Patent Description:
Luminaires with automated and remotely controllable functionality are well known in the entertainment and architectural lighting markets. Such products are commonly used in theatres, television studios, concerts, theme parks, night clubs, and other venues. A typical product will provide control over the functions of the luminaire allowing the operator to control the intensity and color of the light beam from the luminaire that is shining on the stage or in the studio. Many products also provide control over other parameters such as the position, focus, beam size, beam shape, and beam pattern. In such products that contain light emitting diodes (LEDs) to produce the light output it is common to use more than one color of LEDs and to be able to adjust the intensity of each color separately such that the output, which comprises the combined mixed output of all LEDs, can be adjusted in color. For example, such a product may use red, green, blue, and white LEDs with separate intensity controls for each of the four types of LEDs. This allows the user to mix almost limitless combinations and to produce nearly any color they desire.

<FIG> illustrates a typical multiparameter automated luminaire system <NUM>. These systems typically include a plurality of multi parameter automated luminaires <NUM> which typically each contain on-board a light source (not shown), light modulation devices, electric motors coupled to mechanical drive systems, and control electronics (not shown). In addition to being connected to mains power either directly or through a power distribution system (not shown), each automated luminaire <NUM> is connected in series or in parallel to data link <NUM> to one or more control desks <NUM>. The luminaire system <NUM> is typically controlled by an operator through the control desk <NUM>.

Luminaires have been provided using non-LED light sources designed to produce a single narrow beam or a plurality of such beams. Such luminaires may use low etendue, High Intensity Discharge (HID) light sources with a small arc gap in order to facilitate the production of tight, almost parallel light beams. <CIT> and <CIT> provide examples of such a system. Single and multi-color LED sourced luminaires have also been produced with narrow beam capability using sophisticated collimation systems as, for example, disclosed in <CIT>. LEDs however are high etendue light sources by comparison with HID and it is difficult to produce multiple beam systems using LED light sources.

Prior art optical systems utilizing multiple LED emitters may be unforgiving when it is desired to produce a homogeneous image with a light output capable of being blended between units to provide seamless coverage. This mode of operation is often called a wash light as it washes the stage with light. Prior art systems will commonly utilize multiple LED light sources and attempt to blend them into a homogeneous whole. This approach is often unsuccessful because the individual differently colored LED emitters are still visible producing a multi-colored effect when viewing the light rather than the desired appearance of a single color. Other prior art systems use a secondary lens but that has the drawback that the output lens may not then be filled completely and all the light will appear to be emitted from a portion at the centre of the output lens. This reduces the performance of the luminaire as a wash light as it is an important feature of wash luminaires that the effective light source be as large as possible in order to soften and reduce shadowing.

Reference is made to <CIT>, <CIT>, <CIT>, <CIT>, and <CIT> which have been cited as relating to the state of the art of the present invention.

There is a need for a method for producing and controlling a light beam or multiple light beams from an LED sourced wash light luminaire to produce controllable lighting effects from a luminaire with a wash light distribution with a large effective source and true blending output distribution.

It will be appreciated that the scope of the invention is in accordance with the claims. Accordingly, there is provided an automated luminaire as defined in claim <NUM>. Further features are provided in accordance with the dependent claims. The specification may also include description of arrangements outside the scope of the claims provided as background and to assist in understanding the invention.

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals indicate like features and wherein:.

Preferred embodiments of the present disclosure are illustrated in the Figures, like numerals being used to refer to like and corresponding parts of the various drawings.

The present disclosure generally relates to a method for providing special effects in wash light luminaires, specifically to a method relating to providing controllable lighting effects from a luminaire with a wash light distribution with a large effective source and true blending output distribution.

<FIG> illustrates the layout of embodiments of major components of one light engine <NUM> of a luminaire generating a flower effect. Light emitting module <NUM> comprises a single LED or an array of LEDs, which may include a primary optic (not shown). Light emitting module <NUM> may contain a single color of LEDs or may contain multiple dies, each of which may be of common or differing colors. For example, in one embodiment light emitting module <NUM> may comprise one each of a Red, Green, Blue and White LED. In further embodiments light emitting module <NUM> may comprise a single LED chip or package while in yet further embodiments light emitting module <NUM> may comprise multiple LED chips or packages either under a single primary optic or each package with its own primary optic. In some embodiments these LED die(s) may be paired with optical lens element(s) as part of the LED light-emitting module. In a further embodiment light emitting module <NUM> may comprise more than four colors of LEDs. For example, seven colors may be used, one each of a Red, Green, Blue, White, Amber, Cyan, and Deep Blue/UV LED die.

