JPS63201947A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To speedily extinguish dewing and to stably bring a magnetic head into contact with a magnetic sheet by comparing the level of a detection signal with that of a reference signal showing a dewing state, and repeating a driving control until dewing is extinguished. CONSTITUTION:The magnetic sheet 8 is rotated and driven normally by the motor 30 of a sheet rotating and driving means, and the magnetic head 26 is shifted in the radius direction of the magnetic sheet 8 by the step motor 28 of a head shifting means. A dewing detection means 76 detects the dewing state in a device, and the level of the detection signal from the dewing detection means 76 is compared with that of the reference signal showing the dewing state. In the case of generating dewing, the driving control setting the motors 28 and 30 of the sheet rotating and driving means and the head shifting means or either of the means to a locked state for a prescribed time is repeated until dewing is extinguished. Thus, dewing is speedily extinguished when dewing occurs in the device and the magnetic head 26 can be stably brought into contact with the magnetic sheet 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetic recording/reproducing device using a rotating magnetic sheet, and more particularly to a magnetic recording/reproducing device having a function of detecting dew condensation inside the device.

[Conventional technology]

Recently, subjects have been electronically still photographed by combining imaging devices such as solid-state image sensors and image pickup tubes with recording devices that use magnetic recording media such as magnetic sheets that are inexpensive and have a relatively large storage capacity. Electronic still camera systems have been developed that record on a rotating magnetic sheet and reproduce images using a separate television system or printer.

The magnetic sheets used in such systems are usually in the form of magnetic sheet packs. A magnetic sheet pack rotatably stores a magnetic sheet for magnetically recording still image information, etc., and is used by being attached to a rotating magnetic sheet device built into an electronic still camera.

A head carriage drive mechanism using a stepping motor, a gear reduction mechanism, and a lead screen in a rotating magnetic sheet device is generally well known. In this drive system, a predetermined number of pulses are sent to the stepping motor by a microcomputer, and the stepping motor is configured to feed one track at a time. Recording of a video signal representing an image on a magnetic sheet or reading of a video signal from a magnetic sheet is performed using a spindle motor or the like at a speed of approximately 3.600 mm as shown in FIG. This is performed with the magnetic head 202 in close contact with the recording surface 200A of the magnetic sheet 200, which is rotated at high speed at □. A regulation plate 204 is provided at a position facing the magnetic head 202, and the regulation plate 204 allows the recording surface 200 of the magnetic head 202 and the magnetic sheet 200 to be adjusted.
A is constructed such that a stable contact state is maintained by a constant air flow while the magnetic sheet 200 is rotated at high speed, and signals can be recorded and read out reliably.

By the way, for example, when an electronic still camera is suddenly brought indoors from outdoors where the temperature is low, dew condensation occurs inside the camera due to the temperature difference. When such dew condensation occurs on the regulating plate or the recording surface of the magnetic sheet, friction on the contact surface between the two increases, resulting in a problem that the state of contact between the magnetic sheet and the magnetic head becomes unstable. Therefore, if such condensation occurs in the device, for example, JP-A-61-1608
In the magnetic disk family device disclosed in No. 78, a humidity sensor is provided in the device, and when a preset humidity condition is detected, the magnetic head is brought into close contact with the magnetic disk and a humidity sensor is individually sent to the spindle motor. The spindle motor is intermittently driven to rotate by supplying power from the provided charging device for a predetermined period of time based on a timer activated by the charging device.

[Problem that the invention seeks to solve]

However, when the magnetic recording medium is intermittently rotated by a spindle motor with a magnetic head in close contact with a magnetic recording medium such as a magnetic disk, the recording surface of the magnetic recording medium is rotated by the magnetic head every time the rotation stops. There is a problem of being stamped and damaged by.

In view of the above-mentioned problems of the conventional technology, the present invention is capable of quickly eliminating dew condensation that has formed inside a magnetic recording/reproducing device, allowing a magnetic head to stably come into close contact with a magnetic sheet, and It is an object of the present invention to provide a magnetic recording and reproducing device that does not cause damage to the recording surface of a magnetic recording medium by a head.

