Patent Publication Number: US-2010117675-A1

Title: Liquid crystal display device and analysis device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 11/629,175 filed Dec. 11, 2006, which is a national phase filing of PCT/JP05/011922 filed Jun. 29, 2005. U.S. patent application Ser. No. 11/629,175 claims priority under 35 U.S.C. §119(a) to Japanese Patent Application No. 2004-199728 filed Jul. 6, 2004. The entire disclosures of U.S. patent application Ser. No. 11/629,175, PCT/JP05/011922, and Japanese Patent Application No. 2004-199728 are hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a liquid crystal display device of a segment method, dot matrix method, or the like, which displays numerals and texts, and an analysis device including the same. 
     BACKGROUND OF THE INVENTION 
     Recently, liquid crystal display devices are incorporated into a variety of electronic equipment, such as clocks, calculators, analysis devices, home electric appliances and the like as display sections. 
     For example, one type of a liquid crystal display device which displays simple indication such as numerals and texts is a liquid crystal display device of a segment method. The liquid crystal display device of the segment method includes a common electrode which is formed on one of two substrates, a plurality of segmented electrodes which are patterned into the shape of numerals on the other substrate, and a liquid crystal enclosed between the two substrates. A voltage is applied between the common electrode and the segmented electrodes, and an orientation of the liquid crystal enclosed therebetween is changed to control transmission of light. In this way, texts and numerals can be displayed. 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, the above conventional liquid crystal display device has the following problems. 
     In the liquid crystal display device of the segment method as disclosed in Japanese Laid-Open Publication No. 7-128338, if a conductive impurity enters between the above-described common electrode and the segmented electrodes, a short circuit occurs between the common electrode and the segmented electrodes. A difference in potential is lost, and an appropriate indication cannot be displayed (see  FIGS. 5A and 5B ). Even though such a defective indication is not observed when the product is manufactured, it may suddenly appear while in use for some reason. Thus, an inspection of a defective indication at the shipping of products is hardly sufficient as the measures to address such a problem. 
     Moreover, if such a defective indication appears in a liquid crystal display device incorporated in a blood glucose meter which is used by a diabetic patient for measuring a blood glucose level by oneself, the diabetic patient or the like may not notice that the wrong indication is displayed. Blood glucose level control by an injection of insulin or the like conducted in accordance with the erroneously displayed blood glucose level is not an appropriate treatment for the patient who measures the blood glucose level. Particularly, many of the people who take blood, such as diabetic patients, are elderly or visually handicapped people. Thus, it can be expected that they do not notice the defective indication of the liquid crystal display device. However, the conventional liquid crystal display devices incorporated in the blood glucose meters do not include means for detecting defective indication, or means for notifying the defective indication in particular. 
     An object of the present invention is to provide a liquid crystal display device which can detect a defective indication which appears due to a short circuit between a common electrode and a counter electrode thereof caused by a conductive impurity entering into a liquid crystal display panel, and an analysis device including the same. 
     Means for Solving the Problems 
     A liquid crystal display device according to claim  1  includes a liquid crystal display panel, an input and output section, and a control section. The liquid crystal display panel includes a first substrate with a first electrode formed thereon, a second substrate with a common electrode formed thereon and a liquid crystal enclosed between the first substrate and the second substrate. The liquid crystal display panel displays by changing an orientation of the liquid crystal by a difference in potential applied between the first electrode and the common electrode. The input and output section has a first output terminal and a second output terminal configured to drive the liquid crystal display panel. The first output terminal sends a signal to the first electrode. The second output terminal sends a signal to the common electrode. 
     The control section uses the first output terminal and the second output terminal of the input and output section as input and output terminals for a defective indication inspection configured to perform an inspection for a defective indication in the liquid crystal display panel. The control section performs the inspection for a defective indication by detecting whether a signal sent from one of the input and output terminals of the input and output section can be received at the other of the input and output terminals. 
     With such a structure, the first output terminal and the second output terminal which are respectively connected to the first electrode side and the common electrode side opposing the first electrode and which are used as output terminals for driving the liquid crystal when a normal indication is displayed are used as the input and output terminals for the defective indication inspection to perform an inspection for a defective indication in the liquid crystal display panel. During the defective indication inspection, if the signal sent from the one input and output terminal is received at the other input and output terminal, the control section detects an presence of a defective indication. 
     In such a structure, when a conductive impurity enters between the common electrode and the opposing first electrode, a short circuit occurs between the common electrode and the first electrode and a difference in potentials is lost. Thus, an appropriate indication cannot be displayed. 
     Thus, for detecting such the presence of a defective indication, the liquid crystal display device of the present invention uses the output terminal on the first electrode side and the output terminal on the common electrode side which are used as output terminals for driving the liquid crystal when a normal indication is displayed are used as the input and output terminals for the defective indication inspection. Then, whether the signal sent from one input and output terminal can be received at the other input and output terminal or not is checked. If the signal can be received at the other input and output terminal, it means that there is a conductive impurity which connects the first electrode and the common electrode in the liquid crystal. 
     In this way, by only using the output terminals (on the first electrode side and the common electrode side) for driving the liquid crystal are used as the input and output terminal for the inspection to detect that the signal sent from one input and output terminal is received at the other input and output terminal, the defective indication due to a short circuit caused in the liquid crystal display device can be readily detected. 
     The first electrode mentioned above corresponds to a segmented electrode in a liquid crystal display device of a segment method, and to a counter electrode formed on a first substrate at a position which corresponds to dots in a liquid crystal display device of a dot matrix method. 
     A liquid crystal display device according to claim  2  is a liquid crystal display device according to claim  1  in which the control section displays a message notifying that a defective indication appears on the liquid crystal display panel when the control section detects the defective indication. 
     With such a structure, when an appearance of a defective indication is detected, for example, a text saying that defective indication is appearing is displayed on the liquid crystal display panel, lamp is lit, a displayed numerals are flickered, or the like. 
     In this way, it becomes possible to surely notify the user that the current indication is not correctly displayed. Thus, a diabetic patient can be prevented from conducting blood glucose control in reliance on the erroneously displayed blood glucose measured value. 
     A liquid crystal display device according to claim  3  is a liquid crystal display device according to claim  1  in which the control section sounds an alarm sound when it detects the defective indication. 
     With such a structure, an alarm sound is sounded when the presence of a defective indication is detected. In this way, it becomes possible to surely notify the user that the current indication is not correctly displayed. 
     Accordingly, a diabetic patient or a visually handicapped person can be prevented from conducting blood glucose control in reliance on the erroneously displayed blood glucose measured value. 
     A liquid crystal display device according to claim  4  is a liquid crystal display device according to claim  1  in which the control section stops displaying on the liquid crystal display panel when it detects the defective indication. 
     With such a structure, when the control section detects a defective indication, the device is controlled to stop displaying the numerical values or the like on the liquid crystal display panel. 
     In this way, visually handicapped patients such as elderly people can be securely prevented from conducting blood glucose control in reliance on the erroneously displayed blood glucose measured value. Thus, a liquid crystal display device with higher safety can be provided. 
     A liquid crystal display device according to claim  5  is a liquid crystal display device according to any one of claim  1  in which the control section performs the inspection for a defective indication every time power is turned on, and/or the display is switched. 
     With such a structure, the inspection for the defective indication is performed every time when the power is turned on before displaying or the display is switched. 
     In this way, in the liquid crystal display section incorporated in the blood glucose meter, the inspection for a defective indication is performed every time when the power is turned on before displaying or the display is switched. When a defective indication appears, measures such as notifying by an alarm sound is taken. Thus, it becomes possible to prevent the user from believing in the displayed numeral to be correct in the case of appearance of the defective indication. 
     An analysis device according to claim  6  includes a liquid crystal display device according to any one of claim  1  as a display section. 
     With such a structure, the liquid crystal display device of the present invention can be used as, for example, a display section of an analysis device such as blood glucose meter. 
     In this way, the presence of a defective indication caused by a conductive impurity enters into a liquid crystal layer can be detected and notified to the user. Thus, it becomes possible to prevent the user from believing in the displayed numeral to be correct in the case of appearance of the defective indication and conducting wrong treatment such as performing inappropriate blood glucose control or the like. 
     FUNCTION OF THE INVENTION 
     According to the liquid crystal display device of claim  1 , the presence of a defective indication caused by a conductive impurity enters into a liquid crystal layer can be detected. 
     According to the liquid crystal display device of claim  2 , it becomes possible to surely notify the user that the current display is not correct. 
     According to the liquid crystal display device of claim  3 , a user can be prevented from performing blood glucose level control in reliance of an erroneously displayed blood glucose measure value. 
     According to the liquid crystal display device of claim  4 , a visually handicapped patient such as an elderly person can be securely prevented from performing blood glucose level control in reliance of an erroneously displayed blood glucose measure value. 
     According to the liquid crystal display device of claim  5 , when a defective indication appears, measures such as notifying by an alarm sound can be taken. 
     According to the analysis device of claim  6 , the presence of a defective indication caused by a conductive impurity enters into a liquid crystal layer can be detected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view showing a blood glucose meter as an example of an analysis device which includes a liquid crystal display device of the present invention as a display section. 
         FIG. 2A  is a diagram showing a normal indication state of the blood glucose meter of  FIG. 1 ; and  FIG. 2B  is a diagram showing an inspection state for a defective indication. 
         FIGS. 3A and 3B  are diagrams showing how an inspection signal is sent and received when there is no defective indication. 
         FIGS. 4A and 4B  are diagrams showing how an inspection signal is sent and received when a defective indication appears. 
         FIGS. 5A and 5B  are diagrams showing a display section with a defective indication. 
         FIG. 6  is a block diagram showing a connection state with a microcomputer incorporated in the blood glucose meter of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A blood glucose meter (analysis device)  10  including a display section (liquid crystal display device)  11  according to an embodiment of the present invention is described as follows with reference to  FIGS. 1 through 6 . 
     Structure of Entire Blood Glucose Meter 
     As shown in  FIG. 1 , the blood glucose meter  10  according to the present embodiment is a blood glucose measurement device which includes the display section (liquid crystal display device)  11 , and a sensor section  12 , and also incorporates a microcomputer (control section)  15  (see  FIG. 2 ) inside. 
     The display section  11  is a liquid crystal display device of a segment method which displays a blood glucose level measured by depositing blood on the sensor section  12 . As shown in  FIG. 1 , the display section  11  displays a numerical value to two places to the left to the decimal point and one place to the right of the decimal point (result of measurement of the blood glucose level). The display section  11  also displays a remaining battery life of the blood glucose meter  10 , and the like. A normal indication of the display section  11 , an inspection of a defective indication, and the like will be described later in details. 
     The sensor section  12  includes a sensor  12   a  for depositing a blood flowed from a puncture wound formed by a lancet or the like for measuring the blood glucose level at a predetermined position of its tip portion. The blood deposited on the sensor  12   a  is analyzed, and the blood glucose level is measured. 
     The microcomputer  15  is a microcomputer of an internal LCD driver type which drives a liquid crystal of the display section  11 . As shown in  FIG. 2A , the microcomputer  15  includes ports (input and output section which are the first and second output terminals)  15   a  and  15   b  which are connected to an SEG (segmented electrode which is the first electrode) and a COM (common electrode) of the display section  11 . The microcomputer  15  uses the ports  15   a  and  15   b  as ports of the LCD driver for driving the liquid crystal of the display section  11  during normal indication. How the ports  15   a  and  15   b  are handled by the microcomputer  15  in the inspection for a defective indication will be described later in details. 
     Structure of Display Section 
     As shown in  FIG. 1 , the display section  11  includes a liquid crystal display panel  11   a . Furthermore, as shown in  FIGS. 2A and 2B , the display section  11  includes the SEG formed on one of the substrates which form the liquid crystal display panel  11   a  of the display section  11 , and the COM formed on the other substrate. By applying a voltage between the SEG and the COM, an alignment of the liquid crystal enclosed between the two substrates is changed. Thus, segmented portions are respectively switched between a displaying state and a non-displaying state. 
     The SEG is a segmented electrode patterned on one substrate as seven segments for displaying numerals. The COM is an electrode formed across a surface of the other substrate. The SEG and the COM are connected to the ports  15   a  and  15   b  of the microcomputer  15  which functions as the ports of the LCD driver. The SEG and the COM receive a signal (voltage) sent from the microcomputer  15  in accordance with the result of measuring the blood glucose level. Thus, a difference in potentials is generated between the SEG and the COM, and the alignment of the liquid crystal between the SEG and the COM required for displaying a desired numeral is changed to display the blood glucose level. 
     Now, a case of a defective indication caused by an impurity trapped in the liquid crystal display panel  11   a  of the display section  11  is described. 
     As described above, a numeral is displayed on the display section  11  by generating a difference in potentials between the SEG and the COM. However, when a conductive impurity enters between the SEG and the COM, the potential difference between the SEG and the COM is lost. Thus, in the segmented portions where the alignment of the liquid crystal should be changed for display, the alignment of the liquid crystal remains unchanged, causing the portions not to be displayed. This results in a defective indication (see  FIGS. 5A and 5B ). 
     When such a defective indication appears in a liquid crystal display device used as the display section  11  of the blood glucose meter  10  as in the present embodiment, a user may misunderstand that the numerals erroneously displayed is a correct measurement result, and inject insulin for blood glucose control based on the wrong measured value. Such a wrong blood glucose control is just an inappropriate treatment for a diabetic patient. Rather, it may be harmful for the patient. Particularly, many of the diabetic patients who use the blood glucose meter  10  as in the present embodiment have weak eyesight. They may falsely recognize the defective indication as shown in  FIG. 5A  to be “60.0”, for example, without noticing that it is a defective indication. 
     Thus, in the blood glucose meter  10  of the present embodiment, in order to prevent an inappropriate treatment caused by misunderstanding of the user, a defective indication is checked for every time the blood glucose meter  10  is powered on and/or the display is switched, and, when the appearance of a defective indication is detected, the user is notified of the appearance of the defective indication. 
     Structure of Microcomputer 
     As shown in  FIGS. 2A and 2B , the microcomputer  15  includes the port  15   a  connected to the SEG side of the display section  11  and the port  15   b  connected to the COM side. Furthermore, as shown in  FIG. 6 , the microcomputer  15  is connected to the display section  11 , the sensor section  12 , an alarm section  16 , and a power supply section  17 . 
     For a normal indication, in the microcomputer  15 , a signal (voltage) is sent from the port  15   a  to the SEG corresponding to the segments to be displayed based on the blood glucose level measured at the sensor section  12 . To the COM side, a signal (voltage) is sent from the port  15   b  at a timing of displaying. 
     The microcomputer  15  also performs various types of controlling operations such as checking for a defective indication which appears when a conductive impurity enters into the liquid crystal display panel  11   a , analyzing the blood detected at the sensor section  12  and calculating the blood glucose level, and the like, in addition to drive control of the liquid crystal display panel  11   a  of the display section  11 . 
     As shown in  FIG. 2B , specifically, the inspection for a defective indication is performed using the ports  15   a  and  15   b  used as output terminals of the LCD driver as I/O ports (input and output terminals) for the defective indication inspection. 
     The alarm section  16  sounds a buzzer to notify the user that the currently displayed numerical value is a wrong indication when the microcomputer  15  detects a defective indication in the inspection for the defective indication. 
     The power supply section  17  which supplies power to electronic equipment incorporated in the blood glucose meter  10  stops the power supply to the display section  11  when the microcomputer  15  detects a defective indication. 
     An Inspection Method of the Present Blood Glucose Meter 
     An inspection method for a defective indication in the blood glucose meter  10  of the present embodiment is described as follows with reference to  FIGS. 3A through 4B . 
     In the blood glucose meter  10  of the present embodiment, every time the power is turned on, and/or the display is switched, the microcomputer  15  uses the ports  15   a  and  15   b  as the I/O ports. As shown in  FIG. 3A , an inspection signal is sent from one of the ports, the port  15   a , which is connected to the SEG. Whether the inspection signal can be received or not at the other port, the port  15   b  which is connected to the COM, is checked. In other words, whether there is a short circuit between the SEG and the COM of the liquid crystal display panel  11   a  is checked. Such an inspection is performed between all the SEGs and the COMs. Alternatively, as shown in  FIG. 3B , the inspection signal may be sent from the other port  15   b  and whether the inspection signal can be received or not at the one port  15   a  may be checked. 
     If there is an impurity trapped between the SEG and the COM of the liquid crystal display panel  11   a  and there is short-circuit as shown in  FIGS. 4A and 4B , the difference in potentials between the SEG and the COM is lost, and the alignment of the liquid crystal cannot be changed. Thus, the segmented portions which should be displayed cannot be displayed, and a defective indication as shown in  FIGS. 5A and 5B  may appear. 
     In the blood glucose meter  10  of the present embodiment, when appearance of such a defective indication is detected, the inspection signal sent from the one port  15   a  is detected at the other port  15   b  as shown in  FIG. 4A  since there is a short circuit between the SEG and the COM of the liquid crystal display panel  11   a . The same is also true of the case where the inspection signal sent from the other port  15   b  is detected at the one port  15   a  as shown in  FIG. 4B . 
     When the inspection signal sent from the port  15   a  or the port  15   b  is received at the port  15   b  or the port  15   a , the microcomputer  15  controls the alarm section  16  to sound a buzzer. Further, the microcomputer  15  has the liquid crystal display panel  11   a  of the display section  11  to display a message notifying that a defective indication is present. 
     In this way, it becomes possible to surely notify the user that a defective indication appears and the numeral displayed on the liquid crystal display panel  11   a  is wrong. 
     Features of the Present Blood Glucose Meter 
     (1) 
     The blood glucose meter  10  of the present embodiment includes the display section  11 , the microcomputer  15 , and the like. The ports  15   a  and  15   b  used as the output terminals of the LCD driver when a normal indication is displayed are used as the I/O ports for the inspection when the inspection for a defective indication is performed. In a use as the I/O ports, for example, an inspection signal is sent from the one port  15   a  which is connected to the SEG of the liquid crystal display panel  11   a . If the inspection signal is received at the other port  15   b  which is connected to the COM of the liquid crystal display panel  11   a , the microcomputer  15  detects the presence of a defective indication. 
     In this way, it is ensured that a defective indication due to a short circuit caused by an impurity trapped between the SEG and the COM of the liquid crystal display panel  11   a  is detected. As a result, it becomes possible to prevent treatment such as wrong blood glucose control due to a defective indication appearing on the blood glucose meter  10  which is used by diabetic patients including a number of visually handicapped elderly people. 
     (2) 
     In the blood glucose meter  10  of the present embodiment, when the appearance of the defective indication as described above is detected, the microcomputer  15  has the display section  11  to display a message notifying of the “presence of a defective indication”. 
     In this way, it becomes possible to ensure notifying the user of the appearance of the defective indication. As a result, problems such as conducting inappropriate treatment in reliance on an erroneously displayed numerical value can be avoided. 
     (3) 
     In the blood glucose meter  10  of the present embodiment, when the appearance of the defective indication as described above is detected, the microcomputer  15  controls the alarm section  16  to sound a buzzer. 
     In this way, it becomes possible to further ensure notifying the user of the existence of the defective indication. As a result, problems such as conducting inappropriate treatment in reliance on an erroneously displayed numerical value can be avoided. 
     As in the present embodiment, a plurality of warning means, such as displaying a message notifying of a defective indication, an alarm by a buzzer and the like may be combined. 
     (4) 
     In the blood glucose meter  10  of the present embodiment, the inspection for a defective indication as described above is performed every time the power of the blood glucose meter  10  is turned on, and/or the display is switched. 
     In this way, basically, whether there is the presence of a defective indication or not can be checked every time the blood glucose level is measured. Thus, a blood glucose meter with higher safety can be provided. 
     OTHER EMBODIMENTS 
     An embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various modifications can be applied without departing from the gist of the invention. 
     (A) 
     In the above embodiment, the liquid crystal display device of the present invention is described as a display section incorporated in a blood glucose meter. However, the present invention is not limited to such an example. 
     For example, when the present invention is applied as a display section of a variety of analysis devices other than the blood glucose meter, similar effects as described above can be achieved. 
     (B) 
     In the above embodiment, when the presence of a defective indication is detected, the appearance of the defective indication is notified to the user by a combination of displaying a message notifying of the appearance of the defective indication, and the buzzer by the alarm section  16 . However, the present invention is not limited to such an example. 
     For example, among these two control operations, only one of them may be performed. Alternatively, the power supply section  17  shown in  FIG. 6  may be controlled such that when the appearance of the defective indication is detected, the power supply to the display section  11  is stopped. 
     In such an example, it is also possible to avoid the user conducting the blood glucose control without noticing that the displayed numerical value is wrong due to the defective indication. 
     In view of a secure notification to visually handicapped users, it is more preferable to combine a plurality of control operations as in the above-described embodiment. 
     (C) 
     In the above-described embodiment, the LCD driver is incorporated within the microcomputer  15 . However, the present invention is not limited to such an example. 
     For example, even when the LCD driver is provided separately from the microcomputer  15 , the similar effects as described above can be achieved by using the ports of the LCD driver as the I/O ports. 
     (D) 
     In the above-described embodiment, the present invention is applied to the liquid crystal display device of the segment method (the first electrode corresponds to a segmented electrode). However, the present invention is not limited to such an example. 
     For example, the present invention can also be applied to a liquid crystal display device of a dot matrix method with a relatively small number of dots. In such an example, the first electrode corresponds to a counter electrode formed on a first substrate at a position corresponding to the dots. 
     INDUSTRIAL APPLICABILITY 
     The liquid crystal display device of the present invention has effects which enable detection of a defective indication due to an impurity enters into a liquid crystal display panel with a simple structure. Thus, it is applicable not only to liquid crystal display devices of the segment method but also to a wide variety of liquid crystal display devices.