JP2007101826A - Device and method for driving light emitting display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving device and driving method capable of reducing the temperature dependence of the light emission luminance in light emitting elements. <P>SOLUTION: The driving device includes a thermistor Th, in which a voltage source controlled in output voltage in correspondence to an environmental temperature is used as a non-lighting drive power source 5a. A reset period and a lighting drive period are repeated at every one scanning and the output voltage from a non-lighting drive power source in the reset period is applied to the respective light emitting elements E11 to Emn arranged on a display panel 1. In case of a shift to the lighting drive period, the light emission drive current is supplied from constant current circuits I1 to Im to the light emitting elements to be the target for lighting. In such a case, the light emitting element to be the target for lighting rises to the forward voltage in correspondence to the environmental temperature on the basis of the output voltage from the non-lighting drive power source 5a and therefore, the time rising to the forward voltage from the reset period is kept nearly constant regardless of the low-temperature state or the high-temperature state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a driving apparatus and a driving method that can be suitably used for a light-emitting display panel using a capacitive light-emitting element, and in particular, driving that can reduce temperature dependence of light emission luminance in the light-emitting element. The present invention relates to an apparatus and a driving method.

  With the widespread use of mobile phones and portable information terminals (PDAs), there is an increasing demand for display panels that have a high-definition image display function and that can be thin and achieve low power consumption. Liquid crystal display panels have been adopted in many products as display panels that satisfy these requirements. On the other hand, in recent years, an organic EL (electroluminescence) element that takes advantage of the characteristic of being a self-luminous element has been put into practical use, and this is drawing attention as a next-generation display panel that replaces a conventional liquid crystal display panel. This is also due to the fact that the use of an organic compound that can be expected to have good light-emitting characteristics for the light-emitting layer of the device has led to higher efficiency and longer life that can withstand practical use.

  The organic EL element (hereinafter also simply referred to as EL element) is basically formed on a transparent substrate such as glass on a transparent electrode (anode) made of ITO, a light emitting functional layer, and a metal electrode made of aluminum alloy ( Cathode) are sequentially laminated. The light-emitting functional layer is a single light-emitting layer made of an organic compound, or a two-layer structure composed of an organic hole transport layer and a light-emitting layer, or a three-layer structure consisting of an organic hole transport layer, a light-emitting layer, and an organic electron transport layer Further, there may be a multilayer structure in which a hole injection layer is inserted between the transparent electrode and the hole transport layer, and an electron injection layer is inserted between the metal electrode and the electron transport layer. Then, the light generated in the light emitting functional layer is led out through the transparent electrode and the transparent substrate.

  The above-described EL element can be replaced with a configuration of a light emitting element having an electrically diode characteristic and a parasitic capacitance component coupled in parallel to the light emitting element, and the EL element is a capacitive light emitting element. I can say. When a light emission driving voltage is applied to the EL element, first, a charge corresponding to the electric capacity of the element flows into the electrode as a displacement current and is accumulated. Subsequently, when a certain voltage specific to the element (light emission threshold voltage = Vth) is exceeded, a current starts to flow from one electrode (the anode side of the diode component) toward the light emitting functional layer, and light is emitted with an intensity proportional to the current. Then you can think.

  On the other hand, the current / brightness characteristics of organic EL elements are stable with respect to temperature changes, while the voltage / brightness characteristics are highly dependent on temperature changes, and the organic EL elements have received overcurrent. In general, constant current driving is performed for reasons such as severe deterioration and shortening the light emission life. As a display panel using such an organic EL element, a passive drive display panel in which elements are arranged in a matrix has already been put into practical use.

  FIG. 1 shows an example of a conventional passive matrix display panel and its driving circuit, which shows a form of cathode line scanning / anode line drive. That is, m data lines (hereinafter also referred to as anode lines) A1 to Am are arranged in the vertical direction, and n scanning lines (hereinafter also referred to as cathode lines) K1 to Kn are in the horizontal direction. The EL elements E11 to Emn shown as parallel combinations of diode and capacitor symbol marks are arranged at each intersecting portion (total of m × n locations) to constitute the display panel 1.

  Each EL element E11 to Emn constituting the pixel has one end (in the equivalent diode of the EL element) corresponding to each intersection position of the anode lines A1 to Am along the vertical direction and the cathode lines K1 to Kn along the horizontal direction. The anode terminal is connected to the anode line, and the other end (the cathode terminal in the equivalent diode of the EL element) is connected to the cathode line. Further, each anode line A1 to Am is connected to an anode line drive circuit 2 as a data driver, and each cathode line K1 to Kn is connected to and driven by a cathode line scanning circuit 3 as a scanning driver.

  The anode line drive circuit 2 includes constant current sources I1 to Im as lighting drive power sources that operate using a drive voltage from the drive voltage source VH, and drive switches Sa1 to Sam, and the drive switch Sa1. ~ Sam is connected to the constant current sources I1 to Im, so that the currents from the constant current sources I1 to Im are applied to the individual EL elements E11 to Emn arranged corresponding to the scanned cathode lines. It acts to be supplied as a lighting drive current.

  The drive switches Sa1 to Sam supply a ground (GND) potential, which is a reference potential of a circuit as a non-lighting driving power supply, to the individual EL elements E11 to Emn arranged corresponding to the cathode lines. It is configured to be able to. In the description in this specification, the terms of lighting and light emission are mixed, but these have no particular meaning and are used as the same meaning.

  On the other hand, the cathode line scanning circuit 3 is provided with scanning switches Sk1 to Skn corresponding to the cathode lines K1 to Kn, and functions as a non-scanning selection potential and is mainly used to prevent crosstalk light emission. Either a reverse bias voltage from the source VM or a ground (GND) potential as a scanning selection potential can be supplied to the corresponding cathode line.

  A control signal is supplied to the anode line drive circuit 2 and the cathode line scanning circuit 3 from a light emission control circuit 4 including a CPU via a control bus, and the scanning is performed based on a video signal to be displayed. Switching operations of the switches Sk1 to Skn and the drive switches Sa1 to Sam are executed. Thus, the constant current sources I1 to Im are connected to the desired anode line while setting the cathode line to the ground potential at a predetermined cycle based on the video signal, and the EL elements E11 to Emn are selectively emitted. As a result, an image based on the video signal is displayed on the display panel 1.

  In the state shown in FIG. 1, the first cathode line K1 is set to the ground potential to be in a scanning state. At this time, each of the cathode lines K2 to Kn in the non-scanning state is supplied with the above-described reverse bias voltage source VM. A reverse bias voltage is applied. Here, when the forward voltage of the EL element in the scanning light emission state is Vf, each potential is set such that [(forward voltage Vf) − (reverse bias voltage VM)] <(light emission threshold voltage Vth). Therefore, each EL element connected to the intersection of the driven anode line and the cathode line not selected for scanning acts to prevent crosstalk light emission.

  In the display panel driving apparatus having the above-described configuration, when each scanning line is sequentially scanned, the amount of charges charged in the parasitic capacitance of each EL element is all zero or all predetermined potential prior to each scanning. After that, a reset operation is executed, and thereafter, a lighting drive operation for connecting the data line to be driven to the lighting drive power source is executed.

  In the above-described reset operation, all the scanning switches Sk1 to Skn in the cathode line scanning circuit 3 are all connected to the ground side which is the scanning selection potential, and all the driving switches Sa1 to Sam in the anode line driving circuit 2 are non-scanning selected. It is connected to the ground side, which is a potential. Thereby, in the configuration shown in FIG. 1, a reset operation (GND-GND reset) is performed in which the charge amount charged in the parasitic capacitances of the EL elements arranged in the display panel 1 is all zero.

  By performing this operation, the charge charged in the parasitic capacitance of all EL elements is reduced to zero, so that the EL element to be driven next is affected by the charge accumulated by the previous scan. Therefore, it is possible to accurately control the light emission luminance of the EL element.

  In the above-described lighting drive operation (lighting drive period) following the reset operation (reset period), the scanning lines to be scanned among the scanning lines, that is, the first scanning line K1 in the example shown in FIG. Are set to the ground potential, which is the scanning selection potential, and the scanning switches Sk1-Skn are selectively connected so that the other scanning lines K2-Kn are set to the reverse bias potential VM, which is the non-scanning selection potential. Of the data lines, data lines to be driven for lighting (all data lines A1 to Am in FIG. 1) are connected to constant current sources I1 to Im as lighting driving power sources via drive switches Sa1 to Sam. The connected operation is executed.

