阅读说明：本技术 具有整体电容器的nfc供电式led贴纸 (NFC power supply formula LED sticker with whole condenser ) 是由 罗杰·惠特比 伯来迪·S·欧若拉 于 2021-04-08 设计创作，主要内容包括：本申请案涉及一种具有整体电容器的NFC供电式LED贴纸。公开一种LED贴纸,其从附近智能电话接收NFC发射以给所述贴纸中的LED供能。螺旋线(或环形)天线在所述贴纸中用于依据所述NFC发射产生功率。NFC信号处于13.56MHz,13.56MHz是所述智能电话中的NFC天线电路的共振频率。LED部分是通过将预成型微观LED夹置在两个导电层之间以并联连接所述LED而形成的。所述导电层形成用于实现所述13.56MHz共振频率的相对大整体电容器。因此,所述电路中不需要额外电容器来实现13.56MHz的共振。此大大降低所述天线的设计要求。所述LED贴纸还可含有具有其自身的独立环形天线及NFC芯片的NFC标签。公开所述LED贴纸的各种实际应用。(The application relates to an NFC power supply formula LED sticker with whole condenser. An LED sticker is disclosed that receives NFC emissions from a nearby smartphone to power the LEDs in the sticker. A helical (or loop) antenna is used in the sticker to generate power from the NFC transmission. The NFC signal is at 13.56MHz, which is the resonant frequency of the NFC antenna circuit in the smartphone. The LED section is formed by sandwiching a pre-formed micro LED between two conductive layers to connect the LEDs in parallel. The conductive layer forms a relatively large integral capacitor for achieving the 13.56MHz resonant frequency. Thus, no additional capacitor is required in the circuit to achieve a resonance of 13.56 MHz. This greatly reduces the design requirements of the antenna. The LED sticker may also contain an NFC tag with its own independent loop antenna and NFC chip. Various practical applications of the LED sticker are disclosed.)

1. A structure, comprising:

a substrate;

an antenna supported by the substrate, the antenna having an inductance;

a first conductive layer;

a plurality of Light Emitting Diodes (LEDs) deposited over the first conductive layer, the LEDs having first electrodes in electrical contact with the first conductive layer;

a dielectric layer overlying the first conductive layer and located between the LEDs;

a second conductive layer overlying the dielectric layer and the LED, the LED having a second electrode in electrical contact with the second conductive layer such that the first and second conductive layers connect the LED in parallel and form a first capacitor; and is

The first and second conductive layers are electrically coupled to the antenna to generate a voltage difference across the LED to illuminate the LED in the presence of Near Field Communication (NFC) emissions,

wherein an inductance of the antenna and any other inductances and capacitances in electrical components on the substrate are combined with a capacitance of the first capacitor to set a resonant frequency approximately that of the NFC transmission to achieve efficient power transfer.

2. The structure of claim 1, further comprising an NFC tag supported by the substrate, the NFC tag comprising an NFC chip and an NFC antenna.

3. The structure of claim 1, further comprising a weakened region that tears when stressed such that the structure forms an easily tearable seal.

4. The structure of claim 1, further comprising an adhesive layer.

5. The structure of claim 1, wherein the LEDs are arranged in a pattern to convey a message when illuminated.

6. The structure of claim 1, wherein the LEDs are arranged to communicate a pattern of indicia when illuminated.

7. The structure of claim 1, wherein if the structure is torn and opens a circuit on the structure, the LED cannot be illuminated by the NFC emission.

8. The structure of claim 1, further comprising a shorting conductor that prevents illumination of the LED unless the structure is torn to cause the shorting conductor to open.

9. The structure of claim 1, wherein the structure is configured to function as a seal, wherein operation of the LED depends on whether the seal is broken or unbroken.

10. The structure of claim 1, further comprising:

the product is packaged in a packaging way,

wherein exposing the product package to the NFC emission causes the LED to be illuminated.

11. The structure of claim 1, wherein the resonant frequency is within 30% of the frequency of the NFC emissions.

12. The structure of claim 1, further comprising an NFC chip, wherein when an NFC signal is emitted proximate to the structure, the NFC chip is powered and the LED is illuminated.

13. The structure of claim 1, wherein the LEDs are preformed inorganic microscopic LEDs that have been printed over the first conductive layer.

14. The structure of claim 1, wherein the NFC transmission is transmitted by a smartphone.

Technical Field

The present invention relates to an inductively powered Light Emitting Diode (LED) sticker that can be illuminated using Near Field Communication (NFC) emissions from a smartphone or other NFC reader.

Background

The smart phone can wirelessly read the NFC tag or exchange information with other smart phones using NFC signals. The smart phone transmits an NFC signal at the resonant frequency of 13.56MHz of its antenna. The 13.56MHz carrier is modulated to communicate the digital data to the NFC chip. The NFC chip contains a simple processor and limited memory. Transmit power is inductively coupled to the NFC chip through a loop antenna, and the power is used to power components in the NFC chip and to communicate the data. The NFC chip may then also reply with stored digital data at 13.56 MHz. In some cases, the smartphone may be used to wirelessly program the NFC chip. A similar process can be done with RFID (radio frequency identification) tags that also use 13.56 MHz. For example, for Apple iPhone^TMOr Android^TMWell-known downloadable applications of phones' smart phones can be used to program and read NFC tags, RFID tags, and exchange information with other phones using a matched antenna.

There are various products on the market or in the prior art that provide wire loops connected in series with conventional low power LEDs. A few milliwatts of power that a smartphone or other NFC reader can wirelessly emit can cause the LED to illuminate if the phone is close enough and there is sufficient inductive coupling. Only a few milliwatts is sufficient to drive low power LEDs. NFC stickers are typically designed to dissipate up to 50mW, and NFC chips typically consume less than 15 mW.

Fig. 1 is an example of a simple prior art LED sticker 10. The loop antenna 12 has an inductance and the conventional low power LED 14 has a very small capacitance on the order of a few picofarads. Conventional smartphones 16 use NFC applications that control the smartphone 16 to transmit and receive modulated signals at 13.56MHz using an internal antenna. The emitted power, which is generally independent of the emitted data, is sufficient to power the LED 14. The power in the antenna 12 is AC. The parallel LC of the circuit is not designed to resonate at 13.56MHz because the capacitance value is too small. Thus, the coupling between the smartphone NFC antenna and the loop antenna 12 acts like a bad transformer. The efficiency is very low because the resonant frequencies of the two antennas do not match. Therefore, the brightness of the LED 14 is low.

To maximize the power transfer resulting from NFC transmission at 13.56MHz, the resonant frequency of the LED sticker 10 must also be 13.56MHz based on the inductance of the antenna 12 and the overall capacitance of the circuit. Since the resonance is related to the product LC, the inductance of the antenna must be very large, since the overall capacitance is very small. This places significant design requirements on the antenna 12 to achieve a resonant frequency of 13.56 MHz. More windings are added to the antenna 12 to increase its inductance, increase its resistance, and thus lose more power.

As shown in fig. 2, a separate resonant capacitor 20 may be added in parallel with the LED 14 to reduce the inductance requirement of the antenna 12 in order to achieve a 13.56MHz resonance, but this capacitor 20 adds the cost and size of the LED sticker 10.

The LEDs 14 are weak point sources, so the effect has only marginal industrial use and is primarily for entertainment or aesthetics. Known uses of NFC emission of smartphones to drive LEDs include nail stickers that illuminate when the smartphone is overlaid on a nail and NFC functionality is active, and LEDs embedded in credit cards that light up when the card is read by an NFC reader. See, for example, https:// youtu. be/GqXDqqOaQZE (credit card with LED) or https:// www.cnet.com/news/LED-finger-folder-detectors-android-smartphones/(nail sticker).

There is a need for a wirelessly powered LED sticker that is powered by smartphone transmission or other NFC or RFID transmission that maximizes power transfer by having a resonance of 13.56MHz without requiring the addition of a separate capacitor.

Disclosure of Invention

An LED sticker including a loop antenna and optionally an NFC tag is described. The LED portion of the sticker includes a transparent first conductive layer on a translucent or transparent substrate, a printed preformed LED that has been deposited on the first conductive layer, a dielectric layer, and a reflective second conductive layer. The two conductive layers connect all the LEDs in parallel, so a voltage applied across the conductive layers causes the LEDs to illuminate in either printed pattern. Light from the LED passes through the transparent first conductive layer and exits through the substrate. The substrate may be a thin translucent paper.

