JPH031621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement detection circuit for detecting displacement such as the end of a magnetic tape of a tape recorder or rotation stoppage.

[Conventional technology]

In a tape recorder, the end of recording or playback, or the end of magnetic tape forwarding or rewinding, is determined by detecting the arrival of the end of the magnetic tape. The arrival of the end of the magnetic tape is detected by the rotation of the rotating part stopping. To detect this, a detection element such as a Hall sensor is used, and the detection output is integrated by an integrating circuit, and the presence or absence of rotation is determined based on the presence or absence of DC output.

Conventionally, the integrating circuit installed in such a rotation detection circuit requires a capacitor, and when a detection circuit including such a capacitor is constructed using a semiconductor integrated circuit, the semiconductor chip becomes large, and if the capacitor is Even when connecting externally, terminals (pins) must be formed for this purpose on the semiconductor device, which complicates the configuration and
It has drawbacks such as low detection accuracy.

[Problem that the invention seeks to solve]

Therefore, this invention aims to simplify the circuit configuration by removing the integrating circuit using a capacitor, and
An object of the present invention is to provide a displacement detection circuit which enables reduction of the semiconductor chip size when constructed from a semiconductor integrated circuit and improves accuracy in detecting rotational displacement.

[Means for solving problems]

That is, the displacement detection circuit of the present invention includes an encoder 6 that detects the magnetic flux of the magnetic pole (magnetic pole plate 4) attached to the rotating part 2 and converts the rotational displacement of the rotating part into pulses, and a clock signal generator 8 that generates a clock pulse having a higher frequency than the pulse; a gate circuit (AND circuit 10) that takes the logical product of the clock pulse generated by this clock signal generator and the pulse generated by the encoder; A shift register 12 is formed by cascading a plurality of flip-flop circuits 14 ₁ , 14 ₂ , _{14 3} . and an exclusive OR which generates a pulse representing the rotational displacement in response to each pulse generated by the flip-flop circuit together with the pulse generated by the gate circuit.
It is composed of 16.

[Effect]

In the displacement detection circuit of the present invention, a gate circuit performs the logical product of the encoded pulses generated by the encoder in response to the displacement of the rotating part and the clock pulses generated by the clock signal generator. By adding pulses to each flip-flop circuit of the shift register, and adding each pulse generated by the flip-flop circuit together with the pulse generated by the gate circuit to the exclusive OR, an output representing the rotational displacement of the rotating part is obtained from the exclusive OR.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of a displacement detection circuit according to the present invention, and this embodiment is constructed as a rotation detection circuit for detecting the end of a magnetic tape of a tape recorder.

In FIG. 1, a magnetic pole plate 4 on which one or more NS magnetic poles are arranged is attached to a rotating part 2 as a displacement detection part of a rotating table of a tape reel.
An encoder 6 that encodes the rotation of the magnetic pole plate 4 is installed.

Corresponding to the encoder 6, a clock signal generator 8 is installed which generates a clock pulse having a higher frequency than the encoded pulse.

The encoded pulse generated by the encoder 6 according to the amount of rotation of the rotating part 2 or its displacement, and the clock pulse generated by the clock signal generator 8 are connected to a gate circuit that detects the simultaneous presence of both pulses. It is added to the AND circuit 10.

The clock pulse and the AND output of the AND circuit 10 are applied to the shift register 12. This shift register 12 includes a plurality of flip-flop circuits (hereinafter referred to as FF circuits) 14.
₁ , 14 ₂ , 14 ₃ . . . 14 _o are connected in series.

The input pulse of this shift register 12 and each
The output pulses of the FF circuits 14 ₁ , 14 ₂ , 14 _{3 .} . . 14 _o are applied to the exclusive OR 16, and the displacement detection output is taken out from the output terminal 18.

Based on the above configuration, its operation will be explained with reference to FIG.

In FIG. 2, A is the output of encoder 6, B
is the output clock pulse of the clock signal generator 8,
C shows the output of the AND circuit 10, and D shows the output pulse of the exclusive OR 16. and,
The sections t ₁ , t ₃ and t ₅ are rotation stop sections, and the sections t ₂ and t ₄ are rotation sections, and the encoder 6 generates or stops encoding pulses corresponding to each section.
In interval t ₁ , encoder 6 generates a low (L) level output due to the relationship with the position of the magnetic pole, and in interval t ₅ , the relationship is opposite to interval t ₁ , and encoder 6 generates a high (H) level output. ing.

The output of the encoder 6 and the clock pulse shown in FIG. 2B are logically multiplied by an AND circuit 10.
The AND output shown in FIG. 2C is applied to shift register 12.

That is, the output pulse of the AND circuit 10 is FF
The input pulses of the FF circuit 14 ₁ , each FF circuit 14 ₂ to 14 o-1 and the FF circuit _{14 o} are sequentially shifted in synchronization with the clock pulse by the circuits 14 ₁ , 14 ₂ , 14 _{3 .} . . 14 _o. As a result, the final output pulse of the exclusive OR 16 is applied to the exclusive OR 16, as shown by "0" and "1" at the bottom of Fig. 2C. A displacement detection output is generated which is at H level when a displacement occurs in the part, and at L level when there is no displacement. In this case, the displacement detection output is the FF of the shift register 12.
A delay is generated depending on the number of stages in the circuits 14 ₁ to 14 _o , but depending on the state of the detection output, displacement such as rotation detection can be detected. It can be detected from rotating parts such as tables.

Such a displacement detection circuit does not include an integrating circuit that requires a capacitor, so when constructed using a semiconductor integrated circuit, it is possible to reduce the size of the semiconductor chip and improve detection accuracy.

Although the shift register 12 and the exclusive OR 16 are installed in the embodiment, for example, when detecting the end of a magnetic tape from the rotation of the reel stand of a tape recorder, the number of rotations of the reel stand is determined according to the remaining amount of the magnetic tape. Since the output pulse width of the AND circuit 10 increases accordingly, it is also possible to detect the rotating state or the stopped state. Therefore, displacement detection is possible even without the shift register 12 and exclusive OR 16.

Further, in the embodiment, the rotation detection of the reel stand of a tape recorder has been described, but the present invention can also be used to detect displacement other than rotation, and similar effects can be expected.

〔Effect of the invention〕

As explained above, according to the present invention, since an integrating circuit that requires a capacitor is not used, the circuit configuration can be simplified by reducing the number of parts, and the displacement detection accuracy can be improved. When constructed using a semiconductor integrated circuit, the semiconductor chip can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the displacement detection circuit of the present invention, and FIG. 2 is an explanatory diagram showing its operating pulses. 2...Rotating part as a displacement detection part, 4...Magnetic pole plate, 6...Encoder, 8...Clock signal generator, 10...AND circuit as a gate circuit,
12...Shift register, 14 ₁ , 14 ₂ , 14 ₃
...14 _o ... flip-flop circuit, 16 ... exclusive OR.

Claims (1)

[Claims] 1. An encoder that detects the magnetic flux of a magnetic pole attached to a rotating part and converts the rotational displacement of the rotating part into pulses, and this encoder generates a clock pulse having a higher frequency than the generated pulses. A clock signal generator, a gate circuit that takes an AND of the clock pulse generated by the clock signal generator and the pulse generated by the encoder, and a plurality of flip-flop circuits connected in cascade, and the gate circuit generates the flip-flop circuit in the first stage receives the pulses generated by the flip-flop circuit, and receives the pulses generated by the flip-flop circuit together with the shift register to which the clock pulse is applied to the reset input of the shift register and the gate circuit to express the rotational displacement. A displacement detection circuit characterized by comprising: an exclusive OR that generates a pulse;