JPH02236844A - Method and device for detecting tape edge in magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To surely detect a tape edge and to easily design a tape edge detector by detecting the electric resistance value of the tape in a reproducing device, which uses a magnetic tape having a non-recording part whose surface electric resistance value is different from that of a recording part. CONSTITUTION:When a tape loading is completed, a magnetic tape 2 is brought into contact with guide rolls 10 and 10' of tape guide members 6 and 6', and a circuit is formed from a detecting power source 13 through the tape 2 to the positive input terminal of a comparator 14. Consequently based on the comparison output between the positive input terminal of a comparator 14 and a threshold voltage Vref, the recording part 3 of the tape can be identified from a non-recording part 4(5). In such a method, the tape edge can be surely detected, the tape edge detecting device can be arbitrarily arranged, and a freedom degree in designing is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The tape end detection method and tape end detection device in the magnetic recording/reproducing apparatus of the present invention will be explained according to the following items.

A. Industrial application field B. Summary of the invention C. Conventional technologyD. Problem to be solved by the inventionE. Means for solving problemsF. Example [Figures 1 to 3] a. Tape end detection device [Fig. 1, Fig. 2] b. Tape end detection method [Fig. 1] C. Effect d. Application example [Figure 3] G. Effects of the Invention (A. Field of Industrial Application) The present invention relates to a tape end detection method and a tape end detection device in a novel magnetic recording/reproducing device. Specifically, a recording part on which a magnetic layer is formed is a non-recording part having a different surface electrical resistance, for example, a tape in a magnetic recording and reproducing apparatus that uses a magnetic tape having a leader tape part and a trailer tape part at both ends of the recording part. The present invention relates to an end detection method and a tape end detection device, which enables the tape end to be detected based on the difference in electrical resistance between the recording section and the non-recording section, thereby improving the detection of the tape end detection means. A novel tape end detection method and tape end in a magnetic recording/reproducing device that can expand the range and positional freedom and reliably detect the tape top or end without a significant increase in cost. The present invention aims to provide a detection device.

(B. Summary of the Invention) The tape end detection method in the magnetic recording and reproducing apparatus of the present invention includes:
A method for detecting a tape end in a magnetic recording/reproducing apparatus using a magnetic tape having a non-recording part having a different surface electrical resistance from a recording part on which a magnetic layer is formed, the tape end being detected between two tape contact members where the tape contacts. The end of the tape is determined by detecting the electrical resistance value of the tape at the end of the tape.The end of the tape is detected by detecting the electrical resistance of the tape. A detection power source is connected to one of the two tape contact members, and its input terminal is electrically connected to the tape contact portion of the other tape contact member. This device is equipped with a detection circuit that detects the tape end by detecting the resistance value of the magnetic tape between the contact members, and has a high degree of freedom in design regarding the placement of the tape end detection device, and also does not significantly increase costs. This makes it possible to reliably detect the tape end without causing any damage.

(C. Prior Art) In an apparatus using a magnetic tape as a recording medium, it is important to detect the tape end in order to control tape running. This is because if the end of the tape cannot be detected, excessive tension will be applied to the tape during the sudden stop of tape running and the subsequent release of tape loading, which may lead to tape damage, motor overload, head clogging, etc. This is because there is.

Therefore, some type of tape end detection means is usually provided. For example, in an audio tape recorder, the tape top or end is detected when a tension exceeding the allowable tape tension is applied, or % inch or β one-way detection means is used. In VTRs, etc., we focus on the difference in magnetic properties between the surface of the leader tape or trailer tape and the surface of the magnetic layer in the recording section, and detect the top or end of the tape using a magnetic sensor such as a starting coil. The magnetic sensor method, or the optical detection method, which detects the transmission or non-transmission (magnetic layer) of light using a transparent material for the leader tape or trailer tape, such as the VHS method or 8 mm VTR, is known. ．． (D. Problems to be Solved by the Invention) However, in the above-mentioned method, there are restrictions on the detection range and position of the tape end detection means, and there are also problems that require careful attention to prevent malfunctions. There's a problem.

For example, it is difficult to apply the above-mentioned method of detecting tape tension to magnetic tapes with low allowable tape tension, and there are disadvantages in that the tape and tape running system are not sufficiently protected when abnormal tension acts on the tape. be.

In addition, the magnetic sensor method requires precision in the position of the magnetic sensor relative to the tape, which places restrictions on the position of the magnetic sensor.In the optical detection method, the position of the light source and optical sensor is determined by the relationship with the tape cassette. There is almost no degree of freedom in design, and it is also troublesome, such as the need to take measures to reduce the possibility of false detection caused by external light, scattered light, reflected light, etc. There is.

(E. Means for Solving the Problem) By the way, the recording part and the non-recording part of a magnetic tape usually have different electrical resistance values.

Therefore, in view of this point, in order to solve the above problem, the tape end detection method in the magnetic recording and reproducing apparatus of the present invention includes the following steps:
The end of the tape is determined by detecting the electrical resistance value of the tape between two tape contacting members that are in contact with the tape, which has a non-recording area that has a different surface electrical resistance from the recording area where the magnetic layer is formed. , the tape end detection device for this purpose has a contact portion with the tape that is conductive, and
Two tape contact members arranged in a state of being electrically insulated from each other, a detection power supply connected to one of the two tape contact members, and an input terminal connected to the tape contact portion of the other tape contact member. The detection circuit is electrically connected to the magnetic tape and detects the tape end by detecting the resistance value of the magnetic tape between these tape contact members.

Therefore, according to the tape end detection method and tape end detection device in a magnetic recording and reproducing device of the present invention, the tape end detecting device can be operated by using the tape contact member that is necessarily provided on the tape running path of the recording and reproducing device. Since they can be arranged arbitrarily to some extent on the path, the degree of freedom in designing the detection range of the tape end detection device can be expanded, and there is no need to be concerned about how to reduce false detections.

(F. Embodiment) [FIGS. 1 to 3] Details of the tape end detection method and tape end detection device in the magnetic recording/reproducing apparatus of the present invention will be described below according to the illustrated embodiment 1.

(a. Tape edge detection device) [Figures 1 and 2] 2 is a magnetic tape, which includes a recording section 3 in which a magnetic layer is formed on a film base, and a leader tape section 4 provided at both ends of the recording section 3.
and a trailer tape section 5. As the recording section 3, for example, one in which a mixture of binder and magnetic powder is applied onto a film base and a back coat layer is formed on the back surface is used. The recording section 3, leader tape section 4, and trailer tape section 5 each have a different surface electrical resistance, as is clear from their structural differences.

Reference numerals 6 and 6' designate tape guide members made of a material having four electric properties, and are arranged at a predetermined distance +mi and electrically insulated from each other in order to define the tape bus of the magnetic tape 2. It has been done. Since the tape guide members 6 and 6' have the same structure, only the parts of one of the tape guide members 6 will be explained below, and the same parts of the other tape guide member 6 will be described below. By adding "'" to the same reference numerals, the explanation thereof will be omitted.

7 is a metal shaft, which is fixed to a support member 8 made of electrically insulating material.

Reference numeral 9 designates a lower flange, into which the shaft 7 is press-fitted, and is fixed at a position near the lower center end of the shaft 7.

10 is a metal guide roller whose center hole 10a
The shaft 7 is inserted through.

Reference numeral 11 denotes an upper flange, which is fixed to the upper end of the shaft 7.

As shown in FIG. 1, the magnetic tape 2 is run with the tape surface in close contact with the guide rollers 10, 10', and at this time, the side edges of the magnetic tape 2 are
The function is lower flanges 9, 9' and upper flanges 11, 11'.
regulated by.

12 is a detection circuit, which connects the recording section 3 and the leader tape section 4;
Alternatively, it is provided to detect the tape top or tape end by utilizing the difference in surface electrical resistance between the trailer tape section 5 and the trailer tape section 5.

13 is a detection power supply, which is a predetermined voltage (this is E0 (v
), this value is considered to be such that the current flowing through the recording section 3 does not destroy the recorded information or affect the unrecorded tape. ) to the guide roller 10 of the tape guide member 6, the positive pole of which is electrically connected to the shaft 7.

14 is a comparator, the positive input terminal of which is connected to the shaft 7' of the tape guide member 6', and a resistor 15 whose one end is grounded (this resistance value is RO (Ω)
shall be. ) is connected to the anti-ground terminal. Also, the negative input terminal of the comparator 14 is connected to the positive electrode of the reference voltage generating power supply 17 via the resistor 16, and the detection threshold (this is referred to as Eraf (■)) is set to a predetermined value. Alternatively, a variable resistor may be used as the resistor 16 so that an arbitrary set value can be set.

The output signal of the comparator 14 is output to a control circuit (not shown), for example, a mechanical microcomputer, and when the top or end of the tape is detected, the tape running system is controlled to stop in response. .

(b. Tape end detection method) [FIG. 1] The operation of the tape end detection device 1 is as follows.

When tape loading is completed, the tape guide member 6,
One surface of the magnetic tape 2 is wound around the guide rollers 1.0 and 10' of the magnetic tape 6' so as to be in contact therewith. Therefore, the detection power source 13 - shaft 7 - guide roller 1
A circuit is formed in the following order: 0 -> recording section 3 or leader tape section 4 or trailer tape section 5 of the magnetic tape 2 -> guide roller 10'-> shaft 7'-> positive input terminal of the converter 14. Therefore, as shown by the broken line in FIG. 1(A), when the magnetic surface of the recording section 3 of the magnetic tape 2 is wound between the tape guide members 6 and 6', the tape guide member 6 Assuming that the electrical resistance value between R and 6' is R (Ω), the voltage is divided by this resistor R and the resistor 15, and the portion 5a of the Lehrer tape portion 5 is supplied to the converter 14 as a positive input voltage. When the magnetic tape 2 is in the wound state, the resistance value of the magnetic tape 2 between the tape guide members 6 and 6' changes from R (Ω) to R' (Ω) (resistance of 3a and resistance of 4a or 5a). (approximately equal to the combined resistance of ). For example, if the leader tape section 4 and the trailer tape section 5 are made of a material with a lower conductivity than the recording section 3, the resistance value of the package is R'>R, and therefore the converter 14 is connected to the positive input voltage at this time. , is input, and this value and threshold E1. A comparison with f is made by the comparator 14, and the comparator 14 outputs an H mark indicating that the tape is not at the top or end.

Further, as shown in FIG. 1(B), a tape guide member 6,
6', it is determined that the portion 3a of the recording section 3 of the magnetic tape 2 and the portion 4a or t of the leader tape section 4 are less than the threshold E r@f, and a signal indicating the tape top or tape end is generated. Output.

Note that the detection circuit 12 is not limited to the above-mentioned configuration; for example, an AD converter may be provided to digitize the terminal voltage of the resistor l5 by AD conversion, and determine whether or not this value is within a predefined range. You can do it like this. Further, as a tape end detection method, the 6Ii side of the recording section 3 of the magnetic tape 2 is brought into contact with the tape guide members 6, 6', and the side opposite to the magnetic side is brought into contact with the tape guide members 6, 6'. Or, the magnetic surface side may be brought into contact with one tape guide member 6' and the surface opposite to the magnetic surface may be brought into contact with the other tape guide member 6'. A magnetic region for tape top or end detection may be intentionally formed on the surface side, and this diamagnetic surface side may be brought into contact with the tape guide members 6, 6'.

(c. Effect) As described above, in the tape end detection device 1, there is a difference in surface electrical resistance between the recording section 3 and the leader tape section 4 and trailer tape section 5 provided at both ends thereof. Tape top detection or tape end detection is performed by detecting the change in resistance value when the tape is running, so a tape guide member that is necessarily provided on the tape running system can be used. , the degree of freedom regarding the detection range is higher than in the past, and since the detection circuit 12 can be incorporated into an IC chip forming other circuits, there will be no significant increase in cost.

Even if the detection circuit 12 is disconnected, the output signal at this time is different from the signal output when the tape end detection device 1 detects the recording section 3 of the magnetic tape 2. In such a case, the operation of the tape running system control section is stopped to protect the tape running system including the tape and reel motor.

(d. Application example) [Figure 3] Next, the above-mentioned tape end detection device 1 is installed on an 8mm VTR 18.
An example in which this method is applied will be explained, focusing on a tape pass system.

19 is a tape cassette, one side 20 (hereinafter referred to as
This is called the "tape drawer surface." ) Tape outlet 21 at both ends of
, 21' are formed, and a portion 22 of the tape draw-out surface 20 between the tape outlets 21 and 21' is formed as a tape draw-out recess, and a lid for opening and closing the tape draw-out surface 20 is formed. The body 23 is provided so as to be freely movable.

24 and 24' are tape reels with both ends of the magnetic tape 2 fixed and wound with a predetermined amount, which are rotatably stored inside a cassette case, and a part of the magnetic tape 2 is inserted into the tape outlets 21, 21. ' is led out of the cassette case and extends along the tape pull-out surface 20. Reference numeral 25 designates a mechanical chassis of the VTR 18, and reel stands 26 and 26' are arranged spaced apart from each other and rotatably supported near one end of the mechanical chassis, and reel engaging shafts 26a and 26'a are respectively mounted on the mechanical chassis 25. It is set in.

27, 27, . . . are cassette mounting bins erected at predetermined positions on the upper surface of the mechanical chassis 25.

Reference numeral 28 denotes a cassette holding member, which places the tape cassette 19 on the upper end surface of the cassette mounting pins 27, 27, . By engaging the positioning protrusion formed at the upper end with the tape cassette 19, the tape cassette 1
9 positioning is performed.

29 is a first guide post which also controls the tape tension, 30 is an entrance guide post, and 31 is an inclined guide post.As shown by the two-dot chain line in Fig. 3, the first guide post 29 and the entrance guide post are connected to each other during tape loading. 30
As the magnetic tape moves, the magnetic tape on the S reel 24 side is wound around the head drum 32. A tape end detection device using the first guide post 29 and the entrance guide post 30 is provided.

Further, the magnetic tape on the T-reel 24' side is wound around the head drum 32 by the movement of a slant guide block 36 having three inclined guide posts 33, 34, and 35, thereby entering a standby state.

37 is a fixed guide post provided near the tape outlet 21' on the T reel 24'side;
7 is utilized in a tape top detection device together with the inclined guide post 35 closest to it.

38 is a loading ring, and when the loading ring 38 is rotated in a predetermined direction, the magnetic tape 2 is moved by the leading guide post 39, the pinch roller 40, and the loading guide post 41, 41' on the loading ring 38. It is further wrapped around the head drum 32 so that the wrap angle is approximately 220 degrees.

Reference numeral 42 denotes a capstan shaft, which is provided at a position where it can pinch the magnetic tape 2 between it and the pinch roller 40 and run the tape during recording or reproduction.

43 is a fourth guide post, and 44 is a fifth guide post.

As a tape path system, the magnetic tape 2 coming out of the S reel 24 passes through the first guide post 29, the artificial guide post 30, the inclined guide post 31, and then the head drum 32.
After being wrapped around the 4th guide post 43, the 5th guide post 44, and between the capstan shaft 42 and the pinch roller 40, the leading guide post 39, the loading guide post 41, 41', and then the slant guide. A path is formed through the inclined guide posts 34, 35 of the block 36 and the fixed guide post 37 to the T-reel 24'. Then, the magnetic tape 2 is run along such a tape path, the tape end is detected between the first guide post 29 and the entrance guide post 30, and the tape end is detected between the inclined guide post 35 and the fixed guide post 37. Top detection is done.

(G. Effects of the Invention) As is clear from the above description, the tape edge detection method in the magnetic recording/reproducing apparatus of the present invention is effective in detecting a non-recorded area having a different surface electrical resistance value from a recording area on which a magnetic layer is formed. A tape edge detection method in a magnetic recording and reproducing apparatus using a magnetic tape having a tape edge, the tape edge being determined by detecting the electrical resistance value of the tape between two tape contact members with which the tape comes into contact. The tape end detection device in the magnetic recording/reproducing apparatus of the present invention is also applicable to a magnetic recording/reproducing apparatus using a magnetic tape having a non-recording part having a different electric resistance value from the recording part on which the magnetic layer is formed. The tape end detection device includes two tape contact members whose contact portions with the tape have conductivity and are arranged in a state where they are electrically insulated from each other, and one of the two tape contact members. The connected detection power supply and its input terminal are electrically connected to the tape contact portion of the other tape contact member, and the tape end is detected by detecting the resistance value of the magnetic tape between these tape contact members. A detection circuit is provided.

Therefore, according to the tape end detection method or the tape end detection device in the magnetic recording/reproducing device of the present invention, the tape end detecting device can be detected by using the tape contacting member that is necessarily provided on the tape running path of the recording/reproducing device. Since it can be placed arbitrarily on the path to some extent, the degree of freedom in designing the detection range of the tape end detection device can be expanded.
There is no need to worry about how to reduce false positives.

Note that the structure of the tape contact member in the tape end detection device of the present invention is not limited to the above-described structure of the tape guide member, and the contact portion with the tape has at least conductivity and is electrically conductive to each other. Any structure may be used as long as it is insulated.

[Brief explanation of drawings]

1 to 3 show an example of an embodiment in which the tape end detection method and tape end detection device in the magnetic recording/reproducing apparatus of the present invention are applied to the tape end detection method and tape end detection device in a VTR, and FIG. The figures are diagrams for explaining the tape end detection device. (A) is an explanatory diagram of the circuit when detecting the recording section of the magnetic tape, (B) is an explanatory diagram of the circuit when detecting the tape end, and FIG. FIG. 3 is a horizontally cutaway plan view schematically showing the VTR and the tape cassette installed therein in a state in which tape loading has been completed. Explanation of symbols 1... Tape end detection device, 2... Magnetic tape, 3... Recording section, 4, 5... Non-recording section, 6, 6'... Tape contact member, 10, 10' ...Tape contact portion, 12...Detection circuit, 13...Detection power supply, 18...Magnetic recording/reproducing device, 29, 30...Tape contact member, 35, 37...Tape Contact member circuit diagram (when detecting the tape) Fig. 1 CB) Circuit explanatory diagram (when detecting the record) Fig. 1 (, 4) Partial side hole plan view Fig. 2

Claims (2)

[Claims] (1) A method for detecting tape edges in a magnetic recording/reproducing device using a magnetic tape having a non-recording part with a different surface electrical resistance value from the recording part on which a magnetic layer is formed, and in which two tapes contact each other. A tape end detection method in a magnetic recording/reproducing device, characterized in that the tape end is determined by detecting the electrical resistance value of the tape between members. (2) A tape edge detection device in a magnetic recording/reproducing device that uses a magnetic tape having a non-recording part having a different electrical resistance value from the recording part on which a magnetic layer is formed, and where the contact part with the tape is electrically conductive. a detection power source connected to one of the two tape contact members, and a tape contact portion of the other tape contact member; A tape in a magnetic recording and reproducing apparatus, comprising: a detection circuit having an input terminal electrically connected to the tape, and detecting a tape end by detecting a resistance value of the magnetic tape between these tape contact members. edge detection device