Patent Publication Number: US-2005140534-A1

Title: Resistance voltage divider circuit, liquid crystal display driving apparatus using resistance voltage divider circuit, and liquid crystal display apparatus

Description:
FIELD OF THE INVENTION  
      The present invention relates to a resistance voltage divider circuit included in a gradation voltage generation circuit.  
     BACKGROUND OF THE INVENTION  
      A gradation voltage generation circuit generates a gradation voltage for driving a display device such as a liquid crystal element. For example, when a liquid crystal element is driven in a liquid crystal display apparatus, two or more reference voltages are first inputted to the gradation voltage generation circuit. The gradation voltage generation circuit minutely divides a voltage between the reference voltages so as to generate gradation voltages (or gradation voltages for γ correction) necessary for driving the liquid crystal element.  
      Further, more gradation voltages are necessary because display panels such as recent liquid crystal panels display more colors with higher definition. Thus, a voltage difference has decreased between adjacent gradations. This means that a gradation voltage generation circuit formed by resistors requires resistors having low resistance values with high accuracy.  
      For example, a known gradation voltage generation circuit is disclosed in Japanese Patent Laid-Open No. 11-95726. The gradation voltage generation circuit has a resistance voltage divider circuit comprising resistors which include a plurality of reference resistors connected in series. The resistance voltage divider circuit selects the junction points of the reference resistors among the resistors and connects selected reference points, so that the resistance values of voltage dividing resistors can be set minutely. A reference voltage is applied across the resistors to obtain a gradation voltage necessary for the connected reference points. Further, the gradation voltage generation circuit has a resistance wiring layer on each gradation voltage wiring layer via an interlayer insulating film. The gradation voltage wiring layer and the resistance wiring layer are connected to each other via a contact (or a through hole) to constitute each resistance voltage divider circuit.  
      Since it is better to have a lower resistance on the contact, the contact is generally made of a material having a low resistance value. One of the materials having low resistance values is a metal compound of silicon that is called silicide. Because of restrictions on the manufacturing of semiconductors, when the contact is silicified, a resistor under the contact is also silicified. Meanwhile, the resistor is made of a material other than silicide (hereinafter, referred to as non-silicide) in many cases to efficiently form a resistance component in a small area. Therefore, when the resistor is made of a material other than silicide, two materials of silicide and non-silicide are present in the resistor. It is known that a resistance component called an interface resistance appears on an interface between silicide and non-silicide and the interface resistance has a constant value regardless of a resistance range during the manufacturing of semiconductors.  
      When gradation voltages are minutely generated in the resistance voltage divider circuit, it is necessary to accurately generate resistance components with low resistance values. However, in the presence of a large interface resistance component on an interface between a resistor near a contact and an ordinary resistor, it is difficult to generate a low resistance value equal to or lower than the interface resistance.  
     DISCLOSURE OF THE INVENTION  
      The present invention is devised to solve these problem and has as its object the provision of a resistance voltage divider circuit which can accurately form resistors with low resistance values and minutely generate gradation voltages even when a contact (or a through hole) and the resistor are made of different materials such as silicide and non-silicide and an interface resistance occurs on a boundary of the contact and the resistor, and provide a liquid crystal display driving apparatus and a liquid crystal display apparatus which use the resistance voltage divider circuit.  
      In order to attain the object, the resistance voltage divider circuit of the present invention comprises a plurality of resistors which are equal in resistance value and have contacts at equal positions, wherein the contacts at the equal positions of the resistors are connected to one another so as to connect the resistors in parallel, a reference voltage is inputted across the resistors connected in parallel, and a gradation voltage is generated on a junction point of the contact according to a voltage divided by the resistors.  
      With this configuration, the plurality of resistors having the contacts at the equal positions are connected in parallel, so that even when the resistors have a high interface resistance, it is possible to accurately generate the resistors with low resistance values. Therefore, it is possible to more minutely generate gradation voltages with high accuracy.  
      A liquid crystal display driving apparatus using the resistance voltage divider circuit of the present invention comprises the resistance voltage divider circuit and a DA converter circuit for outputting an analog voltage (driving voltage) according to a gradation voltage outputted from the resistance voltage divider circuit and an inputted digital command value.  
      With this configuration, the DA converter circuit outputs a gradation voltage outputted from the resistance voltage divider circuit, as an analog voltage corresponding to the digital command value, thereby driving the liquid crystal element according to an accurate gradation voltage. Therefore, it is possible to improve gradation display, that is, the quality of display on a liquid crystal panel and so on.  
      A liquid crystal display apparatus using the resistance voltage divider circuit of the present invention comprises a plurality of liquid crystal devises formed on a substrate, drive wires which are formed on the substrate and have the plurality of liquid crystal elements connected in a shared manner via a plurality of TFTs, and the liquid crystal display driving apparatus which is connected to the drive wires and drives the drive wires by outputting an analog voltage.  
      With this configuration, it is possible to apply an accurate gradation voltage (analog voltage) from the liquid crystal display driving apparatus to the drive wires of the liquid crystal elements. Therefore, it is possible to improve gradation display, that is, the quality of display on the liquid crystal display apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a structural diagram showing a resistance voltage divider circuit for a liquid crystal display driving apparatus according to Embodiment 1 of the present invention;  
       FIG. 2  is an explanatory drawing showing a parallel resistance of the resistance voltage divider circuit for the liquid crystal display driving apparatus;  
       FIG. 3  is a structural diagram showing a resistance voltage divider circuit for a liquid crystal display driving apparatus according to Embodiment 2 of the present invention;  
       FIG. 4  is a structural diagram showing a resistance voltage divider circuit for a liquid crystal display driving apparatus according to Embodiment 3 of the present invention;  
       FIG. 5  is a structural diagram showing a resistance voltage divider circuit for a liquid crystal display driving apparatus according to Embodiment 4 of the present invention;  
       FIG. 6  is a structural diagram showing a liquid crystal display driving apparatus of the present invention; and  
       FIG. 7  is a structural diagram showing a liquid crystal display apparatus of the present invention. 
    
    
     DESCRIPTION OF THE EMBODIMENTS  
      Embodiments of the present invention will be described below in accordance with the accompanying drawings. All the following embodiments will describe examples in which a resistance voltage divider circuit of the present invention is applied to a liquid crystal display apparatus and a liquid crystal display driving apparatus.  
     Embodiment 1  
       FIG. 1  is a structural diagram showing the resistance voltage divider circuit for a liquid crystal display driving apparatus (a resistance voltage divider circuit included in a gradation voltage generation circuit which generates a gradation voltage for driving a liquid crystal element) according to Embodiment 1 of the present invention.  
      As shown in  FIG. 1 , a plurality of (three in  FIG. 1 ) resistors  11  are provided which are almost equal in resistance value and have a plurality of (seven in  FIG. 1 ) contacts  12 , on which gradation voltages are extracted, at the equal positions with respect to the horizontal direction of  FIG. 1 . Resistance values between the contacts  12  of the three resistors  11  have the relationship of R 11 :R 12 :R 13 : . . . :R 16 =R 21 :R 22 :R 23 : . . . :R 26 =R 31 :R 32 :R 33 : . . . :R 36  where R 11 , R 12 , R 13 , . . . R 16  represent resistance values between the contacts of a first resistor of the resistors  11 , R 21 , R 22 , R 23 , . . . R 26  represent resistance values between the contacts of a second resistor, and R 31 , R 32 , R 33 , . . . R 36  represent resistance values between the contacts of a third resistor.  
      In a preferred embodiment, the plurality of resistors  11  are almost equal in resistance value. In this case, “almost equal” means that the resistance values of the plurality of resistors  11  are all regarded as equal as long as variations in manufacturing conditions are negligible in the manufacturing of semiconductors. For example, in the preferred embodiment, the resistors  11  are formed as wiring layers which are made of polysilicon or the like and are almost equal in length and width in the manufacturing of semiconductors, so that the resistors  11  are almost equal in resistance value. In the present specification, “almost equal” will comply with this use.  
      The contacts  12  at the equal positions of the resistors  11  are connected to one another via gradation voltage output wires  13  so as to connect the resistors  11  in parallel. Reference voltages V 1  and V 2  are inputted to reference voltage supply wires  14 , which are provided on the contacts  12  on both ends of the resistors  11  connected in parallel, and gradation voltages V 51 , V 52 , V 53 , V 54 , and V 55  are generated on the junction points (wires  13 ) of the intermediate five contacts  12  according to voltages divided by the three resistors  11 .  
      To be specific, the resistance voltage divider circuit shown in  FIG. 1  is formed as follows:  
      First, the resistors  11  formed by N+ polysilicon resistors are provided on a substrate. Then, the gradation voltage output wires  13 , which intersect the resistors  11  and are made of a material such as aluminum, are provided on the resistors  11  via an interlayer insulating film (not shown). Subsequently, the resistors  11  and the gradation voltage output wires  13  are connected via the contacts  12  made of a material having a low resistance value (e.g., a metal compound of silicon that is called silicide).  
      In the case of two parallel resistors shown in  FIG. 2 , the relationship of 1/RA=1/R 1 +1/R 2  is established where RA represents a combined resistance and R 1  and R 2  represent resistance values. In the case of R 1 =R 2 =R, 1/RA=2/R, i.e., RA=R/2 is established which is obtained by dividing the original resistance value by the number of resistors. When N resistors of resistance value R are connected in parallel (N is a positive integer equal to or larger than 2), a combined resistance value RN is RN=R/N. Also in the case of R 1 ≠R 2 , the relationship between R 1  and R 2  and the combined resistance RA satisfies R 1 &gt;RA and R 2 &gt;RA. Therefore, it is understood that the more resistors connected in parallel, the lower combined resistance.  
      According to the configuration of Embodiment 1, the three resistors  11  are provided on which resistance values are almost equal and the contacts  12  for extracting gradation voltages are arranged at the equal positions, the contacts  12  at the equal positions are connected via the gradation voltage output wires  13 , and the resistors  11  are connected in parallel, so that the resistors  11  between the contacts  12  are connected in parallel and a resistance value between the contacts  12  can be reduced. Thus, even when a large resistance component (interface resistance) is present on an interface between the resistor  11  near the contact  12  and the resistors  11  on other areas, it is possible to accurately form resistors with low resistance values and minutely generate gradation voltages V 51 , V 52 , V 53 , V 54 , and V 55 . Since the contacts  12  are arranged in lines, wiring for extracting gradation voltages from the contacts  12  can be formed with ease, thereby readily performing layout.  
      Embodiment 1 described the example of the three resistors  11 . As is understood from the effect of the combined resistance, it is preferable to provide the two or more resistors  11 . Further, Embodiment 1 described the example of the seven contacts  12  provided on the resistors  11 . Even in the presence of an interface between silicide (the resistor  11  under the contact  12 ) and non-silicide (other than the resistor  11  under the contact  12 ), the effect of the present invention can be obtained by the resistors  11  configured using a combined resistance on non-silicide portions. That is, at least one contact  12  is necessary on the resistor  11  except for the contacts with the reference voltage supply wires  14 . The effect of the present invention can be obtained by providing at least one gradation voltage output wire  13 .  
     Embodiment 2  
       FIG. 3  is a structural diagram showing a resistance voltage divider circuit for a liquid crystal display driving apparatus according to Embodiment 2 of the present invention.  
      As shown in  FIG. 3 , 2N (N is an positive integer equal to or larger than 2) resistors  21  (four in  FIG. 3 ) having almost equal resistance values are sequentially arranged in parallel with aligned longitudinal directions, and contacts  22  are provided on both ends of the resistors  21 . Of the resistors  21  arranged in sequence, on the uppermost and second uppermost resistors  21  in  FIG. 3 , contacts  23  are provided at the equal positions with respect to the horizontal direction of  FIG. 3 . On the third and fourth uppermost resistors  21  in  FIG. 3 , contacts  24  are provided at the equal positions with respect to the horizontal direction of  FIG. 3 . The embodiment of  FIG. 3  shows an example in which the positions of the contacts  24  are different from those of the contacts  23  with respect to the horizontal direction. No problem is presented even when the positions of the contacts  24  are the same as the contacts  23  with respect to the horizontal direction.  
      Further, the contacts  23  on the uppermost and second uppermost resistors  21  in  FIG. 3  are connected to each other via gradation voltage output wires  25 . The contacts  24  on the third and fourth uppermost resistors  21  in  FIG. 3  are connected to each other via gradation voltage output wires  26 . The contacts  22  on the ends of the odd-numbered resistors  21  (the uppermost and third uppermost resistors  21  in  FIG. 3 ) are connected sequentially via a connecting wire  27 . The contacts  22  on the ends of the even-numbered resistors  21  (the second and fourth uppermost resistors  21  in  FIG. 3 ) are connected sequentially via a connecting wire  28 .  
      The contacts  22  on the leading edges of the first and second resistors  21  are connected to each other, and the contacts  22  on the leading edges of the (2N−1)-th and 2N-th resistors  21  (third and fourth resistors  21  in  FIG. 3 ) are connected to each other. Reference voltages V 1  and V 2  are inputted to the connected ends via reference voltage supply wires (not shown), and gradation voltages V 61 , V 62 , V 63 , V 64 , V 65  and V 66  are generated on the junction points (gradation voltage output wires  25 ) of the contacts  23  and the junction points (gradation voltage output wires  26 ) of the contacts  24  according to voltages. divided by the resistors  21 .  
      To be specific, the resistance voltage divider circuit of  FIG. 3  is formed as follows:  
      First, the resistors  21  formed by N+ polysilicon resistors are provided on a substrate. Then, the gradation voltage output wires  25  and  26  and the connecting wires  27  and  28 , which intersect the resistors  21  and are made of a material such as aluminum, are provided on the resistors  21  via an interlayer insulating film (not shown). Subsequently, a resistance wiring layer and a gradation voltage wiring layer are connected via the contacts  22 ,  23 , and  24  made of a material having a low resistance value (e.g., a metal compound of silicon that is called silicide).  
      Embodiment 2 is similar to the configuration of Embodiment 1 in a principle that the plurality of resistors  21  are connected in parallel to reduce a resistance value. In Embodiment 2, the odd-numbered resistors  21  are connected to each other and the even-numbered resistors  21  are connected to each other, that is, the 2N resistors  21  are alternately connected, thereby reducing the influence of in-plane variations in resistance during a process of manufacturing resistors.  
      When resistors are fabricated in the manufacturing of semiconductors, generally an impurity is diffused into a material of the resistors to control a resistance value. At this point, a concentration of the impurity is varied to a certain degree in a wiring layer which forms the resistors. For this reason, in the case of the resistors arranged in a simple manner as the layout of  FIG. 1 , the first resistor  21  and the last (2N-th) resistor  21  may have a large difference in resistance value. In contrast, when the resistors  21  are alternately connected, that is, the first and third resistors are connected to each other and the second and fourth resistors are connected to each other as shown in  FIG. 3 , it is possible to reduce the influence of in-plane variations in resistance. Therefore, with the layout configuration of  FIG. 3 , even when the resistors have a large interface resistance, it is possible to accurately form the resistors with low resistance values while reducing the influence of the in-plane variations of the resistors  21 , thereby minutely generating gradation voltages.  
     Embodiment 3  
       FIG. 4  is a structural diagram showing a resistance voltage divider circuit for a liquid crystal display driving apparatus according to Embodiment 3 of the present invention.  
      As shown in  FIG. 4 , a first resistor  33  is provided which has contacts  31  on both ends and a plurality of (four in  FIG. 4 ) contacts  32 - 1  to  32 - 4  between both ends. Further, only on portions requiring low resistances, second resistors are provided so as to face the contacts  32 - 1  to  32 - 4  of the first resistor  33 . In  FIG. 4 , a second resistor  34  having contacts  37  on both ends is provided in parallel with the first resistor  33  so as to face the contacts  32 - 1  and  32 - 2  of the first resistor  33 , and two second resistors  35  and  36 , each of which has contacts  37  on both ends, are provided in parallel with the first resistor  33  so as to face the contacts  32 - 3  and  32 - 4  of the first resistor  33 .  
      Further, the contacts  32 - 1  and  32 - 2  of the first resistor  33  and the contacts  37  on both ends of the second resistor  34  are connected via gradation voltage output wires  38 . The contacts  32 - 3  and  32 - 4  of the first resistor  33  and the contacts  37  on both ends of the two second resistors  35  and  36  are connected via gradation voltage output wires  39 . Reference voltages V 1  and V 2  are inputted across (contacts  31 ) the first resistor  33  via a reference voltage supply wire (not shown), and gradation voltages V 71 , V 72 , V 73 , and V 74  are generated on the junction points (wires  38  and  39 ) of the contacts  32 - 1  to  32 - 4  and  37  according to voltages divided by the first resistor  33 .  
      To be specific, the resistance voltage divider circuit of  FIG. 4  is formed as follows:  
      First, the resistors  33 ,  34 ,  35 , and  36  formed by N+ polysilicon resistors are provided on a substrate. Then, the gradation voltage output wires  38  and  39 , which intersect the resistors  33 ,  34 ,  35 , and  36  and are made of a material such as aluminum, are provided on the resistors  33 ,  34 ,  35 , and  36  via an interlayer insulating film (not shown). Subsequently, the resistors  33 ,  34 ,  35 , and  36  and the gradation voltage output wires  38  and  39  are connected via the contacts  32 - 1  to  32 - 4  and  37  made of a material having a low resistance value (e.g., a metal compound of silicon that is called silicide).  
      According to Embodiment 3, the basic resistance voltage divider circuit for a liquid crystal display driving apparatus is constituted of the single first resistor  33 , and the second resistors  34 ,  35 , and  36  are connected in parallel, so that the resistors can be accurately formed with a low resistance value and gradation voltages can be generated minutely. Further, the second resistors  34 ,  35 , and  36  are connected in parallel only on portions having low resistance values which are necessary for minutely generating gradation voltage differences. Thus, in contrast to a configuration having a number of resistors of equal lengths with a large layout area, the resistors are arranged in parallel only on portions necessary for low resistances, so that a layout area can be reduced.  
     Embodiment 4  
       FIG. 5  is a structural diagram showing a resistance voltage divider circuit for a liquid crystal display driving apparatus according to Embodiment 4 of the present invention.  
      As shown in  FIG. 5 , a plurality of (threein  FIG. 5 ) resistors  41  are provided in parallel the vertical direction of  FIG. 5 . The resistors  41  are almost equal in resistance value and have a plurality of ((n+1):n is a positive integer equal to or larger than 2) contacts  42 , on which gradation voltages are extracted, at the equal positions with respect to the horizontal direction of  FIG. 5 . Resistance values between the contacts  42  of the resistors  41  have the relationship of R 11 :R 12 :R 13 : . . . :R 1   n =R 21 :R 22 :R 23 : . . . :R 2   n =R 31 :R 32 :R 33 : . . . :R 3   n  where R 11 , R 12 , R 13 , . . . R 1   n  represent resistance values between the contacts of a first resistor  41 - 1  of the resistors  41 , R 21 , R 22 , R 23 , . . . R 2   n  represent resistance values between the contacts of a second resistor  41 - 2 , and R 31 , R 32 , R 33 , . . . R 3   n  represent resistance values between the contacts of a third resistor  41 - 3 .  
      The intermediate contacts  42  at the equal positions of the resistors  41  are connected by gradation voltage output wires  44  via first switches  45  and second switches  46  (the switches  45  and  46  are examples of a control switch) so as to connect the resistors  41  in parallel. A third switch  47 , a fourth switch  48 , and a fifth switch  49  (the switches  47 ,  48 , and  49  are examples of a power supply switch) are connected to the contacts  42  on the ends of the resistors  41 .  
      Then, a high voltage side reference voltage V 1  is supplied from a first node E 1  and a low voltage side reference voltage V 2  is supplied from a second node E 2  to the ends of the resistors  41  via the third switch  47 , the fourth switch  48 , and the fifth switch  49 . With the supply of the high voltage side reference voltage V 1  and the low voltage side reference voltage V 2 , γ gradation voltages V 81 , V 82 , . . . V 8(n-1)  are outputted from the junction points of the intermediate contacts  42  via the first, second, . . . (n−1)-th gradation voltage output wires  44  according to voltages divided by the three resistors  41 .  
      To be specific, the resistance voltage divider circuit of  FIG. 5  is formed as follows:  
      First, the first resistor  41 - 1 , the second resistor  41 - 2 , and the third resistor  41 - 3  are arranged in parallel along a second direction on a substrate. The resistors are almost equal in length along a first direction (the horizontal direction of  FIG. 5 ), are almost equal in-width along the second direction (the vertical direction of  FIG. 5 ) orthogonal to the first direction, and are formed by N+ polysilicon resistors. That is, the resistors  41  ( 41 - 1 ,  41 - 2 ,  41 - 3 ) almost equal in resistance value are provided in parallel. Then, a gradation voltage output part is provided on the resistors  41  via an interlayer insulating film (not shown). The gradation voltage output part is constituted of the gradation voltage output wires  44  which are orthogonal to the resistors  41 -( 41 - 1 ,  41 - 2 ,  41 - 3 ) and are made of a material such as aluminum, and the first switch  45 , the second switch  46 , the third switch  47 , the fourth switch  48 , and the fifth switch  49  which are composed of P-channel MOS transistors. Subsequently, the resistors  41  and the gradation voltage output wires  44  are connected via the contacts  42  made of a material having a low resistance value (e.g., a metal compound of silicon that is called silicide).  
      According to Embodiment 4, the three resistors  41  almost equal in resistance value are connected in parallel, the intermediate contacts  42  at the equal positions with respect to the horizontal direction of  FIG. 5  are connected, that is, the contacts  42  where the three resistors are almost equal in resistance value are connected so as to connect the nodes having equal voltages, and voltages from the node having equal voltages are outputted as gradation voltages, thereby accurately obtaining gradation voltages with low resistance values. By performing on/off control on the gradation voltage output wires  44 , which output gradation voltages, via the first switch  45  and the second switch  46 , it is possible to adjust the number of voltage dividing resistors R 11 , R 12 , R 13 , . . . R 1   n,  R 21 , R 22 , R 23 , . . . R 2   n,  R 31 , R 32 , R 33 , . . . R 3   n.  With this configuration, it is possible to set and form resistors more minutely and obtain detailed gradation voltages necessary for the gradation voltage output wires  44 . The third switch  47 , the fourth switch  48 , and the fifth switch  49  are provided between the reference voltages V 1  and V 2  and the resistors  41  and control is performed so as to turn off the switches  47 ,  48 , and  49  when necessary, for example, when gradation voltages are not necessary. Thus, it is possible to isolate the resistors  41  and the reference voltages V 1  and V 2  from each other, thereby preventing an unnecessary current flow and reducing power consumption.  
      In Embodiments 1 to 4, the resistors are formed by N+ polysilicon resistors. The resistors may be formed by P+ polysilicon resistors, N+ diffused resistors, or P+ diffused resistors.  
      In Embodiment 4, the first switch  45 , the second switch  46 , the third switch  47 , the fourth switch  48 , and the fifth switch  49  are formed by P-channel MOS transistors. The switches may be formed by N-channel MOS transistors or combinations of a P-channel transistor and an N-channel MOS transistor.  
      Gradations can be formed with high accuracy by using the resistance voltage divider circuit of the present invention. Thus, the resistance voltage divider circuit of the present invention can be used in various forms. For example, the resistance voltage divider circuit is implemented as a drive which generates gradation voltages and driving voltages for driving a display device according to the gradation voltages and a display which is integrated with the drive so as to drive a plurality of display devices formed on a substrate.  
       FIG. 6  is a structural diagram showing a liquid crystal display driving apparatus comprising a plurality of resistance voltage divider circuits according to the preferred embodiments (Embodiments 1 to 4) of the present invention.  
      As shown in  FIG. 6 , a liquid crystal display driving apparatus  51  is constituted of a gradation voltage generation circuit (gradation voltage generation circuit)  53 , which is composed of a plurality of resistance voltage divider circuits  52 , and DA converters (converter circuits)  54 . Gradation voltages between reference voltages are generated from two reference voltages supplied by the resistance voltage divider circuits  52  of the gradation voltage generation circuit  53 , and the gradation voltages are inputted to the DA converters  54 . Driving voltages (analog voltages) for driving a plurality of liquid crystal elements are generated by the DA converters  54  according to the inputted gradation voltages and inputted digital command values (not shown).  
       FIG. 7  is a structural diagram showing a liquid crystal display apparatus comprising the liquid crystal display driving apparatus  51  of  FIG. 6  as a signal line driving circuit.  
      A liquid crystal display apparatus  61  comprises, in addition to the liquid crystal display driving apparatus  51 , a plurality of liquid crystal elements  62  formed on a substrate, a plurality of TFTs (Thin Film Transistors)  63  connected to the liquid crystal elements  62 , a plurality of scanning lines  64  connected to the gates of the plurality of TFTs  63 , a plurality of drive wires  65  which are connected to the opposite ends of the plurality of TFTs  63  from the liquid crystal elements  62  and are driven by the liquid crystal display driving apparatuses  51 , and scanning line drives  66  for driving the plurality of scanning lines  64 .  
      According to the liquid crystal display driving apparatuses  51  or the liquid crystal display apparatus  61  configured thus, the liquid crystal elements  62  can be driven by accurate gradation voltages, thereby improving gradation display, i.e., the quality of display on a liquid crystal panel.  
      Although the embodiments described a liquid crystal as an example, the present invention is not limited to this example. Other display devices, e.g., organic EL devices also belong to the technical scope of the present invention as long as gradation voltages are inputted for driving in a display mode.  
      With the resistance voltage divider circuit of the present invention, it is possible to accurately form resistors with low resistance values and minutely generate gradation voltages. The resistance voltage divider circuit can be also applied to measuring instruments and controllers which require a plurality of reference voltages with high accuracy.