[Means for solving problems]

In order to achieve the above object, the present invention provides a magnetic recording and reproducing apparatus that magnetically records or reproduces signals by bringing a magnetic head into close contact with a magnetic sheet rotatably housed in a magnetic sheet pack. a sheet rotation driving means including a motor for rotationally driving the magnetic sheet; a head transporting means including a motor for transporting the magnetic head in a radial direction of the magnetic sheet; and a dew condensation detector for detecting a dew condensation state within the apparatus. and a detection signal from the dew condensation detection means, and compares the level of the detection signal with the level of a reference signal indicating a dew condensation state, and if dew condensation has occurred, the sheet rotation drive means or the head transfer means The invention is characterized by comprising a control means for controlling the motor of the means to be in a locked state for a predetermined period of time.

[Effect]

In the magnetic recording and reproducing apparatus according to the present invention, the magnetic sheet is driven to rotate steadily by the motor of the sheet rotation driving means, the magnetic head is transported in the radial direction of the magnetic sheet by the motor of the head transporting means, and the dew condensation state inside the apparatus is reduced by condensation. Detected by a detection means,
The level of the detection signal from the dew condensation detection means is compared with the level of a reference signal indicating the state of dew condensation, and based on the comparison result, the control means determines whether or not condensation has occurred. If it is determined that condensation has occurred, drive control is repeated to lock the motors of the sheet rotation drive means and/or the head transfer means for a predetermined period of time until the condensation disappears. As a result, dew condensation quickly disappears due to the heat generated from the motor in the locked state, and the magnetic head can be stably brought into close contact with the magnetic sheet.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the magnetic recording and reproducing apparatus according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the overall shape of an electronic still camera, which is one of the magnetic recording and reproducing devices according to the present invention. In the figure, 1 is a camera body, 2 is a photographic lens barrel, 3 is a finder,
4 is a rotating magnetic sheet device; 5 is a knob for opening and closing the packet of the rotating magnetic sheet device 4; 6 is a shirt release button; 7
8 indicates the upper lid, and 8 indicates the magnetic sheet.

The magnetic sheet 8 is usually used in the form of a sheet pack, and is housed in a case to prevent dust from adhering to the recording surface when removed from the camera body.

The schematic structure of this magnetic sheet pack is shown in FIGS. 2 and 3.

FIG. 2 shows a plan view of the magnetic sheet pack 10, and FIG. 3 is a sectional view taken along line A--A in FIG. 2. l second
As shown in the figure, the magnetic sheet pack 10 has a substantially rectangular shape, and a magnetic sheet 8 on which still image information and the like are recorded is rotatably housed inside a case 12 thereof. A center core 14 as a reinforcing member is provided in the center of the magnetic sheet 8, and the center core 14 is exposed to the outside through an opening 16 in the circular shape of the magnetic sheet pack 100.

A center hole 18 is formed in this center core 14, and an elastic piece (not shown) is formed in this center hole 18, and a rotating shaft 30A (FIG. 4) of a spindle motor 3o, which will be described later, resists the biasing force of this elastic piece. It is designed to fit into the center hole 18 of the center core 14. Magnetic sheet pack 1o has
! A window 2°, on which the regulation plate 74 and the magnetic head 26 are positioned, shown in FIG. J5, is open, and this window 2o is opened and closed by a slideable shutter 22. That is, the shutter 22 closes the window 120 to prevent dust from adhering to the magnetic sheet 8 before the magnetic sheet pack 1o is inserted into the packet of the rotating magnetic sheet group [4], and when the magnetic sheet pack 1o is inserted into the packet, the shutter 22 moves downward in FIG. 2 to open the window portion 20, allowing recording and reproduction on the magnetic sheet 8. A locking recess 24 is formed at the opposite end of the shutter 22 in the magnetic sheet pack IO, and this recess 24 is used for temporarily securing the magnetic sheet pack 1o when it is inserted into a packet.

In FIG. 4, the drive mechanism of the rotating magnetic sheet device 4 is shown. To explain this drive mechanism, a spindle motor 30 for driving the magnetic sheet is disposed in the center, and the rotating shaft 30A of this spindle motor 3o is fitted into the center hole 18 of the center core 14 of the magnetic sheet pack 1° shown in Figure qJ2. Then, the magnetic sheet 8 is rotated within the magnetic sheet pack 10 at a predetermined number of rotations. Further, in FIG. 4, 28 is a step motor for feeding the magnetic head 26, and 46 is a lead screw connected to the output shaft of this step motor 28 via a gear transmitter Mk34. 36 is a head carriage guided by guide shafts 38 and 40 installed in parallel, and 26 is a magnetic head provided on the helad carriage 36. A pin 42 is installed at one end of the head carriage 36, and a spring 4 is attached to this pin 42.
40 is locked at one end, thereby locking the head carriage 36.
is biased toward the right in FIG. On the other hand, the lead screw 46 is screwed into a nut 48 fixed to the main body side, and its left end abuts against the end surface of the rad carriage 36. Therefore, when the step motor 28 is rotated at a predetermined number of rotations, the head carriage 36 is moved at a predetermined pitch in the axial direction of the guide shirt 38, 40 by the movement of the head carriage 36 and the guide shaft 46, and thereby the magnetic head 26 is moved along the magnetic sheet 80. It is possible to move in the radial direction and record still image information on the magnetic sheet 8 track by track.

The magnetic sheet 8 of the magnetic sheet pack 10 is rotated by being attached to the rotation $11130A of the spindle motor 3o at the right of its center. A regulating plate 74 that maintains good contact between the magnetic head 26 and the magnetic sheet 8 at all times is provided inside the upper lid 7 of the camera body, and this regulating plate 74 contacts the outer periphery of the magnetic sheet 8. Magnetic sheet 8 is sandwiched between regulating plates 7
4, the magnetic head 26 is disposed so as to be movable in the radial direction of the magnetic sheet 80 as described above, and is in contact with the recording surface 8Δ (shown in FIG. 5) of the magnetic sheet 8.

FIG. 5 shows a schematic circuit block diagram of the electronic still camera shown in FIG. 1. In the figure, an electrical signal corresponding to a subject image obtained by an imaging section 49 composed of a solid-state imaging device or the like is input to a video signal processing circuit 50. This electric signal is processed by the video signal processing circuit 50 into a predetermined recording FM video signal, and then supplied to the magnetic head 26 and recorded on the magnetic sheet 8. In addition, the video signal processing circuit 50
The reference signal (vertical synchronization signal Vfi711e) necessary for steady rotation of the spindle motor 30 is sent to the servo circuit 6.
Output to 6.

A dew condensation sensor 76 is provided inside the camera body 1 to detect the dew condensation state inside the device, and an output signal from the dew condensation sensor 76 is converted into a digital signal by an A/D conversion circuit 58, and then sent to a control circuit. 52.

The magnetic head 26 moves the recording surface 8 of the magnetic sheet 8 by a step motor 28 as conceptually shown by a dashed line 62.
It is movable in its radial direction R along Δ. The step motor 28 is driven by a motor drive circuit 58 that operates in response to an 8-bit step motor drive signal 56 output from a control circuit 52 to drive four phases A, XSB, and H for 1-2 phase excitation. A pulse is given. Also,
The motor drive circuit 58 is configured to change the voltage values of drive pulses supplied to the A phase, human phase, B phase, and day phase based on the step motor drive signal 56 from the control circuit 52. The moving direction of the magnetic head 26 is determined by the rotating direction of the step motor 28, and the moving distance of the magnetic head 26 is proportional to its rotation angle. For example, each shift pulse of the step motor 28 rotates the step motor 28 by about 18 degrees, thereby moving the magnetic head 26 by about 5 μm. Therefore, 20 shift pulses result in a transfer of 100 μm (1 track). Further, after the recording of the FM video signal, the magnetic head 26 is immediately moved to the next track, so that the next signal recording can be performed promptly.

Here, one shift pulse means one change in the excitation pattern by four-phase drive pulses consisting of A phase, human phase, B phase, and B phase, as shown in FIG. When moving the magnetic head 26 in the forward direction, the excitation pattern is changed from 1001 to 1100 to 011O for each shift pulse.
→0011, and when transferring in the opposite direction, the excitation pattern is changed in the reverse order. Normally, the voltage value of the drive pulse when rotating the step motor 28 at a steady rotation speed is set to about 5V. step motor 28
In order to lock the motors, for example, drive pulses of the same phase are supplied to each of the A phase, A phase, B phase, and B phase. When the step motor 28 is locked in order to keep the magnetic head 26 stationary on a predetermined track, the voltage value of the drive pulse of each phase is set to about 2.5 cm. If condensation is detected by the condensation sensor 76, the step motor 28
In order to lock the motor and actively generate heat, the voltage value of the drive pulse is set to be approximately equal to that when the step motor 28 is driven to rotate.

Further, the step motor 28 exhibits the temperature change shown in FIG. 7 by the above-described excitation method. For example, in the period T1 from time to to time t1 under the condition of an ambient temperature of about 23° C., when the step motor 28 is given drive pulses of the same phase with a voltage value of about 2.5 cm to each phase, the step motor 28 Excitation current flows at the same time and the step motor 28 becomes locked.
temperature ranges from about 23°C to about 32°C, as shown by solid line 98.
The temperature rises to ℃ and then remains constant. The chassis temperature inside the camera body 1 rises to about 26° C. as the temperature of the step motor 28 increases, as shown by a broken line 99. Next, during the period T2 from time t1 to time t2, when driving pulses of the same phase with a voltage value of about 5 cm are applied to each phase of the step motor 28, a larger excitation current flows through each phase at the same time than during the period T1. and the temperature is about 32℃.
℃ to about 52℃. Along with this, the chassis temperature rises from about 2β°C to about 35°C. During the period T3 from after time t2 to time t3, the step motor 2
When a driving pulse of the same phase is supplied to each of the 8 phases with a voltage value lowered from about 5 .ANG. to about 2.5 .ANG. and locked, the temperature returns from about 52.degree. C. to the original about 32.degree. Similarly, the chassis temperature returns from about 35°C to its original temperature of about 26°C.

When the power is turned off and the drive of the step motor 28 is stopped after time t3 has elapsed, the temperature of the step motor 28 and the chassis decreases to approximately 23°C, which is the same as the ambient temperature, in a short time.
℃ (period T4). After time t4 has elapsed, if the step motor 28 is continuously locked again with a drive pulse with a voltage value of about 2.5 cm, the step motor 2
8 and the chassis rise to about 32° C. and 26° C., respectively, which are approximately equal to the temperatures +l during the above-mentioned periods T1 and T3 (period T5). Furthermore, the step motor 28 is turned on at time t5.
If the drive pulse with a voltage value of about 5 V is continuously used to lock the step motor 28 and the chassis after the elapse of , the temperatures of the step motor 28 and the chassis rise again to about 52° C. and 35° C., respectively (period T6). When the step motor 28 is continuously locked by a drive pulse with a voltage value of 2.5 cm after time t6, the temperatures of the step motor 28 and the chassis are maintained at approximately 52°C and 35°C, respectively. In this way, the step motor 28 is driven and controlled so that it is in a locked state for a short period of time using drive pulses whose voltage value is approximately equal to the voltage value during rotational driving, so that the excitation coil does not burn out and generates heat. It can heat the inside of the device. Further, when the step motor 28 is made to generate heat, drive control may be performed so that the stepping motor 28 is caused to step out of rotation so that it is not rotated in the magnetized state, and is equivalently brought into a locked state. Normally, the duration of the locked state is selected to be approximately several seconds, taking into account burnout of the excitation coil, power consumption, and the like.

The spindle motor 30 is driven by a servo circuit 66 activated by a command signal 53 output from a control circuit 52, and its frequency signal generator (FC, )? A predetermined speed, in this example, 3,600 . Rotate steadily with □. Further, the control circuit 52 controls so that a signal is recorded on the magnetic sheet 8 only when the spindle motor 30 reaches a constant rotation speed and enters a servo lock state.

The alarm device 78 is a device that issues various warnings to the operator. For example, when the condensation sensor 76 detects that condensation has occurred within the device, the alarm device 78 is a device that issues various warnings to the operator. It has become.

The control circuit 52 is a circuit that unifies and controls the entire device,
It consists of a memory that stores programs and data necessary to perform various controls, and interfaces with peripheral elements, circuits, devices, etc. Furthermore, the control circuit 52 includes a timer TCI (measurement value CNI) that measures the duration time (TLI) of the lock state of the step motor 28, and a timer TC2 (measurement value CNI) that measures the elapsed time (TL2) after the lock state is released. The value CN2) etc. are provided. In addition, the duration time TL of the locked state is determined in advance when the power is turned on.
I and the elapsed time TL2 after the lock state is released are set.

A power switch SW3 and a shirt release button 6 are connected to the control circuit 52. The spindle motor 30 is started by operating the shirt release button 6 after closing the power switch SW3. That is, the shirt release button 6 operates in two strokes in this embodiment, and in the first stroke, the switch SW1 is closed and power is supplied to each drive circuit section of the apparatus. As a result, the servo circuit 66 outputs a drive signal for driving the spindle motor 30 to the spindle motor 30 via the motor drive circuit 68. Furthermore, in the second stroke of operating the shirt release button 6, the switch SW2 is closed, thereby causing the control circuit 52 to close.
controls each circuit to perform shirt release, shooting, and recording.

Next, a processing routine executed by the control circuit 52 when dew condensation occurs within the apparatus will be described with reference to the flowchart shown in FIG.

The program is started by closing the power switch SW3 and turning on the power. First, in step 100, the switch SW, which is the first stroke of the shirt release button 6, is activated.
It is determined whether or not I is in the closed state, and if it is determined that it is still in the open state, the same process is repeated until it becomes the closed state. Separately from this, if it is determined in step 100 that the switch SW1 is in the open state, the process proceeds to step 101, and in step 101, the control circuit 52 outputs a command signal 53 to the servo circuit 66 to start the spindle motor 30. do. After starting the spindle motor 30, the process proceeds to step 102, and in step 102, the control circuit 52 converts the detection signal output from the dew condensation sensor 76 into A.
/D conversion circuit 58. The control circuit 52' compares the level of this detection signal with the level of a reference signal indicating the condensation state, and if it is determined that condensation has occurred, the process proceeds to step 107, where the step motor is A step motor drive signal 56 is output to the motor drive circuit 58 so that a drive pulse sufficient to cause the motor 28 to be in a locked state is provided. At this time, the motor drive circuit 58 supplies the step motor 28 with drive pulses of approximately 5 cm and the same phase, the voltage value of which is approximately equal to that during rotational drive. As a result, the step motor 28 generates more heat than when the magnetic head 26 is kept at a predetermined position.

After the process in step 107 is completed, the process advances to step 108, and in step 108, the timer TC1 is set to the measured value CN.
Start after raising I to zero (CN1=0). In step 109, the measured value CNI of timer TC1 is always increased by a constant value, and in step 110, the measured value CN
It is determined whether or not I has exceeded the set value duration TLL, and if it is determined that the measured value CNI has not yet exceeded the duration TL1, the process returns to step 109 and the same process is repeated. Along with this, the step motor 28 continues to generate heat. The measured value C is determined in step 110.
If NI exceeds the duration TLI, step 111
In step 111, the control circuit 52 controls the motor drive circuit 58 so that the step motor 28 is unlocked. Accordingly, the step motor 28 no longer generates heat. After the process in step 111 is completed, the process advances to step 112, and in step 112, timer TC2
After setting the measured value CN2 to zero (CN2=0), start. In step 113, the measured value CN2 of timer TC2 is always increased by a constant value, and in step 11
In step 4, it is determined whether the measured value CN2 exceeds the elapsed time TL2 of the set value, and as a result, the measured value CN2 still exceeds the set value elapsed time TL2.
2 does not exceed the duration TL2, the process returns to step 113 and the same process is repeated. If it is determined in step 114 that the measured value CN2 exceeds the elapsed time TL2, the process returns to step 102.

In step 102, the state of condensation inside the device is detected again, and if it is determined that condensation is still occurring, the above-described processing routine is repeated until the state of condensation disappears (steps 107, 108, 109, 110). .111
, 112.113.114).

Separately, if it is determined in step 102 that no condensation has occurred, the process proceeds to step 103, where it is determined whether the spindle motor 36 has entered the servo lock state. If it is determined in step 103 that the servo lock state has not yet been entered, the same processing is repeated until the servo lock state is entered.

