JPH02202105A - Amplifier with high efficiency - Google Patents

Abstract

PURPOSE:To obtain a noiseless amplifier and to reduce a manufacturing cost by setting a high output voltage being always outputted by current capacity in which a high voltage coil is miniaturized relatively at an output state with almost a low output voltage, and outputting the high output voltage when input is increased by the fluctuation of a load. CONSTITUTION:While the output currents of the high voltage coils S21 and S22 with low current capacity and high impedance are decreased gradually under high output VH and are lowered gradually, the output currents of low voltage coils S11 and S12 with high current capacity relatively are increased under low output VL. Therefore, when a current on a VH+line A1 is decreased and a voltage is decreased, the current of a VL+line B1 flows via a diode 6-1, and the current in which those currents are added functions at an output terminal C1. Similarly, the current in which the reduced current of a VH-line A2 and the current large in capacity of a VL-line B2 are added finctions at an output terminal C2. Thus, the high output voltage VH and the low output voltage VL of an amplifier with high efficiency function in parallel, and also, since the diode is energized via the approach of the voltages on both terminals of a semiconductor, such energizing outputs no noise.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a high efficiency amplifier having two power supplies, high output VH and low output VL. The present invention relates to high-efficiency amplifiers that can be specified according to characteristics and extract large dynamic power, while also enabling cost reduction and miniaturization of power amplifiers.

Power amplifiers that use two power sources are often used in audio amplifiers in general, and stereo amplifiers in particular. By detecting the level of the speaker output, switching between high output VH and low output VL and supplying it to the amplifier, large power can be obtained when necessary.

[Prior Art] In the conventional example shown in FIG. 6, the output side of a switch circuit that inputs a high-output VH power supply and a low-output VL main power supply is connected to an amplifier.
When a one-shot multivibrator further connected to a vH/V switching level setting comparator connected to the amplifier and speaker lever receives a switching signal from the comparator, it triggers a switch circuit and applies a high output voltage to the amplifier. supply and extract high power. If the amplifier output is lower than the switching level, the amplifier is set to a low output voltage V,
If the time constant during switching is set to O in order to improve the H/VL switching efficiency, the switching noise during shifting may interfere with AM broadcasting, etc. (Figure 7). (See A).

Therefore, as shown in FIG. 7B, in order to reduce switching noise, a one-shot multi-vibration radar is often used and put into practical use with an appropriate time constant, for example, about 450 m5ec. However, noise cannot be removed sufficiently.

In addition, when continuous waves are input, these amplifiers continue to operate at the high output voltage V,4, so durable components necessary for high power must be used, such as power transformers, power rectifier circuits, etc. Since devices such as capacitors and output transistors have high power specifications, the cost is only about 20% lower than that of comparable high-output high-end amplifiers, and high efficiency using VH/V and switching operation is achieved. The merits of the amplifier are substantially insufficient, and the characteristics of a high efficiency amplifier are extremely poor. In other words, high-efficiency amplifiers that can replace high-end amplifiers are currently expensive because they require many components in the switching circuit, and the power supply path to the power amplifier, which carries a large current, is also complicated. This only leads to worsening of distortion in the amplifier due to wiring.

[Problems to be solved by the invention] Utilizing the low-output VL operation and high-output operation of a high-efficiency amplifier, high-output operation that eliminates switching noise during changing operations and sufficiently corresponds to the burst waveform of a music signal. I can/will make you do something. For example, I
In the NF standard, the burst waveform consists of 20 large-amplitude waves, 480 small-amplitude waves, and 20 repeated large-amplitude waves, with an amplitude difference of 20 dB (based on IKHz sine waves). There is. An amplifier that can handle this can achieve advanced signal processing with little distortion in music sounds with wide amplitude fluctuations and large amplitude differences, communication calls, and the like.

In order to confirm this, we examined continuous waves that require dynamic power and their practical value in terms of their effectiveness, and found that it is not always the case that the same high power output from the beginning to the end is absolute. I came to the conclusion that it is not necessary. It was confirmed that although the effect of waveform distortion due to clipping may be clearly recognized at the beginning, the effective recognition weakens in the latter half, and does not impair practical effectiveness.

As long as the deterioration in signal quality due to clipping does not impair other useful values, such as reducing the attractiveness of the sound quality, elucidation of these conditions will enable the design and manufacture of full-scale high-efficiency amplifiers.

[Means for solving the problem] A transformer is constructed of a low voltage winding with a large current capacity and a high voltage winding with a relatively small current capacity, and the low output voltage VL from the low voltage winding and the High output voltage v from high voltage winding
H is output to the output terminal via at least a diode, and as the high output voltage vH decreases, the current of the low output voltage VL flows through the diode to supply the added current to the output terminal. High-efficiency amplifiers can be noiseless and reduce manufacturing costs.

[Operations and Examples] Low voltage winding Sl constituting the power transformer I shown in Figs. 1 to 3
l, S12 has a sufficient current capacity fii (X2'), the high voltage winding S2L S22 combined with this has a current capacity W
Since a relatively small winding k(XI) is used, the current can be reduced even if a high voltage vH is constantly output. For example, the wire diameters of the high voltage windings S21 and S22 are set to 0.
There is a specification example of 32 mm, low voltage winding Sll, 512 and 0.8 mm.

The voltage output of the power transformer 1 is rectified by the high voltage/low voltage rectifier diode 2.3 and converted to direct current, and then the ripple is sufficiently removed by ripple filter capacitors 4-1, 4-2 and 5-1.5-2. and two systems of DC voltage VH (AJ
;A2), VL (B1;B2).

In addition, high output V) 4 VH tenen line A1 low output VL ■1
A diode 6-1 is provided between the + line Bl and the vH- line A.
A diode 6-2 is provided between the VL- line B2 and the VL- line B2.

This creates a high impedance high voltage winding 521. with a small current capacity (XI). The output current of S22 is high output v
, 4 to gradually lower the voltage, while the output currents of the low voltage windings Sll and S12 with relatively large current magnitudes ffi (X2) are relatively large under low output VL. , VH terminal line Al current becomes small and the voltage drops, V t-wire line Bl passes through diode 6-1.
, and these additional currents act on the output terminal CI. The same goes for the diode 6-2, and the output terminal C2 has v.
An additional current of the reduced current in the H-line A2 and the large current in the VL-line B2 acts.

In this way, the high output voltage vH and low output voltage VL of the high efficiency amplifier act in parallel, and since the diode conducts through the proximity of the voltages at both terminals of the semiconductor, this conduction does not generate switching noise. .

For example, high output V□ is AC60V, low output ■ is AC3
In the case of 0V, although the high output voltage vH is always working, the voltage of the output terminal ClC2 is about 30V, and when the negative side changes and the high output voltage V□ is input, the initial large current is 60V and the output terminal ci, The large voltage fluctuation from 30V to 60V that acts on c2 is not due to the switching operation of the diode 6-1, but rather due to the voltage rise on the one terminal side of the diode 6-1 and the voltage drop on the ten terminal of the diode 6-2. This means that the conduction operation has stopped, and it is possible to prevent the occurrence of switching noise as in the conventional case.

Figure 2 shows one way to improve the fall when the output voltage changes from vH to ■.
2 and diodes 6-1 and 6-2, respectively. Switching between conducting and non-conducting diodes becomes smoother.

FIG. 3 shows another example in which double-wave rectification is performed in place of half-wave rectification using high-voltage rectifier diodes 3-1 and 3-2 to eliminate ripple after rectification.

The circuit configuration after double-wave rectification is the same as the circuit example above, and the same vH
, VL are output.

Usually, IMF dynamic power is used to display practical power. This dynamic power has a waveform close to that of a music signal as shown in FIG. During operation with this IHF burst waveform, the conditions for keeping the high output voltage VH for continuous input of 20 waves are approximately 20 wsec, the capacity and weight of the high voltage windings S21 and S22, and the high voltage capacitor 5-1. The present invention can be reliably implemented by selecting .5-2. The effect of the electric R voltage on the human power waveform is as shown in the figure.

Further, for continuous wave manual power, the voltage changes from VF4 to VI□ in the middle of the continuous wave as shown in FIG. That is, in this example, the output voltage decreases from the high output voltage V l-1 to the low output voltage VL after 20 m5ec. This makes it possible to utilize dynamic power without requiring high-power specifications for transformers and other parts of application circuits that use them.

This amplifier operation does not impair the sound effect as follows.

For example, large-amplitude cymbal waves are reproduced as high-quality high-fidelity sound without clipping. In addition, the high output voltage V ) 4 facilitates clip-free playback for signals with diverse speech voices and large differences in amplitude, such as in the case of communication devices.
Noiseless dynamic power can be easily utilized using the high efficiency amplifier of the present invention. Even if the output voltage changes to a low output voltage VL in the middle of the input continuous wave and the output amplitude becomes small, as mentioned above, a large amplitude with plenty of margin is output at the beginning of the wave, so a fresh high-pitched sound captures the auditory senses. The clear sound quality is at a high level.

[Effect of the invention] Due to the relatively small current capacity of the high voltage winding S21%S22, the high output voltage V4. As the current and voltage decrease, the output state is approximately low output voltage VL, and when the human power increases due to load fluctuations, the high output voltage V8 can be output and large dynamic power can be extracted, so it is small and inexpensive. Excellent high-power amplifiers can be manufactured using power transformers, power filter capacitors, and power amplifier devices. Furthermore, the circuit is very simple, and adjustment work can be omitted. In particular, since the high output voltage VI4 and the low output voltage VL are coupled in parallel with a diode, switching noise does not occur when the output fluctuates, making it a noiseless amplifier that does not interfere with AM broadcasting. And is it big? Since there is no routing of the part where tiffl flows, there is no deterioration of distortion due to variations in wiring.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing one embodiment of the present invention, Fig. 2 is an electric circuit diagram showing another embodiment, and Fig. 3 is an electric circuit diagram showing still another embodiment with some parts omitted. Figure 4 is IH
The F burst human power waveform and the working voltage of the present invention are shown, FIG. 5 shows the working voltage for an input continuous wave, FIG. 6 is a block diagram showing a conventional example, and FIGS. 7 (A) and (B) are the conventional FIG. 3 is an explanatory diagram showing output switching timing. 1 Nidorance 2: Low voltage rectifier 3: High voltage rectifier 4.5: Ripple capacitor 6: Diodes S21, S22: High voltage winding SL1% S12: Low voltage winding Applicant Nippon Marantz Co., Ltd.

Claims (1)

[Claims] 1) A transformer is constructed of a low voltage winding with a large current capacity and a high voltage winding with a relatively small current capacity, and the low output voltage V_L from the low voltage winding and the high voltage winding from the high voltage winding are The output voltage V_H is outputted to the output terminal through at least a diode, and as the voltage of the high output voltage V_H decreases, the current of the low output V_L flows through the diode to supply the added current to the output terminal. A high-efficiency amplifier characterized by: