Abstract: Apparatus and methods for lighting. The apparatus may include a removable recess lighting assembly. The lighting assembly may include a light-emitting diode (“LED”) light source. The LED light source may include an LED. The lighting assembly may define a central axis. The apparatus may include a heat sink. The heat sink may be configured to be mounted in a structure. The heat sink may be configured to retain the lighting assembly. The heat sink may be configured to release the lighting assembly in response to a translation of the lighting assembly along the central axis. The translation may be a translation without a rotation of the light assembly about the central axis. In operation, the lighting assembly may be serviced without causing damage to the structure in which the apparatus is mounted. The lighting assembly may be removed through a defined aperture in the apparatus.

Abstract: A display device including a lower cover; a circuit substrate on the lower cover; a plurality of light sources disposed on a first portion of the circuit substrate; a reflection layer disposed on a second portion of the circuit substrate; a first adhesive disposed between the second portion of the circuit substrate and the reflection layer; a light regulator including light regulating patterns disposed in the reflection layer; and an optical sheet disposed on the light sources.

Abstract: A lighted product display case, containing two end covers and connecters; each end cover has a first lighting assembly and position limiting portions, the first lighting assembly has first contacts corresponding to the position limiting portions; each connecter has a second lighting assembly having second contacts exposed from two ends of the connecter; the first contacts are exposed to the connecters; the connecters are positioned between the two end covers, two ends of each connecter are inserted into position limiting portions of the two end covers so that a case body is formed where the first contacts contact the second contacts so that the first lighting assemblies are electrically connected with the second lighting assemblies. By removable connection between the end covers and the connecters, quick assembly is achieved, products are illuminated and the display effect enhanced. Also, moving and transportation are facilitated to reduce mobility problem and transportation cost.

Abstract: A substrate of a softbox includes a chuck with a plurality of clamping slots; a plurality of connecting members corresponding to clamping slots, respectively, each connecting member including opposite first and second ends, the first end being rotatably connected into a corresponding clamping slot; and a plurality of position limit assemblies being movably mounted in the clamping slots, respectively, each position limit assembly including an abutting portion. The connecting member may rotate to a first position to make the first end abut against the abutting portion. The position limit assembly may be moved to release the first end, making the connecting member be capable of rotating to a second position. When there is no external force applied to the position limit assembly and the connecting member at the second position is rotated, the connecting member may press the abutting portion and return back to the first position.

Abstract: The polyester resin composition includes: a polyester resin A containing 82 to 88 mass % of a polybutylene terephthalate resin and 12 to 18 mass % of a polyethylene terephthalate resin; a metal organic acid salt B that is either one or both of an alkali metal organic acid salt and an alkaline earth metal organic acid salt; and an inorganic filler C having an average particle diameter of 0.05 to 3 ?m in an amount of 1 to 13 parts by mass based on 100 parts by mass of the polyester resin A, wherein the polyester resin composition includes either one or both of alkali metal atoms and alkaline earth metal atoms in an amount of 0.000005 to 0.05 parts by mass based on 100 parts by mass of the polyester resin A, and a content of linear oligomers of polybutylene terephthalate or the like is not more than 1000 mg/kg.

Abstract: A lighting assembly and method generate a three-dimensional lighting effect with parallax, depth and brightness variability or twinkling among different viewing angles using an LED substrate and different optic component layers including one or more obscuration patterns and a reflection chamber for unobscured light from LEDs components not obscured by the one or more obscuration patterns. The LED substrate can employ mini or micro scale package LEDs or their unpackaged LED dies for slim profile lighting assembly. The LED substrate and different optic component layers can be curved, employ direct illumination and occultation imaging.

Abstract: A light-transmitting assembly of a display device, a signal indicator, and the display device are provided in the embodiments of the present disclosure. The light-transmitting assembly of the display device includes: a light-transmitting adjustment member including a plurality of first patterns, a light transmittance of each first pattern is less than a light transmittance of a region of the light-transmitting adjustment member other than the first pattern, and each light-shielding area ratio of the first patterns is a ratio of a sum of areas of all the first patterns in any one region of the light-transmitting adjustment member to an area of the any one region.

Abstract: A projection optical apparatus includes a first housing, a second housing accommodated in the first housing, and a projection system accommodated in the second housing. The projection system includes a first reflector deflecting the optical path of the projection system. The first housing has a plurality of first openings that cause the interior of the first housing to communicate with the exterior of the first housing. The second housing has a plurality of second openings that cause the interior of the second housing to communicate with the exterior of the second housing.

Abstract: Provided is light flux controlling member for controlling a distribution of light emitted from a plurality of light emitting elements disposed on a substrate, which includes a plurality of incidence units for allowing incidence of the light emitted from the plurality of light emitting elements, respectively; and an emission unit which emits the light incident on the plurality of incidence units while guiding the light, and which is disposed between the plurality of incidence units in a direction along the substrate. The light flux controlling member has a rectangular shape with rounded corners in plan view, and includes four corner portions and four side portions, and the inclination angle of the corner portions is different from the inclination angle of the side portions.

Abstract: An illumination system includes: a laser array assembly including: a laser configured to generate a laser light; a crystal phosphor waveguide, adjacent to the laser and in the laser light, configured to: generate of a luminescent light based on receiving the laser light, and direct the luminescent light away from a base end; and a compound parabolic concentrator (CPC), coupled to the crystal phosphor waveguide opposite the base end, configured to: collect the luminescent light from the crystal phosphor waveguide, project the luminescent light away from the crystal phosphor waveguide.

Abstract: A lighting device includes a light source, a substrate and a reflective sheet. The light source is mounted on the substrate. The substrate includes a substrate side opening in a vicinity of the light source. The reflective sheet is provided to cover a surface of the substrate. The reflective sheet includes a reflective sheet side opening at a location corresponding to the light source. The substrate side opening is arranged such that an inner edge portion of the reflective sheet side opening is inserted thereto or the light source is fixed thereto.

Abstract: Lighting module disclosed in an embodiment of the invention, a substrate; a plurality of light emitting devices disposed on the substrate; a first reflective layer disposed on the substrate; a resin layer disposed on the first reflective layer and the light emitting device; and a second reflective layer disposed on the resin layer, wherein the resin layer is a front side surface on which light generated from the plurality of light emitting devices is emitted, a rear side surface facing the front side surface, and first and second side surfaces connecting the front side surface and the rear side surface with each other.

Abstract: A light source apparatus according to an aspect of the present disclosure includes a first light source that emits first light, a second light source that emits second light, a light guide that causes the first light emitted from the first light source to propagate, a wavelength converter containing a phosphor that emits fluorescence when excited with the second light emitted from the second light source, and a light combiner that combines the first light having exited out of the light guide with the fluorescence having exited out of the wavelength converter. The light guide and the wavelength converter are disposed side by side. The light guide has a first end section and a second end section. The wavelength converter has a third end section and a fourth end section. The first light enters the light guide via the first end section thereof.

Abstract: The invention provides a lighting device (12) configured to provide both functional lighting for illuminating a space, and simultaneously to present a spatially dynamic sparkling light display. The device comprises a chamber (14) containing one or more light sources (28). The light sources are arranged to direct light in the direction of a translucent surface portion (20), and in the direction of a plurality of light exit areas (32) delimited by the translucent surface portion. The light exit areas each have a higher transmittance than the surrounding surface portion.

Abstract: A liquid crystal display device with high visibility and a backlight device for implementing the liquid crystal display device are provided. A backlight device (100) for irradiating light to a back surface of a liquid crystal panel (19) in a liquid crystal display device 101 includes: light sources (45); a substrate (51); and a plate-like optical member (29) through which a part of light emitted by the light sources (45) is transmitted. The optical member (29) includes: first region (A11) and two or more second regions (A21), wherein in the first region (A11), the light transmittance increases as separating from a mounting position of one light source (45), and in the second regions (A21), the light transmittance increases as approaching an outer peripheral portion from a central portion of the optical member (29) in a predetermined direction in places in contact with another adjacent second region (A21).

Abstract: The invention provides a lighting device comprising a plurality of solid state light sources and an elongated ceramic body having a first face and a second face defining a length (L) of the elongated ceramic body, the elongated ceramic body comprising one or more radiation input faces and a radiation exit window, wherein the second face comprises the radiation exit window, wherein the plurality of solid state light sources are configured to provide blue light source light to the one or more radiation input faces and are configured to provide to at least one of the radiation input faces a photon flux of at least 1.0*1017 photons/(s·mm2), wherein the elongated ceramic body comprises a ceramic material configured to wavelength convert at least part of the blue light source light into at least converter light, wherein the ceramic material comprises an A3B5O12:Ce3+ ceramic material, wherein A comprises one or more of yttrium (Y), gadolinium (Gd) and lutetium (Lu), and wherein B comprises aluminum (Al).

Abstract: A back-light module includes a substrate, a plurality of light-emitting devices, and an optical film. The light-emitting devices are disposed on the substrate and are arranged in a rectangular array along an X direction and a Y direction. The optical film is disposed on the light-emitting devices and includes a plurality of pyramid structures arranged in arrays. Each pyramid structure includes four bottom edges. An angle between a bottom edge and the X direction and an angle between another bottom edge and the Y direction are greater than 0 degree and less than 45 degrees.

Abstract: The invention provides a lighting device (1) comprising a luminescent element (5) comprising an elongated light transmissive body (100), the elongated light transmissive body (100) comprising a side face (140), wherein the elongated light transmissive body (100) comprises a luminescent material (120) configured to convert at least part of a light source light (11) selected from one or more of the UV, visible light, and IR received by the elongated light transmissive body (100) into luminescent material radiation (8). The invention further provides such luminescent element per se.

Abstract: The disclosure relates to an interchangeable lampshade system. A lampshade system includes an outer shade having a first frame disposed about a first perimeter of the outer shade and a second frame disposed about a second perimeter of the outer shade. The outer shade further comprises a structural side comprising a first side attached to the first frame and a second side attached to the second frame. The lampshade system includes an inner shade configured to be disposed about an interior surface of the structural side of the outer shade. The lampshade system includes a socket component configured to attach the outer shade to a lamp socket, wherein the socket component is attached to one or more of the first frame of the outer shade or the second frame of the outer shade.

Abstract: Provided is a polybutylene terephthalate resin composition which has further improved fluidity (melt fluidity) while maintaining mechanical characteristics. The polybutylene terephthalate resin composition contains 0.05-5 parts by mass of a glycerin fatty acid ester having a hydroxyl value of 200-400, and 0.05-5 parts by mass of a polyvalent alcohol fatty acid ester having a hydroxyl value of 100 or less, with respect to 100 parts by mass of a polybutylene terephthalate resin. The glycerin fatty acid ester preferably contains glycerin and/or a dehydration condensation product thereof, and a fatty acid having 12 or more carbon atoms.

Abstract: The disclosure relates to a lamp fitting apparatus system. A system includes a polygonal socket connector comprising a first tapered fitting, wherein the polygonal socket connector is configured to connect with a lamp socket. The system includes a polygonal bracket comprising a second tapered fitting, wherein the polygonal bracket is configured to attach to a lampshade. The system is such that the second tapered fitting of the polygonal bracket corresponds with the first tapered fitting of the polygonal socket connector, such that the polygonal bracket and the polygonal socket connector form a compressing fitting configured to connect the lampshade to the lamp socket.

Abstract: This invention is concerning an illumination device that can obtain illumination light efficiently. An illumination device 1 used in, for example, a projection display apparatus includes a light source and a light tunnel 14. The light tunnel 14 includes a light incident port 15, a light emission port 16, a light guide path 17, a reflection surface 20 surrounding the light guide path 17, a phosphor layer 19 that generates fluorescent light LF having a different wavelength range from that of excitation light LE when being excited by the excitation light LE, a condensing optical system 13 that diverges the excitation light LE in the vicinity of the light incident port 15 and guides the diverged light into the light tunnel 14 to irradiate the phosphor layer 19, and a wavelength selection element that reflects the fluorescent light LF toward the light emission port 16.

Abstract: In some embodiments, a lighting device comprising two or more light sources and an optical device configured to enhance uniformity of light emitted from the light sources and emerging from a surface of the optical device, an average distance between light sources less than one half of the square root of the area of the surface divided by the number of light sources. In some embodiments, a fixture structure comprising a reflective structure and a heat conductor in contact with the reflective structure and covering not more than 30 percent of the surface area of the reflective structure. In some embodiments, a lighting device comprising a fixture structure, at least one light source mounted on one substrate, and at least one light source mounted on another substrate. Other fixture structures and lighting devices.

Abstract: This reflective member comprises a rectangular bottom surface, four inclined planes joined to the four edges of the bottom surface and whereof each is inclined with respect to the bottom surface so as to slope up from the bottom surface, and four planar corner portion inclined planes, whereof each is disposed in such a manner as to link two adjacent inclined planes.

Abstract: A display device includes: a display panel having a display area and a non-display area; a light source unit supplying light to the display panel; a bottom chassis on which the light source unit is disposed; a mold frame coupled to the bottom chassis; and a diffusion plate fixed to the mold frame and emitting light emitted from the light source unit to the display panel, wherein the mold frame may be transparent.

Abstract: To implement an illuminating device which can adjust the distribution of light of flat lighting and which also has a superior light concentration function, the illuminating device of the present invention implements flat lighting having a light-concentrating member to maximize light concentration.

Abstract: A polyamide resin composition including a polyamide resin (A), a copper compound (B), a bromide of an alkali metal and/or a bromide of an alkaline earth metal (C), and at least one fatty acid compound (D) selected from the group consisting of fatty acid esters, fatty acid amides, and fatty acid metal salts, wherein the fatty acid compound (D) has an acid value of 5 mgKOH/g or less.

Abstract: In a light source unit, a high-pressure discharge lamp includes a first and a second external electrode to emit light as electric power is supplied thereto through a first and a second power supply line, a concave reflection mirror, which reflects the light, has an opening at the center thereof to pass one end of the high-pressure discharge lamp therethrough, and a base holding the one end of the high-pressure discharge lamp to allow the first power supply line to be connected to the first external electrode. Further, there are a reinforcing member covering at least a part of a rear surface of the concave reflection mirror, and a restraint member being held between the rear surface and the reinforcing member to restrain a movable range of the second power supply line. The restraint member makes contact with a part of the second power supply line.

Abstract: Embodiments provide an illumination device comprising an elongated base and a pivotable elongated illumination unit. Said pivotable elongated illumination unit is mounted to be pivotable about a longitudinal axis by means of at least one joint. Both the elongated base and the pivotable elongated illumination unit extend in parallel with said longitudinal axis. In particular, the longitudinal extension of the pivotable elongated illumination unit is limited by two opposing lateral faces. The illumination unit includes at least two illumination elements arranged along the pivotable axis, so that a distance between two neighboring light emitting elements corresponds to 1.5 to 2.5 times the distance between a light emitting element that is positioned adjacently to a lateral face and the corresponding lateral face.

Abstract: A cover for a light source for use in a lamp or luminaire. An outer surface of the cover, opposite the light source, comprises a rounded shape and includes a protrusion extending from the cover. The protrusion extends substantially in a light emission direction and is shaped the protrusion to direct light emitted from the light source in a desired direction.

Abstract: A polyamide resin composition including a polyamide resin (A), a copper compound (B), a bromide of an alkali metal and/or a bromide of an alkaline earth metal (C), and a secondary amine compound (D).

Abstract: The apparatus is designed to modify the quality of a beam of light while maximizing the amount of light directed along a desired trajectory. The light optimization device contains an aperture, a diffuser, a modifying substrate, and a mirror. The aperture enables light to travel through the mirror. The diffuser splits a single beam of light traveling towards the modifying substrate into multiple beams of light, which are traveling towards the modifying substrate. The modifying substrate becomes excited when struck by light, and then produces light with desired characteristics. The mirror reflects light that is generated by, or reflected off of, the modifying substrate, and traveling along suboptimal trajectories. As such, the reflected light is redirected towards the modifying substrate.

Abstract: The invention relates to a light module (10) for a motor vehicle or for a motor vehicle headlight, wherein the light module (10) comprises: a heat sink (6); a carrier plate (3) for at least one light source (2); at least one light source (2) arranged on the carrier plate (3); wherein the carrier plate (3) is secured on the heat sink (6), wherein the carrier plate (3) has one or more reference positions (4) for referencing a light-shaping member, for example for referencing a reflector (1), and wherein the light-shaping member has a securing base (1?), by means of which securing base (1?) the light-shaping member can be referenced to the at least one reference position (4) of the carrier plate (3). In accordance with the invention, the securing base (1?) is assigned at least one return element (7), by means of which the securing base (1?) can be secured at least temporarily in the reference position thereof in relation to the carrier plate (3).

Abstract: A light fixture with a textured reflector surface is disclosed. Embodiments of the present invention provide for a lighting system in which LEDs face, and the majority of light form the LED light source is incident on, a textured surface of a back reflector while producing minimal glare and minimal imaging of the light source. Such a reflector may be referred to as a retro-reflector. The reflector for the light fixture can be made from a relatively inexpensive material such as polycarbonate, which without texturing has a specular or semi-specular surface. This material can be used alone or with a metal substrate to form the reflector. The textured surface can be textured by way of an imprinted pattern or by roughening, and can be extruded. A prismatic texture may be used. The texturing can also be spatially varied.

Abstract: Provided is a light source apparatus including a plurality of semiconductor light sources that output beams of light having different wavelengths; a plurality of light collimating portions that convert the respective beams of light output from these light sources to collimated light beams; a combining portion that combines the plurality of collimated beams produced by these light collimating portions into a single light path; a light guide whose entrance end is disposed in the single light path; a focusing portion that focuses the collimated beams combined by the combining portion onto the entrance end; and a light-distribution-characteristics adjusting portion that adjusts beam diameters of the plurality of beams of light so that numerical apertures of the plurality of beams of light incident on the entrance end become substantially equal.

Abstract: A light fixture with a textured reflector is disclosed. Embodiments of the present invention provide for a lighting system in which LEDs face, and the majority of light form the LED light source is incident on, a textured back reflector while producing minimal glare and minimal imaging of the light source. Such a reflector may be referred to as a retro-reflector. The reflector for the light fixture can be made from a relatively inexpensive material such as polycarbonate, which without texturing has a specular or semi-specular surface. Further, a diffuse white layer to provide color mixing or prevent glare and reflections is not needed. The textured reflector can be textured by way of an imprinted pattern or by roughening, and can be extruded. A prismatic texture may be used. The texturing can also be spatially varied.

Abstract: An optical member formed of resin includes a fixation portion, via which the optical member is fixed to a supporting member on which a light emitting element is supported, a reflective surface having a reflective region configured to reflect light from the light emitting element, and a thermal deformation absorbing portion configured to absorb thermal deformation of the optical member.

Abstract: A light source module includes a plurality of light emitting units, and each of the light emitting units includes a reflection plate, a light extraction plate, a sidewall structure, a light source, and a diffusion plate. The light extraction plate has a plurality of first holes, and the light extraction plate and the reflection plate are opposite to each other. The sidewall structure having a plurality of second holes is located between the reflection plate and the light extraction plate, and the reflection plate, the light extraction plate, and the sidewall structure together constitute a first light guiding cavity. The light source is located in the first light guiding cavity and adjoins the sidewall structure. The diffusion plate is located above the light extraction plate, and a second light guiding cavity is formed between the light extraction plate and the diffusion plate.

Abstract: A lighting fixture includes first and second elongated lamp carriage assembles supporting respective first and second elongated lamps and an enclosure including first and second spaced plates. The first lamp carriage assembly is fixedly coupled between the first and second plates for directing light output by the first lamp in a first direction. The second lamp carriage assembly is slidably and pivotally coupled at its ends to the first and second plates for directing light output by the second lamp in a second direction that crosses the first direction. The lighting fixture can further include a third elongated lamp carriage assembly supporting a third elongated lamp. The third lamp carriage assembly is slidably and pivotally coupled at its ends to the first and second plates for directing light output by the third lamp in a third direction that crosses the first and second directions.

Abstract: There is disclosed a lighting apparatus, more particularly, a lighting apparatus that is able to control a radiation angle of a body provided therein, with being fitted to a lighting space and in an installation spot or in a state of being installed, and to enhance luminance efficiency and save the energy.

Abstract: A reflector array for a lighting fixture can include at least one reflector section and at least one neutral section. The at least one reflector section can include a number of reflectors, where each reflector has at least one reflector wall having a reflective material and an aperture that traverses the at least one reflector wall, where each aperture is configured to receive a light source disposed on a mounting surface of the lighting fixture. The at least one neutral section can include an electrically non-conductive material, where the at least one neutral section is disposed adjacent to the at least one reflector section.

Abstract: The purpose of the present invention is to provide a crystalline unsaturated polyester resin composition which has improved fluidability upon being mixed with an inorganic filler, a white pigment or the like. A crystalline unsaturated polyester resin composition for an LED reflector according to the present invention is a crystalline unsaturated polyester resin composition comprising at least a crystalline unsaturated polyester resin and an inorganic filler, and is characterized in that the crystalline unsaturated polyester resin comprises a crystalline unsaturated polyester and a copolymerizable monomer and/or a copolymerizable prepolymer and the crystalline unsaturated polyester resin composition contains a white pigment. A preferred embodiment of the crystalline unsaturated polyester resin composition for an LED reflector according to the present invention is characterized in that the crystalline unsaturated polyester resin has a solid state in a temperature range that does not exceed 50° C.

Abstract: The present invention relates to a ceiling-mounted light fixture configured to be embedded in the ceiling. The ceiling-mounted light fixture comprises: a cylindrical light fixture body having a screw thread formed on the lower end of the outer surface thereof; a light source unit which is accommodated inside the light fixture body and which has a light-emitting element; and a ring-shaped cap which has a screw thread formed on the inner surface thereof to be coupled to the screw thread of the light fixture body. According to the present invention, a ceiling-mounted light fixture is provided, wherein the diameter of the cylinder of the light fixture is increased to achieve improved light distribution efficiency and enable easy assembly.

Abstract: Provided is a light emitting diode (LED) reflector assembly. The reflector assembly includes a metallic substrate, a porcelain coating overlaying a metallic substrate, and a multi-layer thin-film layer overlaying the porcelain coating.

Abstract: Embodiments of the present invention disclose a backlight and a display device, to reduce the number of LEDs in a backlight, save costs, while avoiding dark areas appearing on the screen, so as to ensure display effect. The backlight comprises a first light guide plate and at least one light-emitting diode assembly, and the light-emitting diode assembly is located on one side of the first light guide plate. The light-emitting diode assembly comprises a second light guide plate, at least one light-emitting diode and a reflective film, wherein the at least one light-emitting diode is located on at least one side of the second light guide plate, and the reflective film is located on at least one side of the second light guide plate.

Abstract: An example electronic device includes a printed circuit board having a first row of light sources coupled to a first surface of the printed circuit board and a second row of light sources coupled to a second surface of the printed circuit board; a panel having a plurality of visual indicators; an first housing having a first row of chambers each having a first opening to receive one of the first row of light sources and a second opening to communicate light from the one of the first row of light sources to one of the visual indicators; and a second housing having a second row of chambers each having a third opening to receive one of the second row of light sources and a fourth opening to communicate light from the one of the second row of light sources to a second one of the visual indicators.

Abstract: The present invention relates to a member for controlling luminous flux including an incident surface receiving light, a reflective surface reflecting the incident light, and a light emitting surface emitting the reflected light to a bottom surface of a plane perpendicular to a central axis connecting a center of the incident surface and a center of the reflective surface, and to a display device and a light emitting device, whereby performance of display device can be enhanced.

Abstract: An adjusting unit disposed between a housing including at least one or more semiconductor optical devices and a case accommodating an SMPS, so as to adjust the height of the casing. At least one or more light emitting modules are mounted on the bottom surface of the housing, and a position determining unit is disposed in the housing in correspondence to an edge of the light emitting module. A heat sink unit is provided in correspondence to the top surface of the housing. Therefore, transport costs can be significantly reduced by securing the loading space. The semiconductor optical devices serving as a light source can be appropriately arranged, and the semiconductor optical devices can be mounted at accurate positions. Furthermore, products can be rapidly mass-produced due to a simplified manufacturing process thereof.

Abstract: A display device includes an exterior surface; a main emission region comprising a side edge when viewed in a viewing direction perpendicular to the exterior surface; and an auxiliary emission region next to the side edge when viewed in the viewing direction. The device further includes a light-guide plate disposed in the auxiliary emission region when viewed in the viewing direction; and a first light source disposed adjacent to the light-guide plate and configured to emit light in a first direction to supply the light to the light-guide plate. An imaginary straight line extending from the first light source in the first direction is tilted with respect to the side edge while not crossing the side edge.

Abstract: An optical transmission apparatus having a temperature control function includes: a package having a cavity; a cooler mounted in the cavity and controlling temperature; and a substrate mounted on the cooler and including a light source mounted thereon to generate light. In spite of the presence of the cooler, the apparatus can be implemented to be compact and have a simple structure.