JPH0210588Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mode switching control circuit for a magnetic recording/reproducing device, in which switches for switching and controlling recording mode, playback mode, and E-E mode, respectively, are built into the same IC. A circuit that supplies three-value control signals to the pins to control switching between the recording mode, playback mode, and E-E mode, and a range that indicates the recording mode and a range that indicates the playback mode via the range that indicates the E-E mode. If two thresholds with different values are set so that they are arranged sequentially, and the three-value control signal has a value lower than one of the thresholds, the recording mode is set, and the value between one threshold and the other threshold is set. If E-
E mode, and a mode switching control signal generation circuit that generates a switching control signal to switch to playback mode when the value is higher than the other threshold, and the three-value control signal switches from the value indicating E-E mode to playback mode. of the switching control signal according to the value indicating the transient recording mode when directly transitioning from the value indicating the E-E mode to the value indicating the recording mode to the value indicating the playback mode. This prevents the occurrence of the 3-value control signal.
- A transitional playback mode when directly transitioning from a value indicating E mode to a value indicating recording mode, and then from a value indicating E-E mode to a value indicating recording mode via a value indicating playback mode. An object of the present invention is to provide a mode switching control circuit for a magnetic recording/reproducing device, which is configured to prevent generation of a switching control signal depending on the indicated value.

Household magnetic recording and reproducing device (hereinafter referred to as VTR)
The following describes the recording mode, playback mode, and mode in which the input recording signal is taken out as an output signal without supplying recording current to the magnetic head (including stop mode, fast forward mode, rewind mode, magnetic tape loading mode, etc.). , E-E mode) are provided. The E-E mode is used, for example, to prevent unnecessary signals from being recorded on the magnetic tape in the loading mode, and to play back and check the signals to be recorded when the power is turned on after the device is in the stop mode. This is a necessary mode for etc.

Here, in order to downsize a VTR, a switch circuit for controlling the mode switching described above is incorporated into an IC. A binary control signal for switching between these two modes is supplied to one external pin, and a switch circuit for switching to the above E-E mode is provided outside of this IC, and this switch circuit is connected from the outside. I was in control. For this reason, the conventional mode switching control circuit requires one external pin terminal for supplying a signal for switching between recording mode and playback mode to the IC, and a switch circuit for switching to E-E mode. Each terminal must be provided separately, making it difficult to make the control circuit compact and easy to configure.Also, two types of control signals, a binary control signal and a control signal from an external circuit, are required, making the circuit design difficult. There were drawbacks such as not being easy.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.

FIG. 1 shows a circuit diagram of an embodiment of a VTR mode switching control circuit according to the present invention. In the same figure,
1 and 2 are terminals provided outside the IC, for example, to which the output of a system controller of a microcomputer is supplied. Terminals 1 and 2 are respectively set to "1, 0" in recording mode and "0" in E-E mode. ,1'',
It is set so that "0,0" is supplied during playback mode. 3 is a pin of the IC, which is connected to a power supply Vcc of voltage, for example, 9V, through a resistor _R1 , and on the other hand, it is connected to the collector of a transistor _Q1 , and on the other hand, a resistor R with the same resistance value as the resistor _R1 is connected to the collector of the transistor Q1. ₂ is connected to the collector of transistor Q ₂ . The emitters of transistors Q ₂ and Q ₂ are both grounded. 4 is a mode switching control signal generation circuit, which has a power supply voltage of 6.5V, approximately 2/3 of the power supply voltage of 9V, and a power supply voltage of 9V.
Two threshold voltages of 3V, which is 1/3 of
The potential of pin 3, which is switched by mode switching, is compared with these threshold voltages, and a mode switching control signal is taken out according to the comparison result.

Reference numeral 5 denotes a mode changeover switch circuit consisting of switches 5a and 5b. The switch 5a is supplied with a changeover control signal according to the result of comparison with a threshold voltage of 6.5V from the mode changeover control signal generation circuit 4, and selects playback mode and recording mode. On the other hand, the switch 5b is supplied with a switching control signal according to the result of comparison with the threshold voltage 3V from the control signal generating circuit 4, and switches between the audio signal recording amplifier mute release mode and the recording amplifier mute mode. It is configured to switch between the two. Note that switching between the recording amplifier mute release mode and the recording amplifier mute mode corresponds to switching between the recording mode, the reproduction mode, and the EE mode.

