JP2000011628A - Cover opening-closing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cover opening-closing structure allowing a lid to be easily opened in a cover opening apparatus for opening/closing with center at a rotary shaft disposed at one side of the apparatus body. SOLUTION: Two slidable operating parts 3, 4 are provided at the side face of the apparatus body and constituted so as to set a cover 1 to a lid open state from a cover close state in different sliding directions whereby the lid opening state can be made similarly by sliding either operating part to thereby facilitate the cover opening operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lid opening / closing device which is effective for a small-sized device such as a portable cassette tape recorder or the like having an opening / closing lid which opens and closes around a rotary shaft provided on one side of a main body. .

[0002]

2. Description of the Related Art Conventionally, a lid opening / closing device of this kind is disclosed in
What is described in -342829 is known. That is, FIG. 8 is an exploded perspective view showing a configuration of a lock portion of a cassette tape recorder using the conventional lid opening / closing apparatus, and FIG. 9 is a side view showing the lid closed state.

In FIGS. 8 and 9, a knob decoration 33 and a lock cam support board 35 for rotatably supporting a lock cam 34 are attached to an intermediate cabinet 32b provided on a main body cabinet 32a of the cassette tape recorder. The lock cam 34 is rotatably supported by a rotation shaft 36 fitted into the shaft hole 35a of the lock cam support board 35, and the operation knob 37 is rotatably supported by the rotation shaft 36. Have been. The operation knob 37 is fitted in the center hole 33 a of the knob decoration 33, and the lock cam 34 is rotated by the operation knob 37 when the lid 31 is closed. A locking piece 31 a is provided on the lid 31 at a position facing the lock cam 34. The lock cam 34 is provided with a locking claw 34b that engages with the locking piece 31a, and a pressing portion 34c that protrudes toward the locking piece 31a when the lid 31 is opened. The lock cam 34 is provided with a spring action portion 34d at a position opposite to the pressing portion 34c about the rotation shaft 36. The spring action portion 34d and the lock cam support substrate 35
The spring spring 3 is provided between the spring spring 3 and the spring base portion 35b.
8 are provided. A mounting hole 35c for the boss 32c formed in the intermediate cabinet 32b is formed in the lock cam support substrate 35, and a mounting hole 33b is similarly formed in the knob decoration 33 and fastened together with screws 39. The operation knob 37 has a knob decoration 3.
3 is formed with a flat plate portion 37a for closing the central hole 33a and a projection 37b serving as an operation point for rotating the lock cam 34 when the lid 31 is opened. The operation knob 37 is always rotated clockwise. It is being rushed. With the above configuration, the lock cam 34 is urged clockwise by the repulsive force of the toggle spring 38 in the closed state of FIG.
The locking piece 31a is pressed against the intermediate cabinet 32b by a, and the closed state is maintained. When the cover is opened, the operation knob 37 is rotated counterclockwise, so that the protrusion 37 b of the operation knob 37 causes the pressing portion 3 of the lock cam 34 to move.
The peripheral surface 32e below 4c is acted on, and the lock cam 35 rotates counterclockwise. The direction of the biasing force of the toggle spring 37 is changed by turning the operation knob 37 counterclockwise at least to a position beyond the neutral point, and the lock cam 34 is turned in the counterclockwise direction opposite to when the lid is closed. It is configured to receive a rotational urging force to obtain an open state.

[0004]

In such a conventional lid opening / closing apparatus, especially in portable equipment, the lid opening operation is often performed with one hand, but the opening / closing operation is performed in one direction. When operating with one hand, the right-handed and left-handed operators have different operation directions, and are inconvenient.
Further, as another problem, the locking portion of the lid is located at one position in the center, and a plurality of locking structures are desired for a more stable lid closing state.

According to the present invention, there is provided a lid opening / closing device which opens and closes around a rotation axis provided on one side of an apparatus main body, wherein the lid is opened by any sliding operation of two operating sections which slide in different sliding directions. When operating the lid of a portable device provided with the lid opening and closing device with one hand, the lid can be easily opened by both right-handed and left-handed persons, and has a pair of locking structures. The object of the present invention is to provide a lid opening / closing device capable of obtaining a more stable lid closing state.

[0006]

According to the present invention, there is provided a lid opening / closing apparatus which opens and closes around a rotation axis provided on one side of a main body of an apparatus main body. A locking portion provided on the side lid facing the side having the rotation axis to hold the lid closed, and a device body on the side having the locking portion of the lid. A lock portion having a locking claw to which the locking portion is locked, and a lid opening operation portion for releasing the locked state of the lock portion to change the lid from the closed state to the open state, The opening operation unit has two operation units slidable on a side surface of the device main body, and the two operation units are configured to change the lid from a closed state to an open state according to different sliding directions. It was done.

[0007] With this, the lid opening operation can be performed by either sliding operation of the two operation units that slide in different sliding directions, and when the lid of a portable device having the lid opening / closing device is operated with one hand. The lid opening operation can be easily performed by both right-handed and left-handed people.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a lid opening / closing device which opens and closes around a rotation axis provided on one side of a main body of an apparatus main body, wherein one side having the rotation axis is provided. A locking portion provided on the side lid facing the side for holding the lid in a closed state, and a locking portion locking the locking portion to the side device body having the locking portion. A lock unit having a locking claw, and a lid opening operation unit for releasing the locked state of the lock unit to change the lid from a closed state to an open state, wherein the lid opening operation unit includes the device It has two operation units that can slide on the side surface of the main body, and the two operation units are configured to change the lid from the closed state to the open state according to different sliding directions. By sliding operation of either of the two operating units that slide Can be performed lid opening operation, when operating the lid opening of portable devices equipped with the cover opening and closing device with one hand, has the effect of capable of performing easily the lid opening operation even in right-handed and left-handed both.

According to a second aspect of the present invention, there is provided a lid opening / closing device which opens and closes around a rotation axis provided on one side of the main body of the apparatus main body, wherein the side surface facing the one side having the rotation axis is provided. A pair of locking portions provided on the lid body for holding the lid in a closed state, and a locking claw for locking the locking portion to a device body on a side surface having the locking portion. A pair of lock cams, a pair of toggle springs for urging the pair of lock cams in different rotation directions in a closed state and an open state of the lid body, and a projection abutting on the pair of lock cams. A slider having an abutting portion and simultaneously rotating the pair of lock cams; and a lid opening operation for operating the slider to release the locked state of the lock cams and change the lid from the closed state to the open state. From the closed state of the lid When the lid is closed, the pair of lock cams are configured to be rotated by the operation of the lid opening operation section through the slider to at least the reverse position of the toggle spring, and have a pair of locking structures. This has an effect that a more stable lid closing state can be obtained.

According to a third aspect of the present invention, the lid opening operation section has two operation sections slidable on a side surface of the apparatus main body, and the two operation sections are interlocked with each slide operation. It has two sliders that slide, and the lid is configured to be changed from the closed state to the open state by sliding any one of the two operation parts, and any one of the pair of operation parts is slid. This also has the effect that the locked state of the pair of locking portions is simultaneously released, and the open state can be obtained.

According to a fourth aspect of the present invention, the two sliders have a coil spring configured to pull each other, and the lid is closed by sliding one of the two operating portions. When the cover is opened from, the other one of the two operation units is configured to be urged to the open state by the pulling force of the coil spring. FIGS. 1 to 7 show an embodiment of the present invention having an operation of opening the lid.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 is a front view (A) and a side view (B) of an entire cassette tape recorder using a cover opening and closing device according to a first embodiment of the present invention in an open state. 2 is an exploded perspective view of the lock block, and FIG. 4 is a partially cutaway view showing a mechanism in a closed state.

In the drawing, reference numeral 1 denotes a lid of a cassette tape recorder, 1a denotes a locking piece constituting a locking portion provided on the lid, 2 denotes a cassette tape recorder main body, and the main body 2 has a lower surface portion. A main cabinet 2a forming a side surface following the main cabinet 2 and an intermediate cabinet 2b disposed on the main cabinet 2a are formed. And lid 1
Is configured to rotate about a rotation shaft 2c provided on an intermediate cabinet 2b on one side of the main body 2 to open and close.
It is provided on one side facing c. Further, a pair of operation knobs 3 and 4 constituting an operation unit for performing an opening operation from the time of closing the lid is provided on one side of the intermediate cabinet 2b facing the rotation shaft 2c.
And 4 are each configured to slide in the direction of the arrow shown in FIG. Further, the operation knobs 3 and 4 are located at the position of the intermediate cabinet 2b.
Are provided with a pair of lock cams 5 and 6 having locking claws 5a and 6a which rotate in conjunction with the locking member 1a, so that the locking pieces 1a of the lid 1 can be locked.

A pair of lock cams 5 forming a lock portion
6 is an intermediate cabinet 2b as shown in FIGS.
The lock cams 5 and 6 are respectively provided on two rotation shafts 8 fitted in shaft holes 7a and 7b provided in the support substrate 7 provided on the back surface of the lock portion. It is supported so as to be free and opposed.

The locking cam 5 has a locking claw 5a for locking a first locking portion 1b provided on a locking piece 1a provided on the lid 1, and a locking piece when the lid 1 is opened. A pressing portion 5b protruding to the side 1a, a first protrusion 5c provided to protrude to contact a first slider 9 described later, and a first protruding portion 5c bent to contact a second slider 10 also described later. 2
5d. Further, the lock cam 5 is provided with a spring action portion 5e at a position opposite to the pressing portion 5b about the rotation shaft 8, and the spring action portion 5e,
A toggle spring 11 is provided between the lock base 7 and a spring base 7c provided on the lock support board 7.

A lock cam 6 provided to face the lock cam 5 has a locking piece 1 a provided on the lid 1.
Locking claw 6a for locking the second locking portion 1c provided on the
And a pressing portion 6b protruding toward the locking piece 1a when the lid 1 is opened, and a first protruding portion 6c protrudingly provided so as to come into contact with a second slider 10 described later. A second protrusion 6 d is provided so as to be in contact with the first slider 9. The lock cam 6 is provided with a spring action portion 6e at a position opposite to the pressing portion 6b about the rotation shaft 8, and the spring action portion 6e and a spring base portion 7d provided on the lock portion support substrate 7 are provided. Between them, a toggle spring 12 is provided.

First slider 9 and second slider 1
0 denotes two through grooves 9a provided in the first slider 9.
And 9b, and two slide shafts 13 penetrating through two through grooves 10a and 10b provided in the second slider 10 and fitting into shaft holes 7e and 7f provided in the lock portion support substrate 7. The grooves 9a and 9b respectively
10a and 10b are slidably supported in the longitudinal direction.

Also, the first slider 9 provided on the first slider 9
The contact portion 9c has a bent shape so as to contact the first protrusion 5c of the lock cam 5, and the second contact portion 9d has a bent shape to engage with the second protrusion 6d of the lock cam 6. .
On the other hand, the first contact portion 1 provided on the second slider 10
0c is in contact with the first protrusion 6c of the lock cam 6, and the second contact portion 10d is in contact with the second protrusion 5d of the lock cam 5.
Is formed by a bent shape so as to be engaged with the second member.

The first slider 9 and the second slider 10 have hook portions 9e and 10e projecting to the back surface of the lock portion support substrate 7 through through grooves 7g and 7h provided in the lock portion support substrate 7, respectively. Is provided,
A coil spring 14 is provided with both ends supported by these two hooks.
Is configured so that the two sliders 9 and 10 maintain elasticity in a state where they are attracted in the sliding direction.

The lock block constructed as described above is fixed to the intermediate cabinet 2b by screws 15 through fixing holes 7g and 7h provided in the lock portion support substrate 7.
It is fixed to. The screw 16 having the step 16a is provided with a long hole 9f provided in the first slider 9, a hole 10f provided in the second slider 10, and the intermediate cabinet 2b.
And is fixed to a boss 3 a provided on the first operation knob 3. Also, screw 16
The screw 17 having the same shape as that of FIG. 1 has a hole 9g provided in the first slider 9, a long hole 10g provided in the second slider 10, and an intermediate cabinet 2b.
And is fixed to a boss 4 a provided on the second operation knob 4.

With the above configuration, when the first operation knob 3 is slid, the step 16a of the screw 16 acts on the hole 10f of the second slider 10, and the second slider 10
Slides in conjunction with the sliding of the operation knob 3. At this time, since the step 16a of the screw 16 passes through the elongated hole 9f of the first slider 9, the sliding of the operation knob 3 causes the first slider to slide. 9 is unaffected. Similarly, when the second operation knob 4 is slid, the step 17a of the screw 17 acts on the hole 9g of the first slider 9, and the first slider 9 slides in conjunction with the slide of the operation knob 4. However, at this time, since the step 17a of the screw 17 passes through the elongated hole 10g of the second slider 10, the sliding of the operation knob 4 does not affect the second slider 10.

The operation of the lid opening / closing device configured as described above will be described below. As described above, FIG. 4 is a partially cutaway view showing the mechanism in the closed state.
In FIG. 4, the first lock cam 5 is a toggle spring 11
The biasing force of (1) rotates clockwise about the rotating shaft 8, and the locking claw 5 a acts on the first locking portion 1 b provided on the locking piece 1 a, thereby causing the lid 1 to rotate. To the intermediate cabinet 2b side. On the other hand, the second lock cam 6 is driven by the rotating shaft 8 by the biasing force of the toggle spring 12.
The lid 1 is similarly urged to rotate counterclockwise around the center, and the locking claw 6a acts on the second locking portion 1c provided on the locking piece 1a, thereby similarly moving the lid 1 to the intermediate cabinet 2.
It is biased to the b side. That is, the lid 1 is kept in the closed state by the two lock cams 5 and 6.

Next, a description will be given of a lid opening operation when the first operation knob 3 is slid to the arrow A side from the above-mentioned closed state. The second slider 10 slides in conjunction with the operation knob 3, and acts on the projection 5d of the lock cam 5 with which the contact portion 10d of the second slider 10 is engaged, thereby causing the lock cam 5 to rotate counterclockwise. That is, the locking claw 5a rotates in a direction to release from a state in which the locking portion 1b is locked. The contact portion 1 provided on the slider 10
0c acts on the projection 6c provided on the second lock cam 6, so that the lock cam 6 rotates clockwise, that is, from the state in which the locking claw 6a locks the locking portion 1c in the cover opening direction. Move.

By the rotation of the lock cams 5 and 6 in the release direction, the state shown in FIG. 5 is obtained. In FIG. 5, the operation knob 3 is slid from the closed state of FIG. 4 to the open state. FIG. 4 is a diagram showing a neutral point during the movement. In the state of FIG. 5, the toggle spring 11 is at the neutral point, and the operation knob 3
At least to a position where the toggle spring 11 exceeds the neutral point, the biasing force of the toggle spring 11 is reversed in the cover opening direction, and the lock cam 5 obtains a rotational biasing force in the cover opening direction. In the state shown in FIG. 5, the second lock cam 6 has already passed the neutral point and has been urged to rotate in the cover opening direction.

FIG. 6 shows a state in which the lock cams 5 and 6 are held in the open state by the toggle springs 11 and 12 from the state of FIG. 5, and the lock cams 5 and 6 are opened by the urging force of the toggle springs 11 and 12. Biased in the direction
A pressing portion 5b provided on the lock cam 5;
Is held in a state where it is protruded toward the locking piece 1a.

Since the first slider 9 is constantly urged in the direction of the second slider 10 by the coil spring 14 shown in FIG. 3, in the above-described opening operation, the slider 10 is slid. During the rotation of the lock cams 5 and 6, the urging force of the coil spring 14 causes the slide cam 10 to slide toward the slider 10, so that the second operation knob 4 interlocked with the slider 9 is
As shown in FIG. 1A, the user slides to a position close to the first operation knob 3.

Next, a description will be given of the opening operation when the second operation knob 4 is slid to the arrow B side in FIG. The first slider 9 slides in conjunction with the operation knob 4, and acts on the projection 6 d of the lock cam 6 engaged with the contact portion 9 d of the first slider 9, thereby causing the lock cam 6 to move clockwise. That is, it turns in the lid opening direction. Further, the contact portion 9c provided on the slider 9 allows
The projection 5c provided on the lock cam 5 is acted on, and the lock cam 5 rotates in the counterclockwise direction, that is, in the cover opening direction. At this time, the second slider 10 is constantly urged in the direction of the first slider 9 by the coil spring 14 shown in FIG. In the process of turning 5 and 6, the coil spring 14 slides toward the slider 9 by the urging force of the coil spring 14. Therefore, in the open state, the operation knob 3 is slid in the same manner as when the operation knob 3 is slid. The state shown in FIG.

Next, the operation when the lid 1 is closed from the open state will be described. In the open state, there is an open state as shown in FIG. 1B, but when the lid 1 is closed from the open state, the state of FIG. 6 is obtained. When the lid 1 is closed from the state described above, the first locking portion 1b of the locking piece 1a and the pressing portion 5b of the lock cam 5 come into contact with each other, and at the same time, the second engagement of the locking piece 1a. When the stop portion 1c and the pressing portion 6b of the lock cam 6 come into contact with each other and the cover is further closed, the lock cam 5 and the lock cam 6 are rotated by the rotating shaft 8 respectively.
The cover 2 is rotated in the closing direction around the opening of the cover 2 at least to a position beyond the neutral point of the toggle springs 11 and 12, as shown in FIG. 5, so that the toggle springs 11 and 12 are attached in the closing direction. An energizing force is generated, and the urging force causes a closed state shown in FIG.

In the process of changing from the open state of FIG. 6 to the closed state of FIG. 4, the first slider 9 is moved by the projection 6d of the lock cam 6 acting on the abutment 9d.
The slider 10 has a protrusion 5d of the lock cam 5 and an abutment portion 1.
By acting on 0d, it slides by the urging force of the toggle springs 11 and 12, respectively, against the pulling action of the coil spring 14. By the sliding of the sliders 9 and 10, the operation knobs 3 and 4 slide in the direction of the arrow shown in FIG. 1A and return to the state shown in FIG.

As described above, according to the present embodiment, the lid opening operation can be performed by any of the two operation sections that slide in different sliding directions, and the portable device having the lid opening / closing device can be operated. When opening the lid with one hand, the lid opening operation can be easily performed by both right-handed and left-handed people. In addition, by having a pair of locking structures, there is an effect that a more stable lid closing state can be obtained.

(Embodiment 2) Next, a second embodiment shown in FIG. 7 will be described. FIG. 7 is a partially cutaway view of the mechanism when the lid is closed. In this embodiment,
The lock cam 18 is an example constituted by one. That is, a locking claw 18a that engages with a locking piece 19a provided on the lid 19, a pressing contact portion 18b that projects toward the locking piece 19a when the lid 19 is open (not shown), First slider 2
A first protrusion 18 c protrudingly provided so as to abut on the abutting portion 20 a of the second slider 21.
a second projection 1 formed by bending so as to abut against a
8d. In addition, the support substrate 22 is the same, the rotary shaft 23 is the same, the toggle spring 24 is the same, the slide shaft 25 is the same, the coil spring (not shown) disposed on the back surface of the support substrate is the same. The screw 27 and the screw 28 for interlocking the operation unit and the slider are 16 and 1
7. The operation knobs 29 and 30 are substantially the same as those of the first embodiment shown as 3 and 4.

The first operation knob 29 from the closed state of FIG.
Is slid in the direction of the arrow, the second slider 21 slides in conjunction therewith, acting on the projection 18d of the lock cam 18 engaged with the contact portion 21a of the slider 21, and the lock cam 18 rotates in the lid opening direction, At least the toggle spring 24
By sliding the operating knob 29 to a position beyond the neutral point, the lock cam 18 is rotationally urged in the opening direction by the urging force of the toggle spring 24 in the opening direction. When the second operation knob 30 is slid in the direction of the arrow from the closed state of FIG. 7, the first slider 20 slides in conjunction therewith, and the protrusion of the lock cam 18 abuts on the abutment portion 20 a of the slider 20. Acting on the portion 18c, the lock cam 18
Rotates in the cover opening direction, and slides the operation knob 30 at least to a position where the toggle spring 24 exceeds the neutral point, so that the lock cam 18 is biased in the cover opening direction by the toggle spring 24 so that the lock cam 18 is moved to the first operation knob 29. Is urged to rotate in the lid opening direction in the same manner as when is slid.

On the other hand, when the lid is closed from the open state, the lid 19 acts on the pressing portion 18b of the lock cam 18 as in the first embodiment, and the protrusion 1
8c and 18d act on the sliders 20 and 21, thereby returning to the original closed state.
According to the second embodiment, although the locking structure is provided with one lock cam, the lid opening operation can be performed by any sliding operation of the two operating units that slide in different sliding directions. When opening the lid of a portable device having an opening / closing device with one hand, the lid opening operation can be easily performed by both right-handed and left-handed people.

[0034]

As described above, according to the present invention, the lid opening operation can be performed by any one of the two operation units that slide in different sliding directions, and the portable device having the lid opening / closing device is provided. When the cover is operated with one hand, the cover can be easily opened by both right-handed and left-handed persons, and the operability is improved and the usability is extremely good. Further, by providing a pair of locking structures, it is possible to provide a lid opening device capable of obtaining a more stable lid closing state.

[Brief description of the drawings]

FIG. 1 is a front view and a side view of a cassette tape recorder using a lid opening / closing device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the entire cassette tape recorder.

FIG. 3 is an exploded perspective view showing a configuration of a lock unit of the cassette tape recorder.

FIG. 4 is a partially cutaway view of the cassette tape recorder when the lid is closed.

FIG. 5 is a partially cutaway view showing the cassette tape recorder in the middle of opening the lid.

FIG. 6 is a partially cutaway view showing the cassette tape recorder when the lid is opened.

FIG. 7 is a partially cutaway view showing a cassette tape recorder using a lid opening / closing device according to a second embodiment of the present invention when the lid is closed.

FIG. 8 is an exploded perspective view showing a configuration of a lock portion of a cassette tape recorder using a conventional lid opening / closing device.

FIG. 9 is a side view showing a cassette tape recorder using a conventional lid opening / closing device when the lid is closed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lid 1a Locking part 2 Main body 2a Main cabinet 2b Intermediate cabinet 3 First opening operation part 4 Second opening operation part 5 First locking part 5a Locking claw 6 Second locking part 6a Locking nail

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Kono 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5D001 AB04 CC03 FF02 FF07 FF09

Claims (4)

[Claims] 1. A lid opening / closing device that opens and closes around a rotation axis provided on one side of a main body of an apparatus main body, wherein the lid is closed on a side lid facing one side having the rotation axis. A locking portion provided for holding a lid state, a locking portion having a locking claw for locking the locking portion to a side device body having a locking portion of the lid, and a locking portion. An opening operation section for releasing the locked state of the cover from the closed state to the open state, and the opening operation section is provided with two operation sections slidable on a side surface of the device main body. Wherein the two operation units are configured to change the lid from a closed state to an open state according to different sliding directions. 2. A lid opening / closing device that opens and closes around a rotation axis provided on one side of the main body of the device main body, wherein the lid is closed by a side lid facing one side having the rotation axis. A pair of locking portions provided for holding a lid state, a pair of lock cams having locking claws to which the locking portions are locked on a device body on a side surface having the locking portions; A toggle spring that urges the lid body in a different rotating direction between a closed state and an open state, and a contact portion that abuts on a projection provided on the pair of lock cams, and simultaneously rotates the pair of lock cams. A lid to be moved, and a pair of lid opening operation sections for operating the slider to release the locked state of the lock cam to change the lid from the closed state to the open state, and to close the lid. When opening the lid from the state, the pair of lock cams Wherein the lid opening / closing device is configured to be operated to rotate at least to a reverse position of the toggle spring via a slider by operating the lid opening operation section. 3. The lid opening operation section has two operation sections slidable on a side surface of the device main body, and the two operation sections have two sliders that slide in conjunction with each slide operation. 3. The lid opening / closing device according to claim 2, wherein the lid is changed from a closed state to an open state by sliding one of the two operation units. 4. The two sliders have coil springs configured to pull each other, and by sliding one of the two operating portions, the lid is changed from a closed state to an open state. 4. The lid opening / closing device according to claim 3, wherein the remaining one of the two operation units is biased to the open state by the tensile force of the coil spring.