JPS5864652A - Noninformation position detecting circuit - Google Patents

Abstract

PURPOSE:To facilitate the IC-implementation of a circuit, and to obtain high detection time precision, by detecting a noninformation position of a recording medium digitally. CONSTITUTION:When an input H is applied to the terminal 3 of a noninformation position detecting circuit corresponding to a fast-forwarding or fast rewinding mode, the output of an NAND circuit 4 varies from H to L after the time when the 2nd-stage and 3rd stage output levels of a counter 2 both go to H passes from the time when the output of an oscillating circuit part 1 is applied to the counter 2. An NAND circuit 6 is applied with an output L through an inverter 5, so its output level is at L invariably. Therefore, the output level of an NAND circuit 7 varies depending upon the output of the circuit 4 and an output pulse appears at an output terminal 8 the same time later.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-information position detection circuit for detecting a gap between at least two pieces of information recorded in a time series on a recording medium such as a tape used in a tape recorder, that is, a pointless position. The present invention relates to a circuit that detects a position where no information exists between two pieces of information during recording, fast-forwarding, or fast-reversing.

For example, when two or more songs are recorded on a tape used in a tape recorder or the like, it is often necessary to fast forward or rewind the tape in order to play back a desired song.

To do this, it is necessary to correctly detect unrecorded sections between songs and control the running or stopping of the tape. Furthermore, since the running speed of the tape is different during playback, fast forwarding, and fast reversing, it is necessary to take this difference into account when correctly detecting unrecorded portions.

Conventionally, in order to detect such unrecorded parts, a first time constant circuit with a large time constant and a second time constant circuit with a small time constant were used.
The first time constant circuit is installed in a switchable relationship with the first time constant circuit, and during playback when the tape running speed is low, the first time constant circuit with a large time constant is used to detect unrecorded parts, while when the tape is fast forwarding when the tape running speed is high. Alternatively, when rewinding, a method has been adopted in which a second time constant circuit with a small time constant is used to detect unrecorded portions.

However, when attempting to incorporate a circuit that makes full use of the conventional method using such a time constant circuit into a semiconductor integrated circuit (IC), the number of circuit components that must be handled as external components to the IC increases. In ICs where the number of external lead wires is limited, this not only becomes a major inconvenience, but also causes a decrease in detection accuracy due to variations in these external components.

The present invention has been made with the intention of eliminating the disadvantages of the conventional methods described above, and by digitally detecting the non-information position of the recording medium, it facilitates the integration of the circuit into an IC, and also achieves high detection accuracy. The present invention provides an information-free position detection circuit that can obtain time accuracy. The configuration and operation of the non-information position detection circuit of the present invention will be described below with reference to the drawings.

The figure is a diagram showing a configuration example of a non-information position detection circuit according to an embodiment of the present invention, and includes an oscillation circuit section 1 that oscillates at a predetermined frequency f, for example, 10 T-type flip-flops FF.
1 to FF10, the output of the oscillation circuit section 1 is input to the first stage T-type flip-flop FF1, and the counter 2 is reset when the recording medium has no information. Predetermined stage of the counter (FF2
．． The output of FF3) and the detection time switching signal input to terminal 3 are input to the NAND circuit 4, the output of a predetermined stage (FF2) of the counter 2, the final stage (FF1o), and the detection time switching signal sound is inverted by the inverter 6. The NAND circuit 6 includes a NAND circuit 6 to which the signal is inputted, and a NAND circuit 7 to which the outputs of the NAND circuits 4 and 6 are inputted. Note that 8 is an output terminal, and the detection time switching signal input to terminal 3 is at a low level ("L") during playback or recording.
”), and on the other hand, it becomes a high level (“H”) during fast forwarding or fast reversing.

When an H'' input is applied to the terminal 3 of the non-information position detection circuit shown in the figure and configured as described above in response to fast forwarding or fast reversing, the following circuit state is established.

That is, if we take the time when the output levels of the second and third stages of the counter 2 are both H'', then t=e/f(
seconds). Therefore, the output of the NAND circuit 4 changes from "H" to L when 67 seconds have elapsed from the time t0 when the output of the oscillation circuit section 1 was added to the counter 2. Inverter 6 inverts the "H" input applied to terminal 3 and adds a "L" output, so its output level is always "-L".Therefore, the outputs of NAND circuits 4 and 6 are The output level of the NAND circuit 7 coupled to the input terminal is NA
It changes depending on the output of the ND circuit 4, and also applies to the output terminal 8. An output pulse is generated after a time of 6/seconds has elapsed.

On the other hand, when a -"L" input is applied to the terminal 3 in response to the reproduction operation, one input of the NAND circuit 40 is fixed at "L", so its output level is fixed at "H". On the other hand, the outputs of the second and tenth stages of the counter 2 and the "H" output obtained by inverting the "'L# input" by the inverter 6 are added to the input of the NAND circuit 6. By the way,
The 2nd stage output and the 10th stage output start from time t□ (
29+2) When 71 seconds have passed, both “H”
Therefore, the output level of the NAND circuit 6 changes from "H" 0 to 'L' after (29+2)/f seconds from time t, and at the same time, an output pulse is sent to the output terminal 8. occurs.

Note that in the illustrated circuit, the second stage output of the counter 2 is coupled to both the 0 and NAND circuits 4 and 6, but by adopting this configuration, the width of the output pulse generated at the terminal 8 can be adjusted to match both operations described above. It remains constant under various conditions.

In the circuit using the present invention that operates in this manner, the counter 2 is reset in two different ways: when there is a signal input from the tape;
If a silent part is detected and this state continues for a predetermined period of time, the reset of counter 2 will be canceled when the signal input stops, and from this point on, the oscillation circuit section will be reset. Start counting input pulses from . As described above, a long detection time is set during playback when the tape running speed is slow, while a short detection time is set during fast forwarding or fast reversing when the tape running speed is high.

As is clear from the above explanation, according to the tape position detection circuit of the present invention, it is possible to set two types of detection time, long and short, with a single circuit, and moreover, the circuit involved in time setting has a digital circuit configuration. Therefore, it is easy to integrate everything into an IC. Also, the detection time setting is
Since this is done based on the oscillation output signal frequency output from the oscillation output signal frequency, the setting accuracy, that is, the detection accuracy can be significantly improved.

Although the above explanation has been made using the example of detecting a position with no information on a tape used in a tape recorder, the present invention can be used to detect a position with no information on a recording medium such as a VTR tape or a video disc to achieve the same effect. I can do it.

[Brief explanation of the drawing]

The figure is a block diagram showing the configuration of a non-information position detection circuit according to an embodiment of the present invention. 1...Oscillation circuit section, 2...Counter,
3...Terminal to which the detection time switching input is applied;
4゜6.7...NAND circuit, 5...
Inverter, 8...Output terminal, FF1 to FF10
...T-type flip-flop.

Claims (3)

[Claims] (1) It is constructed by connecting an oscillation circuit section that oscillates at a predetermined frequency and a frequency divider in multiple stages, and the reset is released at the vanishing point of the information recorded on the information recording medium, and the output signal from the oscillation circuit section is a terminal for inputting a switching signal whose level changes depending on the scanning speed of the information recording medium; a logic circuit section that operates according to an output, and a frequency division ratio of the counter changes according to a change in the level of the switching signal, and a detection time changes. (2) The logic circuit section includes an inverter that inverts the phase of the switching signal, and a first AND circuit whose input terminal is connected to the output generation point of the first frequency divider in the counter and the terminal into which the switching signal is input. and a second AND circuit whose input terminal is connected to a second frequency divider in the counter and an output generation point of the inverter;
The information-free position detection circuit according to claim 1, characterized in that it is constituted by a third AND circuit whose input terminal is connected to the output generation points of the first and second AND circuits. . (3) The first and second AND circuits are both coupled to the output of a third frequency divider located at a stage before the first and second frequency dividers. An information-free position detection circuit according to claim 1, paragraph 2 of the patent.