JPH0610916B2 - Magnetic recording / reproducing device - Google Patents

Description

The present invention relates to a magnetic recording / reproducing apparatus that performs write protect detection using an optical sensor or a magnetic sensor.

Conventionally, a magnetic recording / reproducing apparatus for performing write protect detection using an optical sensor or a magnetic sensor detects write protect as shown in FIG. 1, for example, a phototransistor 2, a light emitting diode 3, and a resistance for current-voltage conversion. 4, a write protect detection circuit A including a resistor 5 for current control and a power supply 7. The presence or absence of write protection is determined by whether or not the optical path is blocked. The control circuit 1 is synchronized with the first and sixth signals 6 for detecting the presence / absence of the magnetic recording medium, and it is not necessary to perform the write protect detection without the magnetic recording medium. If the power supply 7 is 5 V and the current flowing through the light emitting diode 3 is 15 mA and the output of the phototransistor 2 is 3 mA, the power consumption of the write protect detection circuit is 90 mW. If the presence / absence of the write protection is determined when the presence / absence of the magnetic recording medium is detected, the subsequent write protection circuit power of 90 mW becomes a waste power.
Further, when a low power consumption design such as battery driving is performed, the total power consumption is about 2 W, so 90 mW consumed by the write protect detection is about 5%.

The present invention has been made to eliminate such drawbacks.

An embodiment of the present invention will be described with reference to FIG. The write protect detection is performed in the same manner as the method described in FIG.
The power supply 7 of the write protect detection circuit A includes a transistor 9 and resistors 10 and 11 capable of obtaining a bias current.
Power supply 7 to the write protect detection circuit A, or power supply 7 to the write protect detection circuit A
A power supply circuit B for shutting off is provided. The control circuit 8 composed of a microcomputer outputs a second signal for turning on the transistor 9 and a fourth signal for turning off the transistor 9 in synchronization with the first signal 6 for detecting the presence or absence of the magnetic recording medium. Output by line 12. However, once detected, the presence or absence of write protection does not change unless the magnetic recording medium is taken in and out. Therefore, the control circuit 8 is
The second signal is output immediately after the logical value of the signal 6 changes from false to true, that is, when the first signal 6 indicating the presence of the recording medium is input. Then, the second signal is input to the power supply circuit B, and the transistor 9 of the power supply circuit B is turned on. As a result, the write protect detection circuit A operates to detect the presence or absence of write protect. After detection, the write protect detection circuit A outputs a third signal indicating the presence / absence of write protection to the control circuit 8 through the signal line 13. Accordingly, the control circuit 8 outputs the fourth signal to the power supply circuit B. As a result, the transistor 9 of the power supply circuit B is turned off and the power supply to the write protect circuit A is cut off. Therefore, the power required for the write protect detection circuit can be saved.

In the above description, the power supply circuit that supplies power to the write protect detection circuit or shuts off the power supplied to the write protect detection circuit by the transistor has been described. You may carry out by another method. Further, although the description has been made with the optical sensor, the detection may be performed with the magnetic sensor.

Further, although it has been described that the control circuit is configured by the microcomputer, the control circuit may be configured by a logic circuit.

As described above, according to the present invention, the write protect detection circuit is configured to operate only when the insertion of the recording medium is detected. Highly reliable detection can be performed while reducing the power consumption.

[Brief description of drawings]

 FIG. 1 is a diagram for explaining a conventional magnetic recording / reproducing apparatus. FIG. 2 is a diagram for explaining one embodiment of the present invention. 1,8 ...... Control circuit 2 ...... Phototransistor 3 ...... Light emitting diode 4,5,10,11 ...... Resistance 9 ...... Transistor 7 ...... Power supply A ...... Write protect detection circuit B ...... Power supply circuit

Claims (2)

[Claims] 1. A write protect detection circuit for detecting the presence or absence of write protect on a recording medium, a power supply circuit for supplying power to the write protect detection circuit, and a power supply for supplying power from the power supply circuit to the write protect detection circuit. In a magnetic recording / reproducing apparatus comprising a control circuit for outputting a signal for controlling supply or interruption, the control circuit is configured so that, after a signal representing the presence of the recording medium in the magnetic recording / reproducing apparatus is input, The write protect detection circuit outputs a signal instructing the supply of power to the write protection detection circuit, and the write protection detection circuit outputs a signal indicating the presence / absence of write protection of the recording medium. Magnetic recording having a configuration for outputting a signal instructing the detection circuit to shut off the power supply. Reproducing apparatus. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the write protect detection circuit is configured to detect the presence or absence of the write protect by an optical sensor or a magnetic sensor.