The light output from the LEDs in light emitting module <NUM> enters light guide optic <NUM> contained within protective sleeve <NUM>. Light guide optic <NUM> may be a device utilizing internal reflection so as to collect, homogenize and constrain and conduct the light to exit port <NUM>. Light guide optic <NUM> may be a hollow tube with a reflective inner surface such that light impinging into the entry port may be reflected multiple times along the tube before leaving at the exit port <NUM>. Light guide optic <NUM> may be a square tube, a hexagonal tube, a heptagonal tube, an octagonal tube, a circular tube, or a tube of any other cross section. In a further embodiment, light guide optic <NUM> may be a solid rod constructed of glass, transparent plastic, or other optically transparent material where the reflection of the incident light beam within the rod is due to "total internal reflection" (TIR) from the interface between the material of the rod and the surrounding air. The integrating rod may be a square rod, a hexagonal rod, a heptagonal rod, an octagonal rod, a circular rod, or a rod of any other cross section. Light guide optic <NUM>, whether solid or hollow, and with any number of sides, may have entry port <NUM> and exit port <NUM> that differ in cross sectional shape. For example, a square entry port <NUM> and an octagonal exit port <NUM>. Further, light guide optic <NUM> may have sides which are tapered so that the entrance aperture is smaller than the exit aperture. The advantage of such a structure is that the divergence angle of light exiting the light guide optic <NUM> at exit port <NUM> will be smaller than the divergence angle for light entering the light guide optic <NUM>. The combination of a smaller divergence angle from a larger aperture serves to conserve the etendue of the system. Thus, a tapered light guide optic <NUM> may provide similar functionality to a condensing optical system. In a preferred embodiment of the disclosure, light guide optic <NUM> has both a square entry port <NUM> and a square exit port <NUM>. For the desired flower reminiscent effect, it is advantageous to use shapes with opposing sides and to have the same shape cross section along the length of the light guide optic <NUM>.

Light guide optic <NUM> may have an aspect ratio where its length is much greater than its diameter. The greater the ratio between length and diameter, the better the resultant mixing and homogenization will be. Light guide optic <NUM> may be enclosed in a tube or protective sleeve <NUM> that provides mechanical protection against damage, scratches, and dust. In the preferred embodiment, light guide optic <NUM> is of such a length so as to collimate and direct but deliberately provide incomplete homogenization of the light coming from individual LEDs on light emitting module <NUM>. This incomplete homogenization may be advantageously utilized in the remainder of the optical system. Similarly, the exit port of light guide <NUM> is polished, rather than being diffused or textured, to maintain the incomplete homogenization of the input light beams. In one embodiment the beams are less than <NUM>% homogenized such that individual beams or colors from separate LEDs are still clearly visible.

Light guide optic <NUM> within its protective sleeve <NUM> is mounted such that it may be freely rotated along its long, optical, axis through gear <NUM> and motor (not shown) supported by bearing <NUM>. Rotating light guide <NUM> will cause the emitted light beams from exit port <NUM> to also rotate around the optical axis of the system. In fact, the light beam movement and rotation will be complex, as a function of the rotation of the input port of light guide optic <NUM> across the array of LEDs in fixed light emitting module <NUM> and the total internal reflection within the rotating light guide. Thus, the light beams exiting the light guide optic <NUM> will present a complex and dynamic pattern of moving beams. Light guide optic <NUM> may be rotated in either direction and at any speed under control of the operator.

With the disclosure in its basic form, the light from the exit port <NUM> of light guide optic <NUM> will be directed towards and through lens <NUM> that serves to further control the angle of the emitted light beam. Lens <NUM> may be moved towards and away from light guide optic <NUM> in the direction <NUM> along the optical axis of the system shown by line <NUM>. In the position where lens <NUM> is at its furthest separation from the exit port <NUM> of light guide optic <NUM> the emitted light beam will have a narrow beam angle. In the position where lens <NUM> is at its closest separation from the exit port <NUM> of light guide optic <NUM> the emitted light beam will have a wide beam angle. Intermediate positions of lens <NUM> with respect to exit port <NUM> of light guide optic <NUM> will provide intermediate beam angles. Lens <NUM> may advantageously be configured as an achromat so as to minimize chromatic aberration of the emitted light beam or beams. The system illustrated herein utilizes a single lens element as lens <NUM> to provide output beam control. The disclosure is, however, not so limited, and further embodiments may contain different numbers and types of lenses or other optical systems as well known in the art. In particular, further embodiments may utilize systems where lens <NUM> comprises multiple elements. In further embodiments, lens <NUM> may comprise a number of optical lens elements whose relationship to each other is not fixed, and can alter. The elements of lens <NUM> may be meniscus lenses, plano convex lenses, bi-convex lenses, holographic lenses, aspheric lenses, or other lenses as well known in the art. The elements of lens <NUM> may be constructed of glass, transparent plastic, or other optically transparent material as known in the art.

In a preferred embodiment, lens <NUM> comprises a single element constructed, by the use of aspheric surfaces or otherwise, to exhibit achromatic properties such that the colors in the light beam remain homogenized and do not produce objectionable colored fringing to the light beam.

With the layout as described, the effect from the luminaire will be that of a complex pattern of a plurality of light beams created by the reflection of the individual beams from the LEDs in light emitting module <NUM> within light guide optic <NUM>. As no diffusion or other homogenization is provided, these beams will remain in differing colors and patterns through projection lens system comprising lens <NUM>. As the light guide optic <NUM> is rotated, and lens <NUM> is moved towards and away from the exit port <NUM> of light guide optic <NUM>, the effect will be that of a flower or spreading pattern of beams that opens and closes as the lenses are moved.

To change the luminaire into wash light mode instead of beam effect, diffuser arm <NUM> may be swung across the light beam proximate to exit port <NUM> of light guide optic <NUM>. Diffuser arm <NUM> may contain a number of diffusers each of which may have different diffusion properties. In the embodiment illustrated, diffuser arm <NUM> is fitted with first diffuser <NUM> and second diffuser <NUM>, however further embodiments may have differing numbers of diffusers. In operation diffuser arm <NUM> is rotated such that one of the diffusers <NUM> or <NUM> is positioned proximate to exit port <NUM> of light guide optic <NUM> and will serve to diffuse and homogenize the light beams emitting from exit port <NUM> before they pass into the remainder of the optical system. The diffuser serves to merge the light beams into a single homogenized beam and to increase the spread of the light beam. Differing strengths or properties of diffuser <NUM> or <NUM> may provide narrow or wide homogenized beams without the flower effect or for lower powered diffusers a softening of the flower effect. In this mode of operation lens <NUM> will continue to control the overall size of the homogenized beam.

<FIG> illustrates more detail of some of the embodiments of the major components and layout of the light engine <NUM> illustrated in <FIG>. More specifically, in <FIG>, exit port <NUM> of light guide optic <NUM> and the means for moving diffuser <NUM> and <NUM> across that exit port can more clearly be seen. Sub <FIG> illustrates the system in beam flower effect mode where diffuser arm <NUM> is rotated such that neither diffuser <NUM> nor diffuser <NUM> are positioned across exit port <NUM>. In this position the undiffused light beam presents the flower effect.

Motor <NUM> provides the motion for rotating light guide optic <NUM> through gear <NUM>, and motor <NUM> provides the motion for diffuser arm <NUM>. Similar motors and drive systems as well known in the art provide the motion for lens <NUM> along the optical axis of the luminaire. Motors <NUM> and <NUM> may be stepper motors, servo motors, linear actuators, solenoids, DC motors, or other mechanisms as well known in the art. In the embodiment shown, the motors <NUM> and <NUM> operate through gear systems. For example, motor <NUM> drives gear <NUM>. Other mechanisms for actuating the desired movement as are well known in the art are also contemplated.

Sub <FIG> illustrates the system in wash light mode where diffuser arm <NUM> is rotated such that second diffuser <NUM> is positioned across exit port <NUM>. In this position the light beam is diffused by second diffuser <NUM> and presents a homogenized beam without the flower effect.

<FIG> illustrates the light guide assembly including its support structure. Sub <FIG> show the assembly from fully exploded (4a) through fully assembled (4d) to aid comprehension of the structure. Light guide optic <NUM> with exit port <NUM> is inserted into protective sleeve <NUM>. Protective sleeve <NUM> has, as part of its structure, bearing support surfaces <NUM> and <NUM>. Bearing support surfaces <NUM> and <NUM> engage with bearings <NUM> and <NUM> respectively. This allows protective sleeve <NUM> (and thus light guide optic <NUM>) to rotate within bearings <NUM> and <NUM>. Also attached to protective sleeve <NUM> is gear <NUM> which meshes with gear <NUM> shown in <FIG> that is in tum driven by motor <NUM>. The assembly formed by protective sleeve <NUM>, light guide optic <NUM>, bearings <NUM> and <NUM>, and gear <NUM>, is supported within holder <NUM> such that (as shown in <FIG>) light guide optic <NUM> protrudes from the base of holder <NUM> and aligns with light emitting module <NUM>. This assembly also serves to maintain a small separation between entry port <NUM> of light guide optic <NUM> and light emitting module <NUM> such that light transfer from light emitting module <NUM> and light guide optic <NUM> is maximized but the two surfaces do not touch.

It is envisaged that light guide assemblies as shown in <FIG> could be used in multiples or arrays within a single luminaire. For example, an array of rotating light guide assemblies may be used where each light guide is positioned above its own light emitting module. In these embodiments a single motor may drive the rotation of multiple light drive assemblies.

<FIG> illustrates an embodiment of a light guide optic <NUM> without its support structure. Light guide optic <NUM> contains entry port <NUM> and exit port <NUM>. In the embodiment illustrated, light guide optic <NUM> is tapered and has both a square entry port <NUM> and a square exit port <NUM>.

<FIG> illustrates detail of an embodiment of the optical softening diffuser arm <NUM>. Diffuser arm <NUM> is shown in two positions in <FIG>. In position A, diffuser arm <NUM> is positioned such that second diffuser <NUM> is across exit port <NUM> (shown dashed as it is under the diffuser). Also illustrated is an optional feature of diffuser arm <NUM>. First diffuser <NUM> includes mask <NUM> which serves to constrain the light to a masked shape. Mask <NUM> is an opaque mask with a central open aperture with, in this case, a hexagonal shape. Mask <NUM> helps to constrain the projected beam into a more rounded, non square, shape. Mask <NUM> may be of any shape, not just the hexagon illustrated herein, including but not limited to circular, hexagonal, or octagonal.

In position B, diffuser arm <NUM> is positioned such that first diffuser <NUM> including mask <NUM> is across exit port <NUM> (shown dashed as it is under the diffuser). Diffusers <NUM> and <NUM> may offer differing amounts or types of diffusion producing different beam spreads in the output. Diffusers <NUM> and <NUM> may be patterned or molded glass, or plastic, or may be holographic diffusers or other diffuser types as well known in the art. Although two different diffusers <NUM> and <NUM> are shown here the disclosure is not so limited and any number of diffusers or homogenizers may be affixed and selected as part of diffuser arm <NUM>.

<FIG> illustrates the layout of the optical support plate <NUM> of an alternative embodiment of a wash light with special effects luminaire employing an array of light engine modules. Optical support plate <NUM> includes a number of LED light sources each with their own associated light guide <NUM>. In the illustrated embodiment <NUM> LED light sources arranged with a single centre LED light source having two concentric rings of <NUM> and <NUM> LED light sources around it are utilized but in practice use of any number is envisaged. For example, the outer ring may be omitted providing a system with <NUM> LED light sources, or an extra ring or rings may be added providing larger numbers of LED light sources. The <NUM> LED light sources and light guides <NUM> are here arranged in concentric rings but may be also arranged in other configurations. Some percentage of the LED light sources and light guides <NUM> may be fitted with the optical softening diffuser arm <NUM> system to provide a module as illustrated in <FIG>. In the embodiment illustrated, a single central LED light source is fitted with the system as light engine <NUM>. In practice any number of the light guides <NUM> may be fitted with optical softening diffuser system <NUM>. However, in a preferred embodiment, the use of a single centrally mounted light engine <NUM> surrounded by LED light sources with "fully homogenizing" or at least more homogenizing light guides <NUM> provides a good combination of effects and standard wash light usage. Light guides <NUM> that are not fitted with optical softening diffuser system <NUM> may have the exit ports patterned, textured, or diffused or may have diffusion filters similar to diffusers <NUM> and <NUM> permanently attached to or constructed as part of the exit port of the light guide or the light guides may be otherwise designedly shaped to "fully homogenize" light such that these guides always produce a smooth, homogenized light output. In contrast, light guides <NUM> that are fitted with optical softening diffuser system <NUM> may be remotely controlled to produce either a smooth homogenized output, or a harder edged flower effect as desired by inserting or removing the diffusers <NUM> and <NUM> across the beam.

<FIG> illustrates the system shown in <FIG> with the optical support plate <NUM>, this time fitted with output lens module <NUM>. Output lens module <NUM> contains an array of lenses, equal in number to the LED light sources and associated light guides shown in <FIG>. The lenses may be of differing outline shapes in order to fit together into an aesthetically pleasing design and also to minimize any space wasted in between lenses. Such gaps between lenses may reduce the output of the system, and produce undesirable visible gaps in light output when viewing the luminaire. The design presented here is similar to that of a spider's web and provides both functional purpose and aesthetic appeal. The lenses, although of differing shapes, may have substantially the same optical properties. For example, central lens <NUM> may be the same optical strength and provide the same optical effect as edge lens <NUM>. In other embodiments, the lenses associated with LED light sources that are fitted with optical softening diffuser system <NUM> such as the central lens <NUM> associated with the central LED light source in <FIG>, may have the same or different optical properties as the edge lenses <NUM> associated with standard light guide <NUM>.

<FIG> and <FIG> illustrate side elevation views of the system as shown in <FIG>. In <FIG> the output lens module <NUM> containing an array of lenses <NUM> and <NUM> is positioned close to the light guides <NUM> and optical softening diffuser system <NUM> on the central light engine module. In the embodiment illustrated only the central light engine module (light engine <NUM>) is of the reduced homogenization type in a center position. In other embodiments this type of module can be placed in a non central location. In further embodiments there may be more than one of these types of light engines <NUM>. While the reduced homogenizing module may include an electable diffusion module so that its light may be included in a full wash light mode, in other embodiments a full wash light mode can be achieved by a reduced homogenizing light module without a diffuser but a system that dims to dim out such light modules during a full wash light mode. This dimming may be automatically tied in operation when the user selects a full wash mode or in other embodiments it might be manual. In further embodiments all of the modules are of the reduced homogenization type and they all have selectable diffusion module(s). In some embodiments the individual light engine modules are controlled individually and in other embodiments the modules are controlled in groups. The groups may be of like with like or of like geometric location in the array such as outer ring, inner ring, etc. These controls may include a color intensity diffusion flag if so equipped, image multiplier if so equipped, and zoom lens if mechanically configured to be independently controllable (not shown in the figures).

In the position of output from lenses <NUM> and <NUM> in <FIG> the light output will be at a wider angle. In <FIG> output lens module <NUM> has been moved in direction <NUM> away from light guides <NUM> and optical softening diffuser system <NUM>. In this position the output from lenses <NUM> and <NUM> will be a narrow angle. Positions of lens module <NUM> intermediate to those positions shown in <FIG> and <FIG> will produce intermediate beam angles. As the lens module is moved there will be a continuously variable beam angle, or zoom, of the light beams emitted from the light guides <NUM>.

If optical diffusers <NUM> and <NUM> are not positioned across the beam in light engine <NUM> then the lens when it is in its distant, narrow angle, position may be focused on the LED and the multiple internal reflections in light guides optically multiply the chip shape which creates a sharp distinct flower effect. If the lens is moved to the close, wide angle, position then, even without the diffusers <NUM> and <NUM> in place, light engine <NUM> will produce a smoother wash style beam with a less distinct flower effect. In either case, with diffuser <NUM> or <NUM> in place the system in light engine <NUM> will produce a smooth homogenized effect, without the flower effect.

In the embodiment illustrated, the movement of output lens module <NUM> is produced by motors <NUM> acting on lead screws <NUM>. Although a lead screw system is illustrated here, the disclosure is not so limited and other methods of moving the lenses such as belt systems, linear actuators, rack and pinion gears, and other methods well known in the art are envisaged. The output lens module <NUM> is supported by guides <NUM> such that the motion is constrained to be back and forth along the optical axis of the luminaire.

In the embodiment illustrated the entire array of lenses <NUM> and <NUM> moves together as a single module. However, in further embodiments individual lenses or groups of lenses may have their own motor drive systems and be capable of independent movement along the optical axis. In particular, any lenses associated with LED light sources that are fitted with optical softening diffuser system <NUM> such as the central light engine module in <FIG>, may move with the output lens module <NUM>, may be fitted with independent motor control separate from that for the output lens module <NUM>, or may be static with a fixed beam angle.

The design of lenses <NUM> and <NUM> in output lens module <NUM> is such that the individual homogenized beams of light from each of the light beams emitted from the light guides <NUM> are constrained to further overlap and mix as they leave the output lens module <NUM> providing a smooth, contiguous light beam with a wash light distribution with a large effective source (comprising the total output lens module <NUM>) and true blending output distribution.

<FIG> illustrates a complete automated luminaire 150as may be used in a lighting system such as that illustrated in <FIG>. Lens array <NUM> is visible on the external face of the automated luminaire <NUM>.

<FIG> illustrates a further embodiment of the output lenses <NUM> or <NUM> as may be used in the described system. As previously described, it is advantageous for such lenses to be achromatic in their behavior. In other words, they should present as little as possible difference between their optical effect on different colors of light to avoid objectionable colored fringing around the edge of light beams. In a preferred embodiment edge lens <NUM> comprises a single element constructed, by the use of aspheric surfaces or otherwise, to exhibit achromatic properties. In the embodiment illustrated in <FIG>, the edge lens <NUM> does not have a smooth surface, instead there is a microstructure on the lens surface or surfaces. The lens surface or surfaces are covered with small engineered depressions similar to those on a golf ball. The depressions <NUM> are shown here larger than in reality for ease of illustration. In one embodiment the depressions <NUM> may be <NUM> (millimeter) - <NUM> in diameter with a depth of only <NUM>. These depressions <NUM>, along with the use of aspheric lens surfaces, may be used on one or both sides of edge lens <NUM> so as to provide achromatic operation of the lens.

In operation of the luminaire, the LED sources feeding light guides <NUM> and optical softening diffuser system <NUM> may be individually or collectively controlled as to color and intensity to provide either a coordinated wash light or an effects unit as desired. In particular, any LED sources fitted with optical softening diffuser system <NUM> may be controlled such that either they produce the aforementioned dynamic flower effect, or produce a smooth wash beam to match standard light guides <NUM>. The operator may choose to combine or mix these effects to achieve a desired result.

Claim 1:
An automated luminaire, comprising:
a first central light engine module (<NUM>) comprising:
a first light emitting diode (LED) array source (<NUM>) configured to emit a first plurality of colored light beams;
a first light guide (<NUM>) optically coupled to the first LED array source and configured to receive the first plurality of colored light beams emitted by the first LED array source and emit a first homogenized light beam, the first homogenized light beam including visible separation of at least some of the received first plurality of colored light beams; and
a first lens (<NUM>, <NUM>) optically coupled to the first light guide and configured to receive the first homogenized light beam and to move along an optical axis of the first light guide, the first lens (<NUM>, <NUM>) being configured to project a pattern of the visibly separated colored light beams in the first homogenized light beam, the pattern changing size as the first lens moves along the optical axis of the first light guide; and
a plurality of second non-central light engine modules (<NUM>) surrounding the first light engine module, each second light engine module comprising:
a second LED array source (<NUM>) configured to emit a second plurality of colored light beams;
a plurality of second light guides (<NUM>) optically coupled to the second LED array sources and configured each to receive the second plurality of colored light beams emitted by the second LED array sources and emit a second homogenized light beam, wherein the second light guides are more homogenizing than the first light guide; and
a plurality of second lenses (<NUM>) optically coupled to the second light guides (<NUM>) and configured each to receive a second homogenized light beam and to move along an optical axis of the second light guides, wherein the second lenses project each a light beam having a beam angle determined by a distance of the second lens from the second light guide;
wherein the plurality of the lenses (<NUM>,<NUM>) defines a zoom lens system;
wherein the zoom lens system is configured to project the received light with a flower reminiscent effect.