If it is determined in step 103 that the servo lock state has entered, the process proceeds to step 104, and step 10
4, it is determined whether the switch SW2, which is the second stroke of the shirt release button 6, is in the open state or not. If it is still in the released state, the same process is repeated. If it is determined in step 104 that the switch SW2 is in the open state, the process advances to step 105;
An FM video signal is recorded on a predetermined track of the magnetic sheet 8 via the magnetic head 26. After the signal is recorded in step 105, the process proceeds to step 106, and step 1
At 06, the control circuit 52 releases the next shirt release button 6.
In response to this operation, the step motor 28 is driven and controlled so that the FM video signal is immediately recorded on the next track, and the magnetic head 26 is moved to the next track. Step 1
After the process in step 06 is completed, the process moves to another process routine.

As described above, in the electronic still camera of this embodiment, when the dew condensation sensor 76 detects that condensation has occurred within the device, the step motor 28 is rotated without rotating the magnetic sheet. Although the configuration is such that the step motor 28 is kept in a locked state for a certain period of time by a driving pulse of an abbreviated voltage value, and the heat generated from the step motor 28 is actively utilized to eliminate condensation, the present invention is not limited to this.
You may also use . For example, if the spindle motor 30 is a three-phase AC motor, the spindle motor 30 can be made to generate heat by supplying excitation currents of the same phase to the excitation coils of each phase.

In addition, in the above embodiment, measures against condensation when a magnetic sheet is attached are described, but if it is detected that condensation has occurred inside the device, step with the packet open or without the magnetic sheet pack attached. It may be configured such that the motor or spindle motor is not locked and is driven to rotate in a no-load state until dew condensation disappears to generate heat.

As a result, when dew condensation occurs in the device, the heat generated by the existing motor can be actively utilized without damaging the magnetic sheet by the magnetic head, and the condensation can be eliminated in a shorter time than usual.

〔Effect of the invention〕

As explained above, the image recording and reproducing apparatus according to the present invention takes in the detection signal from the dew condensation detection means, compares the level of the detection signal with the level of the reference signal indicating the dew condensation state,
Based on this comparison result, it is determined whether or not condensation has occurred, and if condensation has occurred, drive control is repeated to lock the motor of the sheet rotation drive means or head transport means for a certain period of time until the condensation disappears. Therefore, even if dew condensation occurs inside the device, the condensation disappears quickly due to the heat generated by the motor, and the magnetic head and the magnetic sheet can be stably brought into close contact with each other. Furthermore, the recording surface of the magnetic sheet is not damaged by being engraved by the magnetic head.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the overall shape of an electronic still camera, which is one of the magnetic recording and reproducing devices according to the present invention, Fig. 2 is a plan view of the magnetic sheet pack, and Fig. 3 is A-A on Fig. 4. 4 is a perspective view of the starting mechanism of the rotating magnetic sheet device, FIG. 5 is a block diagram showing the schematic circuit configuration of the electronic still camera shown in FIG. 1, and FIG. 6 is a diagram of the step motor. A waveform diagram showing drive pulses and excitation patterns, Fig. 7 is a characteristic diagram showing heat generation of the step motor, Fig. 8 is a flowchart showing a processing routine executed by the control circuit, and Fig. 9 shows a regulating plate and a magnetic sheet for the magnetic sheet. FIG. 3 is an explanatory diagram showing a state of close contact between magnetic heads. 6... Shirt release button, 8... Magnetic sheet, 49... Photographing section 50... Video signal processing circuit, lO... Magnetic sheet pack, 26...
Magnetic head, 28... Step motor, 52
...Control circuit, 78...Alarm installation, 58.6
8... Motor drive circuit, 58... A/D conversion circuit, 66... Servo circuit, 30... Spindle motor, 74... Regulation plate, 76... Condensation sensor,

Claims (1)

[Scope of Claims] In a magnetic recording and reproducing device that magnetically records or reproduces a signal by bringing a magnetic head into close contact with a magnetic sheet rotatably housed in a magnetic sheet pack, a motor that rotationally drives the magnetic sheet is provided. a head transporting means including a motor for transporting the magnetic head in the radial direction of the magnetic sheet; a dew condensation detection means for detecting a condensation state within the device; and a detection signal from the dew condensation detection means. , a control means that compares the level of the detection signal with the level of a reference signal indicating a state of dew condensation, and controls the motor of the sheet rotation drive means or the head transport means to be in a locked state for a predetermined time if condensation has occurred; A magnetic recording and reproducing device comprising: