CN1274990C - Portable lighting device - Google Patents

Abstract

There is provided a hand held lighting device comprising: a body containing dry cell for providing power; at least one elongate, tubular, translucent lens through which light generated by the device is emitted; at least one incandescent lamp or light emitting diode is located at least one end of the lens, the lens extending a distance past the incandescent lamp or light emitting diode; a wiring which, in use, connects the dry cell to said at least one incandescent lamp or light emitting diode; thus, light generated from the incandescent lamp or the light emitting diode is emitted through the lens to have an appearance similar to that of a fluorescent lamp. There is also provided a hand held lighting device comprising: a body in the form of an elongated straight line having a base; an elongated lamp housing extending longitudinally along one side of the body; a handle at or near the upper end of the body, a lamp housing including a translucent front shield casing having a convex exterior shape when viewed in side elevation, the lamp housing containing an elongated light source, and the lamp housing being pivotally connected to an end of the body opposite the base.

Description

portable lighting device

This case is a divisional application of a patent application titled "lantern structure", filed on "June 23, 2000" and numbered "00809420.9".

field of invention

The present invention relates to a portable illuminating device comprising a casing containing dry batteries and a light source which can be used as a fixed light and as a portable light.

The illuminating device has a rotatable illuminating member and a self-supporting body which can meet various purposes.

Background of the invention

As is well known, the aforementioned light has the advantage that it can be used in a wider range of applications than conventional flashlights.

However, due to the inherent nature of the aforementioned hand lamps, they are subject to bumps and drops, and are often used in outdoor environments, so must be fairly robust. In addition, the lighting device should be relatively portable, and when carried, the light can be held in a comfortable carrying orientation, and the light emitted by the lighting device should be directed forward.

Prior art lanterns of the type to which the present invention pertains tend to be relatively long and slender, making balancing difficult when the lighting portion of the lantern is to be swung into various positions of use. When the lantern is generally in an L-shaped orientation upside down, there is a problem of poor stability.

Summary of the invention

The present invention provides a hand-held lighting device comprising: a generally elongated rectilinear body having a light source extending along its longitudinal side; a base at the lower end of said body against which the lighting device stands; and a The handle at the other end, the handle includes a handle holding portion that is aligned at its uppermost end at an acute angle with respect to a vertical axis passing through the lighting device and a horizontal plane when the lighting device is upright on its base.

Preferably, the light source is located at the front of the device and the handle grip slopes upwardly from the rear of the device towards the front of the device. The angle of inclination is between about 30° and 60°, preferably about 40°. Preferably, the handle grip portion is slightly narrower than the width of the base end of the device.

Preferably, the body is hollow and forms a battery compartment containing dry cells for powering the light source. The light source includes a pair of incandescent bulbs or light emitting diodes mounted at each end of a translucent tubular member mounted to the body. The unit employs suitable wiring and switches to connect the dry cell to the light source.

The present invention also provides a hand-held lighting device comprising: a body containing dry batteries to provide power to the device; at least one elongated, generally tubular, translucent lens (lens) through which light generated by the device is emitted; at least one incandescent lamp or light emitting diode at least one end of the elongated tubular lens extending a significant distance past the incandescent lamp or light emitting diode; and wiring which, in use, connects a dry cell to said at least one incandescent A lamp or light emitting diode; whereby light generated by said incandescent lamp or light emitting diode is emitted through said elongated tubular lens, thereby having an appearance similar to that of a fluorescent lamp.

The tubular lens may be in the form of a diffuser such that light emitted by said at least one bulb or LED is diffused. If two bulbs or two LEDs, or one bulb and one LED, are used, one is placed at each end of the tubular lens. There may be more than one tube lens, and thus more than one light source, if desired.

The body is preferably of generally rectilinear elongate shape and the lens is preferably straight and longitudinally aligned with the body. The lens can be installed in a lamp housing, and the lamp housing is connected to the body through a pivotal joint allowing the lamp housing to rotate through an arc relative to the body. The pivot axis is preferably horizontal and the lamp housing can be rotated through an arc of at least 180°, preferably about 270°.

The present invention also provides a portable lighting device, which includes: a body with a base that is generally elongated and straight; a slender lamp housing extending longitudinally along one side of the body; handle, the elongated lamp housing includes a translucent protective front light cover, which has a convex outer shape when viewed from a side view, the elongated lamp housing contains an elongated light source, and the elongated lamp housing is pivotable Rotately connected to the end of the body opposite to the base.

The elongated light source is preferably one of the following:

Fluorescent tubes; cold-cathode fluorescent lamps; tubular lenses having at least one incandescent lamp at one end; tubular lenses having at least one light-emitting diode at one end.

Preferably, the lamp housing is rotatable through an arc of at least about 180° relative to the body. Preferably, the lamp housing can rotate through an arc of about 270°. The protective lampshade is generally U-shaped in cross-section and is formed as a one-piece moulding, with the light radiating outwards substantially around its entire periphery. A convex shade is generally arcuate with a radius of curvature much greater than the length of the lighting fixture.

The lamp housing may include a translucent front lampshade, a translucent rear lampshade, an upper end and a lower end, the upper end having a pivoting device through which the lamp housing is pivotably connected to the body. The front and rear translucent shades may be in the form of lenses to focus or diffuse the light emitted from the light source. The front and rear lampshades can be welded together, thereby further strengthening the lamp housing and also providing a moisture barrier (moisture protection) for the light source.

The pivoting means includes a frictional pivoting means which enables the lamp housing to be maintained in any selected angular orientation of the lamp housing relative to the body in use. The pivoting device consists of a rod of circular cross-section fixed to the body and a strap fixed to the lamp housing, which wraps around the rod to provide adjustable fastening means to tighten or loosen the The hoop around the stem, thereby increasing or decreasing the frictional grip of the hoop around the stem, thereby providing a suitable retention force that enables the lamp envelope to be selectively positioned in different orientations relative to the body.

The present invention also provides a lantern, which has a lamp housing capable of 360° light radiation, the lamp housing includes a light source and is pivotally connected to the lantern body through a rotating member, the body is a generally rectangular Configured such that the rotating member is offset from the longitudinal axis of the body, the lamp housing can be rotated at least 180° from a first position to a second position so as to traverse the longitudinal axis of the body.

Preferably, the first position is a retracted position whereby said body and said bulb are juxtaposed, each parallel to the longitudinal axis.

Preferably, the lamp housing has a rectangular lens assembly, one side of which is opposite to the side of the body.

The body has a foot extending outwardly from the body to help increase stability when the body rests in a substantially vertical orientation.

Preferably, the lantern includes a handle means pivotally connected to the body.

Preferably, when the front side or the rear side of the body is put down, the body has a predetermined equilibrium position.

Preferably, when a part of the lamp housing is engaged with a part of the rotating device, the lamp housing has a limit rotation position relative to the body.

Preferably, when the lamp housing is at its limit of rotation relative to the body, the lamp housing forms an angle in the range of 0° to 220° relative to the longitudinal axis.

Preferably, the rotating means is formed near the terminal end of the outwardly extending inclined portion of the body.

Preferably, the inclined portion is at an angle relative to the longitudinal axis of said body in the range of 35° to 60°, preferably in the range of 40° to 50°, said angle being to one side of the body, The lamp housing rests on this surface in a fully retracted position.

Preferably, the handle means cooperates with the body to provide a stable tilting platform upon which the lantern can be lowered and the housing tilted when required, thereby providing a low raised desk lamp.

Preferably, the body includes a reflector portion, so that when the lamp housing is close to the body, the light emitted from the lamp housing to the body will be reflected and returned to leave the lighting device through the lamp housing.

Preferably, the reflector is pivotally mounted such that it can be rotated from a first position close to the body to a second position away from the body and close to the lamp housing.

Preferably, when the lamp housing is turned to its limit of rotation, the center of gravity of the lamp housing is closer to the center of gravity of the body than when the lamp housing is rotated about 90° relative to the longitudinal axis of the body , or the longitudinal axis passing through the center of gravity of the body.

Preferably, the lamp housing is rotatable to and remains in a position which can be substantially anywhere between the limits of rotation of the lamp housing relative to the body.

Preferably, the light source is one or a combination of one or more of the following: a fluorescent tube; a cold cathode fluorescent lamp; a tubular lens with an incandescent lamp at least at one end; a tubular lens with an LED at least at one end.

It should be noted that the term "comprising" used in this specification should be interpreted as inclusion rather than exclusion. Also, the terms "upper" and "lower" are used to help explain the present invention, but not to limit the direction in which the lighting device must be used or used.

