JPS6390091A - Time display circuit for magnetic recording and reproducing device or the like - Google Patents

Abstract

PURPOSE:To display a correct time by using correct data obtained before the generation of an error to display the time at the time of generating the error. CONSTITUTION:A time information signal read out from a rotary drum 5 through a head amplifier 6 is demodulated by a circuit 9 in a processing circuit 8 and applied to a gate 11 and a transmission error detecting circuit 10 transmits '1' bit to the gate 11 when the inputted time information is an error or transmits '0' bit in case of correct information. The gate 11 selects and outputs either one of the inputs and interrupts a demodulating signal and sends '1' continuous bits to a microcomputer 12 when the output is '1', or in case of the '0' output, sends the modulating signal. When the '1' continuous bits are inputted, the microcomputer 12 sends the stored time information to a display circuit 13, and in case of generating an error, sends the correct data obtained before the generation of the error to display the correct time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a time table circuit for magnetic recording and reproducing devices, etc., and is particularly applicable to digital audio tape recorders (DAT) and the like.

(Prior Art) Conventionally, there is a method for recording PCM signals on a magnetic tape using a rotating head such as a video tape recorder (VTR). In this system, subcode signals are used for various controls, displays, and the like. Among these, this subcode signal is used to display time in real time, but if an error occurs when reading the subcode signal, accurate time display will not be possible, so conventionally a complicated error correction circuit was required. I was using it.

(Problems to be Solved by the Invention) As described above, the conventional system uses a complicated error correction circuit, resulting in a large memory capacity and high cost. Therefore, if you try to display the time as described above without using a complicated error correction circuit, there is a problem that even if an error occurs when reading the subcode signal, it cannot be corrected, and therefore the time cannot be displayed accurately. was there. In particular, if an error occurs in a digital time display, the current display
There was a problem in that the time displayed was completely different from the displayed time. For example, as shown in Figure 3 (al), although the current display is 09:31:05, an error occurred in the next reading, resulting in a completely different time display of 10:10:1O, and the next If the reading is correct, the display will return to the correct time 0!]:31:06.

(Means for Solving the Problems) A time display circuit of a magnetic recording M generation device or the like according to the present invention records a time information signal as a subcode signal on a magnetic tape, and when the magnetic tape is reproduced. , a magnetic recording and reproducing device configured to detect the time information signal and display the time, comprising: a reading means for reading the time information signal; and a demodulating time information signal output from the reading means. and an adjustment means that receives the time information signal and outputs a bit of rlJ if the input time information signal is incorrect, and outputs a "0" bit if it is correct. and a transmission error detection means for selecting either the output of the demodulation means or the output of the transmission error detection means, and when a bit of "1" is input from the transmission error detection means, the demodulation is performed. The demodulated signal from the demodulating means is blocked and continuous bits of "1" are outputted, and when a bit of "0" is input from the transmission error detecting means, the demodulated signal from the demodulating means is outputted. When the output from the transmission error detection means and the transmission error detection means is the bit "0", time is displayed based on the demodulated signal from the demodulation means, and the output from the transmission error detection means is the bit "11". In this case, the display means is provided with a display means for displaying the time based on the time information stored immediately before.

(Operation) The time information signal read by the reading means is demodulated by the demodulation means and output to the selection means at the next stage. On the other hand, the transmission error detection means outputs an "l" bit if the input time information signal is incorrect, and outputs a "0" bit from bin 1 to the next stage selection means if it is correct. .

The selection means selects and outputs either the output from the demodulation means or the output from the transmission error detection means, and when the rlJ bit is input from the transmission error detection means, If the demodulated signal from the demodulating means is blocked and continuous bits of "1" are input, and if the transmission error detecting means inputs a bit of "10", the demodulated signal from the demodulating means is inputted to the next stage. Output to a subcode microcomputer (hereinafter referred to as subcode microcomputer). In the subcode microcomputer, when the output from the signal processing circuit is "1" in continuous focus, the time information stored immediately before is output to the next stage display circuit. In this way, if an error occurs, the time will not be displayed incorrectly, and the time will be displayed using the correct data before the error occurred, making it appear as if the correct time is being displayed. .

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of a search system of a magnetic recording/reproducing apparatus according to the present invention.

In the figure, 1 is a search switch, 2 is a system microcomputer (hereinafter referred to as system microcomputer),
3 is a motor control circuit, 4 is a motor, 5 is a rotating drum, 6
is a head amplifier, 7 is a comparison circuit, 8 is a signal processing circuit, 1
0 is a transmission error detection circuit, 12 is a subcode microcomputer,
13 is a display circuit. The signal processing circuit 8 is a demodulation circuit 9
and eight OR gates 1-11, 11... (however, only one OR gate is shown in the drawing).

Next, the operation of the search system of the magnetic recording/reproducing apparatus having the above configuration will be explained.

In the figure, when a search switch 1 is turned on, a search signal is output from a system microcomputer 2 to a motor control circuit 3. The motor control circuit 3 controls the motor 4 based on this search signal, and rotationally drives the rotating drum 5 and the like. A magnetic head (
The subcode signal recorded on the magnetic tape (not shown) is read by the head amplifier 6 (not shown).
After being amplified by the comparator circuit 7, the signal is synchronized with the clock and is input to the next stage signal processing circuit 8.

On the other hand, if a ROM is used as the transmission error detection circuit 10, and 10-bit data that satisfies the modulation rules is input, it will output a bit of "0", and if 10-bit data that does not satisfy the modulation rules is input, it will output a bit of "0". Data is written so as to output a "1" pin I.

Here, one of the modulated subcode datums 0 to A9 (0101010101) satisfying the modulation rule as shown in FIG. 2 is sent to the transmission error detection circuit 10 from the signal processing circuit 8.
When 0-bit data is input, the transmission error detection circuit 10 outputs a "0" bit, and modulation subcode datums 0 to A9 (000111
When the 10-bit data (1111) is input, the transmission error detection circuit 10 outputs a bit of "1".

Therefore, when the bit "0" is output from the transmission error detection circuit 10, the eight OR gates I to 11 added to the signal processing circuit 8 become irrelevant to the data flow, and the demodulation circuit 9 The −8-converted demodulated data is output to the subcode microcomputer 12.

After the subcode signal is exchanged with the subcode microcomputer 12, the data is converted by the display circuit 13.
The correct time is displayed on the display section (not shown). Also,
When the bit of rlJ is output from the transmission error detection circuit 10, eight OR gates 1 added to the signal processing circuit 8
The output of 1 is all 11'', and the subcode microcomputer 12
is output to. When data in which all bits are rlJ is input in advance to the subcode microcomputer 12, numbers 0 to 9 are input.
A function is added to convert the data into a so-called hexadecimal FF instead of converting it into a hexadecimal FF, and then outputting the correct data before an error occurs.

As a result, all bits are set to "1" in the subcode microcomputer 12 regardless of the demodulated data output from the demodulation circuit 9.
Since data is input to the display circuit 13, correct data before an error occurs is input to the display circuit 13. For example, as shown in Figure 3 (bl), the current display is 09:
If it is 31:05, even if an error occurs in the next reading, 09:31:05 will be displayed in the same way, and if the next reading is correct, the correct time will be displayed as 09:31:06. .

(Effects of the Invention) As explained above, according to the present invention, if the correct time is displayed, even if an error occurs in the next reading, the previous correct time is displayed as is, so it appears as if the correct time. can be displayed as shown below.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a search system of a magnetic recording/reproducing apparatus according to the present invention, FIG. 2 is a diagram showing an example of input and output of a transmission error detection circuit, and FIG. 3(a). (b) is a diagram showing an example of time display. ■...Search switch 2...System microcomputer 3...Motor control circuit 4...Motor 5...Rotating drum
6... Hesodo amplifier 7... Comparison circuit 8
... Signal processing circuit 9 ... Demodulation circuit 10 ... Transmission error detection circuit 11 ... OR gate 12 ... Subcode microcomputer 13 ...
display circuit

Claims (1)

[Claims] 1) A time information signal is recorded as a subcode signal on a magnetic tape, and when the magnetic tape is played back, the time information signal is detected and time is displayed. The magnetic recording/reproducing device comprises: a reading means for reading the time information signal; a demodulating means for demodulating the time information signal output from the reading means; transmission error detection means that outputs a bit of "1" when the time information signal is incorrect, and outputs a bit of "0" when the signal is correct; It selects and outputs one of the outputs, and when a bit of "1" is input from the transmission error detection means, it blocks the demodulated signal from the demodulation means and outputs consecutive bits of "1". a selection means configured to output a demodulated signal from the demodulation means when a bit of "0" is input from the transmission error detection means; and an output from the transmission error detection means is set to "0". ” bit, the time is displayed based on the demodulated signal from the demodulation means, and when the output from the transmission error detection means is the “1” bit, the time is displayed based on the time information stored immediately before. What is claimed is: 1. A time display circuit for a magnetic recording/reproducing device, etc., comprising display means for performing the following.