JP2574891B2 - Cooling mechanism in magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a cooling mechanism suitable for preventing dew condensation.

[Conventional technology]

Helical scan systems are currently the mainstream in magnetic recording / reproducing devices. In this system, tapes are wound around a drum having a rotary head over a wide angle of 180 degrees or more. A tape is also wound around a fixed head for recording or reproducing a signal on a linear track at a predetermined angle. Because these drums and fixed heads have a large contact area with the tape, under high humidity conditions or under dew condensation,
The coefficient of friction with the tape becomes very large, and the tape is likely to be damaged due to an increase in the running load of the tape. In particular, in recent years, this tendency has been increasing as the thickness and rigidity of tapes have been reduced.

For this purpose, the magnetic recording / reproducing apparatus is equipped with a mechanism for detecting the dew condensation state or humidity inside the apparatus. Thus, when high humidity or dew is detected, the humidity is reduced by energizing a built-in heater or setting the apparatus to a stop mode. Examples of this type of apparatus include JP-A-49-24407, JP-A-49-28312, and JP-A-49-53008.

[Problems to be solved by the invention]

In the above-mentioned conventional technology, damage to the tape can be prevented by eliminating high humidity or dew condensation, but no consideration has been given to power consumption. That is, since a dedicated heater is provided to eliminate high humidity or dew condensation, extra power consumption is required to operate the heater.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling mechanism that solves the above-mentioned disadvantages of the related art and achieves both elimination of high humidity or dew condensation and reduction of power consumption.

[Means for solving the problem]

Normally, a commercial VTR has a cooling mechanism for generating heat inside the apparatus due to large power consumption of a circuit, a power supply, a motor, and the like, and discharging the accumulated heat to the outside.

Therefore, the above-mentioned object is achieved by eliminating the high humidity or dew condensation state by utilizing the amount of heat generated inside the apparatus by controlling the operation of the cooling mechanism.

[Action]

The humidity state in the device is detected by the detector, and if it is larger than a predetermined value, the operation of the cooling mechanism is stopped. Then, the temperature inside the device increases due to the amount of heat generated from a power supply, a circuit, a motor, or the like in the device, and the relative humidity decreases. Therefore, the coefficient of friction between the tape and the guide member does not become abnormally large.

In addition, the humidity detector detects that the humidity in the apparatus is likely to rise at an early stage, weakens the operation of the cooling mechanism at a lower humidity than the friction coefficient between the tape and the guide member increases, That is, the number of rotations of the cooling fan is reduced. As a result, the amount of air flowing into the device is reduced, and a certain degree of cooling effect of the heat source in the device is ensured.

〔Example〕

 Hereinafter, one embodiment of the present invention will be described in detail.

FIG. 2 is a sectional view of the device 1. The mechanical part in the device 1
2, circuit boards 3 and 4, a power supply unit 5, a cooling fan 7, and a motor 6 for driving the cooling fan are arranged as shown in the figure. An insertion port 11 for mounting a cassette 10 in a mechanical section is provided at an upper portion of the front surface of the apparatus 1, and is normally closed by a door 8.
The door 8 is pushed inward by the cassette 10 when the cassette 10 is inserted, and is automatically closed when the insertion of the cassette 10 is completed, so that the next cassette cannot be inserted. Further, an air inlet 9 is provided at a lower portion of the front surface of the device 1. Further, an air outlet 12 is provided on the back of the device 1, and a cooling fan 7 which is rotationally driven by a motor 6.
As a result, the air inside the device 1 is discharged. The power supply 5, the circuit boards 3 and 4, and the various motors mounted on the mechanical unit 2 generate a great deal of heat from the cooling fan 7.
To prevent overheating. Due to the discharge of the air, the surrounding air flows into the device 1 from the gap between the air inlet 9 and the door 8 on the front surface of the device 1.
Thereby, a cooling effect in the device 1 is obtained.

However, conversely, for example, when the ambient temperature is high, dew condensation occurs on the tape guide surface in the apparatus 1. This is due not only to the above-described discharge of the air, but also to the door 8 opening when the cassette 10 is inserted.

FIG. 1 is a diagram showing a system of a cooling mechanism. A plurality of temperature detectors 13, 14 and 17 and humidity detectors 15 and 16 are provided. These signals are taken into the microcomputer 18 and the humidity inside the device 1 is detected, whereby the driving circuit of the motor 6 is driven.
It controls 19.

Next, FIGS. 3 and 4 show specific configurations of these. FIG. 3 shows a case where a temperature detector is used. Signals from the temperature detectors 13 and 14 are input to a relative humidity detection circuit 20, and the relative humidity inside the device 1 is detected. For example, the temperature detector 13 measures the temperature around the device 1, and the temperature detector 14 measures the internal temperature. Furthermore, if the temperature detector 14 measures the internal temperature near the air inlet 9 or the door 8, the temperature near this is originally the lowest inside the apparatus 1, so High humidity or condensation conditions can be grasped. Further, the temperature detectors 13 and 14 may be installed at appropriate places in the apparatus to detect the humidity in the apparatus due to the inflowing air. Above relative humidity detector
The detected value at 20 is compared with a predetermined reference value 22 by a comparator 21.
Here, if the relative humidity is lower than the reference value 22, the power of the drive rotation 19 is turned on, the fan is rotated, and the normal exhaust operation is performed. Further, the detection of the relative humidity in the apparatus 1 is continuously performed.