The above-described reset operation (reset period) and lighting driving operation (lighting driving period) are repeated in the same manner by sequentially changing the scanning lines to be scanned, so that the EL elements arranged on the display panel are as if they are continuously emitting light. The lighting is controlled like this. Many applications have already been filed for the drive device for the passive matrix light emitting display panel including the reset operation as described above, and Patent Document 1 and Patent Document 2 shown below can be cited.
Japanese Patent No. 3646916 Japanese Patent No. 364617

  By the way, the EL elements arranged in the display panel described above have temperature dependency as described above. For example, in the application state of the same voltage value, the EL element has high luminance at high temperature and low luminance at low temperature. Present. Further, under the condition of supplying the same driving current, the forward voltage Vf of the element is low at a high temperature, and the forward voltage Vf of the element is high at a low temperature.

  In particular, in the passive matrix type display device of the constant current drive type as shown in FIG. 1, after the voltage applied to the element at the time of lighting driving reaches the forward voltage Vf, it is driven by the constant current, so that it is related to the environmental temperature. Almost the same luminance characteristics can be obtained. However, since the time until the voltage applied to the element reaches the forward voltage Vf varies depending on the environmental temperature, there arises a problem that the luminance varies depending on the environmental temperature as a result.

  FIG. 2 schematically shows the operation. The horizontal axis indicates a reset period and a constant current period (lighting driving period) corresponding to one scanning period, and the vertical axis indicates a lighting driving target. The both-ends voltage (forward voltage) of one EL element is shown. Here, in the case where the above-described GND-GND reset is executed, the voltage across the EL element is made zero during the reset period. During the constant current period, the voltage across the EL element gradually increases due to the influence of the parasitic capacitance, and reaches the forward voltage Vf corresponding to the environmental temperature.

  At this time, when the environmental temperature is a low temperature state, the forward voltage is high as indicated by Vfc, so that it takes time to rise. For this reason, the light emission luminance of the element is substantially lowered. When the ambient temperature is high, the forward voltage is low as indicated by Vfa, so that the time required for the rise is shortened, and the light emission luminance of the element is substantially increased.

  The influence of the luminance change corresponding to the temperature due to the above action is not so much a problem in a monochrome display panel in which the same emission color is arranged. For example, the emission of R (red), G (green), and B (blue) In color display panels having colors, the luminance characteristics with respect to temperature are different from each other, which causes a problem that the chromaticity balance is lost due to a change in environmental temperature.

  The present invention has been made paying attention to the above-described problems, and in particular, by applying to the above-described passive drive type light emitting display panel in which the lighting control is repeated to repeat the reset period and the lighting drive period for each scan, It is an object of the present invention to provide a driving device and a driving method capable of effectively reducing the temperature dependence of a light emitting element.

  A preferred basic form of the drive device according to the present invention made to solve the above-described problems is, as described in claim 1, a plurality of scanning lines and a plurality of data lines intersecting each other, and each of the scanning lines and each of the scanning lines. A driving device of a light emitting display panel having a light emitting element connected between each scanning line and each data line at an intersection of data lines, wherein each scanning line is scanned with a scanning selection potential or non-scanning. A scanning driver for setting a selection potential and a data driver for connecting each of the data lines to a lighting driving power source or a non-lighting driving power source are provided, and an output voltage value of the non-lighting driving power source is variable It is characterized by being configured to be controlled.

  According to a preferred basic aspect of the driving method according to the present invention made to solve the above-described problem, a plurality of scanning lines and a plurality of data lines intersecting each other and the scanning lines intersecting each other as set forth in claim 11. And a light emitting display panel driving method including light emitting elements connected between the scanning lines and the data lines at the intersections of the data lines, wherein the data lines are connected to a non-lighting driving power source. A reset operation to be performed, a scanning line to be scanned among each scanning line is set to a scanning selection potential, and a data driving target to be driven among the data lines is connected to a lighting driving power source. Are repeatedly executed by sequentially changing the scanning line to be scanned, and the output voltage value of the non-lighting driving power source applied to each data line in the reset operation is variable. Characterized in that it is your.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS A light emitting display panel driving apparatus according to the present invention will be described below based on the embodiments shown in the drawings. FIG. 3 shows the first embodiment. The display panel, the data driver, the scan driver, and the light emission control circuit indicated by reference numerals 1 to 4 are the same as those already shown in FIG. Detailed description thereof is omitted. In the configuration shown in FIG. 3 as well, as already described based on FIG. 1, the reset period and the constant current period (lighting drive period) are set for each scanning period, so that the display panel 1 is arranged. Each EL element operates so as to be selectively lit based on the video signal.

  Reference numeral 5a shown in FIG. 3 indicates a non-lighting drive power supply, which is for each EL element arranged on the display panel 1 through the drive switches Sa1 to Sam and the data lines A1 to Am in the reset period. In addition, the output voltage is supplied and, during the lighting drive period, the output voltage is supplied via the drive switch to a data line that is not a lighting drive target.

  This non-lighting drive power supply 5a is provided with a series connection circuit of a thermistor TH as a temperature sensing element and a resistance element R2, and the non-lighting driving power source 5a is not subjected to non-lighting by a change in the voltage dividing ratio between the thermistor and the resistance element depending on the temperature change. The output voltage from the lighting drive power supply 5a is variably controlled. That is, the series connection circuit of the thermistor TH and the resistance element R2 is connected to the voltage source V2, and the divided output by the thermistor TH and the resistance element R2 is a pnp transistor Tr1 that functions as a voltage follower. It is comprised so that it may supply to the base terminal which is these control electrodes.

  One controlled electrode, that is, the collector electrode of the transistor Tr1 is connected to the ground that is the reference potential point, and the other controlled electrode, that is, the emitter electrode is connected to the voltage source V1 through the resistance element R1. The emitter electrode constitutes an output voltage terminal in the non-lighting driving power source 5a.

  The thermistor TH has a negative characteristic with respect to changes in environmental temperature, and its resistance value increases as the temperature decreases. Therefore, in the configuration of the non-lighting drive power supply 5a shown in FIG. 3, the base potential of the transistor Tr1 increases as the temperature decreases. As a result, the DC resistance value between the emitter and collector of the transistor Tr1 increases, and as a result, the characteristic that the output voltage of the non-lighting drive power supply 5a increases as the environmental temperature decreases is obtained.

  FIG. 4 shows a state of each potential applied to the data line and the scanning line in a reset period and a constant current period (lighting driving period) corresponding to one scanning period made by the configuration shown in FIG. is there. 4A shows potentials in the reset period and constant current period applied to the data lines A1 to Am, and FIG. 4B shows the same reset period applied to the scan line to be scanned. The potential in the constant current period is shown. Further, (c) shows the potential in the same reset period and constant current period applied to the scanning line that is not to be scanned.

  That is, in the reset period, as shown in FIG. 4A, output voltages (shown here as Va to Vc) from the non-lighting drive power supply 5a are supplied to the data lines A1 to Am. In the constant current period, a constant current is supplied from the constant current circuits I1 to Im to the data line to which the EL element to be lit is connected, whereby the forward voltage Vf of the element is supplied to the data line. Will be applied.

  On the other hand, a ground potential (0 V) is applied to the scanning line to be scanned in both the reset period and the constant current period as shown in FIG. Further, as shown in FIG. 4C, the reverse bias voltage VM is applied to each scanning line that is not to be scanned.

  FIG. 5 shows the state of the potential at both ends applied to the EL element to be lit by the above-described operation. That is, in the characteristics shown in FIG. 5, the horizontal axis indicates a reset period and a constant current period (lighting drive period) corresponding to one scanning period, and the vertical axis indicates the same as the example shown in FIG. The voltage between both ends (forward voltage) of one EL element to be lit and driven is schematically shown.

  As shown in FIG. 5, when the environmental temperature is high, the output voltage value from the non-lighting driving power source 5a is set to a relatively low voltage value as indicated by Va, and as the environmental temperature becomes low, The output voltage value from the non-lighting drive power supply 5a is a relatively high voltage value as indicated by Vc. This is applied to all EL elements connected to the scanning line to be scanned through the drive switches Sa1 to Sam during the reset period. In the reset period, as described above, the scan switch to be scanned is set to the scan selection potential (ground potential), and the scan switch not to be scanned is set to the reverse bias voltage VM.

  Therefore, during the reset period described above, the voltage indicated by Va to Vc is accumulated in the parasitic capacitance of each EL element in response to the output voltage from the non-lighting drive power supply 5a that is variably controlled according to the environmental temperature. In the case of shifting to the constant current period, a light emission driving current is supplied from the constant current circuits I1 to Im that are the lighting driving power sources to the EL elements that are the lighting driving target. As a result, the voltage across the EL element gradually increases due to the influence of the parasitic capacitance, and reaches the forward voltages Vfa to Vfc corresponding to the environmental temperature.

  As can be understood from the operation characteristics shown in FIG. 5, for example, in the low temperature state, the voltage indicated as Vc is accumulated in the parasitic capacitance of the EL element to be lit in the reset period, and the state shifts to the constant current period in this state. Thus, the voltage across the EL element rises to a forward voltage indicated by Vfc. On the other hand, in the high temperature state, the voltage indicated as Va in the reset period is accumulated in the parasitic capacitance of the EL element to be lit, and in this state, the voltage across the EL element is in the order indicated by Vfa. Rise to directional voltage.

  In this way, the output voltage value of the non-lighting driving power supply is variably controlled according to the environmental temperature, so that the time for the EL element to be lit to rise to the forward voltage from the reset period is a low temperature state. Regardless of the high temperature state, it is adjusted so as to have a substantially constant period. In other words, the light emission luminance of the EL element to be turned on exhibits a substantially constant value regardless of the low temperature state and the high temperature state, and the temperature dependency of the EL element can be eliminated.

  In the non-lighting drive power supply 5a shown in FIG. 3, the output voltage value is preferably set so as to be variably controlled within a range equal to or lower than the light emission threshold voltage (Vth) of the EL element. Thus, it is possible to prevent each EL element from being in the lighting drive state in the reset period or the like. This is similarly set in the configuration of the non-lighting drive power supplies 5a and 5b shown in FIGS.

  The operation described above shows an example in which the scanning line to be scanned is set to the ground potential in the reset period. On the other hand, it is also possible to execute a reset operation for setting all the scanning lines K1 to Kn to the reverse bias voltage VM in the reset period. FIG. 6 explains the operation. (A) to (c) shown in FIG. 6 are the data lines A1 to Am in the reset period and constant current period corresponding to one scanning period, similarly to (a) to (c) shown in FIG. The states of the potentials applied to the scanning lines K1 to Kn are shown.

  In the reset operation illustrated in FIG. 6, the reverse bias voltage VM is applied to the scanning lines K1 to Kn during the reset period. In the constant current period, the same potential as in the example shown in FIG. 4 is applied to each of the data lines A1 to Am and the scanning lines K1 to Kn. According to this, in the reset period, the output voltages Va to Vc from the non-lighting driving power supply 5a are applied to all the EL elements with the reverse bias voltage VM as a reference.

  Even in the above-described lighting drive operation accompanied by the reset operation, the rise time of the voltage across the EL element to be lit is a substantially constant period regardless of the low temperature state and the high temperature state, and therefore the temperature dependence of the EL element is reduced. It can be eliminated.

  FIG. 7 shows a second embodiment of the display panel driving apparatus according to the present invention. Each part indicated by reference numerals 1 to 4 is the same as the structure shown in FIG. Description is omitted. In the non-lighting drive power supply 5b shown in FIG. 7, the monitor element Ex composed of the EL elements having the same layer structure is used by the same film forming process as the EL elements arranged in the display panel 1. The output voltage from the non-lighting drive power supply 5b is generated using the forward voltage generated in the monitor element Ex.

  That is, the fact that the forward voltage of the monitor element Ex has temperature dependence is utilized, and this monitor element Ex is formed on the display panel 1 like the EL element for display. The degree of thermal adhesion becomes good, and thus accurate temperature compensation can be expected.

  The non-lighting driving power source 5b shown in FIG. 7 includes a constant current source Ix driven by a voltage source V1, and current from the constant current source Ix is supplied to the monitor element Ex formed on the display panel 1. In addition, the anode terminal of the monitor element Ex is supplied to an operational amplifier OP1 that constitutes a buffer amplifier (voltage gain 1). Then, the output of the operational amplifier OP1 is divided by a voltage dividing circuit composed of resistance elements R3 and R4, and the divided output is supplied to the second operational amplifier OP2 constituting the buffer amplifier. It is comprised so that it may become the output of the lighting drive power supply 5b.

  As described above, the forward voltage of the monitor element Ex has a negative temperature-dependent characteristic. Therefore, the output of the non-lighting drive power supply 5b generated by this is in the reset period shown in FIG. The voltage can be used as the voltage indicated by Va to Vc supplied to the display EL elements E11 to Emn.

  FIG. 8 shows a third embodiment of the display panel driving apparatus according to the present invention. The components shown by reference numerals 1 to 4 are the same as those already shown in FIG. Description is omitted. In the configuration shown in FIG. 8, the drive switches Sa1 to Sam in the data driver 2 connect the data lines A1 to Am to the constant current circuits I1 to Im, the ground potential, or the non-lighting drive power supply 5a. It is configured to be able to. In the embodiment shown in FIG. 8, the non-lighting driving power source 5a having the same configuration as that described with reference to FIG. 3 is provided. This is the non-lighting driving power source 5b having the configuration shown in FIG. Can also be used.

  The drive switches Sa1 to Sam shown in FIG. 8 have the above-described reset period, the discharge period for discharging the charge accumulated in the parasitic capacitance of each EL element, and the non-lighting drive power supply for the EL element to be lit next. It operates so as to be set separately from the precharge period in which the output voltage of 5 is applied.

  FIG. 9 shows a state of each potential applied to the data line and the scanning line in a reset period and a constant current period (lighting driving period) corresponding to one scanning period made by the configuration shown in FIG. It is. Note that (a) to (c) shown in FIG. 9 are similar to (a) to (c) shown in FIG. 4 and FIG. 6 described above, and the reset period and constant current period corresponding to one scanning period are described above. The state of each potential applied to the data lines A1 to Am and the scanning lines K1 to Kn is shown.

  In addition, in the reset operation shown in FIG. 9, the first half of the reset period is set separately for a discharge period indicated by d and a precharge period indicated by e. That is, during the discharge period indicated by d in FIG. 9, the drive switches Sa1 to Sam shown in FIG. 8 operate so as to select the ground side. Further, each of the scanning switches Sk1 to Skn is connected to the ground side which is the scanning selection potential.

  Therefore, both ends of each EL element arranged in the display panel 1 are connected to the ground potential, and all the charges accumulated in the parasitic capacitance of each EL element are discharged. In the next precharge period e following this, the drive switches Sa1 to Sam are connected to the non-lighting drive power supply 5a side as shown in FIG. At this time, the ground potential (0 V) is applied to the scanning line to be scanned as shown in FIG. 9B, and the scanning line that is not to be scanned is reversed as shown in FIG. 9C. A bias voltage VM is applied. In the constant current period following the precharge period e, the same control as that already described with reference to FIG. 4 is executed.

  FIG. 10 shows the state of the potential of both ends applied to the EL element to be lit based on the above-described operation. This is similar to the example shown in FIG. The reset period and the constant current period corresponding to one scanning period are shown, and the vertical axis schematically shows the both-ends voltage (forward voltage) of one EL element to be lit and driven.

  According to the embodiment shown in FIG. 8 and FIG. 9, the charge accumulated in the parasitic capacitance of each EL element arranged in the display panel 1 in the discharge period d in the first half of the reset period as shown in FIG. Therefore, it is possible to avoid that the EL element to be lighted next is not affected by the electric charge accumulated by the previous scan, and to control the emission luminance of the EL element with high accuracy. Become.

  After the precharge period e, the same operation as that shown in FIG. 5 is performed. Therefore, the rise time of the voltage across the EL element to be lit is a substantially constant period regardless of the low temperature state and the high temperature state. Therefore, the temperature dependency of the EL element can be eliminated.

  FIG. 11 shows an example in which all the potentials of the scanning lines K1 to Kn are set to the reverse bias potential VM in the precharge period indicated by the symbol e, and the other operations are the same as those shown in FIG. According to this, in the precharge period e, the output voltages Va to Vc from the non-lighting drive power supply 5a are applied to all the EL elements with the reverse bias voltage VM as a reference.

  Even with such a precharge operation, the rise time of the voltage across the EL element to be lit is substantially constant regardless of the low temperature state and the high temperature state, and thus the temperature dependency of the EL element is eliminated. Can do.

  The embodiment described above assumes a driving apparatus that supports monochrome display in which EL elements that emit light of the same color are arranged on the light-emitting display panel 1. On the other hand, FIG. 12 shows a preferred embodiment of the driving apparatus according to the present invention assuming a color display. In the display panel 1 shown in FIG. 12, EL elements having emission colors of R (red), G (green), and B (blue) are used as sub-pixels, and one color pixel is configured by these three sub-pixels. ing.

  That is, as shown in part in FIG. 12, E11R, E12R,... E1nR are sub-pixels that emit red, and E11G, E12G,... E1nG are sub-pixels that emit green. Further, E11B, E12B,... E1nB indicate sub-pixels that emit blue light. In the embodiment shown in FIG. 12, a non-lighting drive power supply 5R corresponding to the R (red) emission color sub-pixel, a non-lighting drive power supply 5G corresponding to the G (green) emission color sub-pixel, A non-lighting driving power source 5B corresponding to the B (blue) emission color sub-pixel is provided.

  These non-lighting drive power supplies 5R, 5G, and 5B have the configuration of the non-lighting drive power supply 5a shown in FIG. 3 described above or the non-lighting drive power supply 5b shown in FIG. It is configured to be individually variably controlled according to the temperature. The outputs from the non-lighting drive power supplies 5R, 5G, and 5B are respectively applied to the sub-pixels in the already described reset period, and the parasitic capacitance of the EL elements that constitute the sub-pixels is controlled for each emission color. For example, the operation is performed so that the voltages indicated by Va to Vc shown in FIG.

  Therefore, according to the configuration shown in FIG. 12, the chromaticity balance of the R (red), G (green), and B (blue) sub-pixels having different luminance characteristics with respect to the temperature is suitably adapted to the temperature change. It becomes possible to arrange.

  In the embodiment shown in FIG. 12, the R, G, B sub-pixels are provided with non-lighting drive power supplies 5R, 5G, 5B, respectively. Depending on the characteristics of the G and B sub-pixels, even if the same output voltage is supplied to the two sub-pixels by sharing the output voltage of one non-lighting driving power supply, the chromaticity balance with respect to the temperature is maintained. Sometimes you can. Therefore, in the case as described above, by providing at least two non-lighting driving power supplies, it is possible to obtain the effect of maintaining the chromaticity balance described above.

  The configuration including the non-lighting driving power supplies 5R, 5G, and 5B shown in FIG. 12 includes a three-input type drive switch as shown in FIG. 8, and includes a reset period, a discharge period d, and a precharge period e. It can also be applied to a driving device for a color display panel that is operated so as to be set separately.

  In the embodiment described above, an example in which an organic EL element is used as a light emitting element arranged in a display panel is shown. However, the same applies to the case where another element having a capacitance is used as the light emitting element. The effect of this can be obtained.

It is a circuit block diagram which showed an example of the conventional passive matrix type display panel and its drive circuit. 2 is a timing chart schematically illustrating a lighting drive operation in the display panel illustrated in FIG. 1. 1 is a circuit configuration diagram showing a first embodiment of a drive device according to the present invention; FIG. It is a timing chart explaining one lighting drive operation by the drive device shown in FIG. FIG. 5 is a timing chart for explaining an action performed by the driving operation shown in FIG. 4. FIG. 4 is a timing chart for explaining another lighting driving operation by the driving device shown in FIG. 3. It is the circuit block diagram which showed 2nd Embodiment of the drive device concerning this invention. It is the circuit block diagram which similarly showed 3rd Embodiment. It is a timing chart explaining one lighting drive operation by the drive device shown in FIG. FIG. 10 is a timing chart for explaining operations performed by the driving operation shown in FIG. 9. FIG. FIG. 9 is a timing chart for explaining another lighting driving operation by the driving device shown in FIG. 8. FIG. It is the circuit block diagram which showed 4th Embodiment of the drive device concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission display panel 2 Data driver 3 Scan driver 4 Light emission control circuit 5, 5a, 5b Non-lighting drive power supply 5R, 5G, 5B Non-lighting drive power supply A1-Am Data line (anode line)
E11 to Emn Light emitting element (organic EL element)
Ex monitor element I1-Im Lighting drive power supply (constant current source)
K1 to Kn Scan lines (cathode lines)
Sa1-Sam Drive Switch Sk1-Skn Scan Switch TH Thermistor (Temperature Sensor)
Tr1 transistor VH drive voltage source VM reverse bias voltage source (non-scanning selection power supply)

Claims (16)

A light emitting display panel comprising a plurality of scanning lines and a plurality of data lines intersecting each other, and light emitting elements respectively connected between the scanning lines and the data lines at the intersections of the scanning lines and the data lines Drive device
A scanning driver for setting each of the scanning lines to a scanning selection potential or a non-scanning selection potential, and a data driver for connecting each of the data lines to a lighting driving power source or a non-lighting driving power source are provided. ,
A drive device for a light-emitting display panel, characterized in that an output voltage value of the non-lighting drive power supply is variably controlled.   2. The drive device of a light emitting display panel according to claim 1, wherein an output voltage value of the non-lighting driving power source is variably controlled according to temperature.   3. The drive device for a light emitting display panel according to claim 2, wherein the output voltage value of the non-lighting drive power supply is configured to have a characteristic of increasing as the temperature decreases.   A scanning line to be scanned is set to a scanning selection potential, and among the data lines, a lighting driving period in which a data line to be lit for driving is connected to a lighting driving power source, and a scanning line to be scanned next is selected for scanning. The output voltage of the non-lighting driving power source is set via the data lines during the lighting driving period in which the data line to be lit for driving is connected to the lighting driving power source among the data lines. 4. The drive device for a light-emitting display panel according to claim 1, wherein a reset period to be applied to a light-emitting element to be lit is set.   In each reset period, a discharge period for discharging the charge accumulated in the parasitic capacitance of each light emitting element arranged in the display panel, and an output voltage of the non-lighting driving power supply for the light emitting element to be lit next 5. The driving device of a light emitting display panel according to claim 4, wherein a precharge period in which is applied is set.   The non-lighting driving power source is provided with a series connection circuit of a temperature sensing element and a resistance element, and the output voltage value is variably controlled by changing a voltage dividing ratio between the temperature sensing element and the resistance element depending on a temperature change. 6. The driving device for a light emitting display panel according to claim 1, wherein the driving device is configured as described above.   The non-lighting drive power supply further includes a voltage follower that receives a divided voltage output by the temperature sensing element and the resistance element at a control electrode, and a direct current resistance value between two controlled electrodes of the voltage follower. 7. The drive device for a light emitting display panel according to claim 6, wherein the output voltage value is variably controlled using a change in the output voltage.   The non-lighting drive power supply uses a monitor element having the same layer structure as the light emitting elements arranged in the display panel, and utilizes the forward voltage of the monitor element depending on a temperature change, 6. The drive device for a light emitting display panel according to claim 1, wherein the output voltage value is variably controlled.   9. The output voltage value of the non-lighting driving power source is configured to be variably controlled within a range equal to or lower than a light emission threshold voltage of the light emitting element. Drive device for light emitting display panel.   The light emitting elements arranged in the display panel include a plurality of elements exhibiting different light emission colors, and at least two non-lighting drive power supplies corresponding to the plurality of light emission colors. 10. The driving device for a light emitting display panel according to claim 1, wherein the output voltage value is variably controlled individually. A light emitting display panel comprising a plurality of scanning lines and a plurality of data lines intersecting each other, and light emitting elements respectively connected between the scanning lines and the data lines at the intersections of the scanning lines and the data lines Driving method,
A reset operation for connecting each data line to a non-lighting drive power supply;
A lighting driving operation for setting a scanning line to be scanned among the scanning lines to a scanning selection potential, and connecting a data line to be lit for driving among the data lines to a lighting driving power source,
The light emission is characterized in that the scanning line to be scanned is sequentially changed and repeatedly executed, and the output voltage value of the non-lighting driving power source applied to each data line in the reset operation is variably controlled. Driving method of display panel.   The method of driving a light emitting display panel according to claim 11, wherein the output voltage value of the non-lighting driving power source is variably controlled according to temperature.   13. The method of driving a light emitting display panel according to claim 12, wherein the output voltage value of the non-lighting driving power source is controlled such that the output voltage value increases as the temperature decreases.   A scanning line to be scanned is set to a scanning selection potential, and among the data lines, a lighting driving period in which a data line to be lit for driving is connected to a lighting driving power source, and a scanning line to be scanned next is selected for scanning. The output voltage of the non-lighting driving power source is set via the data lines during the lighting driving period in which the data line to be lit for driving is connected to the lighting driving power source among the data lines. 14. The method for driving a light emitting display panel according to claim 11, wherein a reset period to be applied to the light emitting element to be turned on is set.   In each of the reset periods, a discharge period in which charges accumulated in the parasitic capacitance of each light emitting element arranged in the display panel are discharged, and an output of the non-lighting driving power supply to the light emitting element to be lighted next. 15. The method of driving a light emitting display panel according to claim 14, wherein control is performed such that a precharge period for supplying voltage is set.   The light emitting display panel according to any one of claims 11 to 15, wherein an output voltage value of the non-lighting driving power source is variably controlled within a range equal to or lower than a light emission threshold voltage of the light emitting element. Driving method.

Images