The conductive layer is very large compared to the printed LED because the LED has a width smaller than the width of human hair, and the area of the sticker can be about 6cm²(one square inch). The gap between the conductive layers is very small. Although there may be many micro-printed LEDs in the decal, the combined area is insignificant compared to the area of the conductive layer. Thus, the overall capacitance of the LED sticker is very high compared to the capacitance of the LED itself. Thus, the inductance required for the antenna to achieve a resonant frequency of 13.56MHz is greatly reduced, simplifying the design of the antenna and reducing its size and resistance. The inductor and the capacitor are connected in parallel to form a resonant LC tank circuit. Thus, power transfer between the NFC emission of the smartphone and the LED sticker is maximized.

Since the capacitance of the LED sticker is relatively large, there is no need to provide an additional "resonant" capacitor in the LED sticker to achieve a resonant frequency of 13.56 MHz. In addition, since the loop antenna can be small, the antenna has low resistance to further improve efficiency.

Independent of the LED/antenna circuit, a separate NFC tag can be laminated above or below the LED sticker. The NFC tag includes an NFC chip and a resonant loop antenna. The NFC antenna may generally overlie the LED antenna because it is ideal for the antenna to be the same size as the smartphone NFC antenna and located directly below the smartphone NFC antenna. The NFC tag operates independently of the LED sticker. The LED may be positioned remote from the antenna so the user can see the LED light when using the smartphone to power the NFC chip and the LED.

NFC emission can couple 50mW or more into the LED and NFC chip, which is suitable for brightly illuminating the LED. The NFC signal of the smartphone may radiate 200mW or more. The read range is typically up to 10 cm. An application that may be downloaded to the smartphone may change the NFC pulse frequency or other aspects of the NFC signal.

In one application of bonding LED stamps, the stamp serves as a tamper-proof seal and does not require any NFC chip. The seal may be weakened along predetermined zones and therefore easily torn along those lines. The seal is bonded across a boundary that can be broken. If the seal is broken, the LED print will not light up when the smartphone applies the NFC signal to it. In another embodiment, the seal may only light up if the seal is broken (e.g., if the breaking of the seal breaks a conductor that previously short-circuited the LED).

The LED may convey a pattern of messages to print or the LED may backlight logos or other graphics in the product package.

In another embodiment, the LED footprint is attached to a pocket, and the smartphone is placed in the pocket not close to the footprint (almost touching) to have a high degree of magnetic coupling. The smart phone pulses the LED print to allow the print to be used in a security vest or for other uses.

Additional uses are envisaged.

Drawings

Fig. 1 is a schematic circuit of a simple LED circuit receiving wireless power from an NFC pulse from a smartphone, where the circuit does not have a resonant frequency of 13.56MHz and is therefore very inefficient.

Fig. 2 illustrates a manner in which the circuit of fig. 1 may be configured to include "resonant" capacitors to reduce the inductance requirements of the antenna and maximize power transfer.

Fig. 3 illustrates an LED sticker with a printed micro LED array sandwiched between two conductive layers to form an integrated large capacitor in parallel with the small capacitance of the micro LEDs. The LED sticker also includes a stand-alone NFC tag with its own antenna and NFC chip.

Fig. 4 is a schematic diagram of the LED and integrated capacitor of fig. 3. The capacitor value is used to determine the inductance required for the antenna to achieve a resonant frequency of 13.56 MHz.

Fig. 5 is a top view of some aspects of the LED structure of fig. 3. The density of the LEDs may be much higher and the LEDs may be printed in any pattern, such as an alphanumeric pattern or logo.

Fig. 6 illustrates the manner in which the LED sticker can be weakened along a predetermined line, so breaking the seal when used as a seal across a boundary will create an open circuit, resulting in the LED sticker not illuminating in the presence of the NFC signal after the seal is broken.

Fig. 7 illustrates the LED sticker of fig. 6 being used as a seal for a package.

Fig. 8 illustrates the manner in which breaking the seal can be used to make the LED sticker operable by removing the short across the LED.

FIG. 9 illustrates the manner in which energizing the seal of FIG. 8 can use an LED pattern or graphic overlay to show "seal broken".

Fig. 10 illustrates a printed LED pattern in the shape of the letter "a".

FIG. 11 illustrates the manner in which tearing of the seal can disable one side of the LED sticker and enable the other side of the sticker.

FIG. 12 illustrates the manner in which energizing the seal of FIG. 11 can show a user whether the seal is broken or unbroken. Only one of the messages will be displayed.

Fig. 13 illustrates the manner in which an LED sticker can convey a message or logo when used in a product package, where the LED sticker is energized by NFC transmission of a customer's smartphone.

Fig. 14 illustrates the manner in which the LED zones may be of any size compared to the antenna zones.

Fig. 15 illustrates the manner in which an LED sticker can be used as a security light, with a user's smartphone placed in a pocket behind the LED sticker and an NFC signal periodically transmitted to the LED sticker. An application downloaded to the phone may select the power and pulse frequency of the NFC signal.

Similar or identical elements in the various figures are denoted by the same reference numerals.

Detailed Description

FIG. 3 is a cross-section of one embodiment of an LED decal 32 according to one embodiment of the present invention. Fig. 3 illustrates how a relatively large capacitor may be formed integral with the printed micro LED layer, avoiding the need for a separate "resonant" capacitor to achieve the 13.56MHz resonant frequency. The capacitance may be about 500pF/mm²And the size of the LED portion of the LED sticker 32 will typically be about 1cm²Or less. The LED sticker 32 may be about one square inch to accommodate a loop antenna. All aspects of the LED decal 32 can be formed by printing in atmospheric conditions.

In fig. 3, the LED sticker 32 is oriented upward, thus emitting light from its top surface. The orientation is reversed when the LED portion of the LED decal 32 is made.

A thin flexible substrate 34, such as PET, PMMA, Mylar, paper, or the like, is first provided. The substrate 34 is translucent or transparent. In a preferred embodiment, the substrate 34 is a thin white paper from Arjo Wiggins. If the substrate 34 is non-conductive, a transparent first conductive layer 36 is deposited on the substrate 34, for example by printing or lamination. First conductive layer 36 may be ITO or sintered silver wire mesh (after curing). The manufacturing process may be a roll-to-roll process.

The preformed microscopic inorganic LED 38 is prepared in solution as an LED ink. The LED ink may be printed in any pattern using screen printing, gravure printing, flexographic printing, inkjet or other techniques. The orientation of the printed LEDs 38 may be controlled by providing a relatively high electrode 40 (e.g., an anode electrode) such that the electrode 40 is oriented upward by employing a least resistive fluid path through the solvent after printing. Note that during fabrication, the LEDs 38 are oriented in the opposite direction with respect to fig. 3. The LED 38 is also self-orienting by providing a heavier cathode electrode 42. The cathode electrode 42 may be a distributed metal electrode, and the LED light is emitted between the distributed metal electrodes. The LEDs 38 are referred to as vertical LEDs because the current travels vertically through the structure. The anode and cathode surfaces may be opposite those shown. The exact location of the LEDs 38 is random, but the approximate number of LEDs 38 printed per unit area may be controlled by the density of the LEDs 38 in the ink. The LED 38 single layer is realized by a printing process. The printed LED ink is then cured, causing the cathode electrode 42 to be electrically connected to the first conductive layer 36.

A dielectric layer 44 is then deposited over the first conductive layer 36 and between the LEDs 38, and the dielectric layer 44 is then cured.

A reflective conductive layer 46, such as ITO or silver nanowire ink, is then deposited over the LEDs 38 and the dielectric layer 44 to connect the LEDs 38 in parallel. The conductive layer 46 is then cured. In the case of silver nanowire inks, curing sinters the nanowires to form a mesh.

A loop antenna 52 is then deposited on the same side of substrate 34 or on the other side of substrate 34 to form a flat spiral having two ends connected to conductive layers 36 and 46.

A phosphor layer 54 (e.g., YAG phosphor) is optionally deposited over the LED portions to form white light using the blue-emitting GaN-based LEDs 38. Blue light may be combined with phosphor emission to provide broad spectrum emission. Any other phosphor may be used to form any color.

Any suitable material may then be deposited to planarize the surface of the LED decal 32.

NFC tag 56 may optionally be adhered to the top or bottom surface of LED sticker 32. The NFC tag 56 operates independently of the LED portion and includes its own loop antenna and NFC chip. The NFC tag 56 may be conventional and may be circular or rectangular. A typical NFC tag includes a resonant capacitor of about 68pF and a loop antenna with an inductance of 2 muh. If the NFC tag 56 overlies the LED 38, the NFC tag 56 should be translucent and preferably transparent, except for its antenna and NFC chip. The NFC chip receives power from its loop antenna and receives and transmits data via its loop antenna. The NFC chip may be wirelessly programmed by the smartphone and may transmit any suitable digital data to the smartphone.

Adhesive layer 58 and any protective layers can then be deposited to allow the LED decal 32 to be adhered to either surface.

When the smartphone emits an NFC signal within about 10cm of the LED sticker 32, the signal inductively couples to the loop antenna 52 to energize the LED 38, and also inductively couples to the NFC antenna to communicate with the NFC chip. Light rays 60 are shown as being emitted by the LED 38.

The translucent substrate 34 and phosphor 54 diffusely reflect the LED light for more uniform light emission.

In one embodiment, the light emission from the LED 38 and phosphor backlight a colored or opaque graphic printed on the paper substrate 34 to convey a logo or message.

More information about forming LED inks and printing the inks to form an LED array sandwiched between two conductive layers may be found in assignee's U.S. patent No. 9,343,593 entitled "Printable Composition of diode liquids or Gel suspensions of Diodes" and related patents, which are incorporated herein by reference.

Since each LED 38 is microscopic, for example having a width of 50 microns or less, and the LED decal 32 can be about 6cm²And thus the total LED area is very small compared to the area of the conductive layer. The gap between conductive layer 36 and conductive layer 46 is very small, e.g., less than 50 microns, and the surface area is very large, resulting in a relatively large capacitance. Thus, no additional "resonant" capacitor is required to achieve resonance.

Fig. 4 is a schematic diagram of the LED sticker 32 showing the conductive layers 36 and 46 as a capacitor 62 and the LED 38 in parallel with the capacitor 62. The area of conductive layers 36 and 46 may be made larger or smaller regardless of the LED ink pattern in order to achieve a desired capacitance value, for example, in the case of using a loop antenna having a predetermined inductance, in order to obtain a resonant frequency of 13.56 MHz.

Fig. 5 is a top view of the LED portion of the LED sticker 32. The LEDs 38 may be printed in any pattern, such as a generally uniform pattern, an alphanumeric pattern, or a logo pattern.

The antenna 52 should be designed so that the overall inductance and capacitance of the circuit has a resonance of 13.56MHz for optimum power transfer. The inductor and the capacitor form a parallel resonance LC tank circuit. Maximum power is transferred between the smart phone transmitting at 13.56MHz and the passive receive circuit having a resonance of 13.56 MHz. The formula of the resonance frequency is f ═ 1/(2 pi √ LC). The capacitance value depends on the area of the gap between conductive layer 36/46, dielectric layer 44, and conductive layer 36/46. It is well known how to use an impedance analyzer to test a circuit for a resonant frequency of 13.56 MHz. The capacitance can be varied as required for a given antenna design to achieve a resonance of about 13.56MHz for maximum power transfer. The smartphone antenna and the LED sticker antenna should ideally have the same shape.

The size of the overall capacitor should be limited to a relatively small area, e.g. less than 1cm²Because the smaller capacitor produces a higher voltage across the LED 38. When the voltage across the LED 38 reaches about 2.5V (the approximate forward voltage of the LED 38), the LED 38 will turn on.

Since the capacitance is much larger than that of the LED 38 itself, a smaller loop antenna 52 can be used, which reduces its resistance, improving efficiency.

Typically, NFC readers transmit in pulses while polling NFC chip transmissions to save power and reduce interference. Thus, the LED 38 will pulse at the NFC pulse rate, which may be several times per second. An application in the smart phone may be used to change the pulse rate or to continue the transmission. The NFC transmission time may be longer if the NFC reader detects the NFC chip.

Although the NFC resonant frequency of 13.56MHz is ideal for maximum power transfer, the resonant frequencies do not have to match, albeit at reduced efficiency. For example, resonances within 30% of the resonance of the NFC antenna will exhibit improved performance compared to the LED sticker of fig. 1, where the coupling is like a bad transformer. Other systems may use other resonant frequencies, and the LED decal 32 may be modified to achieve almost any resonant frequency.

Various practical uses of the LED sticker 32 will now be described, although there are many other uses that will become apparent. Some uses include: 1) visual feedback of the LED sticker 32 within the NFC field; 2) a visual indication that the seal has been broken or not broken; 3) a security light powered by an NFC field emitted by a smartphone; 4) the product packaging that conveys information to the customer as the customer powers the LED sticker 32 with the smart phone increases.

Fig. 6-12 show various techniques for using an LED sticker as an indicator when the seal has been broken.

In fig. 6, an LED sticker 66 similar to the LED sticker 32 of fig. 3 is shown with weakened areas 68 and 69 (dashed lines), such as by partially perforating the outer protective layer of the LED sticker 66. The LED sticker 66 is easily torn along those weakened areas 68 and 69.

Fig. 7 shows that the LED sticker 66 is used as a seal across the boundary of a package 70, such as an envelope or other enclosure. To ensure that the cover of the package 70 has not been opened, the user reads the LED sticker 66 with the NFC emission of the smart phone 72. The LED lights up and can read any data in the NFC chip, or can write to the NFC chip. For example, the NFC chip may be written to communicate that the seal has been checked at a particular time and remains intact. In this way, the status of the seal can be tracked if a different entity is responsible for the package 70. If the seal is torn, the tear will open up delicate traces forming the antenna or LED portion, rendering the LED decal 66 inoperable and irreparable.

In another embodiment, an LED sticker is adhered to the sealed opening of the wine bottle to communicate whether the seal has been broken or not. Another LED sticker is placed on the wine label and conveys information about the wine when energized.

Fig. 8 illustrates a technique for causing the LED decal 74 to be operable only if it is torn along the weakened region 76. The thin metal traces 78 typically short out the antenna loop 80, rendering the LED decal 74 inoperable. When the trace is broken 78 by tampering, the LED sticker 74 becomes operable and illuminated when energized by NFC transmission of the smartphone 72.

FIG. 9 illustrates the manner in which the LED decal 74 can visually convey alphanumeric characters identifying the status of the seal. In one example, the LED decal 74 backlights a graphic printed on a translucent or transparent sheet 75. The light guiding layer may be used to laterally spread the LED light, and the surface of the light guiding layer may be patterned (e.g., roughened) to emit light only in the patterned regions. In another embodiment, the patterning of the LED ink forms a character, such as the letter "a" in fig. 10. Any size LED sticker 74 may be used to display any word or logo. This applies to all LED stickers described herein.

Fig. 11 illustrates an LED sticker 78 having a weakened region 80, wherein tearing along the weakened region 80 results in the left portion of the LED sticker 78 being operable by opening a shorting trace 82 and the right portion of the LED sticker 78 being inoperable by breaking an antenna loop trace 84.

As shown in fig. 12, energizing by NFC transmission from a smartphone will communicate to the user whether the seal is broken or unbroken by backlit graphics or LEDs printed in an alphanumeric pattern.

Fig. 13 illustrates the manner in which the LED sticker 90 may be used in a package. The LED decal 90 is placed on or in the product packaging 92. Energizing the LED sticker 90 via the customer's smart phone 72 may convey information to the customer such as words, logos, "secret" messages, prices, etc. The LEDs may backlight graphics or communicate messages directly. Alternatively, the illumination may provide only feedback to read the NFC chip. The NFC chip on the LED sticker 90 may also communicate any other messages to the customer.

Fig. 14 illustrates the manner in which the LED area 94 in the LED sticker 96 may be independent of the size of the loop antenna 98. The NFC chip 100 and NFC antenna may be located anywhere on the LED sticker 96.

FIG. 15 illustrates the manner in which the LED sticker 102 may be used as an LED safety light on a piece of clothing. The LED sticker 102 is glued to the pocket and the smartphone 72 is placed in the pocket so the NFC antenna loop of the smartphone is very close to the LED sticker 102 antenna, creating a very high magnetic coupling. An application in the smartphone 72 may be used to control the pulse frequency and power so the LED blinks brightly for safety. Many other applications for illuminating LED decals for security or other purposes are contemplated.

Any of the features of the various embodiments may be combined.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of this invention.