and provide an in-vehicle stereo system that can perform appropriate sound field correction regardless of the seat position or the like.

[0007]

[Means for Solving the Problems] An in-vehicle stereo device according to the present invention includes a seat state detector for detecting the state of the seat;
Head position calculation means for calculating the head position of a seated person based on the output of the seat state detector; and control signal calculation means for outputting a delay control signal and an amplitude control signal based on the output of the head position calculation means. It is characterized by having the following.

[0008]

[Operation] The seat condition detection means detects the seat condition such as the position of the seat and the angle of the backrest. The head position calculation means calculates the head position of the seated person based on the output of the seat position detection means. The control signal calculation means calculates and outputs a delay control signal and an amplitude control signal based on the calculated head position. The sound field adjustment means adjusts the delay and amplitude based on the delay control signal and the amplitude control signal. This creates an appropriate sound field depending on the head position.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the overall configuration of an in-vehicle stereo system according to an embodiment of the present invention. CD2, tape deck 4
, tuner 6, etc., are selected by a selection circuit 8 and applied to an amplifier 10. amplifier 10
The musical tone electric signal amplified in the sound field adjustment circuit 12
is input.

On the other hand, the seat is provided with an encoder 18 that detects the fore-and-aft position of the seat and the reclining angle of the seat. Based on the output of the encoder 18, the head position calculation circuit 16 calculates the position of the head. Further, the control signal calculation circuit 14 calculates and outputs a delay control signal and an amplitude control signal based on the calculated head position. The sound field adjustment circuit 12 controls the delay time and amplitude based on this delay control signal and amplitude control signal.

The output of the sound field adjustment circuit 12 is transmitted to the speaker 20.
, 22. That is, the speakers 20 and 22 output musical tones with a delay time and volume corresponding to the head position.

For example, assume that the head and the speaker are in a positional relationship as shown in FIG. When the head position is at H1, the distance LL1 from the left speaker FL is longer than the distance LR1 from the right speaker FR. For this reason, if the left and right speakers FR and FL produce sound at the same volume, the sound from the right will become louder, which is unnatural. Therefore, the control signal calculation circuit 14 outputs an amplitude control signal according to the distance LR1 and the distance LL1 to set an appropriate volume.

[0013] Furthermore, when the head moves to H2 and H3, the ratio of distance LR2 and distance LL2 and distance LR3,
The ratio of distance LL3 changes. Therefore, set the appropriate volume accordingly.

Although FIG. 6 describes the movement of the head in a plane, the movement of the head in the height direction is also taken into account when adjusting the volume.

[0015] Furthermore, if the distance between the head and the speaker is different, the phase of the arriving sound will be shifted. For example, at position H1 in FIG. 6, distance LL1 is smaller than distance LR1.
is longer, so the arrival time of the musical tone is different. This results in
A phenomenon occurs where the left and right musical tones are out of phase. therefore,
The control signal calculation circuit 14 outputs a delay control signal according to the distance LR1 and the distance LL1, and sets an appropriate delay time. This makes the arrival times of the left and right musical tones equal.

Further, when the head moves to H2 and H3, the ratio of distance LR2 and distance LL2 and distance LR3,
The ratio of distance LL3 changes. Therefore, an appropriate delay time is set accordingly.

In controlling the delay time, the heightwise position of the head is also taken into consideration, as in the case of volume adjustment.

FIG. 2 shows a state in which an in-vehicle stereo apparatus according to an embodiment of the present invention is installed in a car. A front right speaker FR and a front left speaker FL are provided at the front, and a rear right speaker RR and a rear left speaker RL are provided at the rear. Further, the driver's seat 30 is provided with an encoder 32 that detects its longitudinal position. An encoder 34 is also provided to detect the angle of the backrest 30a.

An example of the configuration of the head position calculation circuit 16 and the control signal calculation circuit 14 is shown in FIG. Front/rear position encoder 3
The output from 2 is taken into the CPU 42 via the input port 36. Similarly, the output from angle encoder 34 is input to CPU 42 via input port 38. The CPU 42 calculates the head position 46 based on the outputs of both encoders 32 and 34.

In this embodiment, as shown in FIG. 4, the outputs of the encoders 32 and 34 are divided into three levels, and the head position is divided into nine regions from P-1,-1 to P1,1. are doing. The CPU 42 has both encoders 32
, 34, it is calculated to which region the head belongs.

Next, the CPU 42 calculates the delay time and volume of each channel based on the calculated head position. At this time, since both the delay time and volume are affected by reflected sound, etc., it is preferable to previously store values actually measured for each vehicle as a table.

Based on the calculated delay time, the CPU 42 provides delay control signals C1 to C4 to each channel. Similarly, based on the calculated volume, amplitude control signals C5 to C
8 to each channel.

FIG. 5 shows a block diagram of the sound field adjustment circuit 12. The musical tone signals of each channel FR, FL, RR, and RL are once converted into digital signals in A/D converters 50, 52, 54, and 56. This digital signal is then applied to digital delay circuits 58, 60, 62, and 64. Digital delay circuits 58, 60, 62, 64
In , delays are performed based on delay control signals C1 to C4. Furthermore, this signal is provided to digital volume adjustment circuits 66, 68, 70, and 72. In the digital volume adjustment circuits 66, 68, 70, and 72, amplitude control (volume adjustment) is performed based on amplitude control signals C5 to C8.

As described above, the digital signals adjusted for each channel are sent to the D/A converters 74, 76, 78,
80 into an analog signal, and the speaker FR,
Given to FL, RR, and RL. Therefore, sounds with equal volume and no phase difference arrive from the speakers FR, FL, RR, and RL. That is, a preferable sound field is formed.

In this embodiment, the circuit shown in FIG. 5 is constructed from a logic circuit, but a digital signal processor (DSP) may also be used.

[0026]

[Effects of the Invention] The in-vehicle stereo playback device according to the present invention is provided with a seat condition detector for detecting the condition of the seat, and calculates the head position of the seated person based on the output of the seat condition detector. The present invention is characterized in that it includes a control signal calculation means that outputs a delay control signal and an amplitude control signal depending on the head position.

[0027] Therefore, an appropriate sound field can be formed depending on the head position.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the overall configuration of an in-vehicle stereo playback device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which an in-vehicle stereo playback device according to an embodiment of the present invention is attached to a car.

FIG. 3 is a diagram showing details of a head position calculation circuit and a control signal calculation circuit.

FIG. 4 is a diagram showing a region of the head position.

FIG. 5 is a block diagram showing details of a sound field adjustment circuit.

FIG. 6 is a diagram showing the relationship between speakers and head positions.

[Explanation of symbols]

12...Sound field adjustment circuit 14...Control signal calculation circuit 16...Head position calculation circuit 18, 32, 34...encoder

Claims (1)

[Claims] 1. A musical tone output device that outputs a musical tone electrical signal for each channel, which delays the musical tone electrical signal based on a control value of a delay control signal, and adjusts the amplitude of the musical tone electrical signal based on a control value of an amplitude control signal. A seat condition detector for detecting the condition of a seat in an in-vehicle stereo playback device equipped with a sound field adjusting means for changing the sound field, and a speaker provided for each channel and converting a musical tone electric signal from the sound field adjusting means into a musical tone. ,
Head position calculation means for calculating the head position of a seated person based on the output of the seat state detector; and control signal calculation means for outputting a delay control signal and an amplitude control signal based on the output of the head position calculation means. An in-vehicle stereo playback device comprising: