JP2008097269A - Ic tag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize an IC tag by using a coating type solar battery which can reduce the plane area of the solar battery and to suppress the transmission stop of a radio signal due to the drive stop of various circuits. <P>SOLUTION: The solar battery 100 accumulates electricity in an accumulating capacitor 101. A controlling IC 105 and a wireless module 109 are driven by receiving power supply from the accumulating capacitor 101. The controlling IC 105 changes an interval of power supply to the wireless module 109 on the basis of the voltage of the accumulating capacitor 101. The solar battery 100 includes an n-type semiconductor layer composed of a material having an electron acceptive inorganic matter as a main component and containing a basic dye and a p-type semiconductor layer composed of a material having an electron donative organic matter as a main component and containing an electron acceptive compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an active IC tag having a battery inside.

  In recent years, there is an IC tag that records or reads data using radio waves on a tag-like medium and performs communication via an antenna. This IC tag includes an active IC tag in which a primary battery is built in the IC tag, and the IC tag itself transmits a wireless signal including data every predetermined time (for example, 1 second) by a wireless signal. .

  The active type IC tag has a problem that it takes a cost for replacing the battery and a labor cost since the life of the primary battery is as short as about six months. Therefore, an IC tag described in Patent Document 1 has been proposed in which a power source is configured from a solar cell and an electric double layer capacitor. A solar cell converts light into electric power using a photoelectric effect. This electric power is determined from the material forming the solar cell and the plane area of the solar cell. An electric double layer capacitor is a capacitor that functions as a secondary battery that can be repeatedly charged and discharged. The electric double layer capacitor is charged by the power generation of the solar cell. And the various circuits in an IC tag are driven by the electric power supplied by the power supply comprised from a solar cell and an electric double layer capacitor, and the radio signal containing data is transmitted.

Japanese Unexamined Patent Publication No. 2000-306061 (FIG. 1)

However, in the IC tag described in Patent Document 1 described above, in order for the solar cell to charge the electric double layer capacitor with enough power to drive various circuits in the IC tag, it is necessary to generate a large amount of power. Moreover, the problem which takes time to charge was included. Here, in order to generate large electric power, it is necessary to increase the plane area of the solar cell, and there is a problem that the surface area of the IC tag increases.
Further, when a conventionally used solar cell using crystal or amorphous silicon is applied to an IC tag, there is a problem that the flexibility of the IC tag is hindered.

  In addition, if light irradiation is low in an environment such as shade or rain, the power consumed by driving various circuits in the IC tag may be larger than the power charged in the storage capacitor by the solar battery. is there. At this time, the electric power of the electric double layer capacitor gradually decreases while driving various circuits. And when the voltage of the electric double layer capacitor becomes lower than the driving voltage of various circuits, the transmission of wireless signals will stop along with the driving stop of various circuits due to insufficient supply voltage to various circuits. In the case of an IC tag that uses a solar cell as a power source, the user should feel uneasy.

  Therefore, an object of the present invention is to provide a small IC tag by using a high-efficiency expected solar cell formed by coating.

Another object of the present invention is to provide an IC tag that suppresses the stop of transmission of radio signals accompanying the stop of driving of various circuits.
Furthermore, another object of the present invention is to provide an IC tag using a solar cell as a power source that gives the user a sense of security.

Means for Solving the Problems and Effects of the Invention

  The IC tag of the present invention is an IC tag that performs information communication with an external device by radio signals, and is a solar cell coated on a substrate, and a storage capacitor connected to the solar cell via a backflow prevention circuit And a transmitter for receiving a power supply from the storage capacitor and transmitting a radio signal, and a power supply controller for controlling the power supply to the transmitter at predetermined intervals. The solar cell is an n-type semiconductor layer made of a material containing an electron-accepting inorganic substance as a main component and containing a basic dye, and a p-type made of a material containing an electron-donating organic substance as a main component and containing an electron-accepting compound. And a semiconductor layer.

  The present inventors show that the photoelectric conversion characteristics of solar cells can be greatly improved by combining an n-type inorganic semiconductor layer containing a basic dye and a p-type organic semiconductor layer containing an electron-accepting compound. I found out. The present invention is based on this knowledge, and since the photoelectric conversion efficiency per unit area is increased as compared with the conventional one, it can be expected that a large electric power can be obtained even when the plane area of the solar cell is small. Since it can be formed, the IC tag can be miniaturized and the manufacturing process of the solar cell attached IC tag can be simplified.

  On the other hand, the IC tag of the present invention is an IC tag for performing information communication with an external device by radio signals, and a solar cell coated on a substrate and a power storage connected to the solar cell via a backflow prevention circuit. A power supply capacitor, a transmitter for receiving a power supply from the power storage capacitor and transmitting a radio signal, and a power supply controller for controlling the power supply to the transmitter at predetermined intervals. The power supply control unit changes an interval of power supply to the transmitting unit based on a voltage value of the storage capacitor.

  According to this IC tag, the interval of power supply to the transmitter can be changed based on the voltage value charged in the storage capacitor at a predetermined timing. Therefore, for example, even when light irradiation is low in an environment such as shade or rain, the power consumption by the transmitter can be reduced by increasing the interval of power supply to the transmitter. The decrease can be suppressed. Thereby, it is possible to suppress the stop of transmission of radio signals due to the stop of driving of the various circuits due to the shortage of the supply voltage to the various circuits constituting the IC tag.

  Moreover, when the said capacitor | condenser for electrical storage is comprised with an electric double layer capacitor, it is preferable to be provided in contact with the surface side facing the light-incidence surface side of the said solar cell. Thereby, the electric double layer capacitor that can be formed in a sheet shape does not block the incidence of light, so that the solar cell does not impair the light utilization efficiency and the volume of the IC tag can be reduced.

  In addition, it is preferable that the information processing apparatus further includes a notifying unit that notifies the outside of the output status of the transmission digital data generated in response to the operation of the power supply control unit. As a result, it is possible to visually recognize that various circuits are operating, and it is possible to confirm that the solar cell generates power and the various circuits are powered and operating. It will give you a sense of security.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an IC tag according to an embodiment of the present invention.

  As shown in FIG. 1, in the IC tag 1000, the solar cell 100 and the storage capacitor 101 connected via the Schottky barrier diode 102 (backflow prevention circuit) are connected to the IC tag circuit 103. Further, an antenna 104 is connected to the IC tag circuit 103.

  The solar cell 100 will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the solar cell 100. Here, it is assumed that light is incident from the lower side to the upper side.

  The solar cell 100 converts light into electric power using a photoelectric effect, and includes a transparent insulating substrate 110, a transparent electrode 112 serving as a surface electrode, an n-type semiconductor layer 113, and a p-type semiconductor layer 114. The n-type semiconductor layer 113 is composed of a material containing an electron-accepting inorganic substance as a main component and a basic dye, and the p-type semiconductor layer 114 is mainly composed of an electron-donating organic substance. It is made of a material containing an electron-accepting compound as a component, and can be formed by coating. Note that illustrations of leads (electric wires) attached to the electrodes and protective resins for preventing moisture from entering the solar cell 100 are omitted.

  The transparent insulating substrate 110 is preferably one that transmits a wide range of wavelengths in the visible light region. For example, glass, plastic film, or the like can be used in an appropriate form such as a sheet or plate.

  More specifically, the transparent electrode 112 is placed on the upper surface of the transparent insulating substrate 110, and like the transparent insulating substrate 110, it is preferable that the transparent electrode 112 transmits a wide wavelength in the visible light region. (ITO), tin oxide (NESA), indium oxide and the like are used.

  The n-type semiconductor layer 113 is formed by applying an n-type semiconductor coating solution obtained by adding a predetermined amount of a basic dye, a binder resin, and a solvent to an electron-accepting inorganic material on the transparent electrode 112.

Examples of the electron-accepting inorganic material include metal oxide semiconductors such as zinc oxide (ZnO) and titanium dioxide (TiO ₂ ), and a zinc oxide pigment is particularly preferably used. In addition, as this zinc oxide pigment, a powder having an average particle diameter of about several nm to several tens of nm can be used. However, from the viewpoint of photoelectric conversion efficiency, it is desirable to use one having an average particle diameter of 20 to 30 nm.

  Examples of basic dyes include xanthene dyes such as rhodamine B and rhodamine 6G, and thiazine dyes such as methylene blue and methylene violet. Rhodamine B is preferred when a zinc oxide pigment is used as the electron-accepting inorganic material.

  The binder resin can be selected from a wide range of insulating resins such as polyvinyl butyral resin, polyvinyl formal resin, polystyrene resin, polyester resin, and cellulose resin. These binder resins may be used alone or in combination of two or more. In the present embodiment, polyvinyl butyral resin is used.

  Solvents include alcohols such as methanol, ethanol, n-propanol and i-propanol, ketones such as methyl ethyl ketone and cyclohexanone, cyclic or chain ethers such as tetrahydrofuran, dioxane and dimethyl cellosolve, benzene, toluene and xylene. These aromatic hydrocarbons can be used alone or in admixture of two or more.

  Here, the preferable blending ratio (weight) of the electron-accepting inorganic substance and the basic dye is in the range of 80: 1 to 10: 1, more preferably 60: 1 to 20: 1. Moreover, the preferable compounding ratio (weight) of an electron-accepting inorganic substance and binder resin is the range of 40: 1 to 1: 1, More preferably, it is the range of 20: 1 to 5: 1.

  In addition, it is necessary to disperse | distribute and melt | dissolve the material which comprises a semiconductor coating liquid uniformly in the whole molecular level. Therefore, after mixing the materials, it is important to disperse them into fine particles by a conventionally known method using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor or the like.

  The p-type semiconductor layer 114 is formed by applying a p-type semiconductor coating solution obtained by adding a predetermined amount of an electron-accepting compound, a binder resin, and a solvent to an electron-donating organic material on the n-type semiconductor layer 113.

  Examples of the electron-donating organic substance include phthalocyanine pigments, quinacridone pigments, indigo or thioindigo pigments (dyes), and phthalocyanine pigments are particularly preferably used. The phthalocyanine pigment used here is, for example, metal-free phthalocyanine, metal phthalocyanine, and a part of these rings substituted with appropriate substituents. As the central metal of metal phthalocyanine, magnesium (Mg), zinc (Zn), copper (Cu), silver (Ag), aluminum (Al), titanium (Ti), iron (Fe), cobalt (Co), Tin (Sn) etc. are mentioned. The phthalocyanine pigment preferably has an average particle diameter of several μm to several tens of μm. From the viewpoint of photoelectric conversion efficiency, a phthalocyanine pigment having an average particle diameter of 0.1 to 10 μm is used. desirable.

  Examples of electron accepting compounds include quinone compounds such as p-benzoquinone, chloranil and anthraquinone, fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,7,9-tetranitrofluorenone, xanthone compounds, Examples thereof include benzophenone compounds and cyanovinyl compounds. When a phthalocyanine pigment is used as the electron donating organic substance, 2,4,7-trinitrofluorenone is preferable.

  The binder resin can be selected from a wide range of insulating resins such as polyvinyl butyral resin, polyvinyl formal resin, polystyrene resin, polyester resin, and cellulose resin, similarly to the binder resin used for the n-type semiconductor layer 113. These binder resins may be used alone or in combination of two or more. In the present embodiment, polyvinyl butyral resin is used.

  As the solvent, similar to the solvent used for the n-type semiconductor layer 113, alcohols such as methanol, ethanol, n-propanol and i-propanol, ketones such as methyl ethyl ketone and cyclohexane, cyclic such as tetrahydrofuran, dioxane and dimethyl cellosolve Alternatively, chain ethers, aromatic hydrocarbons such as benzene, toluene, xylene and the like can be used alone or in admixture of two or more.

  Here, the preferable blending ratio (weight) of the electron-donating organic substance and the electron-accepting compound is in the range of 20: 1 to 2: 1, more preferably 10: 1 to 10: 3. Moreover, the preferable compounding ratio (weight) of electron donating organic substance and binder resin is the range of 10: 1 to 1: 1, More preferably, it is the range of 6: 1 to 2: 1.

  As described above, the n-type semiconductor layer 113 composed of the electron-accepting inorganic substance, the basic dye, and the binder resin and the p-type semiconductor layer 114 composed of the electron-donating organic substance, the electron-accepting compound, and the binder resin, A junction type semiconductor film is formed. The reason why this solar cell 100 has photovoltaic power is due to an internal electric field in the vicinity of the interface caused by the difference in Fermi level between the two layers at the interface between the n-type semiconductor layer 113 and the p-type semiconductor layer 114. it is conceivable that. That is, it is considered that carriers are generated by absorbing light in the region where the internal electric field works, and are separated into electrons and holes by the internal electric field and finally taken out as current. Moreover, as a mechanism for improving photoelectric conversion efficiency by adding a basic dye to an n-type semiconductor and adding an electron-accepting compound to a p-type semiconductor, the electron concentration by electronic interaction in each layer is It is conceivable that carriers are generated and moved advantageously by increasing the hole concentration or by promoting the dissociation efficiency of carriers or suppressing recombination.

  The back electrode layer 115 is formed by applying a conductive paste in which a conductive substance is dispersed in a resin onto the p-type semiconductor layer 114. As the conductive paste, a carbon paste in which conductive carbon black is dispersed in a resin, a metal paste in which metal fine particles are dispersed in a resin, or the like is used. The thickness of the back electrode layer 115 is preferably about 1 to 50 μm.

  Here, a method for manufacturing the solar cell 100 will be specifically described. After placing the transparent electrode 112 on the transparent insulating substrate 110, using the above-mentioned n-type semiconductor coating solution and p-type semiconductor coating solution, for example, dip coating method, air knife coating method, roller coating method, wire bar coating The n-type semiconductor layer 113 and the p-type semiconductor layer 114 are stacked in this order by a method, a spin coating method, or the like. In general, the thickness is preferably about 0.01 to 3.0 μm, more preferably 0.1 to 2.0 μm. Then, after the stacked n-type semiconductor layer 113 and p-type semiconductor layer 114 are sufficiently dried, a back electrode 115 is formed on the p-type semiconductor layer 114.

  With the above manufacturing method, the transparent insulating substrate 110 and the transparent electrode 112 can be formed without using a vacuum process such as vapor deposition or a high temperature process, which is essential in the conventional manufacturing method, or a gas or deoxygenated environment with safety problems. The n-type semiconductor layer 113, the p-type semiconductor layer 114, and the back electrode 115 other than the n-type semiconductor layer 113 can be formed under a normal atmospheric pressure (normal temperature) environment. In addition, according to this manufacturing method, it is easy to construct not only batch-type production equipment used in conventional solar cells, but also continuous production equipment that can produce long and large-area solar cells, Further, it can be manufactured in a series of steps in combination with an IC tag.

  The configuration of the back electrode 15 may be another conductive film that can be ohmic-bonded to the semiconductor layer. For example, a film made of a metal having a large work function such as Au or Ag may be formed by vapor deposition or sputtering.

