GB2309352A

GB2309352A - A reversed phase audio crossover circuit

Info

Publication number: GB2309352A
Application number: GB9601163A
Authority: GB
Inventors: Kuang Chih Hsu
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-08-28
Filing date: 1996-01-20
Publication date: 1997-07-23
Anticipated expiration: 2016-01-20
Also published as: CN2234165Y; CA2183385A1; DK89496A; GB9601163D0; GB2309352B

Description

TITLE: A REVERSED PEASE AUDIO FREQUENCY DIVIDING CIRCUIT This invention relates to a reversed phase audio frequency dividing circuit.

The use of a speaker can properly amplify a sound source. A speaker generally has a plurality of resistive-capacitive filters for filtering audio frequency passing through, therefore unpleasant and noisy audio frequency can be removed. In order to improve sound quality, several audio response units are installed for responding different audio frequency. When several audio response units are installed, suitable filter means must be used to remove unqualified audio frequency from passing through the respective audio response units. Figure 1A shows a regular audio filter designed for removing low frequency, in which a plurality of capacitors C1, C2, C3 are respectively connected in series to the audio input terminal IN, and a plurality of resistors R1 are respectively connected in parallel to each capacitor.

Figure 2 shows the response curves of the audio frequency before and after passing through the filters, in which the response curve Aa is the original audio frequency response curve; the response curve Bb is the audio frequency response curve obtained from that filtered through C1; the response curve Cc is the audio frequency response curve obtained from that filtered through C1 and C2; the response curve Dd is that audio frequency response curve obtained from that filtered through C1, C2, and C3.

Figure 1B shows a regular audio filter designed for removing high frequency, in which a plurality of inductors L1, L2, L3 are respectively connected in series to the audio input terminal IN, and a plurality of capacitors C1, C2, C3 are respectively connected in parallel to each inductor. From Figure 2, we can see that the gain of output power is greatly reduced when the sound source is filtered through several filters. Because the gain of output power will be greatly reduced if the sound source is filtered through several filters, the original power of the sound source must be relatively increased so that the output power of the speaker can be increased. However, because there is a limitation on the output power of regular audio equipment, it is difficult to compensate the loss of gain due to the operation of filters.

This invention is directed to a reversed phase audio frequency dividing circuit.

According to the present invention, undesired high and low audio frequency is eliminated when positive phase audio frequency offsets negative phase audio frequency, therefore the sound quality of each sound discrimination speaker is improved.

Other objects of the invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists of features of constructions and method, combination of elements, arrangement of parts and steps of the method which will be exemplified in the constructions and method hereinafter disclosed, the scope of the application of which will be indicated in the claims following.

FIG. 1A is a circuit diagram of a low frequency filter circuit according to the prior art; FIG. 1B is a circuit diagram of a high frequency filter circuit according to the prior art; FIG. 2 is the response curves of the audio frequency before and after passing through the filters of the low frequency filter circuit of FIG. lA; FIG. 3A is a circuit diagram of a low-pass filter according to the present invention; FIG. 3B is an alternate form of the low-pass filter of FIG. 3A; FIG. 4 is an audio frequency response curve obtained from the low-pass filter of FIG. 3; FIG. 5A is a circuit diagram of an intermediate-pass filter according to the present invention; FIG. 5B shows an alternate form of the intermediate-pass filter of FIG. 5A; and FIG. 6 is an audio frequency response curve obtained from the intermediate-pass filter of FIG. 5.

For purpose to promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings. Specific language will be used to describe same. It will, nevertheless, be understood that no limitation of the scope of the invention is thereby intended, such alternations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated herein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring to FIG. 3A and 4, sound source input terminal is connected to the master sound coil Lm of the speaker by a main circuit. A sub-circuit is connected in parallel to the main circuit. The sub-circuit comprises a high-pass capacitor Cx at the front end, which permits limited intermediate and high frequency to pass, and an auxiliary sound coil Lx of reversed phase relative to the master sound coil Lm at the rear end. The output terminal of the auxiliary sound coil Lx and the output terminal of the master sound coil Lm are connected in series to grounding terminal. Because the auxiliary sound coil Lx provides an intermediate/high frequency sound signal of reversed phase, it offsets intermediate/high frequency sound waves from the main circuit. Therefore, the area defined by B, C, and D in FIG. 4 offsets the relative upper triangular area above A and C, and the audio frequency wavelength curve can extend to D. This arrangement completely eliminates high frequency sound effect. This low-pass filter further comprises a variable resistor R1 for regulating the volume of the output signal of the sub-circuit. The low-pass filter can be arranged in another form as shown in FIG. 3B.

Referring to FIG. 5A and 6, the design of the intermediate-pass filter is similar to that of the aforesaid low-pass filter. The main circuit is connected between the sound source input terminal IN and the master sound coil LM. A capacitor C1 is installed in the main circuit of the intermediate-pass filter to remove low frequency from inputted sound source. A high-pass capacitor Cx is connected in parallel to the input end of the main circuit for letting high frequency pass. An auxiliary sound coil Lx of reversed phase and a variable resistor R1 are connected in series to the master sound coil LM. Therefore, high frequency and low sound frequency are removed from the sound source when the sound source passes through the intermediate pass filter, and only the intermediate frequency sound are is left (see Figure 6). Furthermore, the intermediate-pass filter can be arranged in another form as shown in Figure SB.

Referring to FIGS. 4 and 6 again, the design of the reversed phase audio frequency dividing circuit causes little loss of the gain. Therefore, sound effect output can be greatly increased, and sound quality can be greatly improved. Because the filter uses only an auxiliary sound coil of reversed phase to match with different capacitors Cl, Cx, the structure is simple, and the installation is easy.

The invention is naturally not limited in any sense to the particular features specified in the forgoing or to the details of the particular embodiment which has been chosen in order to illustrate the invention.

Consideration can be given to all kinds of variants of the particular embodiment which has been described by way of example and of its constituent elements without thereby departing from the scope of the invention. This invention accordingly includes all the means constituting technical equivalents of the means described as well as their combinations.

Claims

CLAIMS:

1. A reversed phase audio frequency dividing circuit comprising a master circuit connected between the input terminal and sound coil of a speaker, and a sub-circuit connected in parallel to said master circuit, said master circuit comprising filter capacitor means for removing audio frequency of predetermined range, said sub-circuit comprising capacitor means for removing audio frequency of predetermined range, and a reversed phase coil connected with the sound coil of said speaker to a grounding terminal.

2. The reversed phase audio frequency dividing circuit as claimed in Claim 1 wherein the sound coil of said speaker has an intermediate section connected to a grounding terminal.

3. The reversed phase audio frequency dividing circuit as claimed in Claim 1 wherein said sub-circuit further comprises a variable resistor for regulating the volume of the audio frequency passing through.