JP2682107B2 - Trapezoidal wave output circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trapezoidal wave output circuit used in a drive / control circuit of a brushless motor used in, for example, audio equipment and video equipment.

2. Description of the Related Art In recent years, motors used in audio equipment, video equipment, etc. have replaced the conventional DC motor having a brush and a commutator with a position detector to detect the rotational position of the rotor for high reliability and long life. The practical use of a so-called brushless motor configured to connect the rotation of the rotor by sequentially conducting the plurality of drive transistors connected in series of the coils of the plurality of phases detected by the above has become popular.

Hereinafter, a trapezoidal wave output circuit in a conventional brushless motor drive / control circuit will be described with reference to the drawings.

FIG. 5 is a circuit connection diagram of a conventional trapezoidal wave output circuit,
(1) is a rectangular wave signal output signal,
The bases of a), the transistor (2b) and the transistor (2c) are connected to the output electrode of the rectangular wave signal output circuit. The emitter of the transistor (2a) is connected to the power supply negative side power supply terminal (39), the collector of the transistor (2a) is connected to the base of the transistor (31) via the resistor (37), and the power source positive side is connected via the resistor (36). It is connected to the side power supply terminal (38). The emitter of the transistor (2b) is connected to the negative power supply terminal (39) of the power source, and the collector of the transistor (2b) is connected to the base of the transistor (28) via the resistor (35) and the resistor (34). Connected to the positive power supply terminal (38). The emitter of the transistor (2c) is connected to the power supply negative side power supply terminal (39), and the collector is a resistor.
It is connected to the base of the transistor (25) via 33 and is connected to the power source positive side power supply terminal (38) via the resistor (32). The bases of the transistors (4) to (10) are commonly connected. The transistors (4) to (1
The emitters of (0) are commonly connected, and the power supply negative side power supply terminal (3
9) Connected to. The collector of the transistor (4) is connected to the same base, and is also connected to the positive power supply terminal (38) of the power source via the constant current source (3).
The transistors (4) to (10) form a current mirror circuit. The base of the transistor (23) is connected to the same collector, and is also connected to the base of the transistor (24), the collector of the transistor (25) and the collector of the transistor (5). The base of the transistor (26) is connected to the collector, and the base of the transistor (27) and the transistor (2
It is connected to the collector of 8) and the collector of the transistor (7). The base of the transistor (29) is connected to the same collector, and is also connected to the base of the transistor (30), the collector of the transistor (31) and the collector of the transistor (9). The emitters of the transistors (23) to (31) are commonly connected and connected to the positive power supply terminal (38). The base of the transistor (17) is connected to the same collector, and is also connected to the collector of the transistor (18) and the collector of the transistor (6). Transistor (1
The base of 9) is connected to the same collector and to the base of the transistor (20) and the collector of the transistor (8). The base of the transistor (21) is connected to the same collector, and is also connected to the base of the transistor (22) and the collector of the transistor (10). The common emitters of the transistors (17) to (22) are connected to the power source positive side power supply terminal (38). The base of the transistor (11) is connected to the same collector, and is also connected to the base of the transistor (12) and the collector of the transistor (18). The collector of the transistor (12) is connected to the power supply negative side power supply terminal (39) via a capacitor (40c) and is also connected to the collector of the transistor (24). The base of the transistor (13) is connected to the same collector, and is also connected to the base of the transistor (14) and the collector of the transistor (20). The collector of the transistor (14) is connected to the power supply negative side power supply terminal (39) via a capacitor (40b) and is also connected to the collector of the transistor (27). The base of the transistor (15) is connected to the collector and
It is connected to the base of the transistor (16) and the collector of the transistor (22). The collector of the transistor (16) is connected to the negative power supply terminal (39) of the power source via the capacitor (40a) and is also connected to the collector of the transistor (30). The common emitters of the transistors (11) to (16) are connected to the power supply negative side power supply terminal (39).

The operation of the trapezoidal wave output circuit in the conventional brushless motor drive / control circuit configured as described above will be described below.

For example, a rectangular wave signal as indicated by V _2a in FIG. 6 is input to the input electrode of the transistor (2a). When V _2a becomes high, the transistor (2a) turns on, causing a voltage drop across the resistor (36), so that the transistor (31) turns on.
At this time, since the current mirror circuit composed of transistors (30) and the transistor (29) is no longer saturated I ₃₀ flows, capacitor (40a), is discharged by I _16. Here, transistor (4) is transistor (10)
, The transistor (21) forms the current mirror circuit with the transistor (22), the transistor (15) with the transistor (16), and the transistor (29) with the transistor (30). Is twice as large as the emitter area of other transistors, the relational expressions of I ₃ = I ₁₆ and I ₃₀ = 2I ₁₆ are established. now,
When V _2a goes low, the transistor (31) turns off and I ₃₀
Current flows through the capacitor (40a), I ₃₀ −I ₁₆ = 2I ₃ −I ₃
= Charged with I ₃ . Therefore, the capacitor (40a) is V
_Charged when _2a is low and discharged when V _2a is high. The corresponding signal waveform is V _40a in FIG.

With respect to the other phases, the rectangular wave signal is converted into the trapezoidal wave by the similar circuit operation. That is, V _2a becomes V _40a becomes V _2b
V _2c is converted to V _40b and V _2c is converted to V _40c .

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the conventional trapezoidal wave output circuit having the configuration as described above, n capacitors are required to convert an n-phase rectangular wave signal into an n-phase trapezoidal wave. . As a result, there is a problem that the cost increases by the number of capacitors and the circuit mounting area increases.

The object of the present invention has been made in view of the above problems in the conventional trapezoidal wave output circuit, and by reducing the number of capacitors to one, the trapezoidal wave output circuit is low in cost and has a small circuit mounting area. Is provided.

Means for Solving the Problems In order to achieve this object, a trapezoidal wave output circuit of the present invention uses a rectangular wave signal of a plurality of phases having different phases as an input signal and outputs either the rising edge or the falling edge thereof. A plurality of edge trigger detection circuits for detecting,
An edge trigger synthesizing circuit that synthesizes the output signal, a charge and discharge circuit that repeats charging and discharging in one capacitor in response to the output signal of the edge trigger synthesizing circuit, an inverting circuit that inverts the operation signal of the charge and discharge circuit, and a charging and discharging circuit. A phase extraction circuit A for extracting one phase from the combined signal of the operation signal of the discharge circuit and the plurality of rectangular wave signals, and one phase from the combined signal of the operation signal of the inverting circuit and the plurality of rectangular wave signals. A phase extracting circuit B, a signal synthesizing circuit for synthesizing an output signal of the phase extracting circuit A and an output signal of the phase extracting circuit B are provided, and a trapezoidal wave is output according to the output signal of the signal synthesizing circuit. It is a thing.

Action The present invention has the above-described configuration, in which one capacitor is repeatedly charged and discharged by the charge / discharge circuit, its operation signal is inverted, and a rectangular wave signal is converted into a trapezoidal wave by synthesizing the signal waveforms of the capacitor. It is intended to suppress the increase in cost due to the increase in the number and reduce the actual phase area of the circuit.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall block diagram of a trapezoidal wave output circuit according to an embodiment of the present invention, in which (71) is a rectangular wave output circuit,
(72a), (72b) and (72c) are edge trigger detection circuits. (73) is an edge trigger synthesis circuit, and (74) is a charge / discharge circuit. (75) is a voltage follower circuit, which complements the output capability of the operation signal of the charge / discharge (74). (76) is an inverting circuit, and (77) is a phase extraction circuit A. (78) is a phase extraction circuit B, and (79) is a signal synthesis circuit.

The operation of the trapezoidal wave output circuit according to the embodiment of the present invention configured as above will be described.

The output signal of the rectangular wave output circuit is V _71a , V _71b , V _{71c in} FIG.
It is. The rising edges of these operation signals are respectively detected by the edge trigger detection circuits (72a), (72b), (72c),
When the operation signal is combined by the edge trigger combining circuit (73), the operation signal waveform becomes V _{73 in} FIG. Next, based on this trigger signal, the charge / discharge circuit (74) repeatedly charges and discharges the capacitor (100). That is, when V ₇₃ is discharged when it is high and charged when it is low, the operation signal waveform of the charge / discharge circuit (74) becomes V ₇₄ . However, the discharge current of the capacitor (100) is sufficiently larger than the charging current, and it has the ability to completely remove the charge of the capacitor (100) when V ₇₃ is high. When the operation signal waveform V ₇₄ of the charge / discharge circuit (74) is inverted by the inversion circuit (76), V ₇₆ is obtained. Next, one phase is extracted from V ₇₄ and V ₇₆ . For example, the V _71a thought the U-phase, V ₇₄
A case where the U phase is extracted from will be described. V _71a and V ₇₄
Is input to the phase extraction circuit A (77), the phase extraction circuit operates as the minimum potential detection circuit, so only when V _71a is high.
Since the signal waveform of V ₇₄ is output, the output signal waveform is V
The _78a, if the V _71b and V-phase and V _71c and W-phase, the V ₇₄ as V _78b is W-phase from V ₇₄ as the V-phase by the same operation
V _78c is extracted. Phase extraction circuit B (78) is also the phase extraction circuit A
Similar to (77), it operates as the lowest potential detection circuit, and V ₇₆ and V
_71a outputs V _77a , V ₇₆ and V _71b outputs V _77b , V
Outputs V _77c from ₇₆ and V _71c . V _78a , V _78b , V _78c and V
_77a , V _77b , and V _77c are combined into a trapezoidal wave by a signal combining circuit (79). FIG. 3 shows a trapezoidal wave synthesis time chart by the signal synthesis circuit (79). For example, U
Consider the case of synthesizing phase V _79a . Signal synthesis path (7
9) operates as a maximum potential detection circuit, and when V _78a and V _77b are input, V _79a which is a U-phase trapezoidal wave is output. By the same operation, V-phase trapezoidal wave V _79b is output from V _78b and V _77c , and W-phase trapezoidal wave V _79c is output from V _78c and V _77a . As described above, it is possible to generate trapezoidal waves of a plurality of phases by charging and discharging one capacitor, so that the cost of the capacitor can be reduced and the circuit mounting area can be reduced.

Next, specific circuit configurations of the charge / discharge circuit, the voltage follower circuit, and the inverting circuit and their circuit operations will be described.

FIG. 7 is a specific circuit connection diagram of the charge / discharge circuit, the voltage follower circuit, and the inverting circuit of the trapezoidal wave output circuit according to the embodiment of the present invention.

Now, the base of the transistor (101) is connected to the output electrode of the edge trigger synthesizing circuit, the collector is connected to the positive power supply terminal (150) of the power source through the constant current source (102) and the base of the transistor (104). Also, the emitter is connected to one end of the capacitor (100), and the emitter is connected to the power supply negative side power supply terminal (151). The capacitor (100)
The other end of is connected to the power supply negative side power supply terminal (151). The capacitor (100) to the constant current source (102) form a charge / discharge circuit.

The constant current source (103) to the resistor (116) form a differential amplifier circuit. The base of the transistor (105) is connected to the emitter of the transistor (112). Capacitor (1
One end of 11) has a collector of a transistor (110), a base of a transistor (112) and a transistor (114).
Is connected to the collector of the transistor (110), the other end is connected to the base of the transistor (112) and one end of the constant current source (115), and plays a role of preventing oscillation of the differential amplifier circuit. . A series circuit of the constant current source (103) to the resistor (116) functions as a voltage follower circuit.

The transistor (120) to the resistor (133) form a differential amplifier circuit. One end of the capacitor (130) is connected to the collector of the transistor (126), the base of the transistor (129) and the collector of the transistor (128),
The other end is connected to the collector of the transistor (129), the base of the transistor (131), and one end of the constant current source (132), and the oscillation of a series of differential amplifier circuits of the transistor (120) to the resistor (133). Plays a preventive role. The base of the transistor (120) is a resistor (137)
Is connected to the base of the transistor (105) through a resistor (136), and is also connected to the emitter of the transistor (131) and one end of the resistor (133) through a resistor (136). The base of the transistor (122) is connected to the power source positive side power feeding terminal (150) via a constant current source (135) and is also connected to the power source negative side power feeding terminal (151) via a resistor (134). There is. The series circuit of the transistor (120) and the resistor (137) constitutes an inverting circuit.

A specific circuit operation of the trapezoidal wave output circuit according to the embodiment of the present invention configured as described above will be described below.

The output signal waveform of the edge trigger synthesis circuit (73) is shown in Fig. 2.
V ₇₃ . Transistor (101) is off when V ₇₃ is low
Therefore, I ₁₀₁ does not flow, and only I ₁₀₂ flows and charges the capacitor (100). When V ₇₃ is high, the transistor (10
1) turns on and I ₁₀₁ flows. At this time, since I ₁₀₁ >> I ₁₀₂ , the capacitor (100) is discharged by I ₁₀₁ . Therefore, the terminal voltage signal of the capacitor (100) becomes V _{74 in} Fig. 2.

The constant current source (103) to the resistor (116) form a differential amplifier. Imaginary short is established and V ₇₄ = V
₁₀₅ , and the constant current source (103) to the resistor (116) work as a voltage follower circuit.

The transistor (120) to constant current source (132) form a differential amplifier. V ₁₂₀ = V ₁₂₂ due to imaginary short circuit
It is. V ₁₂₂ ＝ R ₁₃₄・ I ₁₃₅ ＝ V _74max./2 I
Set the current value of ₁₃₅ and the resistance value of R ₁₃₄ . Where V
_74max means the maximum value of the potential level of the second FIG V _74. V
_{When 105} ≥ V ₇₆ , R from the emitter of the transistor (112)
_Since current flows into the resistor (133) through ₁₃₇ and R ₁₃₆ ,
If R ₁₃₇ = R ₁₃₆ = _RA , then (V ₁₀₅ −V ₁₂₀ ) / _RA = (V ₁₂₀
-V ₇₆ ) / _RA . V ₁₀₅ = V ₇₄ and V ₁₂₀ = V ₁₂₂ = V
_{74max by. / 2, V 74 -V 74max} . / 2 = V 74max. / 2-V 76 ...
... Next, when V ₁₀₅ ≤ ₇₆ , a current flows in the opposite direction to the above, (V ₇₆ −V ₁₂₀ ) / _RA = (V ₁₂₀ −V ₁₀₅ ) / _RA , and V _{74max./2− V 74 = V 76 -V 74max.} / 2 becomes ....

・ According to both equations, the output signal waveform of the inverting circuit is shown in Fig. 2.
A signal waveform like V ₇₆ is obtained by folding back the waveform of V ₇₄ with 1/2 of the maximum value of V being the center. V ₇₆ and V _71a , V _71b , V
_71c is input to the phase extraction circuit A (77), and V _77a , V _77b , and V _77c are obtained as its output signals. V ₇₄ and V _71a , V _71b , V _71c
Is input to the phase extraction circuit B (78) and as its output signal
Get V _78a , V _78b , V _78c . V _77a , V _77b , V _77c and V _78a , V
_78b and _V78c are input to a signal synthesizing circuit (79), and V _79a , V _79b and V _79c of FIG. 3 are obtained as output signals thereof.

As described above, a trapezoidal wave of a plurality of phases can be created by charging and discharging one capacitor, so that the cost of the capacitor can be reduced and the circuit mounting area can be reduced.

As is apparent from the above description, according to the present invention, one capacitor is charged / discharged by the charging / discharging circuit, the operation signal thereof is inverted by the inverting circuit, the terminal voltage signal of the capacitor and the operation signal of the rectangular wave output circuit. Phase extraction circuit B from the combined signal of
One phase is extracted by the phase extraction circuit A from the composite signal of the operation signal of the inverting circuit and the operation signal of the rectangular output circuit, and the operation signal of the phase extraction circuit A and the phase extraction circuit B are extracted. Since a multi-phase trapezoidal wave can be output from the combined signal with the operation signal by the signal combining circuit, the cost increase due to the increase in the number of capacitors can be suppressed, and the excellent effect of reducing the circuit mounting area can be obtained. .

[Brief description of the drawings]

FIG. 1 is an overall block diagram of a trapezoidal wave output circuit according to an embodiment of the present invention, and FIG. 2 is a rectangular wave output circuit of a trapezoidal wave output circuit according to an embodiment of the present invention, an edge trigger synthesis circuit, a charge / discharge circuit, and an inversion circuit. Circuit and phase extraction circuit A
And an output signal waveform diagram of the phase extraction circuit B. FIG. 3 is an output signal waveform diagram of the phase extraction circuit A and the phase extraction circuit B and the signal synthesis circuit of the trapezoidal wave output circuit in one embodiment of the present invention.
FIG. 4 is a specific circuit connection diagram of a charge / discharge circuit, a voltage follower circuit and an inverting circuit of a trapezoidal wave output circuit according to an embodiment of the present invention. FIG. 5 is a circuit connection diagram of a conventional trapezoidal wave output circuit. The figure is a signal waveform diagram of the rectangular wave signal output circuit and the charge / discharge circuit of the trapezoidal wave output circuit. (1) …… Square wave signal output circuit, (40a), (40b),
(40c) …… Capacitor, (71) …… Square wave output circuit,
(72a), (72b), (72c) ... edge trigger detection circuit, (73) ... edge trigger synthesis circuit, (74) ... charge / discharge circuit, (75) ... voltage follower circuit, (76) ...
... Inversion circuit, (77) ... Phase extraction circuit A, (78) ... Phase extraction circuit B, (79) ... Signal synthesis circuit.

Continuation of front page (56) Reference JP 62-293986 (JP, A) JP 2-97294 (JP, A) JP 64-39284 (JP, A) JP 1-206893 (JP , A) JP-A-63-213492 (JP, A)

Claims (1)

(57) [Claims] 1. A plurality of edge trigger detecting circuits for detecting a rising edge or a falling edge of a plurality of rectangular wave signals having different phases as input signals, and an output signal of the edge trigger detecting circuit. An edge trigger synthesizing circuit for synthesizing, a charging / discharging circuit for charging / discharging one capacitor in response to an output signal of the edge trigger synthesizing circuit, an inverting circuit for inverting an output signal of the charging / discharging circuit, and an output of the charging / discharging circuit. A phase extracting circuit B for extracting each phase from the signal and the plurality of rectangular wave signals, and a phase extracting circuit for extracting each phase from the output signal of the inverting circuit and the plurality of rectangular wave signals. Extraction circuit A
A signal combining circuit for combining the output signal of the phase extracting circuit A and the output signal of the phase extracting circuit B, and a trapezoidal wave output configured to output a trapezoidal wave according to the output signal of the signal combining circuit. circuit.