JPS622373B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a column sensor for a tape buffer holding device, particularly a tape loop position of a magnetic tape in a tape buffer section of a magnetic tape device for information processing.
This invention relates to a capacitive column sensor for a magnetic tape buffer holding device that can detect normal and abnormal areas with a single signal.

In general, tape buffering and holding mechanisms using the vacuum column method of magnetic tape devices create a loop in the magnetic tape running between reels, which is sucked into a vacuum column and bent into a certain loop state. This is designed to avoid damage to the tape during high-speed startup, stopping, etc. The column sensor detects the amount of tape or tape loop position in this vacuum column.For example, it detects changes in the amount of tape as changes in capacitance, and controls the reel motor based on this detection signal. The amount of tape in the vacuum column is always maintained at an appropriate level. In addition, this kind of tape buffer mechanism is
It quickly detects when a large amount of magnetic tape is about to get stuck at the bottom of the vacuum column or about to come off the top of the column, and either unwinds too much tape or stops winding and prevents the tape from coming off the column. It is designed to prevent damage to the

The tape buffer mechanism of such conventional magnetic tape devices consists of a column sensor that detects the amount of tape in the vacuum column, and an emergency sensor that detects a tape loop that has reached an abnormal area near the top or bottom of the vacuum column. There are many models that consist of separate sensors (sensors), and are inevitably expensive due to their structure. On the other hand, for systems that use column sensor signals to detect abnormalities in the tape amount or tape loop position, it is necessary to manufacture the column sensor with considerable precision and to strictly control variations in the dimensions and quality of the component parts. In some cases, the level of the abnormal region must be adjusted by adjusting the voltage (volume) or the like. Therefore, in either case, conventional magnetic tape devices have the disadvantage of being complicated in structure and adjustment and expensive.

The present invention eliminates the above-mentioned conventional drawbacks and provides a column sensor for a tape buffer holding device that is simple in structure and inexpensive and can detect the amount of tape in a vacuum column and an abnormal state of the amount of tape with a single signal. With the goal.

Another object of the present invention is to be able to accurately detect an abnormality in the amount of tape without requiring electrical adjustment even if there are variations in component dimensions during manufacturing, and to improve the level of the abnormal area within the column. An object of the present invention is to provide a column sensor for a tape buffer holding device that can set a high value.

The present invention provides a column sensor for a tape buffer and holding device that detects changes in the position of a tape loop in a vacuum column into which the tape enters in a loop shape as a change in capacitance of an electrode. a main body housing including a chamber and an abnormality detection compartment, and a flexible electrode installed in the main body housing spanning each of the compartments, the tape amount detection compartment of the main body housing; communicates with the tape control area of the vacuum column through a long groove, the abnormality detection compartment communicates with the tape abnormality area of the vacuum column through an abnormality detection hole, and the tape amount detection compartment communicates with the tape control area of the vacuum column through an abnormality detection hole. a flexible electrode in the compartment varies in response to tape loop position only when the tip of the tape loop is in the tape control region of the vacuum column due to a pressure difference on either side of the flexible electrode; The flexible electrode in the abnormality detection compartment is
It is characterized in that it changes only when the tape loop passes through the abnormality detection hole.

The tape control area here refers to the area where the reel motor can be controlled to maintain an appropriate amount of tape in the column even if the tape fluctuates within the vacuum column. It is output according to the amount. Note that the present invention is not only applicable to magnetic tape devices, but can also be applied to detecting the amount or loop position of any tape or strip introduced into a column in the form of a loop.

Embodiments of the present invention will be described below with reference to the drawings. In the illustrated embodiment, a case where the present invention is applied to a magnetic tape buffer mechanism of a magnetic tape device will be described.

FIG. 1 is a schematic front view of the magnetic tape device, with the top plate removed. Briefly explaining its structure, the vapor tape 3 enters the supply side vacuum column 6 from the supply reel 1 in a loop shape, passes through the magnetic head 4 and the capstan 5, and then goes through the take-up side vacuum column 6. ' and then wound onto the take-up reel 2. The supply side vacuum column 6 and the take-up side vacuum column 6' have long grooves 8, 8' extending in the longitudinal direction of the columns in their back plates 13, upper abnormality detection holes 9, 9', and lower abnormality detection holes 10, 10'. is formed. Further, vacuum suction holes 7, 7' are provided at the bottom of each column 6, 6', and the magnetic tape 3 is sucked downward by negative pressure from these holes to create a tape loop inside the column.
This provides a buffering effect to the tape between each reel and the capstan.

FIG. 2 is a longitudinal sectional view of a column sensor 40 according to an embodiment of the present invention attached to the back plate 13 of the magnetic tape device shown in FIG. 1, showing a portion of one column 6 in FIG. is cut vertically. The main body housing 41 of the column sensor 40 is divided into three chambers, an upper air chamber 31, a central air chamber 32, and a lower air chamber 33, by partition walls 17 and 17a. The upper air chamber 31 and the lower air chamber 33 function as compartments for abnormality detection in the present invention, and the central air chamber 32 functions as a compartment for tape amount detection. An electrode assembly 42 consisting of three electrodes as shown in FIG. 3 is installed in the main body housing 41, spanning each of the air chambers 31, 32, 33. In order to explain the operation of the electrodes, the spacing between the electrodes of the electrode assembly 42 is shown enlarged in FIG. 2 compared to other parts. The upper and lower air chambers have a space portion on one side adjacent to the vacuum column 6 with respect to the electrode assembly 42 passing through the upper abnormality detection hole 9 and the lower abnormality detection hole 10, respectively, to the upper abnormality area 43 in the vacuum column 6. and the lower abnormal region 44, and the space on the opposite side is the vacuum intake port 1, respectively.
8 and 18a, it communicates with a vacuum source (not shown). Similarly, the central air chamber is connected to the electrode assembly 4
2, the space on one side adjacent to the vacuum column 6 communicates with the tape control area 45 of the vacuum column 6 from the narrow long groove 8, and the space on the opposite side communicates with the tape control area 45 of the vacuum column 6 through the pressure intake port 19 for pressure supply (not shown). connected to the source.

The electrode assembly 42 shown in FIG.
Fixed electrodes 22, 22a having a plurality of small holes 24 are arranged on both sides thereof, and these are assembled together by a mounting pin 21. The insulating plates 27, 27a are hollowed out at a portion 27b surrounded by dotted lines. In addition, code 2
8 is a lead wire of the flexible electrode 29, numerals 23, 23
a are lead wires of the fixed electrodes 22 and 22a, respectively. When such an electrode assembly 42 is attached to the main body housing 41 as described above, each air chamber 3
1, 32, and 33 are hermetically separated into two left and right spaces by a flexible electrode 29.

Top plate 11, back plate 13 (Fig. 2) and side plate 4
In the case where the magnetic tape 3 is placed in a loop shape within the column 6 surrounded by 6 and 47 (Fig. 1),
When the pressure in the concave column 12 of the tape loop is P ₁ and the pressure in the negative column chamber 12a is P ₂ , the vacuum intake ports 18 and 18a of the air chamber 31 and the lower air chamber 33 A pressure P ₂ is applied to each space communicating with the space. In addition, the central air chamber 3
A pressure P ₁ +P ₂ /2 is applied to the space communicating with the pressure intake port 19 of No. 2. These pressures act directly on one side of the flexible electrode 29 through the plurality of small holes of the fixed electrode 22a in each of the air chambers 31, 32, and 33, respectively. The relationship between each pressure is P ₂ <
P ₁ +P ₂ /2<P ₁ .

In the above configuration, when the tip of the tape loop moves up and down within the tape control area 45 of the vacuum column 6 as shown by the solid line 48 in FIG. Since the pressures P ₁ and P ₂ are maintained, the flexible electrodes 29 in the upper and lower air chambers 31 and 33 do not fluctuate due to the vertical movement of the tape loop. That is, the pressure P is applied to the side of the flexible electrode 29 in the upper air chamber 31 facing the vacuum column 6 from the upper abnormal region 43 through the upper abnormality detection hole 9 and the small hole 24 (FIG. 3) of the fixed electrode 22. ₁ is stiff, and therefore this flexible electrode 29 has a pressure relationship (P ₂ <
P ₁ ), the fixed electrode 22a on the vacuum intake port 18 side
are attracted to. Similarly, the flexible electrode 29 existing in the lower air chamber 33 has pressure on both sides.
Since P ₂ is equal, the fixed electrodes 22 and 22a are maintained in a straight state in the middle. and central air chamber 32
In this case, the flexible electrode 29 corresponding to the part of the concave column chamber 12 has a pressure relationship on both sides P ₁ +P ₂ /2<
P ₁ to the fixed electrode 22a side, and the flexible electrode 29 corresponding to the convex column chamber 12a to the fixed electrode 22 side due to the pressure relationship P ₁ +P ₂ /2>P ₂ on both sides. I am drawn to it. Therefore, when the tape loop moves up and down within the tape control area of the column 6, the distance between each electrode in the central electrical chamber 32 changes continuously depending on the position of the tape loop, and the distance between the flexible electrode 29 and the fixed electrode changes continuously. The capacitance C between 22a and 22 is C=
It changes depending on ε ₀ S/d (where ε ₀ is the dielectric constant, S is the area of the opposite electrode, and d is the distance between the opposite electrodes). This is electrically processed as a difference between the capacitance between the flexible electrode 29 and the fixed electrode 22, and the capacitance between the flexible electrode 29 and the fixed electrode 22a, and is used as a control signal. The reel motor is controlled to keep the tape amount within 6 appropriate.

Next, when the tape loop reaches the upper abnormality region 43 of the column and passes through the upper abnormality detection hole 9 as shown by the dotted line 48' in FIG. The pressure on the side facing column 6 changes from P ₁ to P ₂ , which causes electrode 2 to
The pressure on both sides of 9 becomes equal and this flexible electrode 2
9 is in a straight state as shown by the dotted line. At this time, the flexible electrodes 29 of the central air chamber 32 and the lower air chamber 33 are kept at the same position as when the pressure in the column is _P2 and does not fluctuate. Further, when the tape loop enters the lower abnormality region 44 and passes through the lower abnormality detection hole 10 as shown by the dashed line 49 in FIG. The pressure on the side changes from P ₂ to P ₁ , and as a result, the flexible electrode 29 in this area is drawn toward the fixed electrode 22a as shown by the dashed line.
The flexible electrodes 29 in the upper and central air chambers do not fluctuate because the pressure on both sides of the tape loop does not change when the tape loop passes through the lower abnormality detection hole 10.

In this way, when the tape loop enters the abnormal area and passes through the abnormality detection hole 9 or 10, the flexible electrode continuously moves with an area proportional to the tape loop position, as in the tape control area 45. Air chamber 31 that does not move but corresponds to the abnormal area
Alternatively, the total area of the flexible electrodes 29 within 33 changes greatly at once. Therefore, as shown in Figure 4, the capacitance changes suddenly at the position where the tape loop passes the abnormality detection hole (position A in Figure 4). Abnormalities can be detected. In the figure, the proportional portion of straight line B corresponds to the case where the tape loop is in the tape control area of the column. Even if there is some variation in the dimensions of the component parts due to manufacturing, the position of the tape loop that indicates an abnormality (point A in Figure 4) remains the same.
An abnormality in the tape loop position clearly appears as a sudden voltage change (see the dashed line in FIG. 4). Therefore, the level of the abnormal region can be set at a high position in the column, as shown by dotted line 48' in FIG. 2 or dotted line C in FIG. 4.

When trying to detect an abnormality in the tape loop position using a conventional column sensor, if there are variations in component dimensions, the sensor with the characteristics shown by the solid line and the sensor with the characteristics shown by the dashed-dotted line will have different characteristics, as shown in Figure 5. If the abnormality setting level is the same, the tape loop position where the abnormality appears will shift from point b to point a. Therefore, with conventional column sensors, it is necessary to strictly suppress variations in the parts or to adjust the abnormality setting level using a volume control, which results in expensive parts and a long adjustment process. In contrast, in the column sensor of the present invention, the larger the area of the flexible electrode corresponding to the abnormal region of the column, the larger the change in capacitance, and the larger the abnormality setting level can be set. can also be made larger, reducing manufacturing costs. No electrical adjustment of volume or the like is required.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of a magnetic tape device to which the present invention is applied, FIG. 2 is a longitudinal sectional view of a column sensor according to an embodiment of the present invention installed in the magnetic tape device of FIG. 1, and FIG. The figure is a perspective view of an electrode assembly incorporated into the column sensor of the present invention, Figure 4 is a diagram showing the relationship between tape loop position and voltage in the column sensor of the present invention, and Figure 5 is a tape loop in a conventional column sensor. FIG. 3 is a diagram showing the relationship between position and voltage. 3... Magnetic tape, 6... Supply side vacuum column, 8,
8'...long groove, 9,9'...upper abnormality detection hole, 10,1
0'... Lower abnormality detection hole, 17, 17a... Partition wall, 2
2, 22a...Fixed electrode, 29...Flexible electrode, 31
... Upper air chamber (compartmental chamber for abnormality detection), 32... Central air chamber (compartmental chamber for detecting tape amount), 33... Lower air chamber (compartmental chamber for abnormality detection), 40... Column sensor, 41... Main body housing, 43 ...Upper abnormal area, 44...Lower abnormal area, 45...Tape control area.

Claims (1)

[Claims] 1. In the column sensor of the tape buffer holding device, which detects changes in the position of the tape loop in the vacuum column where the tape enters in a loop shape as a change in the capacitance of the electrode, there is a compartment for detecting the amount of tape and a compartment for detecting abnormality. It has a main body housing provided with a compartment, and a flexible electrode installed in the main body housing spanning each of the compartments, and the tape amount detection compartment of the main body housing is connected to the tape amount detection compartment through a long groove. The abnormality detection compartment communicates with the tape abnormality area of the vacuum column through an abnormality detection hole, and the tape control area of the vacuum column is connected to a tape control area of the vacuum column. The flexible electrode moves in response to the tape loop position only when the tip of the tape loop is in the tape control area of the vacuum column due to the pressure difference on both sides of the flexible electrode, and the flexible electrode moves in response to the tape loop position only when the tip of the tape loop is in the tape control area of the vacuum column. A column sensor for a tape buffer holding device, characterized in that a flexible electrode in the chamber changes only when the tape loop passes through the abnormality detection hole.