Abstract:
In order to manufacture a semiconductor device economically and effectively with good manufacturing yield, a power on reset circuit, which sometimes occupies one third of the entire chip area of the semiconductor device for radio frequency identification, is removed to achieve the downsizing of the semiconductor device. A semiconductor device for radio frequency identification comprises one or more flip-flop circuits, wherein an initialization element, functioning to determine that a certain output terminal of the flip-flop circuit is logically fixed to H or L when a power supply voltage is increased, is provided in the flip-flop circuit.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a semiconductor device for radio frequency identification (RFID) and to a reader for reading information stored in the semiconductor device, and, more particularly, to a technique effectively applied to: a flip-flop circuit in the device; a structure of a reader portion located close to the semiconductor device; and the like.  
           [0002]    For example, the following technique has been taken in an automatic identification technique as a technique examined by the inventor of the present invention.  
           [0003]    Containers, such as bottles etc. made of glass, plastic, or other materials, are used in various fields for housing and storing various medicines and samples. There is the possibility that contents in the containers will cause mixtures, chemical reactions or the like of various foreign matters during the manufacture or storage thereof. Therefore, it is necessary to check the contents at regular intervals during the manufacture or storage. Since the check results are automatically registered in a computer, the automatic identification technique has been required.  
           [0004]    Conventionally, a bar code or the like has been attached to the containers for this automatic identification. Also, as a substitute means for the bar cord, there has been used an IC chip for radio frequency identification (RFID), by which information such as identification (ID) numbers or the like, stored in an IC chip, can be read wirelessly from the outside, and therefore the RFID IC chips are attached to such containers as bottles etc.  
           [0005]    Note that the technique described in the gazette of Japanese Patent Laid-Open No. 2002-184872 is recited as an example of the technique relative to the above-mentioned RFID IC chip, and a power on reset circuit exists in FIG. 1 of the gazette, which shows the circuit configuration of the RFID IC chip.  
         SUMMARY OF THE INVENTION  
         [0006]    By the way, as a result of the examination of the technique relative to the RFID IC chip as mentioned above by the inventor, the followings have become apparent.  
           [0007]    That is, the sizes of the conventional bar code and RFID IC chip are not so small. Accordingly, when the size of the container is small, the adhesion space of these identification labels becomes insufficient in area, whereby these labels, adhering to the outside surface of the container, have hindered observations of the contents.  
           [0008]    Also, containers such as bottles etc. frequently have a rotating movement etc., so that, in the case of adhesion of the bar code or RFID IC chip to the outside surface of each container, the position thereof has been shifted at the time of reading the identification information, which causes the reading error. For such reason, there is required a technique for positioning: identification labels, such as a bar code and an RFID IC chip, etc., which adhere to the container; and information readers for reading the identification information of the bar code and the RFID IC chip, etc. Thus, it has been required to sacrifice the economical efficiency and the identification speed for an addition of an alignment device etc.  
           [0009]    Meanwhile, since there are a great number of containers such as bottles etc. and a wide variety of types of the containers, the RFID IC chips are designed for disposable use. Therefore, it is necessary to form the RFID IC chips economically. For its achievement, the downsizing of the IC chip and the improvement of its yield are required.  
           [0010]    However, the power on reset circuit has been in the conventional RFID IC chip as shown in FIG. 1 of the gazette of the Japanese Patent Laid-Open No. 2002-184872. The layout area of this power on reset circuit sometimes reaches the one third of the chip area, whereby the downsizing of the IC chip has been hindered.  
           [0011]    Accordingly, an object of the present invention is to achieve the downsizing of a semiconductor device, by removing the necessity of a power on reset circuit in a RFID semiconductor device (for example, RFID IC chip).  
           [0012]    Also, another object of the present invention is to position easily an information reader for the RFID semiconductor device and to permit the simple and high-speed reading of the data reader.  
           [0013]    The above and other objects and novel characteristics of the present invention will be apparent from the description of this specification and the accompanying drawings.  
           [0014]    The typical ones of the inventions disclosed in this application will be briefly described as follows.  
           [0015]    (1) More specifically, the RFID semiconductor device (RFID IC chip etc.) according to the present invention is characterized in that a flip-flop circuit, incorporated in the semiconductor device, includes an element functioning to logically fix the output of the flip-flop circuit to either H or L when a power supply voltage is increased.  
           [0016]    As described above, by adding said element thereto, the output of the flip-flop when the power supply voltage is increased is fixed to a predetermined value. Therefore, it is possible to eliminate the power on reset circuit and consequently achieve the downsizing of the semiconductor device.  
           [0017]    (2) Further, the RFID semiconductor device according to the present invention is characterized in that it is attached to the container so that the distance from the centerline of the container to the center of the semiconductor device is 3 mm or less.  
           [0018]    Accordingly, since the alignment can be facilitated by attaching the RFID semiconductor device on or near the centerline of the container, it becomes possible to easily identify the content in the container even if the container is rotated or the like.  
           [0019]    (3) Additionally, the RFID semiconductor device according to the present invention further comprises an antenna in the semiconductor device.  
           [0020]    Thereby, since the antenna is incorporated, an external attachment of the antenna becomes unnecessary, thereby allowing for achieving the cost reduction and the overall downsizing.  
           [0021]    (4) Moreover, the RFID semiconductor device according to the present invention is further characterized in that a check of the semiconductor device is performed when the semiconductor device is attached to the container or when the information stored in the semiconductor device is read.  
           [0022]    Therefore, a handling portion or reader portion has an opportunity to come close to or into contact with the semiconductor device when the RFID semiconductor device is attached to the container or when the information is read by the reader. At this time, a quality check of the chip and a removal of the defective product can be automatically carried out.  
           [0023]    (5) Further, the reader for the RFID semiconductor device according to the present invention comprises: a conveyor unit; a plurality of holders for fixing the container to which the semiconductor device is attached; and a plurality of reader portions each located close to the semiconductor device and having an antenna for reading the information stored in the semiconductor device.  
           [0024]    By adopting the structure as described above, the RFID semiconductor device and the reader portion are faced with each other on a conveyor unit such as a belt conveyer etc. for a predetermined time. Therefore, it is possible to ensure sufficient time to read the information and to carry out the high-speed identification of a large number of containers.  
           [0025]    (6) Also, the RFID semiconductor device according to the present invention is attached to the lid or the bottom of the container so that the center of the semiconductor device is made to coincide with the container of the centerline.  
           [0026]    Accordingly, since the center of the semiconductor device is made to coincide with the centerline of the container, the alignment thereof is further facilitated.  
           [0027]    (7) Further, the reader for the RFID semiconductor device according to the present invention comprises: the holder for fixing the container to which the semiconductor device according to item (1) is attached; and an antenna located coincident with the centerline of the container and brought into contact with the semiconductor device to read the information stored in the semiconductor device.  
           [0028]    Therefore, the structure as described above makes it possible to ensure sufficiently the communication distance between the semiconductor device and the antenna. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    [0029]FIG. 1 is a circuit diagram showing a configuration of a flip-flop circuit incorporated in a RFID semiconductor device according to a first embodiment of the present invention.  
         [0030]    [0030]FIG. 2 is a diagram showing the state where the RFID semiconductor device, according to a second embodiment of the present invention, is attached to the bottom of a container.  
         [0031]    [0031]FIG. 3 is a diagram showing the state where the RFID semiconductor device, according to the second embodiment of the present invention, is attached to the lid of the container.  
         [0032]    [0032]FIG. 4 is a diagram showing the structure of a reader according to a third embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
         [0034]    (First Embodiment)  
         [0035]    [0035]FIG. 1 is a circuit diagram showing the configuration of a flip-flop circuit incorporated in a RFID semiconductor device according to a first embodiment of the present invention.  
         [0036]    First, an example of the circuit configuration of the flip-flop circuit incorporated in the RFID semiconductor device according to the first embodiment will be described with reference to FIG. 1.  
         [0037]    There is a counter inside the RFID IC chip serving as the RFID semiconductor device, and a plurality of flip-flop circuits are used as basic circuits of the counter.  
         [0038]    The flip-flop circuit according to the first embodiment, for example, includes: a first gate circuit  12  such as a two-input NAND gate etc.; a second gate circuit  15  such as a two-input NAND gate etc.; and an initialization element  16  such as a capacitor etc. In FIG. 1, NAND gates used as the first gate circuit  12  and the second gate circuit  15  are shown, but NOR gates may be used as them. Also, the initialization element  16  may be a resistor, an inductance, a transistor, the combination thereof, or the like instead of the capacitor.  
         [0039]    An input terminal  11  of the flip-flop circuit shown in FIG. 1 is one of inputs of the first gate circuit  12 , and an output of the first gate circuit  12  is connected to an output terminal  13  of the flip-flop circuit. The output terminal  13  of the flip-flop circuit serves as an output and also serves as one of inputs of the second gate circuit  15 . The initialization element  16  is connected to an output of the second gate circuit  15 . Also, the output of the second gate circuit  15  is connected to the other input of the first gate circuit  12 . Furthermore, a reset terminal  14  of the flip-flop circuit is provided to the other input of the second gate circuit  15 .  
         [0040]    Next, an operation of the first embodiment will be described based on a function of the flip-flop circuit.  
         [0041]    First, when a power supply voltage is gradually increased from zero, a level of each terminal in the flip-flop circuit is indefinite during its initial period. Therefore, even when the power supply voltage is sufficiently increased in the absence of the initialization element  16 , the level of the output terminal  13  remains indefinite as long as the input terminal  11  or reset terminal  14  does not become logically equivalent to L.  
         [0042]    Meanwhile, it takes time to charge the initialization element  16  in the presence of the initialization element  16  (for example, capacitor). Accordingly, when the power supply voltage is sufficiently increased, the input of the first gate circuit  12  becomes logically equivalent to L if the voltage of the initialization element  16  is equal to or lower than a threshold voltage of the first gate circuit  12  (for example, two-input NAND), and further the output terminal  13  is initialized to H level.  
         [0043]    In the semiconductor device such as an RFID IC chip according to the first embodiment, a battery-less operation can be made by supplying energy to the inside thereof using electromagnetic waves. The inner circuit configuration, disclosed in the gazette of Japanese Patent Laid-Open No. 2002-184872, can be taken as an example of the inner circuit configuration of the conventional RFID IC chip. A counter constituted by flip-flop circuits exists in the inner circuit of this RFID IC chip.  
         [0044]    In such circuit, when the power supply voltage is increased, the output of the flip-flop circuit becomes indefinite and the function thereof becomes unstable. Therefore, there is required the power on reset circuit used for the initialization when the power supply voltage is increased.  
         [0045]    By using the flip-flop circuit according to the first embodiment, the initialization can be done automatically and therefore the power on reset circuit becomes unnecessary.  
         [0046]    More specifically, in the RFID IC chip including one or more flip-flop circuits, the flip-flop circuit has therein the initialization element  16 , which functions to determine that a certain output terminal of the flip-flop circuit is logically fixed to H or L when the power supply voltage is increased, whereby the power on reset circuit becomes unnecessary.  
         [0047]    In the field of RFID, particularly, in the field of automatic identification as used by the conventional bar cord, a wide range of applications is expected because of: a price-reduction of the reader; a high-security not altered easily of the reader; a large amount of data stored; readability of the information even in the shielding; and the like. However, there has been a problem of the cost reduction in the chip due to the large chip size.  
         [0048]    The manufacturing cost of one silicon wafer is generally determined by the umber of masks used if the process thereof is identical. Therefore, the smaller the chip size is, the lower the manufacturing cost can be.  
         [0049]    For example, if the chip size is changed from a 0.3 mm square to a 0.15 mm square, the number of chips to be obtained is quadrupled. Therefore, the cost per chip is reduced to a quarter thereof.  
         [0050]    As described in the first embodiment according to the present invention, if the state of the flip-flop circuit is automatically determined when the voltage is increased, the power on reset circuit occupying the one third of the chip area becomes unnecessary, thereby allowing for effectively reducing the chip area.  
         [0051]    (Second Embodiment)  
         [0052]    [0052]FIG. 2 is a diagram showing the state where the RFID IC chip as an RFID semiconductor device, according to a second embodiment of the present invention, is attached to the bottom of a container thereof. FIG. 3 is a diagram showing the state where the RFID semiconductor device, according to the second embodiment of the present invention, is attached to the lid of the container thereof.  
         [0053]    As an example of the structure in the second embodiment, in a container  23  such as a bottle etc., an RFID IC chip  21  is attached in the vicinity of a container centerline  25  on the bottom  24  of the container as shown in FIG. 2.  
         [0054]    [0054]FIG. 3 shows an example of the structure where the RFID IC chip  21  is attached in the vicinity of the container centerline  25  on the upper surface of a container lid  22 .  
         [0055]    Also, though not shown in FIG. 2, a reader portion including an antenna etc. is located so as to contact the RFID IC chip  21  in reading the data stored in the RFID IC chip  21 .  
         [0056]    In addition, since the data reading is performed in a non-contact manner, it is necessary to connect the antenna to the RFID IC chip  21 . However, the antenna may be provided inside the RFID IC chip  21 .  
         [0057]    Conventionally, the bar code and the like have been used to identify the contents of the container  23  such as a bottle etc. However, in checking the inside of the container  23 , there is sometimes the case where the bar code becomes a hindrance and thereby is of no use. In that respect, such disadvantage can be eliminated if the minute RFID IC chip  21  is attached to the bottom or the lid of the container  23 .  
         [0058]    In the case of the minute IC chip in the RFID, for example, a small IC chip with a 0.3 mm square or an IC chip in which a minute antenna is incorporated, it is sometimes difficult to ensure a sufficient communication distance. This is because, since the RFID IC chip receives power supply from the outside by the electromagnetic waves in many cases, the reduction in energy acquisition area inevitably causes that in the communication distance. Therefore, it becomes necessary to align the data reader portion with the IC chip so that the distance therebetween can be set at 1 mm or less. If it is guaranteed that the container such as a bottle etc. has a circular form when viewed from the top or bottom thereof, then a technique of the alignment of the centers of circles is required. Therefore, it is possible to perform the alignment in a simple manner.  
         [0059]    At this time, better effects can be obtained if the distance between the centerline of the container and the center of the IC chip is within a range of 3 mm.  
         [0060]    (Third Embodiment)  
         [0061]    [0061]FIG. 4 is a diagram showing the structure of a reader according to a third embodiment of the present invention.  
         [0062]    First, an example of the structure according to the third embodiment will be described with reference to FIG. 4.  
         [0063]    The reader according to the third embodiment, for example, is constituted from: container positioning mechanisms  31   a ,  31   b  and  31   c ; reading heads  32   a ,  32   b  and  32   c ; coaxial lines  33   a ,  33   b  and  33   c ; RFID IC chips  34   a ,  34   b  and  34   c ; containers  35   a ,  35   b  and  35   c ; a conveyor unit  36  such as a belt conveyer etc.; a suction-attachment device  37 ; and the like. The container positioning mechanisms  31   a  to  31   c  are provided on the conveyor unit  36 , and the coaxial lines  33   a  to  33   c  with reading heads  32   a  to  32   c  are attached into the container positioning mechanisms  31   a  to  31   c , respectively. Also, an antenna is arranged in each of the reading heads  32   a  to  32   c.    
         [0064]    Next, a method of reading information will be described.  
         [0065]    The first container positioning mechanism  31   a  is provided on the conveyor unit  36 , and the first coaxial line  33   a  with the first reading head  32   a  is attached to the first container positioning mechanism  31   a . The first container  35   a , to which the first RFID IC chip  34   a  is attached, is placed on and aligned with the first container positioning mechanism  31   a , and then both of them are fixed. Subsequently, the information, stored in the first RFID IC chip  34   a , is read by the first reading head  32   a  in a non-contact manner.  
         [0066]    Similarly, the second container positioning mechanism  31   b  is provided on the conveyor unit  36 , and the second coaxial line  33   b  with the second reading head  32   b  is attached to the second container positioning mechanism  31   b . The second container  35   b , to which the second RFID IC chip  34   b  is attached, is placed on and aligned with the second container positioning mechanism  31   b , and then both of them are fixed. Subsequently, the information, stored in the second RFID IC chip  34   b , is read by the second reading head  32   b  in a non-contact manner.  
         [0067]    Similarly, the third container positioning mechanism  31   c  is provided on the conveyor unit  36 , and the third coaxial line  33   c  with the third reading head  32   c  is attached to the third container positioning mechanism  31   c . The third container  35   c , to which the third RFID IC chip  34   c  is attached, is separated from the third container positioning mechanism  31   c  by the suction-attachment device  37  after the finish of the information reading.  
         [0068]    More specifically, the information (for example, 128 bit ID number etc.), stored in the RFID IC chips  34   a  to  34   c , is read in the following manner. That is, the containers  35   a  to  35   c  are placed on the container positioning mechanisms  31   a  to  31   c , respectively. Thereby, the alignment thereof is automatically performed, whereby the RFID IC chips  34   a  to  34   c , attached close to the centerlines of the containers  35   a  to  35   c , come close to the reading heads  32   a  to  32   c , respectively. Thereafter, the plurality of containers  35   a  to  35   c  are respectively made into contact with the plurality of reading heads  32   a  to  32   c  in a one-to-one manner, and thereby the information, stored in the RFID IC chips  34   a  to  34   c , is read through the reading heads  32   a  to  32   c . The information to be read is ID numbers or the like of objects, and the read information is recorded in a data processing system via a wireless LAN system etc.  
         [0069]    In FIG. 4, there are shown, as an example, three sets of container positioning mechanisms  31   a  to  31   c , reading heads  32   a  to  32   c , coaxial lines  33   a  to  33   c , RFID IC chips  34   a  to  34   c , and containers  35   a  to  35   c . However, the example shown in FIG. 4 is not limited to the above structure and there is no limitation on the number of components as long as a plurality of components are provided.  
         [0070]    Also, movement from the outside is added to liquid medicine, which is poured in the container such as a bottle etc., by agitation or the like, and thereby the mixing of foreign matters therein is checked in various places. Since these containers are rapidly moved, for example, at a movement speed of 10 to 50 bottles per second, it is necessary to ensure the alignment and the reading time in order to rapidly read the information by the RFID.  
         [0071]    Further, since the chip for the RFID adheres to the lid or bottom of the above-mentioned container, it is necessary to align the minute IC chip with the reading head. The container has a cylindrical shape in general, and the alignment thereof can be facilitated if the configuration of a member holding the container also has a cylindrical or conical shape for the purpose of aligning the centers of cylindrical members with each other.  
         [0072]    The container positioning mechanisms  31   a  to  31   c  used for the alignment are arranged on the conveyor unit  36 , the containers  35   a  to  35   c  are sequentially located and aligned with the container positioning mechanisms  31   a  to  31   c , and the information is read therefrom. If the reading heads  32   a  to  32   c  are moved in synchronization with the container positioning mechanisms  31   a  to  31   c  for a predetermined time, the alignment and the reading time can be ensured. If the synchronizing time thereof can be ensured, the movement speed of the conveyor unit  36  can be increased, thereby allowing for performing the high-speed automatic identification of a great number of containers.  
         [0073]    Also, in the above-described embodiments, a handling device (not shown) or the reading heads  32   a  to  32   c  have an opportunity to come close to or into contact with the RFID IC chip  21  when the RFID IC chip  21  is attached thereto or when the information stored in the RFID IC chip  21  is read by the reader. Therefore, at this time, a quality check of the chip and a removal of the defective product can be automatically performed.  
         [0074]    In the foregoing, the invention made by the inventor has been concretely described based on the embodiments. However, needless to say, the present invention is not limited to the foregoing embodiments and can be variously modified and changed without departing from the gist thereof.  
         [0075]    For example, in the above-described embodiments, there has been described the case where a cylindrical container such as a bottle etc. is used as an example of the shape of the container. However, the shape thereof is not limited to this case, and may be applied as a shape such as a columnar, conical, polygonal columnar, polygonal cone, cup shape, or the like.  
         [0076]    The advantages achieved by the typical ones of the inventions disclosed in this application will be briefly described as follows.  
         [0077]    (1) There is adopted the configuration such that, when the power supply voltage of the RFID semiconductor device is increased, the output of the flip-flop circuit in the semiconductor device is set to a predetermined level. Therefore, it is possible to remove the power on reset circuit, which conventionally occupies one third of the chip area, and thereby downsizing the RFID semiconductor device.  
         [0078]    (2) Since the RFID semiconductor device is provided on the container centerline or close thereto, the alignment can be facilitated. The identification of the content of the container can be simply performed even if the container is rotated.  
         [0079]    (3) There is adopted the configuration such that the RFID semiconductor devices and the reading heads are made into contact in a one-to-one manner for a predetermined time on the conveyor unit. Therefore, it is possible to obtain sufficient time to identify the content, and rapidly identify the contents in many containers.  
         [0080]    (4) The handling device or reader portions have an opportunity to come close to or into contact with the RFID semiconductor device when the RFID semiconductor device is attached to the container or when the information is read by the reader. Therefore, at this time, the quality check of the chip and the removal of the defective product can be automatically performed.