GB2551988A - Bell box cover - Google Patents
Bell box cover Download PDFInfo
- Publication number
- GB2551988A GB2551988A GB1611575.0A GB201611575A GB2551988A GB 2551988 A GB2551988 A GB 2551988A GB 201611575 A GB201611575 A GB 201611575A GB 2551988 A GB2551988 A GB 2551988A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cover
- reflectance
- transmittance
- light
- bell box
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B5/00—Visible signalling systems, e.g. personal calling systems, remote indication of seats occupied
- G08B5/22—Visible signalling systems, e.g. personal calling systems, remote indication of seats occupied using electric transmission; using electromagnetic transmission
- G08B5/36—Visible signalling systems, e.g. personal calling systems, remote indication of seats occupied using electric transmission; using electromagnetic transmission using visible light sources
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- F21V11/00—Screens not covered by groups F21V1/00, F21V3/00, F21V7/00 or F21V9/00
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/11—Anti-reflection coatings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/11—Anti-reflection coatings
- G02B1/111—Anti-reflection coatings using layers comprising organic materials
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/11—Anti-reflection coatings
- G02B1/113—Anti-reflection coatings using inorganic layer materials only
Abstract
A cover 3 for a bell box comprises a body comprising a first portion 26 and a second portion 27. An optical transmittance of the first portion of the body is greater than a transmittance of the second portion. The reflective optical properties of the first portion and the second portion make their boundary indistinguishable to the human eye. The device is suitable for a bell box of a security alarm and may display the name or logo of an alarm installer. The reflectance of the first and second portion <10% and a difference between their reflectance <5%. The transmittance of the first portion may be <5%. The second portion may be opaque. The cover body may have a transmittance >0 and the second portion of the body have an opaque layer. The body may be made from a thermoplastic polymer and dye. An alarm bell box with a back plate may also comprise the cover. A cover for a bell box wherein the first portion of the body and the second portion of the body each have an absorptance >90%.
Description
(54) Title of the Invention: Bell box cover
Abstract Title: A bell box cover with an indistinguishable boundary between different portions (57) A cover 3 for a bell box comprises a body comprising a first portion 26 and a second portion 27. An optical transmittance of the first portion of the body is greater than a transmittance of the second portion. The reflective optical properties of the first portion and the second portion make their boundary indistinguishable to the human eye. The device is suitable for a bell box of a security alarm and may display the name or logo of an alarm installer. The reflectance of the first and second portion <10% and a difference between their reflectance <5%. The transmittance of the first portion may be <5%. The second portion may be opaque. The cover body may have a transmittance >0 and the second portion of the body have an opaque layer. The body may be made from a thermoplastic polymer and dye. An alarm bell box with a back plate may also comprise the cover. A cover for a bell box wherein the first portion of the body and the second portion of the body each have an absorptance >90%.
At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.
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Bell Box Cover
The present invention relates to a cover for a bell box of a security alarm. In particular, it relates to a cover for a bell box of a security alarm that is provided with an illumination mechanism.
Many intruder alarm systems comprise at least one bell box (also known as “external sounders” or “warning devices”), which is typically disposed on an external wall of a property that comprises the alarm system. Such bell boxes may contain an alarm bell and a strobe light which may be activated if there is an attempted break in at the property. Bell boxes can play an important role in an intruder alarm installation because they indicate to the outside world, and therefore any potential intruders, that the property is protected by an alarm system. The bell box can therefore act as a deterrent to potential intruders.
Bell boxes may include means to illuminate the bell box. This may be used, for example, when it is dark outside. This illumination feature has two purposes. First, it clearly highlights to any potential intruders that the property is alarmed even during darkness. Second, the bell box can be personalised with details of the alarm installer, for example it may have a name, logo or the like. The illumination feature can therefore provide enhanced brand visibility for the installer.
It may be desirable to provide an alternative cover for a bell box of a security alarm which at least partially addresses one or more of the problems of the prior art, whether identified herein or elsewhere.
According to a first aspect of the invention there is provided a cover for a bell box, the cover comprising: a body comprising a first portion and a second portion; wherein an optical transmittance of the first portion of the body is greater than an optical transmittance of the second portion; and wherein the reflective optical properties of the first portion and the second portion are such that in use and under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye.
The first aspect of the invention is advantageous for a number of reasons, as now discussed. Because the reflective optical properties of the first portion and the second portion are such that under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye, when no illumination source is provided within the body the first and second portions cannot be visually distinguished by the human eye. However, an optical transmittance of the first portion of the body is greater than an optical transmittance of the second portion and therefore when a light source is disposed within the body, the first portion transmits more light than the second portion. This difference in the optical transmittances of the first portion and the second portion therefore allows the first portion and second portion to be visually distinguishable when the cover is illuminated by a light source from within the body. In this way the light emitted from the bell box cover may be patterned according to the shapes and configurations of the first and second portions. Therefore, the first aspect of the invention allows a pattern to be selectively displayed on the body of the cover by either illuminating the cover from within the body on not.
It will be appreciated that in order for the reflective optical properties of the first portion and the second portion to be sufficiently similar such that under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye a shape of a reflection spectrum of each of the first and second portions may be similar such that they may appear to have a similar colour. For example, the reflection spectrum of the first and second portions may both have a peak at a similar wavelength. For example, the first and second portions may both be the same colour (for example, green) in appearance. However, it will be appreciated that, in general, how similar the reflection spectra of the first and second portions should be in order that under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye will depend on other factors (for example the reflectances of the first and second portions).
It will be appreciated that in use the cover may form part of a bell box and therefore may be provided on an exterior wall of a building. Therefore, it will be appreciated that “in use” the cover may be viewed from a distance of at least 1 m, for example from a distance of at least 2 m. That “in use” and under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye should be construed accordingly.
As discussed above, the shapes and configurations of the first and second portions form a pattern. It will be appreciated that the reflective optical properties of the first portion and the second portion being such that in use and under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye is intended to cover situations where the pattern the shapes and configurations of the first and second portions could be resolved by the human eye if the optical properties were such that the first and second portions were markedly different in appearance (for example if the first and second portions had different and easily discernible appearances).
It will be appreciated that in use the cover may form part of a bell box and therefore may be provided on an exterior wall of a building. Therefore, “ambient lighting conditions” should be construed accordingly. Typically ambient lighting conditions in use will be sunlight during the day.
It will be appreciated that the population has a wide range of visual acuities and that substantially visually indistinguishable to the human eye should be construed as substantially visually indistinguishable to the human eye of a person with average visual acuity. A person with average visual acuity may be considered to be a person with 6/6 or 20/20 vision.
It will be appreciated that if the boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye then the first portion cannot be visually distinguished from the second portion. It will be appreciated that the first portion may be adjacent to the second portion such that at least part of the first portion shares a boundary with the second portion.
How similar the reflection spectra of the first and second portions should be in order that under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye may be dependent on the total reflectance of the first and second portions. If the total reflectance of the first and second portions is high then the first and second portions will be brightly coloured whereas if the total reflectance of the first and second portions is low then the first and second portions will be a dark colour. In general it is easier to visually distinguish a difference in the reflection spectra of two brightly coloured objects than a difference in the reflection spectra of two dark coloured objects. For example, bright blue and bright purple are more easily distinguished than dark blue and dark purple. Therefore, in general the higher the total reflectance of the first and second portions the more similar the reflection spectra of the first and second portions should be in order that under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye.
Therefore, it may be preferable, but not essential, that the reflectance of the first portion and a reflectance of the second portion are both low. For example, the reflectance of the first portion and a reflectance of the second portion may both be below a threshold value. For example, the reflectance of the first portion and a reflectance of the second portion may both be below 20%, for example below 10%, for example below 5%.
A reflectance of the first portion and a reflectance of the second portion may both be less than 10%.
For a sufficiently small reflectance of the first portion and the reflectance of the second portion, both the first portion and the second portion will appear black, or a dark colour.
It will be appreciated that the reflectance of an object is the ratio of the radiant flux (i.e. the radiant energy per unit time) reflected by that object to the radiant flux incident on that object. It will be appreciated that in general, the reflectance of an object is dependent on the wavelength of the light. Unless otherwise stated, it will be appreciated that herein the reflectance of an object is an average reflectance across the visible spectrum. Furthermore, it will be appreciated that in general, the reflectance of an object is dependent on the angle of incidence and the polarisation of the incident light. Unless otherwise stated, it will be appreciated that herein the reflectance of an object is for unpolarised light at normal incidence.
A difference between the reflectance of the first portion and the reflectance of the second portion may be less than 5%.
With such an arrangement there is very little contrast between the first and second portions when illuminated by an external light source. Therefore, when no light source is provided from within the body, the first and second portions may be substantially indistinguishable to the human eye.
In a preferred embodiment, the difference between the reflectance of the first portion and the reflectance of the second portion is less than 2%. In an even more preferred embodiment, the difference between the reflectance of the first portion and the reflectance of the second portion is less than 1%.
The first portion of the body may have a transmittance greater than zero and less than 5%.
Since the transmittance of the first portion is less than 5%, third parties cannot easily see into the cover, which may be desirable. In a preferred embodiment, the first portion of the body has a transmittance greater than zero and less than 2%. In an even more preferred embodiment, the first portion of the body has a transmittance greater than zero and less than 1%.
It will be appreciated that the transmittance of an object is the ratio of the radiant flux (i.e. the radiant energy per unit time) transmitted by that object to the radiant flux incident on that object. It will be appreciated that in general, the transmittance of an object is dependent on the wavelength of the light. Unless otherwise stated, it will be appreciated that herein the transmittance of an object is an average transmittance across the visible spectrum. Furthermore, it will be appreciated that in general, the transmittance of an object is dependent on the angle of incidence and the polarisation of the incident light. Unless otherwise stated, it will be appreciated that herein the transmittance of an object is for unpolarised light at normal incidence.
The second portion of the body may be opaque.
It will be appreciated that an opaque object is an object with a transmittance of substantially zero. In practice, an object may be considered to be opaque if its transmittance is less than 0.1%.
With such an arrangement, the contrast of the pattern than can be formed by illuminating the cover from within the body can be maximised.
The body may be formed from a material with a transmittance greater than zero and the second portion of the body may be provided with an opaque layer.
The material may comprise a thermoplastic polymer and a dye.
The thermoplastic polymer may comprise, for example, polycarbonate, polyethylene or polypropylene. Such thermoplastic polymers may allow the body to be injection moulded.
It will be appreciated that any type of dye may be used. The type of dye may be dependent on the base thermoplastic polymer of the plastics material. The dye may, for example, comprise a solvent dye. It will be appreciated that the quantity of dye added to the base thermoplastic polymer will be dependent on: the optical properties of the thermoplastic polymer and the dye (for example how much light they absorb) and the thickness of the body.
In one embodiment, the plastics material comprises polycarbonate and a mixture of solvent dyes. The mixture of solvent dyes comprises a red dye and a blue dye, the international codes being: solvent red 135 and solvent blue 104. Each of these two dyes is used in the amount of 0.005% by weight in the plastics material.
The cover may further comprise a light-emitting module disposed proximate to an interior surface of the cover and operable to emit light.
The light-emitting module may comprise a lighting panel. The lighting panel may be of the form of a generally flat, thin panel. A size and shape of the lighting panel may generally match those of a front face of the bell box.
The cover may further comprise one or more fixing features on the body arranged to releasable engage with the light-emitting module.
At least a part of the first portion may be provided with a layer of light transmitting material.
According to a second aspect of the invention there is provided a cover for a bell box, the cover comprising: a body comprising a first portion and a second portion; wherein an optical transmittance of the first portion of the body is greater than an optical transmittance of the second portion; and wherein the reflectance of the first portion and a reflectance of the second portion are both less than 10% and a difference between the reflectance of the first portion and the reflectance of the second portion is less than 5%.
It will be appreciated that, where compatible, the cover according to the second aspect of the invention may comprise any or all features of the cover according to the first aspect of the invention.
The second aspect of the invention is advantageous for a number of reasons. The first portion allows the cover to be illuminated by a light source within the body. When such a light source is disposed within the body, the first portion will transmit more light than the second portion. In this way the light emitted from the bell box cover may be patterned according to the shapes and configurations of the first and second portions.
Since the reflectance of the first portion and the reflectance of the second portion are both less than 10%, both the first portion and the second portion will appear black, or a dark colour. Furthermore, the difference between the reflectance of the first portion and the reflectance of the second portion is less than 5% and, as a result, there is very little contrast between the first and second portions when illuminated by an external light source. Therefore, when no light source is provided from within the body, a boundary between the first and second portions may be substantially indistinguishable to the human eye.
In a preferred embodiment, the first portion of the body has a transmittance greater than zero and less than 2%. In an even more preferred embodiment, the first portion of the body has a transmittance greater than zero and less than 1%.
In a preferred embodiment, the difference between the reflectance of the first portion and the reflectance of the second portion is less than 2%. In an even more preferred embodiment, the difference between the reflectance of the first portion and the reflectance of the second portion is less than 1%.
The second portion of the body may be opaque.
According to a third aspect of the invention there is provided a cover for a bell box, the cover comprising: a body comprising a first portion and a second portion, the first portion being adjacent to the second portion such that at least part of the first portion shares a boundary with the second portion; wherein an optical transmittance of the first portion of the body is greater than an optical transmittance of the second portion; and wherein the first portion of the body and the second portion of the body each have an absorptance greater than 90%.
It will be appreciated that, where compatible, the cover according to the third aspect of the invention may comprise any or all features of the cover according to the first aspect of the invention or the cover according to the second aspect of the invention.
According to a fourth aspect of the invention there is provided an alarm bell box comprising: a back plate; and the cover of the first, second or third aspects of the invention arranged to releasably engage the cover so as to define an internal volume.
According to a fifth aspect of the invention there is provided a method of forming a cover for a bell box, the method comprising: forming a body from a first material with a first transmittance; and providing a layer of a second material on a part of a surface of the body such that the layer of the second material is not applied to a first portion of the body and is applied to a second portion of the body; wherein an optical transmittance of the first portion of the body is greater than a transmittance of the second portion; and wherein the reflective optical properties of the first portion and the second portion are such that in use and under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye.
It will be appreciated that, where compatible, the method according to the fifth aspect of the invention may comprise any or all features of the cover according to the first aspect of the invention.
Figure 2
The body may be formed from the first material by injection moulding.
The first material may comprise a thermoplastic polymer and a dye.
Providing the layer of the second material may comprise: providing a mask on the first portion of the surface; applying a layer of the second material over the surface; and removing the mask.
According to a sixth aspect of the invention there is provided a method of forming a cover for a bell box according to the first, second or third aspects of the present invention, the method comprising: forming a body from a first material with a first transmittance; and providing a layer of a second material on a part of a surface of the body such that the layer of the second material is not applied to a first portion of the body and is applied to a second portion of the body; wherein an optical transmittance of the first portion of the body is greater than a transmittance of the second portion.
It will be appreciated that, where compatible, the method according to the sixth aspect of the invention may comprise any or all features of the cover according to the first, second or third aspects of the invention.
human
Various aspects and features of the invention set out above or below may be combined with various other aspects and features of the invention as will be readily apparent to the skilled person.
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:
Figure 1 shows a back plate for a bell box according to an embodiment of the present invention.
shows a cover according to an embodiment of the present invention for releasable cooperation with the back plate of Figure 1;
Figure 3 shows a bell box comprising the back plate of Figure 1 connected to the cover of Figure 2 via a hinge, the cover being disposed in an open configuration; and
Figure 4A shows a lighting panel being inserted into an interior of the cover of Figure 2;
Figure 4B shows the lighting panel received in and engaged with an interior of the cover of Figure 2;
Figure 5 is a schematic illustration of a first embodiment of a cover according to an embodiment of the present invention;
Figure 6 is a schematic illustration of a second embodiment of a cover according to an embodiment of the present invention;
Figure 7 is an illustration of a third embodiment of a cover according to an embodiment of the present invention when not illuminated from an interior of the cover; and
Figure 8 is an illustration of the third embodiment of a cover according to an embodiment of the present invention when illuminated from an interior of the cover.
A security alarm system may comprise, among other components, one or more bell boxes. A bell box 1 according to an embodiment of the present invention is now described with reference to Figures 1 to 8.
The bell box 1 comprises a back plate 2 and a cover 3. The back plate 2 is for attachment to a surface. In use, the bell box 1 is typically provided on an external wall of a building that is protected by the security alarm system. The back plate 2 is typically attached to a surface of the exterior wall using screws or the like, in a conventional manner. To achieve this, the back plate 2 comprises six apertures 5 that allow back plate 2 to be attached to the external surface of a building (for example a wall), in a conventional manner. Each of the six apertures 5 is provided as an elongate slot on a generally circular insert 6 which is connected to a main body of the back plate 2 such that it can rotate relative thereto. This rotation of the circular inserts 6 (relative to the back plate 2) can aid an installer since it allows a greater tolerance for the placement of holes for fixing screws (which holes may be drilled in a brick wall or the like).
Referring to Figure 3, the cover 3 is connected to the back plate 2 by a hinge such that the cover 3 can rotate relative to the back plate 2 about an axis 9. The cover 3 can rotate between an open positon (as shown in Figure 3), wherein the back plate 2 can be accessed, and a closed position. When the cover 3 is disposed in the closed position the cover 3 cooperates with the back plate 2 so as to define an internal volume. The back plate 2 and cover 3 may be considered to form a housing of the bell box 1.
The cover 3 comprises a main section 24 and a generally u-shaped lens section 25. The main section 24 and the lens sections together form a body of the cover 3.
When the cover 3 is disposed in the closed position the cover 3 can be fixed to the back plate 2. This fixing is achieved by way of one or more fixing members 8 such as, for example, conventional screws or bolts. For this purpose, the back plate 2 further comprises two attachment features 7 for releasable engagement with the two fixing members 8 (see Figure 2).
Each fixing member 8 is generally of the form of a bolt with a shank portion and a head portion. The shank portion is inserted into a fixing aperture in the cover 3 from an external surface 10 of the cover into the internal volume defined by the back plate 2 and the cover 3. In particular, the fixing apertures for the fixing members 8 are provided on a surface 10 of the generally u-shaped lens section 25 of the cover 3. The shank portion passes through the fixing aperture in the cover 3 and engages with one of the attachment features 7. The engagement may for example be achieved by rotation of the fixing member 8. The head portion is larger than the fixing aperture in the cover 3 and remains on an exterior of the cover 3. Optionally, the head portion may be received within a recess formed on the exterior surface 10 of the cover 3.
The internal volume defined by the back plate 2 and the cover 3 houses internal components of the bell box 1. Such internal components are typically attached to the back plate 2. As can be seen in Figures 1 and 3, in the example embodiment the following are attached to the back plate 2: two piezo sounders 11, a micro-switch 12 and a compartment 13 for housing control electronics (not shown). The compartment 13 may also house a battery arranged to provide power to the control electronics. The control electronics are connected to the micro-switch 12 and the two piezo sounders
11. The control electronics are also connected to one or more other components of the security alarm, for example a control panel, which is typically internal to a building to which the bell box is attached. The compartment 13 may also house a visual signalling device (for example a strobe light), which may be connected to the control electronics.
The micro-switch 12 acts as an anti-tamper switch. To achieve this, the micro-switch 12 comprises an actuator lever 14 which is forced closed when the cover 3 of the bell box is disposed in the closed position. The micro-switch 12 is biased open such that it is arranged to spring open when the cover 3 moves towards the open position.
The lens section 25 may be formed from a light transmitting material and a visual signalling device (for example a strobe light), which may be housed within the compartment 13, may be arranged to emit light through the lens section 25 in the event of the alarm system being triggered.
The bell box further comprises a lighting panel 15. The lighting panel 15 is of the form of a generally flat, thin panel. A size and shape of the lighting panel 15 generally match those of a front face of the bell box 1. In particular, the size and shape of the lighting panel 15 generally match those of a front face of the main section 24 of the cover 3. As shown in Figures 4A and 4B, the lighting panel 15 is connected to an interior surface 16 of the main section 24 of the cover 3 by way of fixing features 17, 18. To achieve this connection, the lighting panel 15 may be inserted into an internal space of the cover 3 at an angle to the interior surface 16 such that a leading edge 19 of the lighting panel 15 engages with first fixing features 17 provided on one side of the cover 3. This is illustrated in Figure 4A, which shows the lighting panel 15 being inserted into the internal space of the cover 3 generally along arrow 20 at an angle of around 40° to the interior surface 16. Once the leading edge 19 of the lighting panel 15 engages with the first fixing features 17 an opposed or trailing edge 21 is pushed towards the interior surface 16 of the cover 3 until the lighting panel 15 is generally parallel to the interior surface 16. This is illustrated in Figure 4B, which shows the trailing edge 21 being pushed towards the interior surface 16 of the cover 3 generally along arrow 22. When the lighting panel 15 is generally parallel to the interior surface 16, the trailing edge 21 of the lighting panel 15 engages with second fixing features 18. The lighting panel is then retained generally parallel to the interior surface 16 of the cover 3 by first and second fixing features 17, 18.
In use, the lighting panel 15 is operable to emit light. In particular, the lighting panel 15 is operable to emit light generally uniformly from a surface of the lighting panel 15 which, in use, is disposed adjacent to the interior surface 16 of the cover 3. The light is emitted in a direction that is generally perpendicular to said surface of the lighting panel 15.
In use, the lighting panel 15 is electrically connected to control electronics, which may be disposed within the compartment 13. This electrical connection is achieved via a wire 23. By sending a suitable control signal to the lighting panel 15 via wire 23, the emission of light from the lighting panel may be controlled remotely.
The lighting panel 15 may comprise a plurality of light-emitting diodes (LEDs) disposed along one edge of the lighting panel 15. The plurality of LEDs may all be connected to the wire 23. For example, the LEDs may be mounted on a generally strip shaped printed circuit board (PCB) that extends along the edge of the lighting panel 15. The connection of each of the LEDs to the wire 23 may be via said PCB. Each of the LEDs may be arranged to emit light in a direction generally parallel to a plane of the lighting panel 15. The lighting panel 15 may be considered to form a waveguide and the light emitted by the LEDs may be transmitted to an opposite edge of the lighting panel 15 to the LEDs by total internal reflection. The lighting panel 15 is further provided with a plurality of light directing features that are arranged to direct a portion of light propagating through the plane of the lighting panel 15 out of the lighting panel 15 in a direction that is generally perpendicular to the plane of the lighting panel 15. The plurality of light directing features is arranged such that light is emitted generally uniformly from a surface of the lighting panel 15.
As will be described further below, at least a portion of the cover 3 is formed from a light transmitting material. The light emitted by the lighting panel 15 is transmitted by such portions of the cover 3. The effect is that when light is emitted by the lighting panel 15, the bell box 1 appears to be illuminated from within its interior volume.
The body of the cover 3 of the bell box 1 according to an embodiment of the present invention is formed from a plastics material with a transmittance greater than zero and less than 5% and with a reflectance less than 10%. The plastics material may therefore have an absorptance greater than 85%.
It will be appreciated that the transmittance of an object is the ratio of the radiant flux (i.e. the radiant energy per unit time) transmitted by that object to the radiant flux incident on that object. It will be appreciated that in general, the transmittance of an object is dependent on the wavelength of the light. Unless otherwise stated, it will be appreciated that herein the transmittance of an object is an average transmittance across the visible spectrum. Furthermore, it will be appreciated that in general, the transmittance of an object is dependent on the angle of incidence and the polarisation of the incident light. Unless otherwise stated, it will be appreciated that herein the transmittance of an object is for unpolarised light at normal incidence.
It will be appreciated that the reflectance of an object is the ratio of the radiant flux (i.e. the radiant energy per unit time) reflected by that object to the radiant flux incident on that object. It will be appreciated that in general, the reflectance of an object is dependent on the wavelength of the light. Unless otherwise stated, it will be appreciated that herein the reflectance of an object is an average reflectance across the visible spectrum. Furthermore, it will be appreciated that in general, the reflectance of an object is dependent on the angle of incidence and the polarisation of the incident light. Unless otherwise stated, it will be appreciated that herein the reflectance of an object is for unpolarised light at normal incidence.
A tint meter, such as the Window Tint Meter WTM-1100 marketed by Guangzhou Landtek Instruments Co. Ltd. of China, typically comprises a light source and a light detector. When the light source and the light detector are placed on opposite sides of a light transmitting material, the tint meter can be used to determine the transmittance of the material. When the light source and the light detector are placed on the same side of a light transmitting material, the tint meter can be used to determine the reflectance of the material at an angle of incidence of approximately 45°.
In an example embodiment, the body of the cover 3 of the bell box 1 is formed from a material with a transmittance of approximately 0.2%. The plastics material may, for example, comprise a thermoplastic polymer and a dye. The thermoplastic polymer may comprise, for example, polycarbonate, polyethylene or polypropylene.
The dye may be any light absorbing material than is suitable for achieving the abovementioned optical properties (i.e. a transmittance greater than zero and less than 5% and a reflectance of less than 10%). It will be appreciated that any type of dye may be used. The type of dye may be dependent on the base thermoplastic polymer of the plastics material. It will be appreciated that the quantity of dye added to the base thermoplastic polymer will be dependent on: the optical properties of the thermoplastic polymer and the dye (for example how much light they absorb) and the thickness of the body of the cover 3.
In an embodiment, the cover 3 may be formed by injection moulding and may have a thickness of approximately 3 mm.
In one specific embodiment, the plastics material comprises polycarbonate and a mixture of solvent dyes. The mixture of solvent dyes comprises a red dye and a blue dye, the international codes being: solvent red 135 and solvent blue 104. Each of these two dyes is used in the amount of 0.005% by weight in the plastics material. For such an embodiment, when the cover 3 has a thickness of approximately 3 mm the plastics material may have a transmittance of around 0.2% when measured with the Window Tint Meter WTM-1100. The above-described embodiment, wherein the plastics material comprises polycarbonate and 0.005% by weight of each of solvent red 135 and solvent blue 104, the reflectance of the plastics material as determined by the Window Tint Meter WTM-1100 at an angle of incidence of approximately 45° is approximately 5.6%.
A portion of the exterior surface of the cover 3 is provided with an opaque layer having a reflectance of less than 5%. It will be appreciated that an opaque object is an object with a transmittance of substantially zero. In practice, an object may be considered to be opaque if its transmittance is less than 0.1%. The opaque layer may be applied by printing techniques such as screen printing, in a conventional manner. The opaque layer may comprise an ink, such as, for example, a gloss vinyl screen ink, or a paint. The opaque layer may have an absorptance greater than 95%. The opaque layer may have a reflectance, as determined by the Window Tint Meter WTM-1100 at an angle of incidence of approximately 45°, of approximately 4.6%.
The opaque layer (for example black ink) may be selectively to a portion of the exterior surface of the cover 3 using conventional screen printing. To achieve this, the rest of the exterior surface of the cover 3 (i.e. those parts that the opaque layer is not to be applied to) may be provided with a mask. Once the mask is in place, a layer of opaque material is applied to the exterior surface of the cover 3 and, subsequently, the mask is removed from the exterior surface of the cover 3.
In this way, the body of the cover 3 comprises two portions. Such an arrangement is shown rather schematically in Figure 5, wherein the cover 3 comprises a first portion 26 which is not provided with the opaque layer; and a second portion 27 that is provided with the opaque layer. Such an arrangement is advantageous for a number of reasons. The first portion 26 allows the cover 3 to be illuminated by a light source within the body, for example the lighting panel 15.
The reflective optical properties of the first portion 26 and the second portion 27 are such that under ambient lighting conditions a boundary between the first portion 26 and the second portion 27 is substantially visually indistinguishable to the human eye when no illumination source is provided within the body of the cover (for example when the lighting panel 15 is switched off). However, the optical transmittance of the first portion 26 of the body is greater than the optical transmittance of the second portion 27 and therefore when a light source is disposed within the body (for example when the lighting panel 15 is switched on), the first portion 26 transmits more light than the second portion 27. In fact, since the second portion 27 is provided with the opaque layer it will not transmit any light when a light source is illuminated within the body. When such a light source is disposed within the body, the first portion 26 transmits light, while the second portion 27 will block the light. This therefore allows the first portion 26 and second portion 27 to be visually distinguishable when the cover is illuminated by a light source from within the body. In this way the light emitted from the bell box cover 3 may be patterned according to the shapes and configurations of the first and second portions 26, 27. Therefore, embodiments of the invention allow a pattern to be selectively displayed on the body of the cover 3 by either illuminating the cover 3 from within the body on not (for example by switching the lighting panel 15 on or off).
Although shown rather schematically as a rectangular shape in Figure 5, it will be appreciated that the first portion 26 may have a number of different forms. For example, the first portion 26 may have a shape that corresponds to a brand name, logo or trademark of an installation company.
Since the transmittance of the first portion 26 is less than 5%, third parties cannot easily see into the cover. This is desirable to ensure the security of the bell box 1.
Since the reflectance of the first portion 26 and the reflectance of the second portion 27 are both less than 5%, both the first portion 26 and the second portion 27 will appear black, or a dark colour. The difference between the reflectance of the first portion 26 and the reflectance of the second portion 27 is less than 5% and, as a result, there is very little contrast between the first and second portions 26, 27 when illuminated by an external light source. Therefore, when no light source is provided from within the body (for example when the lighting panel 15 is switched off) the first and second portions 26, 27 may be substantially indistinguishable to the human eye.
In practice, the second portion 27 may be provided with a layer of black ink and may therefore appear black to the human eye. The colour of the first portion 26 may be dependent on the absorption characteristics of the dye that is added to the thermoplastic polymer. It will be appreciated that, in the absence of a light source within the body of the bell box 1, the first portion 26 will be very dark (since it has a reflectance of less than 5%) and it will therefore be almost black but with a tint that is dependent on the colour of the dye. The first portion 26 may, for example, have a red, brown, green, blue or purple tint. The first portion 26 may appear black to the human eye in the absence of a light source within the body of the bell box 1 and may have a colour dependent on the absorption characteristics of the dye when illuminated form from within the body of the bell box 1.
At least part of the first portion 26 may be provided with a light transmitting layer of paint or ink or the like. For example part of the first portion 26 may be provided with a layer of white or coloured ink or the like. Such an arrangement is shown rather schematically in Figure 6, wherein the cover 3 comprises a first portion 26 which is not provided with the opaque layer; and a second portion 27 that is provided with the opaque layer. A central portion 28 of the first portion 26 is provided with a layer of white or coloured ink and an edge portion 29 of the first portion 26 is provided with no ink.
By virtue of this white or coloured ink, the central portion 28 of the first portion 26 will be visually distinguishable from the edge portion 26 of the first portion 26 and the second portion 27. When no light source is provided from within the body (for example when the lighting panel 15 is switched off) the edge portion 29 of the first portion 26 and second portion 27 are substantially indistinguishable to the human eye (they appear black). However, the central portion 28 of the first portion 26 is distinguishable by virtue of the white or coloured ink and may display, for example, a brand name, logo or trademark of an installation company. When a light source is provided from within the body (for example when the lighting panel 15 is switched on) both the central portion 28 and the edge portion 29 of the first portion 26 transmit light and are therefore distinguishable from the second portion 27 to the human eye. The colour of the edge portion 29 (which is not provided with a layer of ink) is dependent on the optical properties of the plastics material from which the cover 3 is formed (for example the colour of the dye) and the spectrum of the light source. The colour of the central portion 29 is dependent on the optical properties of the plastics material from which the cover 3 is formed (for example the colour of the dye), the optical properties of the layer of ink and the spectrum of the light source.
In this way, the bell box 1 may be arranged to display a pattern such as a brand name, logo or trademark of an installation company when not illuminated. When illuminated, an additional boarder of potentially different coloured light may be provided around this pattern.
It will be appreciated that in some embodiments of the invention, the first portion is not a single continuous solid region of the cover 3 (as, for example, is shown in Figures 5 and 6). Rather, the first portion may comprise a plurality of distinct regions of the cover
3. For example, the first portion may comprise a plurality of letters which may together form a brand name. Additionally or alternatively, the first portion may comprise additional wording and/or logos. In general, embodiments of the present invention may comprise a combination of the arrangements schematically shown in Figures 5 and 6.
Such a further embodiment of the present invention will now be described with reference to Figures 7 and 8. Figure 7 shows the cover 3 of the bell box 1 with no illumination from within the body and Figure 8 shows the cover 3 of the bell box 1 illuminated from within the body.
In this embodiment, the first portion of the cover 3 comprises three distinct parts: a first part 30, a second part 31 and a third part 32.
The first part 30 further comprises a plurality of distinct parts, each part being of the shape of a letter, the plurality of parts together forming the word Orisec”. Each letter of the first part is generally of the form of the embodiment described above with reference to Figure 6. Each part comprises a central portion 33 that is provided with a layer of white ink and an edge portion 34 that is not. Therefore, the central portions 33 of the first part 30 are therefore visible when the cover 3 is not illuminated (see Figure 7). When the cover 3 is illuminated, both the central portions 33 and the edge portions 34 of the first part 30 are illuminated and distinguishable from the second portion.
The second part 31 further comprises a plurality of distinct parts, each part being of the shape of a letter, the plurality of parts together forming the phrase “Professional Security Systems”. Each letter of the first part is generally of the form of the embodiment described above with reference to Figure 5. Therefore, the second part 32 is not visible when the cover 3 is not illuminated (see Figure 7) but is distinguishable from the second portion when the cover 3 is illuminated (see Figure 8).
The third part 32 is generally of the form of a logo and comprises two distinct parts 32a, 32b. Each part 32a, 32b is provided with ink 35. This ink 35 is visible when the cover 3 is not illuminated (see Figure 7). The ink 35 may comprise a plurality of dots of white ink. The dots may be sufficiently small that from a distance, on the generally black background of the rest of the third part 32, the third part 32 appears to be grey. When the cover 3 is illuminated, both of two distinct parts 32a, 32b of the third part 32 are illuminated and distinguishable from the second portion of the cover 3.
Although in the above-described embodiment the reflectance of the first portion 26 and the reflectance of the second portion 27 are both low. In particular, the reflectance of the first portion and the reflectance of the second portion are both below 10%. With such an arrangement, the reflective optical properties of the first portion 26 and the second portion 27 are such that under ambient lighting conditions a boundary between the first portion 26 and the second portion 27 is substantially visually indistinguishable to the human eye when no illumination source is provided within the body of the cover (for example when the lighting panel 15 is switched off). However, it will be appreciated that in alternative embodiments, the reflectance of the first portion and/or the reflectance of the second portion may be equal to or above 10%. For such embodiments, the shape of a reflection spectrum of each of the first and second portions may sufficiently similar such that they appear to have a similar colour.
It will be appreciated that the terms “transmittance” and “optical transmittance” are intended to be synonymous.
While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not limiting. Thus it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.
Claims (18)
1. A cover for a bell box, the cover comprising:
a body comprising a first portion and a second portion;
wherein an optical transmittance of the first portion of the body is greater than an optical transmittance of the second portion; and wherein the reflective optical properties of the first portion and the second portion are such that in use and under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye.
2. The cover of claim 1 wherein a reflectance of the first portion and a reflectance of the second portion are both less than 10%.
3. The cover of claim 1 or claim 2 wherein a difference between the reflectance of the first portion and the reflectance of the second portion is less than 5%.
4. The cover of any preceding claim, wherein the first portion of the body has a transmittance greater than zero and less than 5%.
5. The cover of any preceding claim, wherein the second portion of the body is opaque.
6. The cover of claim 5 wherein the body is formed from a material with a transmittance greater than zero and wherein the second portion of the body is provided with an opaque layer.
7. The cover of claim 6 wherein the material comprises a thermoplastic polymer and a dye.
8. The cover of any preceding claim further comprising a light-emitting module disposed proximate to an interior surface of the cover and operable to emit light.
9. The cover of claim 8 wherein the light-emitting module comprises a lighting panel.
10. The cover of claim 8 or claim 9 further comprising one or more fixing features on the body arranged to releasable engage with the light-emitting module.
11. The cover of any preceding claim wherein at least a part of the first portion is provided with a layer of light transmitting material.
12. A cover for a bell box, the cover comprising:
a body comprising a first portion and a second portion;
wherein an optical transmittance of the first portion of the body is greater than an optical transmittance of the second portion; and wherein the reflectance of the first portion and a reflectance of the second portion are both less than 10% and a difference between the reflectance of the first portion and the reflectance of the second portion is less than 5%.
13. A cover for a bell box, the cover comprising:
a body comprising a first portion and a second portion;
wherein an optical transmittance of the first portion of the body is greater than an optical transmittance of the second portion; and wherein the first portion of the body and the second portion of the body each have an absorptance greater than 90%.
14. An alarm bell box comprising: a back plate; and the cover of any preceding claim arranged to releasably engage the cover so as to define an internal volume.
15. A method of forming a cover for a bell box, the method comprising: forming a body from a first material with a first transmittance; and providing a layer of a second material on a part of a surface of the body such that the layer of the second material is not applied to a first portion of the body and is applied to a second portion of the body;
wherein an optical transmittance of the first portion of the body is greater than a transmittance of the second portion; and wherein the reflective optical properties of the first portion and the second portion are such that in use and under ambient lighting conditions a boundary between the first portion and the second portion is substantially visually indistinguishable to the human eye.
16. The method of claim 15 wherein the body is formed from the first material by injection moulding.
17. The method of claim 15 or claim 16 wherein first material comprises a 10 thermoplastic polymer and a dye.
18. The method of any one of claims 15 to 17 wherein providing the layer of the second material comprises:
providing a mask on the first portion of the surface;
15 applying a layer of the second material over the surface; and removing the mask.
Intellectual
Property
Office
Application No: GB1611575.0 Examiner: Mr Steven Scott
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1611575.0A GB2551988A (en) | 2016-07-01 | 2016-07-01 | Bell box cover |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1611575.0A GB2551988A (en) | 2016-07-01 | 2016-07-01 | Bell box cover |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB201611575D0 GB201611575D0 (en) | 2016-08-17 |
| GB2551988A true GB2551988A (en) | 2018-01-10 |
Family
ID=56891160
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1611575.0A Withdrawn GB2551988A (en) | 2016-07-01 | 2016-07-01 | Bell box cover |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2551988A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3942990A1 (en) * | 1989-12-19 | 1991-06-20 | Leybold Ag | Anti-reflection coating for transparent substrates - comprises 1st layer of dielectric metal oxide, nitride 2nd layer, and 3rd layer of dielectric metal oxide |
| US20090257241A1 (en) * | 2005-02-04 | 2009-10-15 | Adac Plastics, Inc. | Trim component with concealed indicium |
| CN102952428A (en) * | 2011-08-21 | 2013-03-06 | 比亚迪股份有限公司 | Printing ink composition, method for forming near-infrared light antireflection layer on substrate surface, and near-infrared light antireflection material |
-
2016
- 2016-07-01 GB GB1611575.0A patent/GB2551988A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3942990A1 (en) * | 1989-12-19 | 1991-06-20 | Leybold Ag | Anti-reflection coating for transparent substrates - comprises 1st layer of dielectric metal oxide, nitride 2nd layer, and 3rd layer of dielectric metal oxide |
| US20090257241A1 (en) * | 2005-02-04 | 2009-10-15 | Adac Plastics, Inc. | Trim component with concealed indicium |
| CN102952428A (en) * | 2011-08-21 | 2013-03-06 | 比亚迪股份有限公司 | Printing ink composition, method for forming near-infrared light antireflection layer on substrate surface, and near-infrared light antireflection material |
Also Published As
| Publication number | Publication date |
|---|---|
| GB201611575D0 (en) | 2016-08-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |