JPS5823352A - Loading block guide mechanism for video tape recorder - Google Patents

Abstract

PURPOSE:To perform loading without any trouble, by guiding a pair of loading blocks having taper pins drawing out a tape and guide pins along a pair of guide holes povided to lengthwise direction of a guide stand. CONSTITUTION:At the loading mode, a loading motor (not shown) is turned to drive shafts 28 and 26 via shafts 17 and 27 and gears 18-21. Arms 23a, 23b and 25a, 25b are bent or extended in interlocking with said driving and loading blocks 51 and 52 fitted to the tip of the arms are forwarded or reversed. In this case, guide pins 60 and 53 of loading blocks 51 and 52 slide in lengthwise left and right guide holes provided at upper base (not shown). The loading blocks 51 and 52 are provided with tape guides 54 and 62 and taper pins 55 and 63. Thus, the loading blocks 51 and 52 are moved without any throuble in a narrow gap to load/unload the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a loading block guide mechanism for a video tape recorder.

A cassette-type video tape recorder is equipped with a tape loading mechanism that pulls out a tape from a cassette and loads it on a guide sill surface.

At present, there are two main types of loading methods: the β method, in which the tape is mounted on a guide cylinder by rotating the loading disk in one direction, and the β method. The latter can be made smaller than the former because it does not include a loading disk.

However, in the latter case, it is difficult to narrow the cassette width because the capstan that drives the tape at a constant speed must enter the cassette notch.

Therefore, it is possible to downsize both the loading mechanism and the cassette by leaving the loading method unchanged and running the tape at a constant speed outside the cassette. When mounting on a guide sill, the width of the moving path of the loading means is subject to great control.

In view of the above-mentioned points, the present invention provides a method for guiding a movable guide table for planting an inclined pin and a guide pin along a loading path. The present invention proposes a loading block guide mechanism for a video tape recorder, which is characterized by being able to load the tape without contacting obstacles such as a fixed head surrounding the tape.

[Margin below]

Hereinafter, the present invention will be explained according to an illustrative embodiment.

The first feature of this embodiment is that it is provided with a mode setting cam that switches modes by rotation.

This mode setting cam (force is applied to the second position rotated 45° clockwise from the first position for setting the stop mode [Fig. 1(b)])
The fast forward mode and rewind mode are set while the tape is stored in the position [Figure 2 (a)], and the third device r is rotated 270 degrees counterclockwise from the first position (Figure 1 (C)). ], the Bose mode is set upon completion of loading, and the fourth position is rotated 45 degrees counterclockwise from the third position [Figure 1 (
d)], the pinch roller is pressed to set the recording mode and reproduction mode. In addition, this mode setting cam T has an idler regulating cam (1b) formed on the upper stage of the gear part (1a), a spiral loading cam (1c) on the lower surface, and a further upper surface of the idler regulating cam (1b). A pinch roller moving cam (1d) is attached to the idler regulating cam (1b), and an idler regulating lever (2) that regulates the movement of the tape winding idler and a troding completion detection lever (3) are in contact with the idler regulating cam (1b). Furthermore, the pinch roller moving cam (1d) is provided with a pinch roller moving lever (
4), and further the loading cam (1c)
There is a loading pin (5) that drives the loading mechanism.
are engaged. Therefore, in the stop mode, the idler regulation lever (2) is activated by the idler regulation cam (
By entering the recessed portion 1b), the brake shoe is placed in the first position, and the idler is set in the neutral position, and the brake shoe is pressed against the reel stand.

Further, in the fast forward mode and the rewind mode, the idler regulating lever (2) is disengaged from the recessed portion and is in the second position, releasing regulation of the idler. Furthermore, in the pause mode, the loading pin (5) is rotated clockwise to complete loading, and the pinch roller moving lever (4) is rotated clockwise to pinch the tape and cap the pinch roller. The idler regulation lever (2) is in the second position, and the loading completion detection lever (3) enters the recess of the idler regulation cam (1b) to detect the completion of loading and set the mode. The cam (which has stopped rotating in the clockwise direction, and the pinch roller moving lever f4 in the recording mode and playback mode) is further rotated clockwise to press the pinch roller against the capstan.

Each drive system will be explained below with reference to the drawings from FIG. 2 onwards.

First, the drive system for the mode setting cam +X+ is as shown in FIG.
7) rotatably supports the mode setting cam (1);
The first gear ( 9
) is engaged with the loading motor support plate (11) attached to the lower surface of the bottom board (6) with respect to the double-sided second gear (1) fixed to the lower part of the second support shaft (8). A part (12a) of the double gear of the third gear 02 which is pivotally supported is meshed with the part (12a) of the spur gear of the third gear O2.
2b), the drive shaft of loading motor αJ (i3
A configuration is adopted in which a fourth gear 04) integrated with a) is meshed with the fourth gear 04). Therefore, the loading motor α3 is operated by the fourth gear 041 and the third gear f15, which constitute a deceleration mechanism, and the third gear (12+) and the second gear (1■), which constitute a deceleration and rotational axis changing mechanism. The rotation is transmitted to the first gear (9), and the mode setting cam (1) can switch the setting mode by the loading motor (13) which is driven in both directions.

Further, as shown in FIG. 3, the drive system of the loading mechanism connects the bottom board (the fan-shaped gear 05) supporting the loading bin (5) that engages with the loading cam (1c) with the mode setting The fan-shaped gear 151 is connected to the first support shaft (7) so as to be rotatable about the third support shaft F[+ mounted on the bottom substrate (ω). A loose fitting through hole (i5a) is formed, and the fifth gear +181, which is pivotally supported on the fourth support shaft Jη, meshes with a portion of the small diameter gear (18a), and the fifth gear (a portion of the old large diameter gear) (18b) is meshed with the sixth gear 0gl and the seventh gear (20), and the seventh gear is further meshed with the eighth gear (21), and the sixth gear 09)
The left loading arm is fixed to the first block which is integrally fixed to the eighth gear 121), and the right loading arm) is fixed to the second block +241 which is integrally fixed to the eighth gear 121). Therefore, while the mode setting cam (〃) rotates 2700 times from the first position to the third position, the loading cam (1c) gradually changes its diameter to engage the loading bin (5). The fan-shaped gear (151) is guided counterclockwise around the third support shaft (161) and rotates counterclockwise.
The first block device is rotated counterclockwise and the second block (24) is rotated clockwise, and the later-described loading blocks attached to the ends of the left and right loading arms 1231a are moved from the unloading position to the loading position. I am guiding you to. The loading cam (1c) rotates from the first position to the second position to fast-forward or rewind the tape, and from the third position to the fourth position to perform recording/playback. It rotates without changing its diameter, keeping the loading bin (5) in place and rendering the double-ended loading arm inoperative. The second block (241 and the eighth gear 〇 However, the first block and the sixth gear (19+) have a cylindrical body at the center that also penetrates the bottom substrate in order to support a tension applying lever to be described later.

Furthermore, as shown in FIG. 4, the reel drive system has four pillars 1 on the lower surface of the bottom board (shown by dashed lines).
2g) ■3 Fix the reel motor (goods) to the left side of the lower surface of the sub-board (■) fixed by the old screw, and its drive shaft (34
a) and the first boot IJ CE attached to the bottom board.
Nyahu H36 which is supported through the upper board and the upper board described below.
), a first connecting belt i is attached to a second pulley attached to the lower part of the reel motor (34), and the rotation of the reel motor (34) is controlled between normal rotation in recording/reproduction mode, high speed rotation in fast forward mode, and high speed rotation in rewind mode. It is switched to 3 stages of reverse rotation and high speed rotation.

Furthermore, as shown in FIG. 4, the capstan drive system includes a capstan motor (3
9) and a fifth booby IJ fixed to its drive shaft (39a); 401, and a flywheel boo fixed to the lower part of the capstan shaft (41) passing through the bottom board and the top board. A second connecting bell l-(43) is mounted on 4z.The drawing number 441 is the flywheel pulley +421(7) lower t1 d6 supports f451 f
461 (47) f481 (49) (50) Therefore, it is a rotation detecting body that incorporates a rotation detecting means for the flywheel boot 1/42.

The configuration of the loading mechanism, which is the second feature of this embodiment, will be explained below with reference to the drawings from FIG. 5 onwards.

First, the double-ended arm +23)i has two leaf springs (23aX23b) and (25a) (25), respectively.
b) is rotatably supported by connectors (23c) and (25c), and overstroke during loading is prevented by the leaf springs (23a), (23b), (25a), and (25).
It is absorbed by elastic deformation in the thickness direction (b). In addition, the loading blocks placed at the ends of the loading arms have almost symmetrical shapes, and the loading blocks on the right side are rotatably supported on the right side loading arm. a right side guide shaft ridge, which is fixed to the upper part of this guide shaft (hereinafter referred to as "right side tape guide"), and a right side movable guide stand (hereinafter referred to as "right side") on which a right side tape guide (goods) and a right side tilting pin [stock] which is inclined at approximately 12 degrees are installed. , a right slider 6η which is rotatably supported at the middle part of the guide shaft and has a guide groove (57a) formed on its outer peripheral surface; and a right slider 6η which is fixed to the lower part of the guide shaft and is in circumferential contact with a guide rail to be described later. the right side positioning arm which defines the rotational state of the right side moving guide stand [Co., Ltd.], the right side slider (571) and each through hole (57c) (58) at the right side positioning arm.
Similarly, the left side loading block [Co., Ltd.] also has a right side coil spring (59) whose end is inserted into a) to bias the positioning arm member clockwise against the right side slider +571. As shown in Fig. 6, it is equipped with a left side moving guide stand (-, etc.) on which a left side guide shaft '60), a left side slider 161), a left side tape guide (G) and a left side tilt pin (631) tilted at 12 degrees are installed. The left moving guide stand (64) is urged to rotate counterclockwise with respect to the left slider (61).

These loading blocks must pass through a narrow space from the unloading position to the loading position. Therefore, in this embodiment, as shown in FIG. The upper portions of the sliders 571 and 611 are cut off to define loading paths for the sliders 571 and 611, and as shown in FIG. Attach the rail (Akira) and the left side guide rail, and make the right side positioning arm and the left side positioning arm (not shown) circumferentially surround both guide rails (1Fi81, f69).During loading, the surface moving guide stand (56) 164
The longitudinal direction of the device 1 is aligned substantially along the loading path to avoid collisions with components disposed close to the loading path. Further, the two moving guide stands (64) that move on the upper surface of the upper substrate (64) change the state relative to the two sliders (571 (61)) at the loading position and the unloading position, and at the loading position, the two moving guide stands (64) At the positioning block σ0) ff1), which also serves as a stop for removing the through hole t66) tp, both the movable guide stands:'@!
The tape guide side of 611 is defined, and the inclined pin side is defined by the winding angle defining plate (2) 1, which abuts so that the defined position can be adjusted by adjustment screws (72a) (73a). Both moving guide stands 6η (6
1) in the horizontal direction of the figure.
57 with the specified storage fittings and the left side moving guide stand (
61) is defined on the storage regulation board 1751.

Therefore, both moving guide stands +57) '611 are loaded by the storage angle 4 fixed fittings t741 and the storage regulation plate 75) during unloading, and by the two guide rails 75) during loading. At times, its rotational state is determined by the positioning block 70+ 711 and the wrapping angle regulation hi 172+ ('73+).

Further, as shown in FIG. 7, the pinch roller moving mechanism moves the pinch roller moving lever (4) that comes into contact with the pinch roller moving cam (1d) to the seventh position of the bottom substrate f6).
A support shaft ('7G+) is rotatably supported, and a pinch roller support lever shaft is also pivotally supported on the seventh support shaft 76+, and an expansion spring is disposed between the pinch roller moving lever (4) and the seventh support shaft 76+. This absorbs the overstroke of the pinch roller ff91 during crimping, and the expansion is controlled by a rotation regulating pin (mounted on the pinch roller moving lever (4)).
4a), and the pinch roller moving lever (4a)
) is opposed to the pinch roller pressure detection switch (81). In addition, the pinch roller support shaft (
In 77a), a pinch roller guide hole (82) is formed across the right side guide hole (82) in the -L section substrate rim to ensure a moving path for loading and pinch roller crimping. Through hole tta! The right slider 67) has a sufficient length so that the right slider 67) can stably slide between the right guide holes at the intersection of the right sliders 82+ and 82+. Therefore, as is clear from the shape of the pinch roller moving cam (1d), the pinch roller (79) of this embodiment rotates in the second half of the loading period, that is, after the tape has been sufficiently pulled out, and rotates around the capstan. (41), the tape moves slightly as the recording mode or playback mode is switched, and the tape is elastically clamped, and this clamping is controlled by the pinch roller pressure detection switch (81). Upon detection, the power to the loading motor OJ is de-energized.

Next, as is clear from FIGS. 4 and 6, the back tension applying mechanism has a rotating shaft (with which a back tension detection arm (incorporated) for establishing a back tension pin) is inserted through the cylindrical body CgJ. c) At the same time, a band (a cylindrical body around which rice is wrapped) is fixed to the lower end of the bottom board (the rotating shaft that reaches the bottom surface of the mark), and one end of this band (a cylindrical body around which rice is wrapped) is fixed to the bottom board (the rotating shaft that reaches the bottom surface of the mark). When the back tension detecting arm A back tension applying lever (distributed by the wholesaler, applicable Similarly, the 8th support shaft (8
A tension release lever (wall) is pivotally supported by the tension release lever (96a) and is biased to rotate counterclockwise by the tension release spring (96a).
, rotate the pack tension applying lever needle counterclockwise to completely separate the brake shoe □□□, and move the first movable pin m) to turn the back tension detection lever clockwise. The back tension pin is held in a notch of a cassette (not shown), and both loading blocks f51)
+52) At the timing when the carloading position is almost reached, the second movable pin 1m set on the first block releases the regulation of the back tension applying lever +941 in order to rotate the tension release lever (η clockwise). Accordingly, the back tension detection lever jl'14) 6 (loading position (i.e., back tension detection position) is reached due to the biasing of the index spring shaft, and the detected tension of the back tension pin (a3) causes the supply reel stand (93) to It gives braking force to.

Next, the idler mechanism includes an idler support lever (corporate) which is pivotally supported by the bottom board (in other words, the shaft (2)), and an idler support shaft (2018) is mounted on the top surface of this idler support lever (2).
9! ! is planted and a third movable pin 001 is planted on the lower surface, and the idler regulation lever (2) is biased to rotate by the regulation spring (ioi) as shown in FIG. When the cam (1b) comes into contact with the concave part and is in the stop F mode, the notch (2) of the idler regulation lever (2)
The third movable pin 4 engages with the idler support shaft (9) on the upper surface of the upper substrate (chi) to restrict its rotation.
The idler (+02), which is pivoted to When the idler regulating cam (1b) is in the mode, the idler regulating cam (1b) is rotated counterclockwise, so that the idler (102) can be freely rotated, and the idler (102) is rotated along with the shaft (goods) on the upper board (1 stroke). A ninth gear (1) rotates integrally and meshes with the idler (102).
03), the idler gear (102) selectively meshes with a gear part (93a) of the supply reel stand (93) or a gear part (104a) of the take-up 17 heel stand (104). The rotation of the reel motor (2) is transmitted to the two reel blades (104). The reel motor circle changes the direction of rotation in each of the winding and fast-forward modes, and decelerates the rotation in the recording and reproducing modes, and the applied voltage is switched according to each mode.

Furthermore, the reel braking mechanism interlocked with the idler regulating lever (2) is a braking part (105a)' (
The brake lever (105) is connected to a brake force applying lever (107) via a connecting plate (106), and is connected to the brake lever (105) via a connecting plate (106). The direction of the sliding force is regulated by a 9 support shaft (ins), and the braking force applying lever (107)
The brake pin (110) is pivotally supported by a tenth support shaft (109) and is installed on the idler regulating lever (2) by penetrating the upper board (2), and the brake pin (110) is loosely fitted therein. The braking part (105a) (1osb) comes into pressure contact with both the reel stands) η and (104).

Also, the device of this embodiment is as shown in FIG. 4 detection switches are arranged, and in addition to the pinch o-ra pressure contact detection switch, the loading completion detection lever (
a loading completion detection switch (111) that detects the completion of loading in conjunction with 3) and stops the loading motor 03 to set a temporary stop mode; and a loading completion detection switch (111) that detects unloading in conjunction with the idler regulation lever (2). an unloading detection switch (112) that stops the loading motor (13) and sets a stop mode; A high-speed transfer mode detection switch (113) for stopping the rotation of the motor (13) and setting a fast forward mode or rewind mode is fixed on the upper substrate 1 (b).

The loading motor (controls the rotation and stopping of the bush).

In the loading state, the tape guide mechanism is guided by the members shown in FIG. (
115), a full-width erasing head (116), the left tape guide (opening), the left inclined pin ((to), a 10' inclined guide cylinder (117), a right inclined bin (55),
The left side guide pin, the audio/control signal recording/reproducing head (118), and the second fixing are guided to the idle pin (119), the capstan (41), and the pinch roller (79) to reach the cassette winding side.

In addition, the apparatus of this embodiment has a tape start end detection mechanism and a tape end detection mechanism of the same configuration on the tape supply side and the tape winding side, respectively, and the tape end detection mechanism is configured as shown in FIG. C) Supply I11 Positioning guide (1
20) is hollow in the axial direction, and the light emitted horizontally by the light emitting member (122) fixed on the upper substrate (color of the upper substrate) by the first fixing fitting (121) is transmitted into the supply side positioning guide (120). The reflected light is vertically reflected by a first reflecting member (123) arranged at the cassette (C), and the reflected light is transmitted through the tape running section by a second reflecting member (124) arranged above the supply side positioning hole of the cassette (C). A light detection member (126) is placed on the side of the cassette holder (125) on the opposite side of the tape (T) to reflect the light in the horizontal direction, and the transparent tape at the end of the tape passes through the side of the cassette holder. The light detection member (
126). In addition, figure number (12) in Figure 9
7) is a holder for the light emitting member (122);
B) is a holder for the photodetecting member (126), and the eighth
In the figure, (129) is the winding side positioning guide, (1'
30) indicates the second fixture.

The operation of the device of this embodiment will be explained below for each mode.

(Al Stop mode) This mode is a mode in which the cassette can be attached and detached, and when the cassette is attached, the tape is stretched over the front of the cassette and both tape guides (one hoop, both inclined pins) are
l +551 , the brake shoe (η is in a non-contact state) that applies back tension is in the unloading state with the above-mentioned vinyl roller ΔU79) and the above-mentioned back tension bottle 79) having entered the cassette notch, and the brake lever is in a non-contact state. (ios) said both side moving part (105aX
105b) is in pressure contact with the circumference ml of both reel stands j931 (104) to regulate the running of the tape, and the idler (
102) is defined in the neutral position. Note that this unloading state is detected by the unloading detection switch (112).
), and when setting the stop mode from another mode, the mode setting cam (the rotation of the force is stopped by this detection output).

(bl High-speed transfer mode) This mode is a mode in which the tape is stretched at the front of the cassette and is unloaded, causing the tape to travel at high speed. Therefore, the mode setting cam (the force is , the tip of the idler regulation lever (2) is connected to the idler regulation cam (1b).
It comes out of the recess, rotates 45 degrees, and stops rotating by the detection output of the high-speed transfer mode detection switch (113). By rotating the idler regulation lever (2),
In the idler (102), the regulation is released and the rotation of the reel motor (to), which is driven at high speed at the same time as the mode is set, swings in one direction according to the set mode, and drives one reel stand at high speed.

(C) Pause mode: This mode is a mode in which the tape stretched inside the cassette is pulled out, loaded, and timed for recording and playback. Therefore, the mode setting cam (force) rotates counterclockwise from the first position 2, and the loading cam (1
c) to operate the loading mechanism by guiding the loading pin (5) that engages with the idler cam (1).
b) The idler regulating cam (2) engaged with the reel table fl1131 (1o4) and the idler (102) are released from the neutral position by the idler regulating cam (2), and in the latter half of loading, the pinch roller The moving cam (1d) causes the pinch roller to face the capstan (41), and in the fifth position rotated by 270 degrees, the loading completion detection switch (111) is turned.
The rotation is stopped by the detection output. On the other hand, the second movable pin 197), which rotates counterclockwise with loading, releases the rotation restriction of the back tension applying lever (941) by the tension release lever (96), and moves the The tension detection arm (841 is rotated and assisted. Also, the double-ended ding block! 511 +521 that moves along the openings of both guide through holes C (g) with loading is connected to the both guide through holes +66) t. - Both tape guides (115) (119), etc. facing
By rotating it relative to the guide, its longitudinal direction is aligned with the through-holes of the guides, and at the loading completion position, both the positioning blocks ffO+ 711 and the adjustable regulation plate σ2+ 731 for both winding materials are rotated relative to each other. The moving guide table '5G+'84J is positioned by the plate springs (23aX23b) (
The overstroke of loading is absorbed by the elastic deformation of 25a) and (25b), and the
''''The tape wound around the inclined guide cylinder (117) has a winding angle of approximately 1 in the left direction in the figure.
It is adjustable by the two inclined pins II 163) which are inclined at 2 degrees. In this temporary stop mode, the capstan motor (not shown) and the capstan motor (not shown), which rotate simultaneously with the start of loading, continue to rotate in order to ensure a smooth start of recording and reproduction.

(d) Recording and reproducing mode: This mode is a mode in which the tape is run at a constant speed in a loaded state. The specific operation is to press the pinch roller σ9, and the mode setting cam (↓), which rotates further counterclockwise from the third position depending on the mode setting, is moved by the pinch roller moving cam (1d). The pinch roller moving lever (4) is further rotated to bring the pinch roller aω into pressure contact with the capstan, and the rotation is stopped at a fourth position rotated by 45 degrees based on the detection output of the pinch roller pressure contact detection switch (81). The overstroke of the pinch roller moving lever (4) is achieved by the expansion spring interposed between the pinch roller support lever surface and the pinch roller support lever surface.

On the other hand, the take-up reel stand (104) transmits the rotation of the reel motor (2), which is driven at low speed at the same time as the mode setting, via an swingable idler (102), and connects the pinch roller (79) and the The tape that is transferred at a constant speed by the capstan (41) is wound up.

[Margin below]

As described above, according to the present invention, since the longitudinal direction of the movable guide table is guided along the guide hole which is the loading path, there is no fear that the movable pin will collide with an obstacle such as a fixed rod. This greatly contributes to the miniaturization of the device.

[Brief explanation of the drawing]

Each figure shows a mechanism according to an embodiment of the present invention. FIG. 1 is a diagram showing the engaged state of the lever according to the rotational position of the mode setting cam, and FIG. 2 is a plan view showing the drive mechanism of the mode setting cam. figure,
FIG. 3 is a plan view showing the loading mechanism, and FIG. 4 is a plan view of the lower surface of the bottom substrate. 71' Fig. 5 is a partially cutaway perspective view of the right loading lock, Fig. 6 is a plan view of the upper board, Fig. 7 is a plan view of the bottom board in recording/reproducing mode, and Fig. 8 is a plan view of the bottom board in stop mode. FIG. 9 is a plan view of the main part of the bottom substrate, and a sectional view of the tape start/end detecting section. Description of main drawing numbers: Upper board, [611i1 Iron... Guide hole, (511+521... Loading block, (117)... Guide cylinder, (55) + 63)
... Inclined pin, +541 +62) ... Tape guide, 1561 (1341 ... Moving guide stand, +57
1 f61+...Slider, (53) Thread...Guide shaft, (58)...Positioning arm, (59)...Coil spring, 168+ 169+...Guide rail. Figure 1 (a) FF / Rew (C) PAUSE ℃, (d) PLAY / RFC Figure 2 Figure 3 Figure 4 , - Figure 6 Figure 7 Figure 2 Figure 8 +8b 4+8188 2, Fall)' °“. 9-56 ゛°62 ・53rat ., -m-゛ ・
)・e・1.・0,o,=,'1u1d,'
27 ・ ・ ・
, -+l〆/l / \1\ ζ-1 2 LJ \, -! -S-%2,7゜7
j'le'-1~・'23
,ノ'7-1;(,:Tomo ○ '9- 9B-1, -25C・S゛ri -
1. +01 110 - 2a77 Sei.1
Figure 9 Shiori'25a 5'25b 1

Claims (1)

[Claims] (1) In a video tape recorder in which a loading block is guided along a pair of guide holes formed in the upper substrate and constitutes a loading path, and a tape is mounted on a guide cylinder, a pair of slopes are used to pull out the tape. a pair of movable guide stands on which pins and guide pins are respectively planted; a pair of sliders that slide in the guide holes; a pair of guide shafts fixed to the guide shafts, a pair of positioning arms fixed to the lower parts of the guide shafts, and a pair of positioning arms respectively arranged on the lower substrate along each side of the guide holes. an idle rail, and a pair of coil springs that bias the positioning arms to rotate to urge the positioning arms to the guide rails. A loading block guide mechanism for a video tape recorder, characterized in that the two moving guide blocks are arranged so that loading is performed with the longitudinal direction of the movable guide blocks aligned with the guide hole.