  Next, in order to confirm the effect of the solar cell 100 described above, a specific example employing the above-described configuration and a comparison including an n-type semiconductor layer to which no basic dye is added and a p-type semiconductor layer to which no electron-accepting compound is added. An experimental result of actually measuring photoelectric conversion efficiency will be described using an example.

[Specific Example 1]
The solar cell 100 used for the test has the single-configuration hetero pn junction semiconductor layer described above. First, the semiconductor coating solution is adjusted.

  12 parts by weight of zinc oxide powder (manufactured by Teika: MZ-500, average particle size 20-30 nm), rhodamine with respect to 1 part by weight of polyvinyl butyral resin (Sekisui Chemical Co., Ltd .: ESREC BM-1) as a binder resin 0.3 parts by weight of B (manufactured by Tokyo Chemical Industry Co., Ltd.) and 20 parts by weight of isopropyl alcohol as a solvent are placed in a container together with a 1 mmφ zirconium ball and stirred for 1 hour using a planetary ball mill to form a slurry. An n-type semiconductor dispersion was obtained.

  Further, 4 parts by weight of a metal-free phthalocyanine powder (manufactured by Tokyo Chemical Industry Co., Ltd., average particle size 2 to 10 μm) with respect to 1 part by weight of polyvinyl butyral resin (Sekisui Chemical Co., Ltd .: ESREC BX-1) as a binder resin, 1 part by weight of 2,4,7-trinitrofluorenone (manufactured by Tokyo Chemical Industry Co., Ltd.) and 20 parts by weight of dimethyl cellosolve as a solvent are placed in a container together with a 1 mmφ zirconium ball, and 2 using a planetary ball mill. The mixture was stirred for a time to obtain a slurry-like p-type semiconductor dispersion.

  In producing the solar cell 100, first, an ITO glass provided with a transparent electrode 112 made of an indium tin oxide is placed horizontally on a transparent insulating substrate 110 made of glass, and the ITO glass is placed on the ITO glass. The n-type semiconductor coating solution described above was applied by a roller coating method to form an n-type semiconductor layer 113 having a thickness of 1.0 μm. After the n-type semiconductor layer 113 is sufficiently dried at room temperature, the above-described p-type semiconductor coating solution is applied onto the n-type semiconductor layer by the same roller coating method to form a p-type film having a thickness of 1.0 μm. A type semiconductor layer 114 was formed.

  After sufficiently drying the obtained pn junction semiconductor layer, on this semiconductor layer, 6 parts by weight of conductive carbon paste (manufactured by Lion Corporation: W-310A) and polyvinyl acetal resin (manufactured by Sekisui Chemical Co., Ltd .: ESREC) KW-1) A conductive paste liquid mixed and stirred with 4 parts by weight was applied by a roller coating method to form a back electrode layer 115 having a thickness of 10 μm, thereby obtaining a solar cell 100 of Example 1.

[Specific Example 2]
The solar cell of Example 2 was obtained in the same manner as Example 1 except that oxytitanium phthalocyanine crystal (manufactured by Sanyo Dye Co., Ltd.) was used as the electron-donating organic substance constituting the p-type semiconductor layer instead of the metal-free phthalocyanine powder. Produced.

[Specific Example 3]
A solar cell of Example 3 was fabricated in the same manner as Example 1 except that a copper phthalocyanine crystal (manufactured by Across) was used as the electron-donating organic substance constituting the p-type semiconductor layer instead of the metal-free phthalocyanine powder. .

[Comparative Example 1]
A n-type semiconductor coating solution not containing rhodamine B and a p-type semiconductor coating solution not containing 2,4,7-trinitrofluorenone were prepared, and the other conditions were the same as in Example 1, and the solar cell of Comparative Example 1 Was made.

Measurement of photoelectric conversion characteristics of these obtained solar cells was performed by attaching a lead wire to each electrode of the solar cell, and using a solar simulator (manufactured by Yamashita Denso Co., Ltd .: YSS-E40), 100 mW from the transparent electrode side of the solar cell. The characteristics of the solar cell were measured with a solar cell evaluation apparatus (manufactured by Eihiro Seiki Co., Ltd .: MP-160) while irradiating pseudo solar light of / cm ² (AM-1.5).
Table 1 below shows the photoelectric conversion characteristics of each solar cell obtained from the experiment.

  From this table, specific examples 1 to 3 to which rhodamine B (basic dye) and 2,4,7-trinitrofluorenone (electron-donating compound) were added were compared with Comparative Example 1 having a conventional structure in which these were not added. It can be seen that the conversion characteristics are greatly improved.

In particular, the solar cell 100 of Example 1 has an open circuit voltage Voc = 0.64 V, a short circuit current Isc = 0.25 mA / cm ² , a fill factor FF (fill factor) = 0.34, and a conversion efficiency of 0.05%. was gotten. These values are larger than those of conventional solar cells.

  Returning to FIG. 1, it is preferable that the capacity of the storage capacitor 101 is large. However, in consideration of mounting on an IC tag, a tantalum capacitor having a capacity of several μ to several tens μF is usually used. The Schottky barrier diode 102 is a backflow prevention diode that prevents current from flowing from the storage capacitor 101 side to the solar cell 100 side. For example, the voltage of the power storage capacitor 101 is the voltage of the solar battery 100 when the power is stored in the power storage capacitor 101 when there is little light irradiation and the solar battery 100 does not generate power due to the photoelectric effect. Higher than. At this time, a current flows from the storage capacitor 101 side to the solar cell 100 side, and the voltage of the storage capacitor 101 decreases. Therefore, by connecting the Schottky barrier diode 102, it is possible to prevent a current from flowing from the storage capacitor 101 side to the solar cell 100 side and to prevent the voltage of the storage capacitor 101 from decreasing.

  The IC tag circuit 103 is provided with various circuits that are driven by being supplied with electric power from the storage capacitor 101. A detailed internal configuration of the IC tag circuit 103 will be described with reference to FIG. The IC tag circuit 103 includes a control IC 105 (including a power supply control unit), a transistor 106, a voltage detection circuit 107, a reference voltage generation circuit 108, a wireless module 109 (a transmission unit), and a light emitting diode 116 (a notification unit). Has been.

  The control IC 105 stores a central processing unit (CPU) that is a central processing unit, a program for controlling an interval of power supply to the wireless module 109, a program for generating digital data to be transmitted, and wireless signal data. ROM (Read Only Memory), RAM (Random Access Memory) for temporarily storing data processed by the CPU, and the like are provided. The control IC 105 is driven by power supplied from the storage capacitor 101. Then, according to the signal output from the voltage detection circuit 107, the voltage value charged in the storage capacitor 101 is determined at a fixed determination timing. In accordance with the determination timing, a signal for ON / OFF control of the transistor 106 is transmitted to control the supply of power supply voltage to the wireless module 109 with high power consumption. Also, digital data is transmitted to the wireless module 109.

  The transistor 106 is a switching element configured to be turned on when a LOW signal is received from the control IC 105 and turned off when a HIGH signal is received. The transistor 106 supplies power to the wireless module 109 from the storage capacitor 101 when it is ON.

  The voltage detection circuit 107 compares the voltage value of the storage capacitor 101 with a reference voltage. When the voltage value of the storage capacitor 101 is equal to or higher than the reference voltage, a HIGH signal is output, and when the voltage value of the storage capacitor 101 is smaller than the reference voltage, a LOW signal is output. When the signal output from the voltage detection circuit 107 is a HIGH signal, the control IC 105 transmits a LOW signal to the transistor 106, and the transistor 106 is turned on.

  The reference voltage generation circuit 108 is supplied with electric power from the storage capacitor 101 and generates a reference voltage serving as a comparison reference for comparison with a voltage value corresponding to the voltage value of the storage capacitor 101 by the voltage detection circuit 107. is there. The voltage detection circuit 107 and the reference voltage generation circuit 108 can be configured by a conventionally known circuit. For example, the reference voltage generation circuit 108 is supplied with power from the storage capacitor 101 by a series circuit of a constant current source and a diode, and generates a reference voltage by a forward voltage of the diode. The reference voltage is a value corresponding to a voltage equal to or higher than the driving voltage of various circuits of the IC tag circuit 103. The voltage detection circuit 107 includes a resistance circuit that divides the voltage value of the storage capacitor 101 and a comparator that compares the voltage obtained by the division and the forward voltage (reference voltage) of the diode. . Thereby, the voltage detection circuit 107 can determine whether or not the voltage value of the storage capacitor 101 is equal to or higher than the driving voltages of various circuits of the IC tag circuit 103.

  The wireless module 109 is driven by being supplied with power from the storage capacitor 101 when the transistor 106 is ON. Then, the digital data output from the control IC 105 is received, and a radio signal including this data is transmitted from the antenna 104.

  The light emitting diode 116 is connected to the 7th pin of the control IC 105 via a resistor, and blinks in accordance with a HIGH / LOW signal of digital data sent from the 7th pin. Thus, it can be visually recognized that the IC tag circuit 103 is driven, the solar cell 100 generates power, and power is supplied to various circuits of the IC tag circuit 103 so that the IC tag operates normally. Can be confirmed.

  Here, a flow until the radio signal is transmitted from the antenna 104 will be described. First, power is supplied from the storage capacitor 101 to the first pin of the control IC 105, and the control IC 105 is driven. The control IC 105 determines the signal output from the voltage detection circuit 107 input to the fifth pin of the control IC 105 at a fixed determination timing. When the determined signal is a HIGH signal, the control IC 105 transmits a LOW signal from the 6th pin of the control IC 105 to the transistor 106 to turn on the transistor 106. When the transistor 106 is turned on, power is supplied from the power storage capacitor 101 to the fifth pin of the wireless module 109, and the wireless module 109 is driven. Immediately after the wireless module 109 is driven, digital data is output from the 7th pin of the control IC 105 and received by the 3rd pin of the wireless module 109. Based on the received digital data, a wireless signal including this data is transmitted from the first pin of the wireless module 109 via the antenna 104. The light emitting diode 116 is connected via a resistor between the 7th pin of the control IC 105 and the 3rd pin of the wireless module 109, and blinks in accordance with the HIGH / LOW of the digital data.

  Next, the relationship between the voltage value of the storage capacitor 101 and the radio signal transmission interval will be described with reference to FIGS. FIG. 4 is a waveform diagram in each part of the IC tag circuit 103 when light is sufficiently irradiated. FIG. 5 is an enlarged view of a one-dot chain line portion of FIG. FIG. 6 is a waveform diagram in each part of the IC tag circuit 103 when light is not irradiated so much. 4 to 6, (a) is a waveform of the voltage determination timing of the storage capacitor 101, (b) is a voltage waveform of the storage capacitor 101, (c) is an output waveform of the 6th pin of the control IC 105, (d ) Is an output waveform of the 7th pin of the control IC 105.

  Here, a case where the wireless module 109 transmits a wireless signal at intervals of 1 sec will be described as an example. At this time, the voltage value of the storage capacitor 101 is determined according to the signal output from the voltage detection circuit 107 at intervals of 1 sec and at a determination timing about 100 msec before the normal transmission timing. For example, various circuits of the IC tag circuit 103 have a rating of 3V and are driven with a voltage of about 2.4 to 3.6V. The solar cell 100 generates power by the photoelectric effect and can store a maximum of 2.8 V in the capacitor for storage 101. The reference voltage generation circuit 108 sets the forward voltage of the diode serving as the reference voltage to 0.6 V and the resistance division ratio to 3: 1 so as to detect whether or not the voltage value of the storage capacitor 101 is 2.4 V or more. It is assumed that it is set. Note that the solar cell 100 constantly generates power by the photoelectric effect and charges the storage capacitor 101 when light is irradiated, regardless of the transmission state.

  First, at time T1 (100 msec before time T2), as shown in FIG. 4A, the voltage of the storage capacitor 101 is determined according to the signal output from the voltage detection circuit 107. Since this determination timing is a HIGH signal, a LOW signal for turning on the transistor 106 is transmitted from the 6th pin of the control IC 105 as shown in FIG. Accordingly, the wireless module 109 is driven while the transistor 106 is ON. Immediately after transmitting the LOW signal for turning on the transistor 106, as shown in FIG. 4D, digital data is transmitted from the 7th pin of the control IC 105, and the wireless module 109 transmits a wireless signal. And until time T3 which performs the next transmission, as shown in FIG.4 (b), the capacitor | condenser 101 for electrical storage is charged with the solar cell 100, and a voltage value rises.

  The vicinity of time T2 will be described in detail with reference to FIG. FIG. 5 shows the vicinity of time T2 on a finer time axis, and the vicinity of time T2 corresponds to the time from time T2 to time T5. During 12.7 msec from time T2 to T5, as shown in FIG. 5C, a LOW signal for turning on the transistor 106 is transmitted from the 6th pin of the control IC 105. Accordingly, the wireless module 109 is driven while the transistor 106 is ON. When the LOW signal for turning on the transistor 106 is transmitted, as shown in FIG. 5D, digital data is transmitted from the 7th pin of the control IC 105 for 9.1 msec from time T4 to T5. 109 transmits a radio signal. At this time, the voltage of the digital data transmitted from the 7th pin of the control IC 105 is 2.8 V at time T4. However, at time T5, the voltage drops to 2.3V. This is because the power of the storage capacitor 101 is consumed over time due to the power consumption accompanying the driving of the wireless module 109. The voltage value of the storage capacitor 101 decreases from 2.8V to 2.3V between times T2 and T5 as shown in FIG. 5 (b).

  Here, a case where the storage capacitor 101 is not sufficiently charged because the solar cell 100 is not irradiated with light due to an environment such as shade or rain will be described with reference to FIG. From time T7 to T8, as shown in FIG. 6C, the voltage of the storage capacitor 101 gradually decreases every time the wireless module 109 is driven. This is because the power consumed by driving the wireless module 109 is greater than the power charged in the storage capacitor 101 by the power generation of the solar battery 100. If radio signals are continuously transmitted at intervals of 1 sec in this environment, the supply voltages (voltages of the storage capacitor 101) of various circuits of the IC tag circuit 103 become equal to or lower than the drive voltage. Then, driving of various circuits stops due to insufficient driving voltage, and transmission of radio signals stops.

  Therefore, at time T9 (100 msec before time T10), the voltage of the storage capacitor 101 is determined according to the signal output from the voltage detection circuit 107 as shown in FIG. Since this determination timing is a LOW signal, a LOW signal for turning on the transistor 106 is not transmitted from the 6th pin of the control IC 105 as shown in FIG. That is, the driving of the wireless module 109 is stopped and the transmission of the wireless signal is stopped. While the driving of the wireless module 109 is stopped, no power is consumed by driving the wireless module 109 that consumes a large amount of power. Therefore, until the time T12 near the timing of the next transmission, FIG. As shown in b), the voltage value of the storage capacitor 101 increases. While the voltage value of the storage capacitor 101 is increasing, at time T11 immediately before time T12, which is the next determination timing, as shown in FIG. The determination is made according to the signal output from the detection circuit 107. Since this determination timing is a HIGH signal, a LOW signal for turning on the transistor 106 is transmitted from the 6th pin of the control IC 105 as shown in FIG. Accordingly, the wireless module 109 is driven while the transistor 106 is ON. Immediately after transmitting the LOW signal that turns on the transistor 106, as shown in FIG. 6D, digital data is transmitted from the 7th pin of the control IC 105, and the wireless module 109 transmits a wireless signal.

  Thus, the control IC 105 compares the voltage value of the storage capacitor 101 with the reference voltage by the voltage detection circuit 107 at a fixed determination timing. Based on the comparison result, the power supply interval to the wireless module 109 is changed by switching the transistor 106. As shown in FIG. 6, when the voltage value of the storage capacitor 101 is smaller than the reference voltage at the determination timing, the power supply interval to the wireless module 109 is controlled to be after the next determination timing. .

  Next, a control sequence of the control IC 105 will be described with reference to FIG. FIG. 7 is a flowchart showing a control sequence of the control IC 105.

  First, when the voltage value of the storage capacitor 101 is equal to or higher than the reference voltage of 2.4 V (S1: Yes), the control IC 105 transmits a LOW signal to supply power to the wireless module 109 to drive (S2). ). Then, the digital data is transmitted to the wireless module 109 (S3). At the determination timing (S4: Yes), it is again determined whether the voltage value of the storage capacitor 101 is 2.4 V or more (S1). Since light irradiation is low in environments such as shade and rain, when the voltage of the storage capacitor 101 is lower than 2.4 V (S1: No), the system waits until the next determination timing is reached (S4: No). At the next determination timing (S4: Yes), it is determined again whether the voltage value of the storage capacitor 101 is 2.4 V or more (S1).

  Here, an example of digital data generation (steps S2 and S3 in FIG. 7) will be described with reference to FIGS. FIG. 8 is a flowchart showing a control sequence for transmitting digital data. FIG. 9 is a waveform diagram of digital data.

  As described above, the control IC 105 turns on radio wave transmission in response to the ON state of power supply to the wireless module checked at a 1-sec cycle (S10: Yes) (S11). Then, a radio wave adjustment signal (High signal 500 μsec → Low signal 1.5 msec), which is signal A, is transmitted (S12). Subsequently, a frame synchronization signal (Low signal 100 μsec × 2 bytes → H, L100 μsec period inversion signal × 2 bytes) and a data start bit signal (High signal 100 μsec), which are signals B, are transmitted (S13, S14). Thereafter, a device code signal (1 byte, 100 μsec interval) and an ID code signal (4 bytes, 100 μsec interval), which are signals C, are transmitted (S15, S16). Then, a separator signal (L signal 100 μsec → H signal 100 μsec) as signal D is transmitted (S17). Finally, an ID code XOR signal (4 bytes, 100 μsec interval) which is a check bit signal E is transmitted (S18), and radio wave transmission is turned off (S19).

  In the above-described embodiment, an example in which a tantalum capacitor having a capacity of several μ to several tens μF is used as the storage capacitor 101 is described. However, an electric double layer capacitor having a large capacity, for example, 0.1 F or more may be used. Good. In this case, the electric double layer capacitor 101 is preferably formed in a sheet shape and placed on the back electrode layer 115 of the solar cell as shown in FIG. The electric double layer capacitor 101 is based on the principle of an electric double layer generated at the interface between activated carbon and electrolyte, and is a capacitor that functions as a secondary battery that can be repeatedly charged and discharged. The electric double layer capacitor 101 can store electric power generated by the solar cell 100 due to the photoelectric effect. As described above, by placing the electric double layer capacitor 101 on the surface side facing the light incident surface of the solar cell 100, the incidence of light is not blocked. Therefore, the light use efficiency of the solar cell 100 mounted on the IC tag can be maximized.

  As described above, according to the IC tag according to the present embodiment, the solar cell 100 capable of being formed by combining the n-type semiconductor layer 113 containing the basic dye and the p-type semiconductor layer 114 containing the electron-accepting compound. By using it, the photoelectric conversion characteristics of the solar cell 100 can be greatly improved. Thereby, since the photoelectric conversion efficiency per unit area is increased as compared with the conventional case, the plane area of the solar cell 100 can be reduced, and as a result, the IC tag can be reduced in size and the solar cell. The manufacturing process of the attached IC tag can be simplified.

  Further, even when light irradiation is low in an environment such as shade or rain, the power consumption by the wireless module 109 can be reduced by increasing the interval of power supply to the wireless module 109, and the storage capacitor 101 Voltage drop can be suppressed. As a result, it is possible to suppress the stop of transmission of radio signals due to the stop of driving of various circuits due to insufficient supply voltage to the various circuits of the IC tag circuit 103.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, in this embodiment, the storage capacitor 101 is directly connected to the IC tag circuit 103 and the IC tag circuit 103 is driven by the voltage of the storage capacitor 101. However, as shown in FIG. A DC / DC converter 117 may be connected between the capacitor 101 and the IC tag circuit 103 to boost the voltage of the storage capacitor 101 and drive the IC tag circuit 103.

  In the above-described embodiment, the power of the solar battery 100 is stored in the power storage capacitor 101. However, not only the power storage capacitor 101 but also an element that can store power, such as a secondary battery, may be used. .

  Furthermore, in the embodiment described above with reference to FIG. 10, the electric double layer capacitor 101 is placed on the solar cell 100, but as shown in FIG. 12, light enters from the upper side to the lower side on the paper surface. In such a case, the electric double layer capacitor 101 may be placed on the substrate 118, and the solar cell 100 may be formed on the electric double layer capacitor 101. Moreover, you may mount in the surface on the opposite side to the surface in which the solar cell 100 of the board | substrate 118 is formed.

  In addition, in the above-described embodiment, only one layer is hetero pn-junction to constitute the solar cell 100. However, according to necessary power, as shown in FIG. 13, the n-type semiconductor layer 113 and the p-type semiconductor layer 114 Are stacked in multiple layers, and a dual hetero pn junction may be used to obtain a desired voltage value necessary for driving the IC tag.

  Further, as shown in FIGS. 14A and 14B, the transparent electrode 122 and the back electrode layer 125 are divided, and the transparent electrode 122 and the back electrode layer 125 that are adjacent to each other are connected by the connection electrode 126, respectively. As a configuration in which cells are connected in series, a desired voltage value suitable for driving an IC tag may be obtained.

  Furthermore, in the above-described embodiment, when the power supply to the wireless module 109 is stopped, the power supply to the wireless module 109 is stopped until the next determination timing, but without waiting for the next determination timing, When the voltage value of the storage capacitor 101 is equal to or higher than the reference voltage, power may be supplied to the wireless module 109. That is, the wireless signal may be transmitted without waiting for the next determination timing.

  In addition, in the above-described embodiment, based on the result of comparing the voltage value of the storage capacitor 101 with the reference voltage by the voltage detection circuit 107, whether or not to supply power to the wireless module 109 is determined in binary. However, the interval for supplying power to the wireless module 109 may be determined based on the difference between the voltage of the storage capacitor 101 and the reference voltage. For example, when the voltage value of the storage capacitor 101 is smaller than the reference voltage, the interval for supplying power to the wireless module 109 may be increased in proportion to the difference.

  In the above-described embodiment, the power supply control for changing the interval of power supply to the wireless module 109 based on the voltage value of the storage capacitor 101 has been described for the case where a coated and formed solar cell is used as a power source. However, this power control can also be applied to the case where an electromotive force element such as another solar cell, for example, a solar cell using crystal or amorphous silicon, or a dye-sensitized organic solar cell is used as a power source.

It is a block diagram of the IC tag by one Embodiment of this invention. It is a schematic block diagram of a solar cell. It is a detailed block diagram of the IC tag by one Embodiment of this invention. It is a wave form diagram in each part of an IC tag circuit when light is fully irradiated. It is an enlarged view of the dashed-dotted line part of FIG. It is a wave form diagram in each part of an IC tag circuit when not much light is irradiated. It is a flowchart showing the control sequence of IC for control. It is a flowchart showing the control sequence which transmits digital data. It is a waveform diagram of digital data. It is a schematic block diagram of a solar cell and an electric double layer capacitor. It is a modification of an IC tag. It is a modification of the mounting position of an electric double layer capacitor. It is the modification which formed the solar cell by the dual hetero pn junction. It is the modification which formed the solar cell in series by the connection electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Solar cell 101 Capacitor for electrical storage 102 Schottky barrier diode 103 IC tag circuit 104 Antenna 105 IC for control
106 transistor 107 voltage detection circuit 108 reference voltage generation circuit 109 wireless module 110 electrically insulating transparent substrate 113 n-type semiconductor layer 114 p-type semiconductor layer 116 light emitting diode 1000 IC tag

Claims (4)

An IC tag that performs information communication with an external device by radio signal,
A solar cell coated on a substrate;
A storage capacitor connected to the solar cell via a backflow prevention circuit;
A transmitter for receiving a power supply from the storage capacitor and transmitting a radio signal;
A power supply control unit that controls power supply to the transmission unit at predetermined intervals, and
The solar cell is
An n-type semiconductor layer composed mainly of an electron-accepting inorganic substance and containing a basic dye;
An IC tag comprising: a p-type semiconductor layer comprising a material containing an electron-donating organic substance as a main component and an electron-accepting compound. An IC tag that performs information communication with an external device by radio signal,
A solar cell coated on a substrate;
A storage capacitor connected to the solar cell via a backflow prevention circuit;
A transmitter for receiving a power supply from the storage capacitor and transmitting a radio signal;
A power supply control unit that controls power supply to the transmission unit at predetermined intervals, and
The IC tag, wherein the power supply control unit changes a power supply interval to the transmission unit based on a voltage value of the storage capacitor.   The IC tag according to claim 1 or 2, wherein the storage capacitor is an electric double layer capacitor provided in contact with a surface facing the light incident surface of the solar cell. 4. The information processing apparatus according to claim 1, further comprising a notifying unit that notifies the outside of an output state of digital data for transmission generated in response to an operation of the power supply control unit. IC tag.

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