JPS5888850A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To decrease the number of terminals of a control microcomputer used in a magnetic recording/reproducing device, by detecting the presence or absence of a miserasion preventing bar with a microcomputer terminal which detects the loading/unloading state. CONSTITUTION:If miserasion preventing bar exists, a detecting switch 18 for presence or absence of the miserasion preventing bar is turned off. Then the input terminals B and C of a control microcomputer used in a magnetic recording/reproducing device depend on the state of a cassette loading and unloading detecting switches 16 and 17 respectively. While in case no miserasion preventing bar exists with the switch 18 turned on, a video recording command switch 19 is operated to set a computer input terminal O at a low level. Thus the terminals B and C are set at a low level respectively regardless of the state of the switches 16 and 17. As a result, no input terminal is required for the detecting signal for presence/absence of the miserasion preventing bar. Accordingly, the number of terminals required for the control microcomputer of a magnetic recording/reproducing device are decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing device in which the number of terminals used in a microcomputer is reduced.

In magnetic recording and reproducing devices using cassette tapes that use a microcomputer as a system control circuit to control the system, the conventional method of determining whether or not recording is possible is based on the presence or absence of an accidental erasure prevention piece on the cassette. ing. In this method, the presence or absence of an erroneous erasure prevention piece is detected using a dedicated detection switch, and the detection signal is input to a dedicated terminal of a microcomputer. Similarly, the loading and unloading states of the tape were detected by dedicated detection switches, and the detection signals were input to dedicated terminals of the microcomputer.

Therefore, the microcomputer has five terminals for inputting a detection signal for detecting the presence or absence of an accidental erasure prevention piece, a terminal for inputting a loading completion signal, and a terminal for inputting an unloading completion signal. It was necessary for detection, loading completion, and unloading completion detection. Generally, as multi-functional processing progresses, the number of pins on a microcomputer becomes insufficient, but the fact that three bins of a microcomputer are required for the above-mentioned detection is due to the large number of bins and large volume. This requires a microcomputer, resulting in an increase in the area occupied by the microcomputer and an increase in the cost of the magnetic recording/reproducing device.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to reduce the number of terminals used by using the terminals of a microcomputer in combination.

In the present invention, conventionally, the microcomputer 2 bins for detecting the loading state and unloading state are used only to detect three modes: loading completion, unloading completion, and loading/unloading operation. Focusing on the fact that the completion mode was not used, the number of microcomputer bins was reduced by one pin by using the previously unused mode to detect the presence or absence of an accidental erasure prevention piece. The points are distinctive.

The present invention will be described below with reference to embodiments. FIG. 1 shows a block diagram of the main parts of a magnetic recording and reproducing apparatus according to an embodiment of the present invention.

In FIG. 1, 1 is a system control circuit (hereinafter referred to as a microcomputer), 2 is an operation command input circuit (for example, an operation button), 3 is a means for detecting the presence or absence of an erroneous erasure prevention piece, and 4 is a signal indicating whether or not loading has been completed. 5 is a circuit that generates a signal indicating whether unloading is completed (hereinafter referred to as unloading completion signal generating circuit); 6 is a circuit that generates a signal indicating whether loading and unloading are completed. A circuit for controlling the presence/absence signal generating circuit 4.5 (hereinafter referred to as a control circuit); 7 indicates a magnetic tape running control circuit controlled by the microcomputer 1; The control circuit 6 detects the presence or absence of an accidental erasure prevention piece when a recording command is issued, and if there is no erasure prevention piece,
Both the outputs of the loading and unloading completion signal generation circuits 4.5 are controlled so that they are forced into the loading and unloading completion mode.

Further, in FIG. 1, A is a recording command input terminal, and B and C are loading completion and unloading completion terminals provided in the microcomputer, respectively.

Next, a specific example of the embodiment of the present invention described above is shown in FIG. 2, and the present invention will be described in detail. The reason why the parts are surrounded by broken lines in FIG. 2 is to clarify the correspondence between FIG. 2 and FIG. 1, and corresponding parts are given the same reference numerals. Further, 8 is a switch for detecting the presence or absence of an accidental erasure prevention piece, 9 is a loading state detection switch that is turned on when loading is completed, 10 is an unloading state detection switch that is turned on when unloading is completed, and 11 is a switch for detecting the unloading state. OR circuit, 12.15 is the 1st. A second AND circuit is shown.

Next, the operation of the circuit shown in FIG. 2 will be explained.

(1) When the wA erasure prevention piece is present, that is, when the switch 8 is on, the output of the OR circuit 11 becomes a logical 1 regardless of the presence or absence of the recording command input from the terminal A.
Therefore, signals depending on the on/off state of the loading state detection switch 9 and the unloading state detection switch 10 are obtained at terminals B and C of the microcomputer, respectively.
L //, if terminal C is ``LH'', it means loading is completed; conversely, if terminal B is ``LH'' and terminal C is 1L, it means unloading is completed, and if both are ``H'', then loading is completed. This means that loading or unloading is in progress.

(2) When there is no accidental erasure prevention piece, that is, when switch 8 is off, the output of OR circuit 11 depends on the presence or absence of a recording command input from terminal A. (a) When there is a recording command, that is, terminal When the signal A is 1H, the output of the OR circuit 11 becomes 1L, and both terminals B and C of the microcomputer are forced to 1L. This detects the absence of the erase prevention piece. At the same time, the device stops operating under the control of a microcomputer, which will be described later, to prevent recording on tape.

(b) When there is no recording command, that is, when the signal at terminal A is L, the signals at terminals B and C turn on the loading state detection switch 9 and the unloading detection switch 10, as in (1) above. , depends on OFF. In this case, the absence of the erasure prevention piece cannot be determined from the signals at terminals B and C, but there is no risk of it being recorded on tape, so the device can operate even without the accidental erasure prevention piece. You may continue.

If we summarize the above information in a table, it will look like Table 1.

On the other hand, focusing on the signal levels of terminals B and C, the operation of this specific example is summarized as shown in Table 2 below.

Table 2 As is clear from the above explanation, in this embodiment, five microcomputer terminals were required to detect the presence or absence of the accidental erasure prevention piece and to detect the loading and unloading states. , only two are required, saving one terminal.

Next, the operation of the microcomputer 1 in the above embodiment will be explained with reference to the flowchart in FIG. When the microcomputer enters the error recording prevention routine from the main routine for system control of the magnetic recording/reproducing device, it first determines whether the operation command signal directly input to the microcomputer from the operation command input circuit 2 is a recording command signal. (Step S1). When the operation command signal is other than the recording command signal, the main routine is immediately returned and the running state of the magnetic tape is operated as instructed by the operation command signal.

On the other hand, when the operation command signal is a recording command signal, step S
2, it is determined whether the input signal at terminal B is 1H" or 1L" (step 82). Here, when the input signal of terminal B is "L", there is a possibility that there is no erroneous erasure prevention piece, and the process moves to the next step.

On the other hand, when the input signal of terminal B is "H", there is at least a piece to prevent accidental erasure, so even if the operation command is a recording command, the main routine returns to zero.Next, the input signal of terminal B is "H". When the signal is "L", the process advances to step S3, and it is determined whether the input signal at the terminal C is "1H" (step S5).

Here, if the input signal at the terminal C is 1L", it is determined that there is no erroneous erasure prevention piece. Therefore, if the result in step S3 is NO, the device is stopped (step S4).
Recording on tape is prevented. On the other hand, when the input signal at terminal C is 1H, there is at least a piece to prevent accidental erasure, so even if the operation command is a recording command, the process returns to the main routine. .

In this way, according to this embodiment, by controlling the microcomputer, it is possible to prevent recording on a tape when there is no erroneous erasure prevention piece. Incidentally, the completion of loading, the completion of unloading, or the detection of these operations in progress can be carried out, for example, by checking the levels of the input signals at terminals B and C in a routine after the above-mentioned recording prevention routine is completed. can.

Next, another specific example of the present invention is shown in FIG.

In the figure, 16 is a loading state detection switch;
17 is a switch for detecting the unloading state, and 1B is a switch for detecting the presence or absence of an accidental erasure prevention piece.

Reference numeral 19 indicates a recording button, B and C are input terminals of the microcomputer as in FIG. 2, and 0 is a microcomputer input terminal for a recording command signal.

The operation of this specific example will be explained below.0 When the erroneous erasure prevention piece is present, the switch 18 for detecting the presence or absence of the erroneous erasure prevention piece is off, so the loading state detection microcomputer terminal B is connected to the loading state detection switch. Similarly, the unloading state detection microcomputer terminal C depends on the unloading state detection switch 17.

On the other hand, when there is a fever on the erroneous erasure prevention piece, the switch 1B for detecting the presence or absence of the erroneous erasure prevention piece is on. At this time, when the recording command, that is, the recording button 19 is pressed, the recording microcomputer terminal 0 is latched to L, so the microcomputer terminal B for loading state detection and the microcomputer terminal C for unloading state detection are used for loading state detection, respectively. Switch 16. Unloading state detection switch 17
does not depend on , both are L.

Note that if there is no recording command, the recording microcomputer terminal O is H.
Therefore, as in the case of the accidental erasure prevention strip, the loading state detection microcomputer terminal B is connected to the loading state detection switch 16, and the unloading state detection microcomputer terminal C is used to detect the unloading state. Each depends on the switch 17.

Therefore, when a recording command is issued and there is no accidental erasure prevention piece, the switch 18 for detecting the presence or absence of an accidental erasure prevention piece is on, so that both the loading state detection microcomputer terminal B and the unloading state detection microcomputer terminal C are set to L. and forces the state to complete loading and unloading.

In this specific example, as in the first specific example, detection of the presence or absence of the erroneous erasure prevention piece and detection of loading and unloading states can be performed using two terminals.

As explained above, according to the present invention, the presence or absence of the erroneous erasure prevention piece can be detected by the two terminals, the loading state detection microcomputer terminal and the unloading state detection microcomputer terminal. This has the great effect of reducing the number of terminals used on a computer by one terminal compared to the conventional method. This also allows the use of a microcomputer with lower 2 links and lower output.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a magnetic recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific example of the above embodiment, and FIG. 3 is the operation of FIG. 2. FIG. 4 is a circuit diagram showing another specific example of the above embodiment. 1... System control circuit (microcomputer) 2... Operation command input circuit 3... Means for detecting the presence or absence of the accidental erasure prevention piece 4... Loading completion signal generation circuit 5... Unloading completion signal Generation circuit 6... Control circuit agent Patent attorney Susuki 1) Toshiyuki Diagram 4 Flash

Claims (2)

[Claims] (1) A means for detecting the presence or absence of an erroneous erasure prevention piece, a means for generating a recording command signal when recording is commanded, a control circuit to which the signals output from these two means are input, and a control circuit that is controlled by the output signal of the control circuit. means for generating a signal indicating whether or not loading has been completed; and means for generating a signal indicating whether or not unloading has been completed; and first and second input terminals of a microcomputer individually connected to the two means; The circuit detects the presence or absence of the accidental erasure prevention piece when a recording command is issued, and if there is no accidental erasure prevention piece, the signals input to the first and second input terminals forcefully enter the loading completion and unloading completion states. The means for generating a signal indicating whether or not the loading and unloading are completed is controlled so as to be controlled. A magnetic recording/reproducing device characterized in that: (2) The patented device is characterized in that the control circuit comprises means for detecting the presence or absence of the accidental erasure prevention piece and means for generating the recording command signal.