When the value detected by the relative humidity detection circuit 20 is higher than the reference value 23, the power supply of the drive circuit 19 is turned off, the rotation of the fan is stopped, and the exhaust operation is not performed. Therefore device 1
The surrounding air flowing into the inside is lost, and it does not become highly humid or condensed. However, when the exhaust by the fan 7 is stopped, the internal temperature and the temperature of the heating element itself increase due to the heat generated from the heating element in the apparatus 1. Accordingly, the temperature of the heating element is detected by the temperature detection circuit 23 based on information from the temperature detector 17 attached to the heating element (power supply, circuit, motor, etc.). The detected value is compared with a predetermined reference value 25 by the comparator 24. When the detected value is lower than the reference value 25, the rotation of the fan 7 is stopped as it is, and the detection by the relative humidity detecting circuit 20 is continued. However, when the detected value is higher than the reference value 25, the comparator 26 further compares the detected value with a predetermined reference value 27. This reference value 27 is the reference value
A value higher than 25 is desirable, for example, a temperature for guaranteeing the operating performance or life of the heating element. If the detected value is lower than the reference value 27, the power supply of the drive circuit 19 is turned on, the fan 7 is rotated, and the exhaust operation is restarted. Then, the inflow of air from the surroundings is restarted, and the detection by the relative humidity detection circuit 20 is continued. On the other hand, if the detected value is higher than the reference value 27, the alarm display circuit 28 displays an alarm indicating to the operator that the temperature of the heating element is too high, To ON. At this time, even if some operation is being performed on the apparatus main body, the operation is not automatically stopped.
For example, in the case of broadcasting or the like, it is extremely harmful if the operation is automatically stopped, and the subsequent judgment is left to the operator.

As still another method, there is a method in which the reference value 22 to be compared by the comparator 21 has a predetermined width, and the response when the detected value is within this range is made different. At this time, the level of the voltage or current supplied from the drive circuit 19 to the motor 6 is reduced so that the motor 6 rotates at a lower rotation speed than usual.
As a result, the exhaust from the inside of the apparatus 1 and the inflow from the surroundings are gradually performed, and a slight cooling effect of the internal heating element is obtained. Therefore, the degree of causing a rapid temperature change inside the apparatus 1 is reduced. As a result, the occurrence of high humidity or dew inside the apparatus can be smoothly avoided.
The above-described reference value can be further subdivided, and the driving circuit 19 can be finely controlled in accordance with the subdivision to more stably prevent the occurrence of high humidity or dew.

FIG. 4 is a block diagram when a humidity detector is used. Those having the same functions as those shown in FIG. 3 are denoted by the same numbers. First, humidity is detected by a humidity detection circuit 29 based on a signal from the humidity detector 15. It is preferable that the humidity detector 15 is attached to the same position as the temperature detector 13 so that the humidity is detected by touching the air around the device 1 as soon as possible. The value detected by the humidity detecting circuit 29 is compared with a predetermined reference value 31 by a comparator 30. The driving circuit 19, the temperature detecting circuit 23, the comparators 24 and 2
6. The operation of the alarm display circuit 28 is the same as that described with reference to FIG.

Next, another embodiment will be described with reference to FIG. When the detected value of the temperature detecting circuit 23 is compared with the reference value 25 by the comparator 24 and the detected value is lower, the humidity detecting circuit 29 further detects the humidity, as shown in FIG. You may continue, but other methods are conceivable. As shown in FIG. 4, humidity is detected by a humidity detection circuit 32 based on a signal from a humidity detector 16 different from the humidity detector 15. The detection value of this humidity detector 32 and the magnitude of the detection value of the humidity detector 29 are discriminated by a discriminator 33,
The larger detected value is input to the comparator 30 and compared with the reference value 31. For example, unlike the humidity detector 15, the humidity detector 16 is installed at the back of the mechanical unit 2, that is, near the drum. In this way, the humidity detection circuit that initially detected high humidity
Even if the detection value from 29 falls below the reference value 31, the humidity detection circuit 32 can detect a high humidity state due to air flowing into the inside of the apparatus 1 with a predetermined time delay. Thus, the release of the high humidity state can be detected more safely.

〔The invention's effect〕

According to the present invention, dew condensation and high humidity can be avoided by the amount of heat generated inside without providing a dedicated heater or the like, so that power consumption and cost of the apparatus can be reduced. In addition, since heating is not locally performed by a heater or the like, deterioration in accuracy due to thermal deformation of the mechanism component can be reduced, and the running and scanning performance of the tape can be maintained with high accuracy.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of one embodiment of the present invention, FIG. 2 is a sectional view of the entire apparatus, and FIGS. 3 and 4 are block diagrams of a cooling mechanism. 1 ... device, 2 ... mechanical unit, 6 ... motor, 7 ... fan, 10 ... cassette, 13,14,17 ... temperature detector, 15,16 ... humidity detector, 19 ... drive circuit.

Claims (2)

(57) [Claims] A magnetic head scanning mechanism for transmitting and receiving a signal obtained by scanning a magnetic tape with a magnetic head; a tape driving mechanism for moving the magnetic tape in a predetermined direction at a predetermined speed; A magnetic recording / reproducing apparatus including a processing circuit and a discharge mechanism for discharging air from the apparatus; a humidity detector for detecting humidity in the apparatus; and a signal from the humidity detector being larger than a predetermined value. Means for controlling the discharge operation by the discharge mechanism when the discharge operation is performed, wherein the magnetic head scanning mechanism, the tape drive mechanism, and the circuit are heated to generate heat inside the apparatus. A cooling mechanism in a magnetic recording and reproducing apparatus. 2. The magnetic head scanning mechanism or the tape driving mechanism or the circuit has a temperature detector for detecting a temperature of a heating element, and when an output of the temperature detector becomes a predetermined value or more. 2. The cooling mechanism according to claim 1, wherein the discharging mechanism is operated.