These and other features of the invention will become apparent from the description of the embodiments given below by way of example. In the description, reference is made to the drawings, but specific features shown in the drawings should not be construed as limiting the invention.

Brief description of the drawings

Below in conjunction with accompanying drawing, only describe the embodiment of the present invention as an example, in the accompanying drawing:

Fig. 1 is a side view of a portable lighting device;

Fig. 2 is a perspective view of the portable lighting device of Fig. 1;

Fig. 3 is a rear view of the portable lighting device of Fig. 1;

Fig. 4 is a front view of the portable lighting device of Fig. 1;

Fig. 5 is a top view of the portable lighting device of Fig. 1;

Fig. 6 is a sectional view of the portable lighting device taken along the plane VI-VI of Fig. 1;

Fig. 7 is a sectional view of the portable lighting device taken along the plane VII-VII of Fig. 4;

Fig. 8 is a sectional view of the portable lighting device taken along the plane XIII-XIII of Fig. 4;

Fig. 9 is a perspective view of the portable lighting device in Fig. 1, wherein the lamp housing is rotated away from the body;

Figure 10 is a perspective view of a lantern implementing the present invention;

Fig. 11 is a rear perspective view of the lantern in Fig. 10;

Fig. 12 is a perspective view of the lantern in Fig. 10 in a folded down position;

Figure 13 is a side view of the lantern of Figure 12;

Figure 14 is a front view of the lantern of Figure 10;

Fig. 15 is a sectional view of the lantern in Fig. 12;

Fig. 16 is a view similar to Fig. 10, wherein the lamp housing shown is in its extreme position of turning to the farthest;

Figure 17 is a perspective view of Figure 16;

Figure 18 is a side view of the lantern of Figures 10 to 16 in different orientations;

Figure 19 is a perspective view of the lantern of Figure 10 with a reflector;

Figure 20 shows the rotatable mirror at the limit of rotation; and

Figure 21 is a cross-sectional view similar to Figure 15 with the fluorescent lamp replaced by a tubular lens and a light emitting diode (LED).

Detailed description of the embodiment

As shown, a portable lighting device 10 has a generally elongated linear body 12 . For example, it follows from FIGS. 5 and 6 that the body is generally rectangular in plan view. The body 12 has a flat base 14 on which the lighting device 10 can stand when used as a desk lamp or the like. A battery cover molding 16 forms part of the base and is removable to replace the battery compartment indicated by dashed line 18 . What you should know is that the battery box contains 6 "D cell" type dry batteries.

The body 12 has a lamp housing 20 connected thereto by a pivotal connection 22 at the upper end of the body. A detailed description of the pivot connection 22 will be given below. The lamp housing 20 is made from a translucent central portion 24 formed by a front lamp housing 26 and a rear lamp housing 28 welded together along weld lines 30 .

An elongated light source 32' is provided in the form of a tubular translucent lens 32 mounted within the lamp housing 20 and a pair of incandescent lamps 34 located at opposite ends of the tubular lens 32. The tubular lens 32 thus has the appearance of a longitudinal fluorescent lamp, but in reality the illumination is provided by two incandescent lamps 34 .

The lamp housing 20 also includes a lower end portion 36 and an upper end portion 38 that receives the pivot connection 22 . If desired, a suitable lamp socket can be installed, and the tubular lens 32 and incandescent lamp 34 of the light source 32' can be replaced by a fluorescent lamp. Alternatively, the incandescent lamp 34 is replaced with one or more light emitting diodes (LEDs).

A handle 40 is integrally formed with the body 12 and is located at the operative upper end of the lighting device. As shown in FIG. 3 , the handle 40 is narrower than the rest of the body 12 and defines an opening 42 for a user's fingers to receive while carrying the lighting device 10 . The handle 40 is inclined upwards from the rear of the lighting device 10 towards the front, and the angle of inclination is about 40°. When the handle 40 is held, the light emitted by the lamp 34 projects forwardly and slightly downwardly, thereby providing a forwardly projecting light source 32' when the lighting device 10 is held in a comfortable position.

The battery that powers the lighting device 10 can be quite heavy, so to make carrying the lighting device 10 more comfortable, the handle 40 protrudes slightly from the rear of the body 12 . Combined with the acute angle of the handle, the center of mass of the lighting device 10 hangs below the wearer's hand when the lighting device 10 is carried in a conventional manner. Obviously, the angle of the handle 40 may be other than 40°, with angles between 30° and 60° considered to provide the same features.

A switch 44 is located on the upper side of the handle 40, within easy reach of the user's thumb, to turn the light source 32' on and off. A three position slide switch can be selected as the switch 44, so that two light sources can be set so that in the first position, only one light source is in the closed circuit, and in the second position, two light sources are in the closed circuit. in line. The third position is an off (interrupt) position.

Viewed from a side view, ie, the view of FIG. 1 , the front surface 48 of the headlight housing 26 has a protruding shape. This curved form of the lampshade 26 significantly increases the strength of the lamp housing 20 and also diffuses the light from the light source 32' more. It should be noted that the curvature of the surface 48 is arcuate, the radius of curvature being rather large, ie much longer than the overall body. The curved form of the lampshade 26 also provides the lighting device 10 with a very aesthetically pleasing appearance.

7 and 8 show the pivot connection 22 in detail. Body 12 includes a shaft 50 spanning opposite sides thereof and providing a relatively rigid mounting shaft to which lamp housing 20 is attached. The lamp housing 20 is provided with a pair of hoops 52 sleeved on the shaft 50 , as shown in FIG. 8 , and is clamped around the shaft 50 by several screws 54 . The degree of clamping of the collar 52 on the shaft 50 can be varied by adjusting the screw 54 . Furthermore, by properly sizing the ferrule 52 and shaft 50, the ferrule 52 and shaft 50 can create comparable amounts of friction as when the lighting device 10 is assembled on a production or assembly line. Preferably, lamp housing 20 can be rotated to any selected position within an arc of approximately 270°. In this way, the lighting device 10 can stand upright on its base 14, and the lamp housing 20 can be rotated away from the body 12 to any selected position.

Since the entire periphery of the lampshade 24 is translucent, when the lamp housing 20 leaves the body 12 and stands vertically upward, the lamp housing 20 disperses light in an arc of approximately 360°, like a candle. Also, the lamp housing 20 can be at right angles to the length of the body 12 so that the lamp can be used as a desk lamp or the like. It should be noted that during the assembly process, the screw 54 should be adjusted to make the friction clamping force of the ferrule 52 on the shaft 50 optimal, so that the lamp housing 20 can be rotated relatively easily relative to the body 12, and the lamp can also be rotated. The position of the shell 20 relative to the body 12 remains at any selected arcuate position to which it is rotated.

The lighting device 10 need not, if desired, take the full form described herein, although it is considered advantageous to have the form shown in the drawings for the reasons described above. It is conceivable that the lighting device 10 is relatively simple to manufacture, thus relatively cheap, and not only robust, but also applicable to many different purposes, making the lighting device 10 multifunctional.

Although friction means in the form of collar 52 and shaft 50 are preferred, rotationally engaging means such as a ratchet mechanism that can be indexed may also be used.

FIG. 9 shows the lamp housing 26 in a raised position relative to the body 12 . In this position, the side 12A of the body 12 is visible and the presence of the rectangular mirror 12B is noted.

When the lamp housing 20 is close to the side 12A, the reflector 12B ensures that the entire visible spectrum of the light generated by the light source 32' in the lamp housing 20 is reflected away from the side 12A of the body, preventing most of the visible light from being absorbed by the side 12A of the body. Guarantees the maximum portion of usable light.

Reflector 12B can be a very glossy sheet, silver plated, white or other highly reflective sheet, and this material can be metal plastic or metal coated plastic.

Preferably, the sheet is laid between the left and right halves of the body 12, or is adhered to, or attached to, the sides 12A. The most basic form of reflector 12B is a white plastic paste.

Another feature of the lamp housing 26 is that when the lamp housing 20 is close to the body side 12A, the side 26A (see FIGS. 7 and 9 ) directed outward is made of a frosted or translucent lens, while the opposite side 26B is made of a pure or transparent lens. constitute. This ensures that when the light source 32' in the lamp housing 20 is turned on, the reflector 12B receives a large amount of light due to the transparency of the side 26B, which will return and pass through the side 26B after reflection, resulting in more light passing through the side 26A. Spread effectively. This is particularly advantageous if the lighting device 10 is used for reading. Although the matte and clear finishes cannot be represented in the figures, it can be seen from FIG. 7 that 26A and 26B have different hatchings in the illustrated cross-sections.

10 to 21 illustrate a lighting device in the form of a lantern 102 having a generally rectangular lens assembly or housing 104 rotatably connected to a generally rectangular body 106 by a pivot assembly 108 . The lantern 102 of FIG. 10 shows the lamp housing 104 in a deployed position, while FIGS. 12 , 13 and 15 show the lamp housing in a retracted position relative to the body 106 .

In the view of FIG. 10 , the body 106 has a generally rectangular configuration having a front surface 110 , a rear surface 112 and left and right sides 114 and 116 . The pivot assembly 108 is formed by two extensions 118 and 120 inclined from the body 106 at approximately 45° from vertical, although an angular range of 15° to 60° may also be used.

In FIG. 10 , the light housing 104 is shown in a vertical orientation. With the help of the feet 122, this orientation ensures that the center of gravity of the light housing 104 is located between the forward end 122A of the foot 122 and the rearward end 122D of the base 122D. between. This results in a stable position for the configuration of the lantern 102 shown in FIGS.

And when the lamp housing 104 turns to the furthest turning position as shown in FIG. 16 , its center of gravity is actually very close to the center of gravity of the body 106 .

The quality of all dry batteries and the body 106 is greater than that of the lamp housing 104, which ensures that the phenomenon of overturning will not occur.

A rotatable handle 123 is disposed between one half 106A and the other half 106B of the body 106 and can be rotated from a position adjacent to the side 112 until it contacts the lamp housing 104 . Therefore, the position of the lamp housing 104 determines the rotation limit of the handle 123 .

Pivot assembly 108 cooperates with forward end 122A of foot 122 so that when lamp housing 104 is turned to its furthest pivotable position as shown in FIG. is represented by axis 130), forming a tripod arrangement that maintains body 106 in a stable orientation, while lamp housing 104 forms an angle above axis 130 (axis 130 represents a substantially horizontal surface).

Furthermore, the handle 123 cooperates with the rearwardly facing end 122D as shown in FIG. Since the body 106 holds approximately four D cell batteries, the body 106 in the lantern 102 will have sufficient mass to generate a moment about 123A of the handle 123 than the lamp housing 104 and upper body portion including the pivot assembly 108 about the same point. The torque generated is much greater. This structure results in a very flexible and variable layout, with which the user obtains a considerable degree of stability.

The lantern 102 includes a switch 124 on the body 106, and the lamp housing 104 includes an access plate 104A which secures the lens on the lamp housing 104 to the lens holder 126 with a screw 104B. Alternatively, a lampshade 104C composed of five sides as shown in FIG. 17 is used as the limit of the lamp housing 104 .

In the retracted orientation shown in FIG. 12 , the lamp housing 104 of the lantern 102 is close to the body 106 . As can be seen in FIG. 14, an access panel 128 is provided on the front surface 110 of the body 106 to allow a user of the lantern 102 to access the battery compartment to replace or install dry batteries. The lantern 102 is characterized in that the entrance panel 128 is made of a highly reflective material, such as a silver plated polymer material, reflective metal, plastic metal, or painted white material, among others. This ensures that when the lantern 102 has the lamp housing 104 in the retracted position as shown in Figure 12, and the light source is turned on, the light emitted by the lamp housing 102 toward the direction of the body 106 is mostly reflected by the plate 128 and returns and passes through the lamp housing 104 shots later. This ensures that in the retracted position, the lantern 102 can stand upright on a table and produce sufficient light for reading or other activities.

Another feature of the lantern 102 is that when the lamp housing 104 is rotated to the vertical or over-center position as shown in FIG. 16, the lamp housing 104 emits light in a 360° circle around its longitudinal axis in a manner similar to a candle.

As shown in FIG. 15, a cross-section of the lantern 102 shows the pivot assembly 108 including a pivot clamp 108A secured to the body 106 with a friction screw 108B. The torque applied to the friction screw 108B determines the degree of friction that the pivoting clamp 108A applies to the sleeve or shaft 108C integrally formed with or secured to the reduced portion 126A of the lens holder 126 . The pivoting clamp 108A allows the lens holder 126 and lamp housing 104 to be positioned anywhere between the rotational extremes of the lens holder 126 and holds the lens holder 126 in that position without any outside assistance. The pivoting clamp 108A does this by virtue of friction with the bushing or shaft 108C.

Lens holder 126 includes a fluorescent tube and electrical connection support 135, while cover plate 104A or lampshade 104C has suitable sockets to receive fluorescent lamp terminals 137 and electrically connect these ends to allow current to flow through the two fluorescent tubes.

There is enough space between the body halves 106A and 106B to accommodate four D-size dry batteries 139, and on top of the body 106 contains a printed circuit board 141 with appropriate wiring and controls leading to the pivoting position of the body 106. Switch 124 on the upper surface near assembly 108 .

Figures 19 and 20 illustrate an additional feature which makes lamp housing 104 highly efficient and provides a wide range of options for the user.

A rotating reflective plate 128A, if used, eliminates the need for an entrance plate 128 that reflects white light. That is, the plate 128 would not need to reflect white light.

The rotating reflector 128A is made of a sheet material with a surface 128B capable of reflecting the visible spectrum. The reflective material may be any of the currently available reflective materials such as polished, silver plated, coated or may be a white sheet of metal or plastic as desired.

The other side 128C could have the same reflective properties, but this is not desirable.

Reflector plate 128A has two mounting wings 128D and 128E that are bent at right angles or attached to surface 128B. Wings 128D and 128E have coaxial holes through which pivot assembly 108 passes. This mounting structure allows the reflector 128A to rotate with the lamp housing 104 at the same time or at any time thereafter, if desired.

Therefore, when the lamp housing 104 is rotated to its limit rotation position as shown in FIG. emit light. A similar effect occurs when both the lamp housing 104 and the reflector 128 are in the retracted position.

Fig. 21 is a section similar to Fig. 15, in which like parts have been given the same reference numerals. The difference between the embodiments of Figures 15 and 21 is that the light source 32' of Figure 15 (which is a fluorescent lamp) is replaced by a tubular lens 32 and a light emitting diode (LED) 34'. If desired, another light-emitting diode 34 " shown by a phantom line in Fig. 21 can be provided at the other end of the tubular lens 32. The structure is similar to that described above with reference to Figs. 1 and 4. Another option is that the The light source can be a cold cathode fluorescent lamp with a diameter of about 3 to 6 mm.

It will be understood that the invention disclosed and defined herein also extends to all other combinations of two or more of the individual features mentioned above or evident from the text or drawings. All of these different combinations form further aspects of the invention.

The above-described embodiments of the invention and variations thereof will be apparent to those skilled in the art without departing from the scope of the invention.

Claims (7)

1. portable lighting device, it comprises:

One can contain the body of all dry cells with generator electric power;

What at least one was elongated is the translucent lens of tubulose totally, is launched by this lens by the light that device produces;

At least one incandescent lamp or light emitting diode are positioned at least one end of elongated tubular product such lens, and described elongated tubular product such lens extend a significant distance through incandescent lamp or light emitting diode; And

Circuit, this circuit makes dry cell be connected in described at least one incandescent lamp or light emitting diode during use;

Thus, the light that described incandescent lamp or light emitting diode produce is launched through described elongated tubular product such lens, thereby has the outward appearance that is similar to fluorescent lamp.

2. portable lighting device as claimed in claim 1 is characterized in that described tube lens is a diffuser, makes that the light of described at least one bulb or light emitting diode emission is spread.

3. portable lighting device as claimed in claim 1 is characterized in that, when using two bulbs or two light emitting diodes, or when a bulb and a light emitting diode, an end that is placed in the described tube lens.

4. portable lighting device as claimed in claim 1 is characterized in that, described lighting device comprises two light sources, and each is formed by at least one tubulose translucent lens and at least one incandescent lamp or light emitting diode.

5. portable lighting device as claimed in claim 1 is characterized in that, described body is totally for the straight line elongated shape, and lens are straight and vertically align with body.

6. any one described portable lighting device in the claim as described above is characterized in that described lens are installed in the lamp housing, and this lamp housing allows lamp housing to be connected in body with respect to the hinge connector that body turns over a radian by one.

7. portable lighting device as claimed in claim 6 is characterized in that a pivot axis is a level, and lamp housing can turn at least 180 ° radian, preferably about 270 ° radian.

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