That is, as is clear from FIG. 2, which shows the range indicating the recording mode and the range indicating the playback mode sequentially arranged through the range indicating the E-E mode, when the potential of pin 3 is 3V or less, If there is, record amplifier mute release mode (NM) in recording mode (REC), and if pin 3 potential is between 3V and 6.5V, record amplifier mute mode (M) in E-E mode (E-E), pin If the potential of 3 is 6.5V or more, the recording amplifier mute mode (M) is set in the playback mode (PB).

For example, when entering the recording mode, "1, 0" are supplied to terminals 1 and 2, respectively. As a result, only the transistor _Q1 is turned on and the pin 3 is set to the ground potential, and the control signal generation circuit 4 compares the ground potential with the threshold voltage 3V and uses the control signal obtained to set the switch 5a to the recording mode and E- While the switch 5b is switched to the E mode side, the switch 5b is switched to the recording amplifier mute release mode (that is, the recording mode side), and the VTR is placed in the recording amplifier mute release mode in the recording mode.

On the other hand, when setting to the E-E mode, "0, 1" are supplied to terminals 1 and 2, respectively. As a result, only transistor _Q2 is turned on, and the potential at pin 3 is halved.
Vcc (4.5V), and the control signal generating circuit 4 compares 4.5V with the threshold voltage 3V, and the switch 5b is switched to the recording amplifier mute mode, and the control signal generating circuit 4 switches the switch 5b to the recording amplifier mute mode. V and the threshold voltage of 6.5 V are compared, and the switch 5a is switched to the EE mode and recording mode by the control signal, and the VTR is placed in the recording amplifier mute mode in the EE mode.

On the other hand, when entering the reproduction mode, "0, 0" are supplied to terminals 1 and 2, respectively. As a result, both transistors Q ₁ and Q ₂ are turned off, and the potential of pin 3 is set to Vcc (9V), and the control signal generated by comparing 9V and the threshold voltage of 6.5V in the control signal generation circuit 4 The switch 5a is switched to the reproduction mode, while the switch 5b is switched to the recording amplifier mute mode, so that the VTR is placed in the recording amplifier mute mode in the reproduction mode.

In this case, the reason why the recording mode is not set when terminals 1 and 2 are "0, 0" is that when the connectors connected to terminals 1 and 2 are removed, terminals 1 and 2 become "0, 0". This is to prevent unwanted signals from being recorded on the magnetic tape if the recording mode is entered at this time. In addition, the range indicating the recording mode and the range indicating the playback mode are arranged sequentially through the range indicating the E-E mode.
The reason why I chose -E mode between a threshold voltage of 3V and a threshold voltage of 6.5V and selected a playback mode with a threshold voltage of 6.5V or higher is that generally both playback mode and recording mode are E-
In many cases, the transition is from E mode, recording mode,
The three-value control signal for controlling switching between the playback mode and the E-E mode changes directly from the value indicating the E-E mode to the value indicating the playback mode, and changes from the value indicating the E-E mode to the recording mode. This prevents generation of a switching control signal according to a value indicating a transient recording mode when transitioning from a value indicating a playback mode to a value indicating a playback mode through a value indicating a three-value control signal from a value indicating an E-E mode to a value indicating a recording mode. of the switching control signal according to the value indicating the transient reproduction mode when directly transitioning from the value indicating the E-E mode to the value indicating the recording mode via the value indicating the reproduction mode. This prevents the occurrence. This sets the playback mode to the threshold voltage
If you select E-E mode between 3V and threshold voltage 6.5V and set the threshold voltage to 6.5V or higher, for example, when switching from E-E mode to recording mode, it will first shift to 1/2Vcc playback mode and then switch to recording mode. This eliminates the possibility that the operation may become uncertain due to the

In addition, threshold voltages of 7.2V and 5.8V are also set in the mode switching control signal generation circuit 4 in addition to the above-mentioned threshold voltage, and a control signal for switching control of each mode is supplied to the control signal generation circuit 4. 7.2V
Voltages between 5.8V and 5.8V are detected. This results in
The output of the audio signal monitor amplifier is grounded, and the pop noise that may occur when switching the above recording mode ←→EE mode, playback mode ←→EE mode, and recording mode ←→playback mode. (drop sound) is not output from the line output and is muted (Monitor muting mode (MM))
be done.

As described above, the mode switching control circuit of the magnetic recording/reproducing apparatus according to the present invention incorporates switches for switching between the recording mode, the reproduction mode, and the E-E mode in the same IC, and switches between the recording mode, the reproduction mode, and the E-E mode.
Same switch to control E-E mode respectively
A circuit that is incorporated into an IC and supplies a three-value control signal to one pin of the IC for switching and controlling the recording mode, the playback mode, and the E-E mode, and the E-E mode. Two thresholds having different values are set so that a range indicating the recording mode and a range indicating the playback mode are sequentially arranged through the range, and when the three-value control signal is a value lower than one of the thresholds, If the value is between the one threshold value and the other threshold value, the E-E mode is selected, and if the value is above the other threshold value, the reproduction mode is generated. A mode switching control signal generation circuit is provided to output the three-value control signal to the E-
A transitional transition when directly transitioning from a value indicating the E mode to a value indicating the playback mode, and from a value indicating the E-E mode to a value indicating the playback mode via a value indicating the recording mode. The switching control signal is prevented from being generated in accordance with the value indicating the recording mode, and the three-value control signal directly shifts from the value indicating the E-E mode to the value indicating the recording mode, and the E-E The structure is configured to prevent generation of the switching control signal according to the value indicating the playback mode during transition from the value indicating the playback mode to the value indicating the recording mode via the value indicating the playback mode. , the IC terminal that supplies the control signals for switching and controlling each of the above modes requires only one pin, and the recording mode and playback mode can be switched and controlled using a binary control signal, and the E-E mode can be controlled by an external circuit. The number of IC terminals can be reduced compared to conventional circuits that perform switching control using control signals, and the control circuit can be made smaller and simpler than conventional circuits.
Furthermore, only one type of three-value control signal is required for the control signal, which makes the circuit design easier than the conventional circuit described above. Since the ranges indicating the playback mode are arranged sequentially, it is possible to directly transition from the E-E mode to the playback mode without going through the recording mode, so the transition that occurs when changing from the E-E mode to the playback mode via the recording mode can be avoided. Ensures transition from E-E mode to playback mode without any uncertainties in mode switching operations (for example, the drawback of switching to playback mode after unnecessary information such as noise has been recorded on the tape). can be done,
Furthermore, since it is possible to directly shift from E-E mode to recording mode without going through playback mode, there is no uncertainty in the transient mode switching operation that occurs when moving from E-E mode to record mode via playback mode. It is possible to ensure that the transition from E-E mode to recording mode occurs without any problems (for example, the disadvantage that the information to be recorded on the tape cannot be recorded immediately because the playback mode time has to elapse). It has features such as:

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the circuit of the present invention.
FIG. 2 is a diagram for explaining the mode switching operation of the circuit shown in FIG. 1, 2... Three-value control signal input terminal, 3... Pin, 4... Mode switching control signal generation circuit, 5...
Mode changeover switch circuit, Q ₁ , Q ₂ ... transistor, R ₁ , R ₂ ... resistance, Vcc ... power supply.

Claims (1)

[Claims for Utility Model Registration] A switch for controlling recording mode, playback mode, and E-E mode is incorporated into the same IC, and
The recording mode, the playback mode, and
A circuit for supplying a three-value control signal for switching and controlling each of the E-E modes, and a range indicating the recording mode and a range indicating the playback mode are sequentially arranged through the range indicating the E-E mode. Two thresholds with different values are set so that the three-value control signal has a value lower than one of the thresholds. If so, the E-E mode;
a mode switching control signal generation circuit that generates a switching control signal to switch to the playback mode when the value is higher than the other threshold, and the three-value control signal changes from the value indicating the E-E mode to Directly transitions to the value indicating the playback mode and selects the E-E
Preventing generation of the switching control signal according to the value indicating the recording mode during transition from the value indicating the mode to the value indicating the playback mode via the value indicating the recording mode, and the three values. The control signal directly transitions from the value indicating the E-E mode to the value indicating the recording mode, and the E-E
The switching control signal is configured to prevent generation of the switching control signal in response to the value indicating the reproduction mode during transition from the value indicating the mode to the value indicating the recording mode via the value indicating the reproduction mode. A mode switching control circuit for a magnetic recording/reproducing device, characterized in that: