JP3940395B2 - Method and apparatus for driving light emitting element - Google Patents

Description

  The present invention relates to a driving method and apparatus for causing a light emitting element such as an organic EL (electroluminescence) to emit light.

FIG. 13 shows a conventional method for driving a light-emitting element. The driving method of FIG. 13 is called a simple matrix driving method, anode lines A ₁ to A _m and the cathode lines B ₁ .about.B _n arranged in matrix (lattice), the anode lines are arranged in the matrix form The light emitting elements E _{1,1 to} Em _{, n} are connected to the intersections of the cathode lines, and either one of the anode lines or the cathode lines is sequentially selected and scanned at regular time intervals, and in synchronization with this scanning. By driving the other line with current sources 52 _{1 to} 52 _m as drive sources, the light emitting element at an arbitrary intersection point is caused to emit light.

There are two drive methods by the drive source: cathode line scan / anode line drive and anode line scan / cathode line drive. FIG. 13 shows the case of cathode line scan / anode line drive, and shows the cathode line B _1. with connecting the cathode line scan circuit 51 to .about.B _n, it is obtained by connecting the anode line drive circuit 52 comprising a current source 52 ₁ to 52 _m to an anode line a ₁ to a _m. The cathode line scanning circuit 51 sequentially applies the ground potential (0 V) to the cathode lines B _{1 to} B _n by scanning the switches 53 _{1 to} 53 _n while sequentially switching the switches 53 _{1 to} 53 _n to the ground terminal side. Further, the anode line drive circuit 52, the cathode line scanning circuit current source 52 ₁ to 52 to an anode line A ₁ to A _m by in synchronism with the switch scanning on and off control of the switches 54 ₁ through 54 _m of 51 _m Are connected, and a drive current is supplied to the light emitting element at the desired intersection position.

For example, a case where the light emitting element E _2,1 and E _{3, 1} Taking as an example, as shown, the switch 53 ₁ of the cathode line scan circuit 51 is switched to the ground side, the first cathode line B ₁ When the ground potential is applied, the switches 54 ₂ and 54 ₃ of the anode line drive circuit 52 are switched to the current source side, and the current sources 52 ₂ and 52 ₃ are connected to the anode lines A ₂ and A ₃ . By repeating such scanning and driving at high speed, the light emitting element at an arbitrary position is caused to emit light, and each light emitting element is controlled to emit light at the same time.

By applying a reverse bias voltage VCC having the same potential as the power supply voltage to the cathode lines B2 to Bn other than the cathode line B1 being scanned, erroneous light emission is prevented .

By the way, each of the light emitting elements _{E2,1 to} Em _{, n} connected to each intersection position is connected in parallel to the light emitting element E having a diode characteristic as shown in the equivalent circuit in FIG. The conventional driving method described above has the following problem due to the parasitic capacitance C in the equivalent circuit.

15A and 15B _, only the light emitting elements E _{1,1 to} E _{1, n} connected to the anode line A ₁ in FIG. 13 are extracted, and the respective light emitting elements E _1,1 to E E _{1, n} is illustrated using only the parasitic capacitance C, but when the anode line A ₁ is not driven during the scanning of the cathode line B ₁ , as shown in FIG. parasitic capacitance C _{1, 2} -C 1, _n of the parasitic capacitance C _{1, 1} other light emitting elements E _{1, 2} to E 1 except, _n light-emitting elements E _{1, 1} tethered to the cathode line B ₁ of each The cathode lines B _{2 to} B _n are charged in the direction shown in the figure by a reverse bias voltage V _CC applied to them.

Next, when the scanning position moves from the cathode line B ₁ to the next cathode line B ₂ , for example, when the anode line A ₁ is driven to emit light from the light emitting elements E ₁ and ₂ , the circuit state at this time is (B). In addition to charging the parasitic capacitance C _1,2 of the light emitting element E _1,2 to be emitted, the light emitting elements E _1,3 to E connected to the other cathode lines B _{3 to} B _n charge flows current in a direction as indicated by the arrow is made also to the parasitic capacitance C _1,3 ~C 1, _n of E _{1, n.}

By the way, the light emitting element cannot perform normal light emission unless the voltage at both ends thereof rises above a specified value. In the case of the conventional driving method, as shown in FIGS. 15A and 15B, when the anode line A ₁ is driven to emit light from the light emitting element E _1,2 connected to the cathode line B ₂ , light is emitted. emitting element not only parasitic capacitance C _{1, 2} of E _{1, 2,} anode lines a ₁ other light emitting element connected to E _{1, 3} to E 1, _n parasitic capacitance C _{1, 3} -C 1 that _{should, n is} also charged, and the voltage across the light-emitting element E _1,2 connected to the cathode line B ₂ cannot rise above a specified value until the parasitic capacitance of all these light-emitting elements is fully charged. .

  For this reason, in the case of the conventional driving method, there is a problem that due to the parasitic capacitance, the rising speed until light emission is slow and high-speed scanning cannot be performed. In addition, since the parasitic capacitance of all the light emitting elements connected to the anode line must be charged, the current capacity of the drive source for the drive connected to each anode line must be increased, which means that the circuit is downsized. There was room for consideration from the point.

  The problem increases as the number of light emitting elements increases. In particular, when an organic EL is used as the light emitting element, the organic EL has a large parasitic capacitance C due to surface light emission, and the problem becomes more remarkable. The present invention has been made in order to solve the above-described problems. The object of the present invention is that the rising speed from the start of supply of drive current to light emission is high, and high-speed scanning can be performed. It is an object to provide a driving method and a driving device of a light emitting element capable of downsizing a driving source.

In order to solve the above problems, the present invention employs the following means. That is, according to the first aspect of the present invention, a light emitting element is connected to each intersection position of an anode line and a cathode line arranged in a matrix, and one side of the anode line and the cathode line is used as a scanning line and the other side is provided. It was a drive line, while scanning the scanning lines in a predetermined cycle, in synchronization with the scanning, through a pre-Symbol the drive line parasitic capacitance and the light emitting elements of the light emitting element to be emitted is connected, and the scan lines Driving a light-emitting element having a simple matrix driving method in which a current is charged to charge a parasitic capacitance of the light-emitting element, and the voltage at both ends of the light-emitting element is raised to a predetermined value or more by the charging and is forward-biased to emit light. In the method
Prior to switching the scan to the next scan line, all the scan lines and all the drive lines are connected to a reset voltage having the same potential, respectively, and the light emitting elements previously emitting light and other light emitting elements The charge of the parasitic capacitance of both is equal to 0 state,
After the reset, the current source is connected to the drive line connected to the other end of the light emitting element that should emit light among the light emitting elements connected to the switched scanning line. It is.

  According to a second aspect of the present invention, in the first aspect of the present invention, the reset voltage is a ground potential.

  According to a third aspect of the present invention, in the first aspect of the present invention, the reset voltage is a power supply potential.

The invention of claim 4, wherein, the light emitting device is characterized in the this consisting of an organic EL.

According to a fifth aspect of the present invention, there is provided a light emitting element connected to each intersection position of a plurality of anode lines and cathode lines arranged in a matrix, and a scanning line composed of any one of the plurality of anode lines and cathode lines. A scanning circuit for selecting a scanning line to be scanned, a drive circuit for connecting a current source to a desired drive line among the other drive lines in synchronization with scanning of the scanning line, the scanning circuit, and the scanning circuit A light emission control circuit for controlling a drive circuit, and the light emission control circuit scans the scanning line at a predetermined cycle, and in synchronization with the scan, the parasitic capacitance of the light emitting element to emit light and the light emitting element by passing a current through said drive lines and said scanning lines are connected to charge the parasitic capacitance of the light-emitting element, by forward launch the voltage across the light-emitting element in the above stated values the charging In scan the driving device of the light emitting element to emit light,
Prior to switching scanning to the next scanning line, the light emission control circuit connects all scanning lines and all drive lines to a reset voltage having the same potential , and then connects one end to the switched scanning line. A current source is connected to a drive line to which the other end of the light emitting element to be emitted is connected .

In the case of the configuration as described above, prior to switching to scanning to the next scanning line, all scanning lines and all drive lines were connected to a reset voltage having the same potential, and light was emitted before that. The other end of the light emitting element that should emit light among the light emitting elements whose one end is connected to the switched scanning line after the reset is completed after the charge charges of the parasitic capacitances of the light emitting element and the other light emitting elements are both equal to zero. since There current source is connected to a drive line which is connected, only the parasitic capacitance of the light emitting element to emit light is, Ru is charged by the current source via the drive line.

As described above, according to the first to fifth aspects of the present invention , since only the parasitic capacitance of the light emitting element to emit light is charged by the current source through the drive line, the current source should emit light. By simply charging the parasitic capacitance of the light-emitting element, the voltage across it can be instantly raised to a potential at which light can be emitted and biased in the forward direction. Thus, the capacity of each current source can be reduced, and the drive device can be reduced in size.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first driving method according to the present invention. This first driving method is an example in which all the cathode lines and all the anode lines are once lowered to the ground potential (0 V) and reset when scanning moves to the next cathode line.

In FIGS 4, A ₁ to A ₂₅₆ are anode lines, B ₁ .about.B ₆₄ cathode lines, the light-emitting element E _1,1 ~E _256,64 is tethered at each intersection position, 1 cathode line scanning circuit, 2 Is an anode line drive circuit, 3 is an anode reset circuit, and 4 is a light emission control circuit.

The cathode line scanning circuit 1 includes scanning switches 5 _{1 to} 5 ₆₄ for sequentially scanning the cathode lines B _{1 to} B ₆₄ . One terminal of each of the scanning switches 5 _{1 to} 5 ₆₄ is connected to a reverse bias voltage V _CC (for example, 10 V) consisting of a power supply voltage, and the other terminal is connected to a ground potential (0 V).

The anode drive circuit 2, on a drive source serving current source 2 ₁ to 2 _256, and a drive switch ₆₁ through ₂₅₆ for selecting the respective anode lines A ₁ to A _256, any drive switch Thus, the drive current sources 2 ₁ to 2 ₂₅₆ are connected to the anode line.

The anode reset circuit 3 includes shunt switches 7 _{1 to} 7 ₂₅₆ for resetting the anode lines A _{1 to} A ₂₅₆ to the ground potential (0 V).

The light emission control circuit 4 controls on / off of these scanning switches 5 _{1 to} 5 ₆₄ , drive switches 6 _{1 to} 6 _256, and shunt switches 7 _{1 to} 7 ₂₅₆ .

Next, the light emission operation by the first driving method will be described with reference to FIGS. The operation described below is performed by scanning the cathode line B ₁ to illuminate the light emitting elements E _1,1 and E _2,1 and then moving to the cathode line B ₂ to scan the light emitting elements E _2,2 and E _3,2. An explanation will be given by taking the case of shining as an example. For easy understanding, the light emitting elements that are shining are indicated by a diode symbol, and the light emitting elements that are not shining are indicated by a capacitor symbol. The reverse bias voltage V _CC applied to the cathode lines B _{1 to} B ₆₄ was 10 V, which is the same as the power supply voltage of the device.

First, in FIG. 1, the scanning switch 5 ₁ is switched to 0V side, the cathode line B ₁ is being scanned. A reverse bias voltage of 10 V is applied to the other cathode lines B _{2 to} B ₆₄ by the scanning switches 5 _{2 to} 5 ₆₄ . Furthermore, current sources 5 ₁ and 5 ₂ are connected to the anode lines A ₁ and A ₂ by drive switches 6 ₁ and 6 ₂ . The other anode lines A _{3 to} A ₂₅₆ are given 0 V by shunt switches 7 _{3 to} 7 ₂₅₆ .

Therefore, in the case of FIG. 1, only the light-emitting element E _{1, 1} and E _2,1 is forward biased, current source 5 ₁ and 5 ₂ arrows driving current flows as from a light emitting element E _{1, 1} Only E _2,1 is emitting light. In the state of FIG. 1, the light emitting elements shown by hatching the capacitors are charged in the direction of polarity as shown in the figure. When the scanning is shifted from the light emitting state of FIG. 1 to the state where the light emitting elements E _2,2 and E _{3,2 of} FIG. 4 emit light, the following reset control is performed.

That is, before the scan shifts from the cathode line B _{1 in} FIG. ₁ to the cathode line B ₂ in FIG. 4, first, as shown in FIG. 2, all the drive switches 6 _{1 to} 6 ₂₅₆ are turned off and all the scan switches are turned on. 5 _{1 to} 5 ₆₄ and all shunt switches 7 _{1 to} 7 ₂₅₆ are switched to the 0V side, and all of anode lines A _{1 to} A ₂₅₆ and cathode lines B _{1 to} B ₆₄ are shunted to 0V once, and all reset by 0V is performed. . When this all reset to 0V is performed, all of the anode line and the cathode line have the same potential of 0V, so that the charge charged in each light emitting element is discharged through the route indicated by the arrow in the figure. The charged charges of all the light emitting elements become zero instantly.

As described above, after the charges of all the light emitting elements was 0, as shown in FIG. 3, switching only the scanning switch 5 ₂ corresponding to the cathode lines B ₂ to 0V side, to scan the cathode line B ₂ . At the same time, with only the drive switches 6 ₂ and 6 ₃ current source 2 ₂ and switched to 2 ₃ side, it turns the shunt switch 7 _1, 7 _{4-7 256,} the anode lines A _1, A ₄ to A ₂₅₆ Apply 0V.

When the cathode line B ₂ is scanned by switching the switch, the charge charges of all the light emitting elements are set to 0 as described above. Therefore, the light emitting elements E _2,2 and E _3,2 to be _lighted next are emitted. In FIG. 3, charging current flows all at once through a plurality of routes as shown by arrows in FIG. 3, and the parasitic capacitance C of each light emitting element is instantaneously charged.

That is, the light-emitting element E _{2, 2,} the current source 2 ₂ → with the drive switch 6 ₂ → anode line A ₂ → emitting element E _{2, 2} → scan switches 5 ₂ routes the charging current flows, the scanning switches 5 ₁ → Cathode line B ₁ → Light emitting element E _2,1 → Light emitting element E _2,2 → Scan switch 5 ₂ route, scanning switch 5 ₃ → Cathode line B ₃ → Light emitting element E _2,3 → Light emitting element E _2,2 → Scanning switch 5 ₂ routes, ..., also the charging current flows simultaneously from scan switches 5 ₆₄ → the cathode line B ₆₄ → the light emitting element E _{2, 64} → the light emitting element E _{2, 2} → scan switches 5 ₂ routes, the light-emitting element E _{2 and 2} are instantaneously charged by these plural charging currents to emit light, and instantaneously shift to the steady state shown in FIG.

Further, the light-emitting element E _3,2, together with the charging current flowing in the normal route of the current source 2 ₃ → drive switches 6 ₃ → anode line A ₃ → the light emitting element E _3,2 → scan switches 5 _2, scanning switch 5 ₁ → cathode line B ₁ → emitting element E _{3, 1} → emitting element E _3,2 → scan switches 5 ₂ routes, the scanning switches 5 ₃ → cathode line B ₃ → the light emitting element E _3,3 → emitting element E _3,2 → scan switches 5 ₂ routes, ..., scanning switch 5 ₆₄ → the charging current can flow simultaneously from the cathode line B ₆₄ → the light emitting element E _3,64 → emitting element E _3,2 → scan switches 5 ₂ routes, emission The element E _2,2 is instantly charged by the plurality of charging currents to emit light, and instantaneously shifts to the steady state shown in FIG.

  As described above, in the first driving method, all the cathode lines and anode lines are once connected to the ground potential of 0 V and reset before moving to the next scanning. When switched to, the light emitting elements on the switched scanning line can emit light instantaneously.

The other light emitting elements other than the light emitting elements E _2,2 and E _3,2 to be _lighted are also charged through the route shown by the arrow in FIG. Since it is in the reverse bias direction, there is no possibility that other light emitting elements other than the light emitting elements E _2,2 and E _3,2 emit light erroneously.

In the example of FIGS. 1 to 4, the case where the current sources 2 ₁ to 2 ₂₅₆ are used as the drive source is shown, but the same can be realized even when a voltage source is used.

5 to 8 show a second driving method according to the present invention. This second driving method is an example in the case where all of the cathode lines and the anode lines are once reset to the power supply voltage V _CC = 10 V before scanning is shifted to the next cathode line. In order to realize this resetting method, in the circuits of FIGS. 5 to 8, three-point changeover switches are used as the drive switches 6 _{1 to} 6 ₂₅₆ , the first contact is opened, and the second contact is the current source 2 _1. ~ 2 _256, a third contact which are connected to the power supply voltage V _CC = 10V. Note that the circuit configuration of the other parts other than the drive switches 6 _{1 to} 6 ₂₅₆ is the same as that of the first driving method described above, and the description thereof is omitted.

Next, the light emission operation by the second driving method will be described with reference to FIGS. In the operation described below, as in the first driving method described above, the cathode line B ₁ is scanned to light up the light emitting elements E _1,1 and E _1,2, and then the scan is shifted to the cathode line B _2. The case where the light emitting elements _E2,2 and _E3,2 are illuminated is taken as an example.

First, in FIG. 5, the scanning switches 5 ₁ is switched to 0V side, the cathode line B ₁ is being scanned. A reverse bias voltage of 10 V is applied to the other cathode lines B _{2 to} B ₆₄ by the scan switches 5 _{2 to} 5 ₆₄ . Further, current sources 5 ₁ and 5 ₂ are connected to the anode lines A ₁ and A ₂ by drive switches 6 ₁ and 6 ₂ . The other anode lines A _{3 to} A ₂₅₆ are given 0 V by shunt switches 7 _{3 to} 7 ₂₅₆ .

Therefore, in the case of FIG. 5, only the light-emitting element E _{1, 1} and E _2,1 is biased in the collimating direction, a current source 5 ₁ and 5 ₂ arrows driving current flows as from a light emitting element E _{1, 1} Only E _2,1 is emitting light. In the state of FIG. 5, the light emitting elements shown by hatching the capacitors are charged in the direction of polarity as shown in the figure. When the light emission state of FIG. 5 is the light-emitting element E _{2, 2} and E _3,2 of Figure 8 migrating scanning to a state of emitting is performed a reset control as follows.

That is, before the scan shifts from the cathode line B _{1 in} FIG. 5 to the cathode line B ₂ in FIG. 8, first, as shown in FIG. 6, all the shunt switches 7 _{1 to} 7 ₂₅₆ are turned off and all the scan switches are turned on. 5 _{1 to} 5 ₆₄ and all drive switches 6 _{1 to} 6 ₂₅₆ are switched to the 10V side, all of the anode lines A _{1 to} A ₂₅₆ and cathode lines B _{1 to} B ₆₄ are shunted to 10V once, and all reset by 10V is performed Call. When this all reset to 10V is performed, all of the anode line and the cathode line have the same potential of 10V. Therefore, the charge charged in each light emitting element is discharged through the route indicated by the arrow in the figure. The charged charges of all the light emitting elements become zero instantly.

As described above, after the charges of all the light emitting elements was 0, as shown in FIG. 7, switching only the scanning switch 5 ₂ corresponding to the cathode lines B ₂ to 0V side, to scan the cathode line B ₂ . At the same time, the drive switches 6 ₂ and 6 ₃ are switched to the current sources 2 ₂ and 2 ₃ , and the other drive switches 6 ₁ and 6 _{4 to} 6 ₂₅₆ are switched to the open end side. Further, the shunt switches 7 ₁ , 7 _{4 to} 7 ₂₅₆ are turned on, and 0 V is applied to the anode lines A ₁ , A _{4 to} A ₂₅₆ .

When the cathode line B ₂ is scanned by switching the switch, the charge charges of all the light emitting elements are set to 0 as described above. Therefore, the light emitting elements E _2,2 and E _3,2 to be _lighted next are emitted. In FIG. 7, charging current flows all at once through a plurality of routes as indicated by arrows in FIG. 7, and the parasitic capacitance C of each light emitting element is instantaneously charged.

That is, the light-emitting element E _{2, 2,} the current source 2 ₂ → with the drive switch 6 ₂ → anode line A ₂ → emitting element E _{2, 2} → scan switches 5 ₂ routes the charging current flows, the scanning switches 5 ₁ → Cathode line B ₁ → Light emitting element E _2,1 → Light emitting element E _2,2 → Scan switch 5 ₂ route, scanning switch 5 ₃ → Cathode line B ₃ → Light emitting element E _2,3 → Light emitting element E _2,2 → Scanning switch 5 ₂ routes, ..., also the charging current flows simultaneously from scan switches 5 ₆₄ → the cathode line B ₆₄ → the light emitting element E _{2, 64} → the light emitting element E _{2, 2} → scan switches 5 ₂ routes, the light-emitting element E _{2 and 2} are instantaneously charged by the plurality of charging currents to emit light, and instantaneously shift to the steady state shown in FIG.

Further, the light-emitting element E _3,2, together with the charging current flowing in the normal route of the current source 2 ₃ → drive switches 6 ₃ → anode line A ₃ → the light emitting element E _3,2 → scan switches 5 _2, scanning switch 5 ₁ → cathode line B ₁ → emitting element E _{3, 1} → emitting element E _3,2 → scan switches 5 ₂ routes, the scanning switches 5 ₃ → cathode line B ₃ → the light emitting element E _3,3 → emitting element E _3,2 → scan switches 5 ₂ routes, ..., scanning switch 5 ₆₄ → the charging current can flow simultaneously from the cathode line B ₆₄ → the light emitting element E _3,64 → emitting element E _3,2 → scan switches 5 ₂ routes, emission The element E _2,2 is instantaneously charged by the plurality of charging currents to emit light, and instantaneously shifts to the steady state shown in FIG.

  As described above, in the second driving method, all of the cathode lines and the anode lines are once connected to the power supply voltage of 10 V and reset before moving to the next scan. When switched to, the light emitting elements on the switched scanning line can emit light instantaneously.

The other light emitting elements other than the light emitting elements E _2,2 and E _3,2 to be _lighted are also charged through the route shown by the arrow in FIG. Since it is in the reverse bias direction, there is no possibility that other light emitting elements other than the light emitting elements E _2,2 and E _3,2 emit light erroneously.

In the examples of FIGS. 5 to 8, the case where the current sources 2 ₁ to 2 ₂₅₆ are used as the drive source is shown, but the same can be realized by using a voltage source.

9 to 12 show a third driving method according to the present invention. In the third driving method, all the cathode lines B _{1 to} B ₆₄ are all reset to 10 V before scanning is shifted to the next cathode line, and the anode lines A _{1 to} A ₂₅₆ are preset for the next light emission. In this example, Since the circuit configuration itself is the same as that in the second driving method described above, the description thereof is omitted.

Next, the light emission operation by the third driving method will be described with reference to FIGS. In the operation described below, the cathode line B ₁ is scanned to emit the light emitting elements E _1,1 and E _1,2, and then the cathode line B ₂ is scanned, as in the first and second driving methods described above. Take the case where the light emitting elements E _2,2 and E _3,2 are illuminated.

First, in FIG. 9, the scanning switches 5 ₁ is switched to 0V side, the cathode line B ₁ is being scanned. A reverse bias voltage of 10 V is applied to the other cathode lines B _{2 to} B ₆₄ by the scanning switches 5 _{2 to} 5 ₆₄ . Furthermore, current sources 5 ₁ and 5 ₂ are connected to the anode lines A ₁ and A ₂ by drive switches 6 ₁ and 6 ₂ . The other anode lines A _{3 to} A ₂₅₆ are given 0 V by shunt switches 7 _{3 to} 7 ₂₅₆ .

Therefore, in the case of FIG. 9, only the light-emitting element E _{1, 1} and E _2,1 is forward biased, current source 5 ₁ and 5 ₂ arrows driving current flows as from a light emitting element E _{1, 1} Only E _2,1 is emitting light. In the state of FIG. 9, the light-emitting elements shown by hatching the capacitors are charged in the direction of polarity as shown in the figure. When the scanning is shifted from the light emitting state of FIG. 9 to the state where the light emitting elements E _2,2 and E _{3,2 of} FIG. 12 emit light, the following reset control is performed.

That is, before scanning is transferred to the cathode line B ₂ in FIG. 12 from the cathode line B ₁ in FIG. 9, first, as shown in FIG. 10, switching all the scanning switches 5 ₁ to 5 ₆₄ to 10V side, the all reset Call. Further, with respect to the anode line, only the drive switches 6 ₂ and 6 ₃ corresponding to the light emitting elements E _2,2 and E _2,3 to be lighted next are preset by connecting them to the 10V side, and the other drive switches 6 ₁ , 6 _{4 to} 6 ₂₅₆ are connected to the open end side. Further, the shunt switches 7 ₁ and 7 _{4 to} 7 ₂₅₆ are turned on and connected to 0V.

And all reset to 10V of the cathode lines B ₁ .about.B _64, the anode lines A _2, preset to 10V supply of A ₃ is performed, electric charge stored in each light emitting element is indicated by an arrow in FIG. The charge of the light emitting elements E _{2,1 to} E _2,64 , E _{3,1 to} E _3,64 connected to the anode lines A ₂ and A ₃ to be charged and discharged through such a route and then to emit light Becomes 0 instantly.

As described above, after the electric charge of the light-emitting element E _2,1 to E _{2, 64} and E _3,1 ~E _3,64 to 0, as shown in FIG. 11, 0V side scan switch 5 ₂ And the cathode line B ₂ is scanned. At the same time, the drive switches 6 ₂ and 6 ₃ are switched to the current sources 2 ₂ and 2 ₃ side.

When the cathode line B ₂ is scanned by switching the above-described switch, the charging current is applied to the light emitting elements E ₂ , ₂ and E ₃ , ₂ to be emitted at once by a plurality of routes as indicated by arrows in FIG. The parasitic capacitance C of each light emitting element is instantaneously charged.

That is, the light-emitting element E _{2, 2,} the current source 2 ₂ → with the drive switch 6 ₂ → anode line A ₂ → emitting element E _{2, 2} → scan switches 5 ₂ routes the charging current flows, the scanning switches 5 ₁ → Cathode line B ₁ → Light emitting element E _2,1 → Light emitting element E _2,2 → Scan switch 5 ₂ route, scanning switch 5 ₃ → Cathode line B ₃ → Light emitting element E _2,3 → Light emitting element E _2,2 → Scanning switch 5 ₂ routes, ..., also the charging current flows simultaneously from scan switches 5 ₆₄ → the cathode line B ₆₄ → the light emitting element E _{2, 64} → the light emitting element E _{2, 2} → scan switches 5 ₂ routes, the light-emitting element E _{2 and 2} are instantaneously charged by these plural charging currents to emit light, and instantaneously shift to the steady state shown in FIG.

Further, the light-emitting element E _3,2, together with the charging current flowing in the normal route of the current source 2 ₃ → drive switches 6 ₃ → anode line A ₃ → the light emitting element E _3,2 → scan switches 5 _2, scanning switch 5 ₁ → cathode line B ₁ → emitting element E _{3, 1} → emitting element E _3,2 → scan switches 5 ₂ routes, the scanning switches 5 ₃ → cathode line B ₃ → the light emitting element E _3,3 → emitting element E _3,2 → scan switches 5 ₂ routes, ..., scanning switch 5 ₆₄ → the charging current can flow simultaneously from the cathode line B ₆₄ → the light emitting element E _3,64 → emitting element E _3,2 → scan switches 5 ₂ routes, emission element E _{2, 2} emits light is charged instantaneously by the plurality of the charging current, moves instantaneously to the steady state shown in FIG. 12.

  As described above, in the third driving method, all the cathode lines are reset to 10 V before shifting to the next scan, and the anode lines are preset for the next light emission. When switched, the light emitting elements on the switched scanning line can emit light instantaneously.

Note that other light-emitting elements other than the light-emitting elements E _2,2 and E _3,2 to be _lighted are also charged according to the route indicated by the arrow in FIG. Since it is in the reverse bias direction, there is no possibility that other light emitting elements other than the light emitting elements E _2,2 and E _3,2 emit light erroneously.

  In the third driving method, all the cathode lines are reset to 10V. Instead, all the cathode lines may be reset to 0V.

9 to 12 show the case where the current sources 2 ₁ to 2 ₂₅₆ are used as the drive sources, but the present invention can be similarly realized by using the voltage sources.

By the way, as apparent from the drawings of FIGS. 3, 7, and 10 described above, when the driving method according to the present invention is used, the light emitting element E _{2 to} emit light next time when the next scanning is started. _{, 2} and E _3,2 are not only charged from the current sources 2 ₂ and 2 ₃ but also from the cathode lines B ₁ and B _{3 to} B ₆₄ to which the reverse bias voltage is applied to the anode lines A ₂ and A ₃ . It is simultaneously charged through other connected light emitting elements.

For this reason, when the number of light-emitting elements connected to the anode line is large, the light-emitting elements E _2,2 and E _3,2 emit light in a short time only by the charging current through the other light-emitting elements. can do. Therefore, in such a case, the current sources 2 ₁ to 2 ₂₅₆ of the anode line drive circuit 2 are not required if the cathode line is scanned at a cycle shorter than the light emission duration time due to the charging current through the other light emitting elements. be able to.

  Further, although the above example has been described by taking the case of the cathode scanning / anode driving method as an example, it is naturally possible to carry out the same in the anode scanning / cathode driving method.

It is explanatory drawing of the 1st step of the 1st drive method of this invention. It is explanatory drawing of the 2nd step of the 1st drive method of this invention. It is explanatory drawing of the 3rd step of the 1st drive method of this invention. It is explanatory drawing of the 4th step of the 1st drive method of this invention. It is explanatory drawing of the 1st step of the 2nd drive method of this invention. It is explanatory drawing of the 2nd step of the 2nd drive method of this invention. It is explanatory drawing of the 3rd step of the 2nd drive method of this invention. It is 4th step explanatory drawing of the 2nd drive method of this invention. It is explanatory drawing of the 1st step of the 3rd drive method of this invention. It is explanatory drawing of the 2nd step of the 3rd drive method of this invention. It is explanatory drawing of the 3rd step of the 3rd drive method of this invention. It is explanatory drawing of the 4th step of the 3rd drive method of this invention. It is explanatory drawing of the conventional drive method. It is a figure which shows the equivalent circuit of a light emitting element. It is explanatory drawing of the charging / discharging state at the time of the scanning transfer in the conventional drive method.

Explanation of symbols

1 Cathode line scanning circuit 2 Anode line drive circuit 2 ₁ to 2 ₂₅₆ Current source (drive source)
3 Anode reset circuit 4 Light emission control circuit 5 _{1 to} 5 ₆₄ Scan switch 6 _{1 to} 6 ₂₅₆ Drive switch 7 _{1 to} 7 ₂₅₆ Shunt switch A _{1 to} A ₂₅₆ Anode line (drive line)
B ₁ .about.B ₆₄ cathode lines (scan lines)
E _{1,1 to} E _256,64 Light emitting element V _CC power supply voltage

Claims (5)

A light emitting element is connected to each intersection position of the anode line and the cathode line arranged in a matrix, and one side of the anode line and the cathode line is used as a scanning line and the other side is used as a drive line. while scanning in, in synchronization with the scanning, the parasitic capacitance of the previous SL parasitic capacitance and the light emitting element by flowing a current through the said drive lines and said scanning lines are connected the light emitting element of the light emitting element to be emitted In the driving method of the light emitting element consisting of a simple matrix driving method in which the voltage across the light emitting element is raised to a predetermined value or more by the charging and biased in the forward direction to emit light.
Prior to switching the scan to the next scan line, all the scan lines and all the drive lines are connected to a reset voltage having the same potential, respectively, and the light emitting elements previously emitting light and other light emitting elements The charge of the parasitic capacitance of both is equal to 0 state,
After resetting, the current source is connected to the drive line connected to the other end of the light emitting element to be emitted among the light emitting elements connected to the switched scanning line. Device driving method. The method for driving a light emitting device according to claim 1,
A method for driving a light emitting element, wherein the reset voltage is a ground potential. The method for driving a light emitting device according to claim 1,
A method for driving a light emitting element, wherein the reset voltage is a power supply potential. The method for driving a light emitting element according to any one of claims 1 to 3, wherein the light emitting element is made of an organic EL. A light emitting element connected to each intersection position of a plurality of anode lines and cathode lines arranged in a matrix and a scanning line to be scanned are selected from scanning lines composed of either one of the plurality of anode lines or cathode lines. A scanning circuit; a drive circuit for connecting a current source to a desired drive line among the other drive lines in synchronization with scanning of the scanning line; and a light emission control circuit for controlling the scanning circuit and the drive circuit. The light emission control circuit scans the scanning line at a predetermined cycle, and in synchronization with the scanning, the parasitic capacitance of the light emitting element to emit light and the drive line to which the light emitting element is connected and the scanning by passing a current through the line to charge the parasitic capacitance of the light-emitting element, the light-emitting element which emits light by forward biasing launched a voltage across the relevant light emitting element than the specified value by the charging In the operated device,
Prior to switching the scan to the next scan line, the light emission control circuit connects all the scan lines and all the drive lines to a reset voltage having the same potential , and then one end of the switched scan line has one end. A drive device for a light emitting element, characterized in that a current source is connected to a drive line to which the other end of the light emitting element to be emitted is connected among the connected light emitting elements.

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