BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:
FIG. 1 is a block diagram showing a main part of a related-art plasma display apparatus;
FIG. 2 is a drawing showing an example of the configuration of a related-art AC/DC power supply circuit;
FIG. 3 is a drawing showing an example of the circuit configuration of a related-art X-electrode drive circuit;
FIG. 4 is a drawing showing a connection between the X-electrode drive circuit and the AC/DC power supply circuit in the related-art configuration;
FIG. 5 is a drawing showing the arrangement of circuits of a related-art plasma display apparatus;
FIG. 6 is a block diagram showing a main portion of a first embodiment of a plasma display apparatus according to the present invention;
FIG. 7 is a drawing showing an X-electrode drive circuit and an AC/DC power supply circuit implemented on the same circuit board;
FIG. 8 is a drawing showing a variation of the first embodiment of the plasma display apparatus according to the present invention;
FIG. 9 is a block diagram showing a main portion of a second embodiment of the plasma display apparatus according to the present invention;
FIG. 10 is a drawing showing a Y-electrode drive circuit and an AC/DC power supply circuit implemented on the same circuit board; and
FIG. 11 is a drawing showing a variation of the second embodiment of the plasma display apparatus according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 6 is a block diagram showing a main portion of a first embodiment of a plasma display apparatus according to the present invention. A plasma display apparatus shown in FIG. 6 includes a plasma display panel 11, an address-electrode drive circuit 12, a Y-electrode drive circuit 13, an X-electrode drive circuit 34, a scan circuit 15, a drive control circuit 16, a signal processing circuit 17, and an AC/DC power supply circuit 18. In FIG. 6, the same elements as those of FIG. 1 are referred to by the same numerals, and a description thereof will be omitted.
In the plasma display apparatus shown in FIG. 6, the X-electrode drive circuit 34 is provided in place of the X-electrode drive circuit 14, and the X-electrode drive circuit 34 and the AC/DC power supply circuit 18 are implemented on the same circuit board (print circuit board) 35. The provision of the X-electrode drive circuit 34 and the AC/DC power supply circuit 18 on the same circuit board 35 eliminates the need for an electric cable that connects between these two circuits.
The configuration and operation of the plasma display panel 11, the address-electrode drive circuit 12, the Y-electrode drive circuit 13, the scan circuit 15, the drive control circuit 16, and the signal processing circuit 17 shown in FIG. 6 are the same as the configuration and operation described in connection with FIG. 1.
FIG. 7 is a drawing showing the X-electrode drive circuit 34 and the AC/DC power supply circuit 18 implemented on the circuit board 35. In FIG. 7, the same elements as those of FIG. 4 are referred to by the same numerals, and a description thereof will be omitted.
Since the AC/DC power supply circuit 18 and the X-electrode drive circuit 34 are implemented on the same circuit board 35, the voltage VS0 generated by the AC/DC power supply circuit 18 is supplied to the X-electrode drive circuit 34 via printed wiring 41 on the circuit board 35. The length of the printed wiring 41 is substantially shorter than the length of the related-art electric cable 18a, so that the voltage drop of the voltage VS0 caused by an electric current running through the printed wiring 41 can be ignored.
The X-electrode drive circuit 34 has the same circuit configuration as the X-electrode drive circuit 14, except that the energy-supply-purpose condenser Cvs1 is removed. Since the voltage drop along the printed wiring 41 can almost completely be ignored in this case, the condenser Cvs0 provided in the AC/DC power supply circuit 18 can be utilized as an energy-supply-purpose condenser, so that there is no need to provide another energy-supply-purpose condenser in the X-electrode drive circuit 34.
The circuit configuration and operation of the AC/DC power supply circuit 18 are the same as the circuit configuration and operation described in connection with FIG. 2. The circuit configuration and operation of the X-electrode drive circuit 34 are the same as the circuit configuration and operation described in connection with FIG. 3, except that the condenser Cvs0 is used as an energy-supply-purpose condenser.
Further, the transformer 23 transmits an electric power from the primary side to the secondary side via changes in magnetic flux (magnetic coupling), so that the input side and output side of the transformer 23 are not electrically connected with each other (i.e., not directly connected through an electrical conductor). Also, the optical coupling unit 27 comprised of the light-emission device 25 and the light-detection device 26 transmits information from the input side to the output side via changes in light intensity (optical coupling), so that the input side and output side are not electrically connected with each other (i.e., not directly connected through an electrical conductor). In this manner, the primary side (hot side) and the secondary side (cold side) are electrically insulated from each other.
FIG. 8 is a drawing showing a variation of the first embodiment of the plasma display apparatus according to the present invention. In FIG. 8, the same elements as those of FIG. 7 are referred to by the same numerals, and a description thereof will be omitted.
In the configuration shown in FIG. 6 and FIG. 7, the AC/DC power supply circuit 18 and the X-electrode drive circuit 34 are implemented on the same circuit board 35, whereas in the variation shown in FIG. 8, an AC/DC power supply circuit 18A and an X-electrode drive circuit 34A are implemented separately on an AC/DC-power-supply circuit board 36 and an X-electrode-drive circuit board 37, respectively.
The AC/DC-power-supply circuit board 36 and the X-electrode-drive circuit board 37 are placed side by side, and are connected with each other through a circuit-board connector 42 and a circuit-board connector 43. The voltage VS0 generated by the AC/DC power supply circuit 18A is supplied to the X-electrode drive circuit 34A via the circuit-board connector 42. The length of the circuit-board connector 42 is substantially shorter than the length of the related-art electric cable 18a, so that the voltage drop of the voltage VS0 caused by an electric current running through the circuit-board connector 42 can be ignored.
The X-electrode drive circuit 34A has the same circuit configuration as the X-electrode drive circuit 14, except that the energy-supply-purpose condenser Cvs1 is removed and that resistors R3 and R4 are additionally provided. Since the voltage drop along the circuit-board connector 42 can almost completely be ignored in this case, the condenser Cvs0 provided in the AC/DC power supply circuit 18A can be utilized as an energy-supply-purpose condenser, so that there is no need to provide another energy-supply-purpose condenser in the X-electrode drive circuit 34A.
The AC/DC power supply circuit 18A has the same circuit configuration as the AC/DC power supply circuit 18, except that a switching circuit 44 is provided. The function and operation of the switching circuit 44 will later be described.
The basic circuit configuration and operation of the AC/DC power supply circuit 18A are the same as the circuit configuration and operation described in connection with FIG. 2, except that the switching circuit 44 is provided. The basic circuit configuration and operation of the X-electrode drive circuit 34A are the same as the circuit configuration and operation described in connection with FIG. 3, except that the condenser Cvs0 is used as an energy-supply-purpose condenser.
In the configuration shown in FIG. 7, the AC/DC power supply circuit 18 and the X-electrode drive circuit 34 are implemented on the same circuit board 35, whereas in the configuration shown in FIG. 8, the AC/DC power supply circuit 18A and the X-electrode drive circuit 34A are implemented separately on the AC/DC-power-supply circuit board 36 and the X-electrode-drive circuit board 37, respectively. With the provision of the AC/DC power supply circuit 18A and the X-electrode drive circuit 34A on the respective separate circuit boards, there is a merit in that no modification is necessary to the AC/DC-power-supply circuit board 36 carrying the AC/DC power supply circuit 18A even when modification is made to the X-electrode drive circuit 34A.
Various standards are defined for industrial products. The UL standard, for example, is provided by the UL that is a safety testing organization in the United States that performs an inspection and test relating to the safety of commercial products for the benefit of the public. The UL sets a standard relating to the danger of fire and electric shock caused by products, performs inspections and tests for individual products, and allows a UL mark to be attached to the products that passed its inspections and tests. In order to obtain a UL-standard approval for the AC/DC power supply circuit 18 that is implemented on the circuit board 35, there is a need to submit the entirety of the circuit board 35 for inspection and to request inspections and tests to be conducted. If modification is made to the X-electrode drive circuit 34 on the circuit board 35 after the approval is obtained, such modification is considered as a modification to the circuit board 35, so that a further inspection will need to be conducted for the entirety of the circuit board 35.
With the configuration shown in FIG. 8, on the other hand, the AC/DC power supply circuit 18A and the X-electrode drive circuit 34A are provided separately on the AC/DC-power-supply circuit board 36 and the X-electrode-drive circuit board 37, respectively, so that no modification is necessary to the AC/DC-power-supply circuit board 36 carrying the AC/DC power supply circuit 18A even when modification is made to the X-electrode drive circuit 34A. Accordingly, once an approval is obtained for the AC/DC-power-supply circuit board 36, there is no need to request an approval again, no matter what modification is thereafter made to the X-electrode drive circuit.
Moreover, the configuration shown in FIG. 8 is provided with the resistors R3 and R4, which serve as a voltage detection circuit in the X-electrode drive circuit 34A. The voltage VS0 that appears between the opposite ends of the smoothing condenser Cvs0 is divided by the resistors R3 and R4. The divided voltage is supplied to the optical coupling unit 27 via the circuit-board connector 43 and the switching circuit 44. In the optical coupling unit 27, the light-emission device 25 emits light with the intensity responsive to the divided voltage level. The light-detection device 26 receives light from the light-emission device 25, and supplies a signal responsive to the intensity of the received light to the pulse generating circuit 22. The pulse generating circuit 22 controls the generation of the pulses in response to the signal from the light-detection device 26. This feedback control serves to adjust the voltage between the opposite ends of the smoothing condenser Cvs0 to a predetermined voltage (i.e., to the sustain discharge voltage VS0).
Since the voltage VS0 to be controlled is used in the X-electrode drive circuit 34A, it is preferable to perform the feedback control based on the voltage level that is detected on the X-electrode-drive circuit board 37 where the X-electrode drive circuit 34A is implemented (i.e., where the controlled voltage is actually used). Through such feedback control, it becomes possible to set the voltage VS0 more accurately. The resistors R3 and R4 described above are provided to detect the voltage level of the voltage VS0 (or, more accurately, the divided voltage level) on the X-electrode-drive circuit board 37.
The switching circuit 44 selects an input from the X-electrode-drive circuit board 37 during the normal operation in which the plasma display apparatus is used by a user, and the selected input is supplied to the optical coupling unit 27. The setting of the switching circuit 44 may be changed in response to a control signal applied to the switching circuit 44 according to need, so that the voltage level divided by the resistors R1 and R2 is selected for provision to the optical coupling unit 27. The resistors R1 and R2 are not necessary for the purpose of the normal operation in which the plasma display apparatus is used by a user. Unless the resistors R1 and R2 are provided, however, an operation test cannot be conducted with the AC/DC-power-supply circuit board 36 alone.
In the AC/DC power supply circuit 18A of FIG. 8, the resistors R1 and R2 are provided on the AC/DC-power-supply circuit board 36, and provision is made such that the switching circuit 44 allows feedback control to be performed based on the voltage detected by the resistors R1 and R2. With this provision, it is possible to perform an operation test for the AC/DC power supply circuit 18A even if the AC/DC-power-supply circuit board 36 is provided alone without a connection to the X-electrode-drive circuit board 37.
FIG. 9 is a block diagram showing a main portion of a second embodiment of the plasma display apparatus according to the present invention. A plasma display apparatus shown in FIG. 9 includes a plasma display panel 11, an address-electrode drive circuit 12, a Y-electrode drive circuit 33, an X-electrode drive circuit 14, a scan circuit 15, a drive control circuit 16, a signal processing circuit 17, and an AC/DC power supply circuit 18. In FIG. 9, the same elements as those of FIG. 1 are referred to by the same numerals, and a description thereof will be omitted.
In the plasma display apparatus shown in FIG. 9, a Y-electrode drive circuit 33 is provided in place of the Y-electrode drive circuit 13, and the Y-electrode drive circuit 33 and the AC/DC power supply circuit 18 are implemented on the same circuit board (print circuit board) 38. The provision of the Y-electrode drive circuit 33 and the AC/DC power supply circuit 18 on the same circuit board 38 eliminates the need to handle and store an electric cable that supplies the sustain discharge voltage VS0 to the Y-electrode drive circuit 33.
In the configuration shown in FIG. 1, the voltage VS0 is supplied from the AC/DC power supply circuit 18 to the X-electrode drive circuit 14 via the electric cable 18a, and is further supplied from the X-electrode drive circuit 14 to the Y-electrode drive circuit 13 via the electric cable 18b. In the configuration shown in FIG. 9, the voltage VS0 is first supplied from the AC/DC power supply circuit 18 to the Y-electrode drive circuit 33, and is then supplied from the Y-electrode drive circuit 33 to the X-electrode drive circuit 14 via the electric cable 18b.
The configuration and operation of the plasma display panel 11, the address-electrode drive circuit 12, the X-electrode drive circuit 14, the scan circuit 15, the drive control circuit 16, and the signal processing circuit 17 shown in FIG. 9 are the same as the configuration and operation described in connection with FIG. 1.
FIG. 10 is a drawing showing the Y-electrode drive circuit 33 and the AC/DC power supply circuit 18 implemented on the circuit board 38. In FIG. 10, the same elements as those of FIG. 4 are referred to by the same numerals, and a description thereof will be omitted.
Since the AC/DC power supply circuit 18 and the Y-electrode drive circuit 33 are implemented on the same circuit board 38, the voltage VS0 generated by the AC/DC power supply circuit 18 is supplied to the Y-electrode drive circuit 33 via printed wiring on the circuit board 38. The length of the printed wiring is short, so that the voltage drop of the voltage VS0 caused by an electric current running through the printed wiring can be ignored.
In the related-art configuration shown in FIG. 1, the Y-electrode drive circuit 13 and the X-electrode drive circuit 14 have the same circuit configuration for their sustain circuit portions for performing sustain discharge. Namely, the circuit configuration shown in FIG. 3 that shows a portion corresponding to the sustain circuit for generating sustain discharge that is included in the X-electrode drive circuit 14 is identical to the configuration of the sustain circuit of the Y-electrode drive circuit 13.
The Y-electrode drive circuit 33 shown in FIG. 10 according to the present invention has the same circuit configuration as the related-art Y-electrode drive circuit 13, except that the energy-supply-purpose condenser Cvs1 is removed. Since the voltage drop along the printed wiring can almost completely be ignored in this case, the condenser Cvs0 provided in the AC/DC power supply circuit 18 can be utilized as an energy-supply-purpose condenser, so that there is no need to provide another energy-supply-purpose condenser in the Y-electrode drive circuit 33.
The circuit configuration and operation of the AC/DC power supply circuit 18 are the same as the circuit configuration and operation described in connection with FIG. 2. The circuit configuration and operation of the Y-electrode drive circuit 33 relating to the sustain discharge are the same as the circuit configuration and operation described in connection with FIG. 3, except that the condenser Cvs0 is used as an energy-supply-purpose condenser.
Further, the transformer 23 transmits an electric power from the primary side to the secondary side via changes in magnetic flux, so that the input side and output side of the transformer 23 are not electrically connected with each other (i.e., not directly connected through an electrical conductor). Also, the optical coupling unit 27 comprised of the light-emission device 25 and the light-detection device 26 transmits information from the input side to the output side via changes in light intensity, so that the input side and output side are not electrically connected with each other (i.e., not directly connected through an electrical conductor). In this manner, the primary side (hot side) and the secondary side (cold side) are electrically insulated from each other.
FIG. 11 is a drawing showing a variation of the second embodiment of the plasma display apparatus according to the present invention. In FIG. 11, the same elements as those of FIG. 10 are referred to by the same numerals, and a description thereof will be omitted.
In the configuration shown in FIG. 9 and FIG. 10, the Y-electrode drive circuit 33 and the AC/DC power supply circuit 18 are implemented on the same circuit board 38, whereas in the variation shown in FIG. 11, an AC/DC power supply circuit 18A and a Y-electrode drive circuit 33A are implemented separately on an AC/DC-power-supply circuit board 36 and a Y-electrode-drive circuit board 39, respectively.
The AC/DC-power-supply circuit board 36 and the Y-electrode-drive circuit board 39 are placed side by side, and are connected with each other through a circuit-board connector 46 and a circuit-board connector 47. The voltage VS0 generated by the AC/DC power supply circuit 18A is supplied to the Y-electrode drive circuit 33A via the circuit-board connector 46. The length of the circuit-board connector 46 is short, so that the voltage drop of the voltage VS0 caused by an electric current running through the circuit-board connector 46 can be ignored.
The Y-electrode drive circuit 33A has the same circuit configuration as the Y-electrode drive circuit 13, except that the energy-supply-purpose condenser Cvs1 is removed and that resistors R3 and R4 are additionally provided. Since the voltage drop along the circuit-board connector 46 can almost completely be ignored in this case, the condenser Cvs0 provided in the AC/DC power supply circuit 18A can be utilized as an energy-supply-purpose condenser, so that there is no need to provide another energy-supply-purpose condenser in the Y-electrode drive circuit 33A.
The AC/DC power supply circuit 18A is the same circuit as the AC/DC power supply circuit 18A described in connection with FIG. 8, and has the same circuit configuration as the related-art AC/DC power supply circuit 18, except that the switching circuit 44 is provided. The basic circuit configuration and operation of the sustain circuit of the Y-electrode drive circuit 33A are the same as the circuit configuration and operation described in connection with FIG. 3, except that the condenser Cvs0 is used as an energy-supply-purpose condenser.
In the configuration shown in FIG. 10, the AC/DC power supply circuit 18 and the Y-electrode drive circuit 33 are implemented on the same circuit board 38, whereas in the configuration shown in FIG. 11, the AC/DC power supply circuit 18A and the Y-electrode drive circuit 33A are implemented separately on the AC/DC-power-supply circuit board 36 and the Y-electrode-drive circuit board 39, respectively. Accordingly, the same merits as those described in connection with FIG. 8 are provided with respect to circuit modification and standard approvals.
Further, in the configuration shown in FIG. 11, the resistors R3 and R4 are provided to detect the voltage level of the voltage VS0 (or, more accurately, the divided voltage level) on the Y-electrode-drive circuit board 39. The switching circuit 44 selects a voltage from the Y-electrode-drive circuit board 39 during the normal operation in which the plasma display apparatus is used by a user, and the selected voltage is supplied to the optical coupling unit 27. On the other hand, the switching circuit 44 selects a voltage level from the resistors R1 and R2 in the situation in which the AC/DC-power-supply circuit board 36 is provided alone without a connection to the Y-electrode-drive circuit board 39, thereby making it possible to perform an operation test on the AC/DC power supply circuit 18A alone. These advantages are the same as the merits described with respect to the configuration shown in FIG. 8.
Further, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention.
The present application is based on Japanese priority application No. 2006-187100 filed on Jul. 6, 2006, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.
Patent Application
20080007490
