JP2010048985A - Semiconductor integrated circuit, self-luminous display panel module, electronic equipment, and driving method for power supply line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems that moving picture characteristics and flicker characteristics change and visibility may be decreased due to variable control of a peak brightness level. <P>SOLUTION: A power supply line-driving circuit that drives a power supply line connected to each pixel disposed in a matrix on a self-luminous display panel is provided with the following functions: a function of, in a light-emitting period of the self-luminous element, time-sequentially supplying a first drive power supply set as being fixed and a second drive power supply set as being variable in a range of applying a forward voltage to the self-luminous element, to the corresponding power supply lines; and a function of, in a non-emitting period of the self-luminous element, supplying a third drive power supply controlling the self-luminous element into a non-emission state to the power supply lines. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The invention described in this specification relates to a power supply line driving technique for a self-luminous display panel. Note that the invention has aspects as a semiconductor integrated circuit, a self-luminous display panel module, an electronic device, and a power supply line driving method.

The organic EL display panel has not only high contrast but also a wide viewing angle and a high response speed. In addition, a backlight light source is unnecessary, and it is suitable for thinning. For this reason, the organic EL display panel is attracting attention as a favorite of the next generation flat panel.
JP 2002-251167 A

  By the way, the organic EL display panel can control the peak luminance level by the light emission time length of the organic EL element OLED. The brightness level control function will be described with reference to FIGS. FIG. 1 shows that one frame period is 100% and what percentage is used as a light emission period. In the figure, the length of the bar graph indicated by shading is the light emission period length. For example, FIG. 1B means that 25% of one frame period is used for the light emission period, and FIG. 1C means that 50% of one frame period is used for the light emission period.

Note that if the total light emission period length in one frame period is the same, the number of light emission periods in one frame period is not necessarily limited to one, and can be divided into a plurality of times.
FIG. 2 shows the relationship between the pixel gradation and the luminance level due to the difference in the light emission period length. The vertical axis in FIG. 2 is the luminance level, and the horizontal axis is the signal potential Vsig or drive current Isig corresponding to the pixel gradation. As shown in FIG. 2, the peak luminance level can be increased as the total light emission period length is longer. That is, the variable range of the luminance level can be increased.

  However, the method of variably controlling the peak luminance level only by the length of a single light emission period as shown in FIG. 1 has a problem that it is difficult to achieve both moving image performance and flicker performance. For example, as the light emission period length is increased, the peak luminance level can be increased, but there is a problem that the moving image response characteristic is degraded. On the other hand, as the light emission period length is shortened, the moving picture response characteristic can be improved. On the other hand, there is a problem that the peak luminance level is lowered and flicker is conspicuous.

Accordingly, the inventors are a power supply line driving circuit for driving a power supply line connected to each pixel arranged in a matrix on a self light emitting display panel, and the light emitting period of the self light emitting element is fixedly set. A first drive power supply and a second drive power supply that is variably set within a range in which a forward voltage is applied to the self-luminous element,
A semiconductor integrated circuit including a power supply line driving circuit for supplying a third driving power supply for controlling the self-light emitting element to a non-light emitting state to the power supply line during the non-light emitting period of the self light emitting element is proposed.

  The second driving power source described above is variably controlled so that the potential difference from the first driving power source becomes smaller as the average luminance level of the frame image is higher. The first driving power source is lower as the average luminance level of the frame image is lower. It is desirable to variably control so that the potential difference with the driving power source becomes large.

Alternatively, the second driving power source described above is variably controlled so that the potential difference from the first driving power source becomes smaller as the peripheral illuminance of the self light emitting display panel becomes higher, and as the peripheral illuminance of the self light emitting display panel becomes lower. It is desirable to variably control the potential difference with the first drive power supply so as to increase.
Note that the second driving power source described above is preferably output to the power source line a plurality of times within one frame period.

  When the driving technique proposed by the inventors is adopted, the peak luminance level can be variably controlled without changing the period length from the start of light emission to the end of light emission by the variable control of the second drive power supply. . Moreover, since the period length from the start of light emission to the end of light emission does not change, the change in display quality accompanying the change in peak luminance level can be minimized.

Hereinafter, the best mode of the invention proposed by the inventors will be described for an active matrix driving type organic EL panel which is an example of the position of the self-luminous display panel.
In addition, the well-known or well-known technique of the said technical field is applied to the part which is not illustrated or described in particular in this specification.
Moreover, the form example demonstrated below is one form example of invention, Comprising: It is not limited to these.

(A) External structure of organic EL panel module First, an external example of an organic EL panel module will be described. However, in this specification, not only a panel module in which the pixel array unit and the drive circuit are formed on the same substrate, but also, for example, a drive circuit manufactured as an application specific IC is mounted on the same substrate as the pixel array unit It is called a panel module. The application-specific IC here corresponds to the “semiconductor integrated circuit” in the claims.

FIG. 3 shows an appearance example of the organic EL panel module. The organic EL panel module 1 has a structure in which a counter substrate 5 is bonded to a support substrate 3.
The support substrate 3 is made of glass, plastic or other base material. The counter substrate 5 is also made of glass, plastic or other transparent member as a base material. The counter substrate 5 is a member that seals the surface of the support substrate 3 with a sealing material interposed therebetween.

Note that the transparency of the substrate only needs to be ensured only on the light emission side, and the other substrate side may be an impermeable substrate.
In addition, the organic EL panel 1 is provided with an FPC (flexible printed circuit) 7 for inputting an external signal and a driving power source as necessary.

(B) Form 1
(B-1) System Configuration Example FIG. 4 shows a system configuration example of the organic EL panel module 11 according to this embodiment. The organic EL panel module 11 includes a pixel array unit 13, a signal line drive unit 15, a write control line drive unit 17, a power supply line drive unit 19, and a drive power generation unit 21 arranged on a glass substrate. have.

(B-2) Configuration of Each Device Hereinafter, examples of devices (functional blocks) constituting the organic EL panel module 11 will be described in order.

(A) Pixel Array Unit The pixel array unit 13 has a matrix structure in which white units constituting one pixel on the display are arranged in M rows × N columns. In this specification, a row refers to a pixel column composed of 3 × N sub-pixels 23 extending in the X direction in the drawing. A column refers to a pixel column composed of M sub-pixels 23 extending in the Y direction in the drawing. Of course, the values of M and N are determined according to the display resolution in the vertical direction and the display resolution in the horizontal direction.

  FIG. 5 shows an example of the arrangement of the sub-pixels 23 constituting the white unit. FIG. 5 shows an example in which a white unit is configured by sub-pixels 23 corresponding to R, G, and B pixels corresponding to the three primary colors. Of course, the configuration of the white unit is not limited to this. In addition, the sub-pixel 23 may have a sub-pixel structure such as a color conversion type using a filter or a multi-light-emitting type as well as the primary color light-emitting type.

  FIG. 6 shows a pixel circuit example of the sub-pixel 23 corresponding to active matrix driving. Various types of circuit configurations have been proposed for this type of pixel circuit. FIG. 6 shows one of the simplest circuit examples.

  In the case of FIG. 6, the pixel circuit includes a thin film transistor (hereinafter referred to as “sampling transistor”) N1 that controls a sampling operation, a thin film transistor (hereinafter referred to as “drive transistor”) N2 that controls a supply operation of a drive current, The storage capacitor Cs and the organic EL element OLED are included.

  In the case of FIG. 6, the sampling transistor N1 and the drive transistor N2 are N-channel MOS transistors. The operation state of the sampling transistor N1 is controlled by a write control line WSL connected to the gate electrode. When the sampling transistor N1 is on, the potential of the signal line DTL corresponding to the pixel data is written to the storage capacitor Cs.

  The storage capacitor Cs is a capacitive load connected between the gate electrode and the source electrode of the drive transistor N2. The signal potential Vsig held in the holding capacitor Cs gives the gate-source voltage Vgs of the driving transistor N2. A signal current Isig corresponding to this voltage is drawn from a power supply line DSL as a current supply line and supplied to the organic EL element OLED.

  Note that, as the signal current Isig increases, the current flowing through the organic EL element OLED increases and the emission luminance increases. That is, the gradation is expressed by the magnitude of the signal current Isig. As long as the supply of the signal current Isig continues, the organic EL element OLED continues to emit light with a predetermined luminance.

  In the case of this embodiment, the power supply line DSL is wired in units of rows and supplies driving power to all the subpixels 23 located in the same row. In the case of this embodiment, the power supply line DSL is driven by ternary drive power supplies VH, VM, and VSS. Of the ternary drive power supplies, two drive power supplies VH and VM are power supplies that can keep the organic EL element OLED in the on state, and the remaining one drive power supply VSS controls the organic EL element OLED in the off state. It is a power supply.

Among these, the drive power supply VH is a fixed drive power supply, and corresponds to the first drive power supply in the claims. The drive power supply VM is a variably set drive power supply, and corresponds to the second drive power supply in the claims. In this specification, the drive power supply VM is also referred to as a variable drive power supply.
The minimum value of the drive power supply VM is set in a range in which the organic EL element OLED can be maintained in a light emitting state. On the other hand, the maximum value of the drive power supply VM matches the drive power supply VH.

  The drive power supply VH here corresponds to the first drive power supply in the claims. The drive power supply VSS corresponds to the third drive power supply in the claims. In this embodiment, the drive power supply VSS is set to a potential lower than the cathode electrode potential Vcat of the organic EL element OLED. A method for setting the drive power source VM will be described later.

(B) Signal Line Driver The signal line driver 15 outputs a reference potential (hereinafter referred to as “offset potential”) Vofs necessary for correcting the characteristics of the sub-pixel 23 and a signal potential Vsig corresponding to the pixel gradation. A circuit device applied to the line DTL. The signal line DTL is wired in units of columns and applies a potential to all the subpixels 23 located in the same column.

(C) Write Control Line Drive Unit The write control line drive unit 17 is a circuit device that applies a control pulse that gives the write timing of the offset potential Vofs and the signal potential Vsig to the write control line WSL. In the case of this embodiment, the write control line WSL is wired in units of rows as described above. Therefore, the operation of the writing control line driving unit 17 is synchronized with the horizontal scanning clock, and operates to output a control pulse to the pixel column of the next row every time the horizontal scanning clock is input.

  In the case of this embodiment, the write control line driving unit 17 has a basic configuration in which each output stage has a shift register corresponding to each row (pixel column) and an output stage corresponding to each row. The shift register is used, for example, to sequentially transfer a timing signal that gives rise timing and fall timing of the control pulse to the next row. The output stage includes a logic circuit that generates a control pulse based on a timing pulse supplied from the shift register, a level shifter that converts the control pulse into a potential suitable for driving, and a buffer circuit that actually drives the write control line WSL Consists of.

(D) Power Line Drive Unit The power line drive unit 19 is a circuit device that controls the drive operation of the sub-pixel 23 in conjunction with the control operation of the write control line WSL. As described above, the power supply line drive unit 19 applies any one of the ternary drive power supplies to the power supply line DSL in time sequence.
In this specification, a period in which the organic EL element OLED emits light is referred to as a light emission period, and a period in which the organic EL element OLED does not emit light is referred to as a non-light emission period.

  Note that the light emission period corresponds to a period in which the drive power supply VH or VM is applied to the power supply line DSL in a state where the signal potential Vsig is written in the storage capacitor Cs of each subpixel 23. In the non-light emitting period, the drive power supply VSS is supplied to the power supply line DSL in the period until the signal potential Vsig of the next frame is written in the subpixel 23 and in the state where the signal potential Vsig is written in the storage capacitor Cs of each subpixel 23. Corresponds to the period during which is applied.

  In the former period constituting the non-light-emitting period, the driving power supply VSS is applied to the power supply line DSL during the initialization operation of the potential of the storage capacitor Cs and during the preparation period of the threshold correction operation, and the other period is a high potential. Drive power source VH is applied.

  In the case of this embodiment, the power supply line drive unit 19 has an output stage corresponding to each row (pixel column) as a basic configuration. The output stage includes a level shifter that converts a control pulse into a potential suitable for driving, and a buffer circuit that actually drives the write control line WSL. In the case of this embodiment, ternary driving power for the output stage is supplied from the driving power generator 21.

(E) Drive power generation unit The drive power generation unit 21 is a circuit device that generates drive power to be applied to the power supply line DSL corresponding to each row.
FIG. 7 shows a circuit configuration example of the drive power supply generation unit 21. The drive power generation unit 21 includes a one-frame average luminance detection unit 31, a variable drive power generation unit 33, and a drive timing generation unit 35.

  Among these, the 1-frame average brightness detection unit 31 is a circuit device that calculates the average brightness level of the input image data Din corresponding to all the pixels constituting the 1-frame screen. Incidentally, the input image data Din is given in the data format of R (red) pixel data, G (green) pixel data, and B (blue) pixel data. In the case of this embodiment, the average luminance level is calculated as a value where the maximum luminance level is 100%.

When calculating the average luminance level, the one-frame average luminance detection unit 31 first converts R pixel data, G pixel data, and B pixel data corresponding to each pixel into a luminance level in units of pixels.
The average luminance level may be calculated in units of one frame or may be calculated as an average value in units of a plurality of frames.

  The variable drive power supply generation unit 33 is a circuit device that generates a drive power supply VM having a magnitude corresponding to the average luminance level. FIG. 8 shows a circuit configuration example of the variable drive power generation unit 33. The variable drive power supply generation unit 33 includes a variable drive power supply value setting unit 41, a digital / analog conversion circuit 43, and a level shift buffer circuit 45.

  The variable drive power supply value setting unit 41 is a circuit device that sets a variable drive power supply value corresponding to the detected average luminance level. In the case of this embodiment, the variable drive power supply value setting unit 41 uses a lookup table having input / output characteristics shown in FIG. That is, the variable drive power supply value setting unit 41 uses the average luminance level as an input value and the variable drive power supply value as an output value.

In FIG. 9, the horizontal axis represents the average luminance level, and the vertical axis represents the voltage. As shown in FIG. 9, the cathode electrode potential Vcat is assigned to 0% of the average luminance level, and the drive power supply VH is assigned to 100% of the average luminance level.
FIG. 10 shows the relationship between the variable range of the drive power supply VM, which is a variable drive power supply, and the peak luminance level. In FIG. 10, the horizontal axis represents voltage, and the vertical axis represents luminance [nit]. Here, the peak luminance level is expressed because the drive power supply is a voltage that defines the peak luminance level.

The digital / analog conversion circuit 43 is a circuit device that converts a variable drive power supply value read as a digital value into an analog voltage.
The level shift buffer circuit 45 is a buffer circuit that converts the level of the analog voltage input from the previous stage into a voltage level necessary for driving the sub-pixel 23. This level shift buffer circuit 45 is applied to the drive timing generator 35 in FIG.

The drive timing generator 35 is a circuit device that switches the outputs of the three types of drive voltages VH, VM, and VSS in time sequence to generate drive pulses necessary for driving the power supply line DSL. The generated drive pulse is transferred line by line between each row (horizontal line).
FIG. 11 shows an example of drive pulse output patterns. This output pattern is common to all the write control lines WSL.

  As shown in FIG. 11, the drive pulse output pattern is generated so as to be repeated in units of one frame. As described above, the initialization timing of each row (horizontal line) is arranged so as to be shifted every horizontal scanning period.

  A period indicated by a double arrow in FIG. 11 is a period for writing the signal potential Vsig to each sub-pixel 23, and the other period is basically a period that can be used for light emission of the organic EL element OLED. However, the period of the drive power supply VSS is a non-light emission period that is set regardless of the writing of the signal potential Vsig.

  Further, as shown in FIG. 11, the output timings of the drive power supplies VH, VM, and VSS are fixed. In the case of FIG. 11, the number of drive power supplies VH arranged during the light emission period is five. In this specification, the first, second, third, fourth, and fifth output periods are referred to in the order of appearance. In this embodiment, the output period length of the third drive power supply VH is the longest, the output period length of the second and fourth drive power supplies VH is the second longest, and the output of the first and fifth drive power supplies VH. The period length is set to be the shortest.

  Such an arrangement is performed in order to concentrate the peak of the luminance distribution in the third output period. When the output period lengths are the same, the luminance distribution has five peaks, and moving image blur easily occurs. Considering this display characteristic, in this embodiment, the output period length of the drive power supply VH located at the center of the light emission period is set to the longest.

  Four drive power sources VM, which are variable drive power sources, are arranged so as to fill the output period of the drive power source VH. In the case of this embodiment, it is assumed that the output period lengths of the drive power source VM are the same. Of course, the drive power supply VM, which is a variable drive power supply, can be varied from Vcat corresponding to 0% of the luminance level to VH corresponding to 100% of the luminance level. Accordingly, the depth of the recess shown in FIG. 11 is varied depending on the size of the drive power source VM, and the luminance distribution changes. The fifth output period of the drive power supply VH

  FIG. 12 shows how the luminance distribution changes when the drive power supply VM, which is a variable drive power supply, is varied. In the figure, the potential of the drive power supply is indicated by a thin line, and the luminance distribution is indicated by a thick line. Incidentally, FIGS. 12A to 12C show the output pattern and luminance distribution of the driving power source used in this embodiment. FIG. 12A shows the output pattern and the luminance distribution of the drive power supply when the drive power supply VM which is a variable drive power supply has the maximum voltage (drive voltage VH).

  FIG. 12B shows an output pattern and luminance distribution of the drive power supply when the drive power supply VM that is a variable drive power supply is an intermediate voltage. FIG. 12C shows the output pattern and luminance distribution of the drive power supply when the drive power supply VM which is a variable drive power supply is the minimum voltage (cathode electrode potential Vcat).

  On the other hand, FIG. 12D shows an output pattern and a luminance distribution when the driving voltage is driven only by a binary voltage. In the case of FIG. 12D, the driving voltage when no light is emitted is smaller than the cathode electrode potential Vcat. For this reason, when the split light emission method is adopted in the driving of the binary voltage, the forward bias and the reverse bias with respect to the organic EL element OLED are repeated.

  The repetition of the forward bias and the reverse bias imposes a heavy burden on the panel including the organic EL element OLED, and may cause damage. In this regard, in the case of the drive voltage application method according to the embodiment, the minimum value of the drive voltage VM is the cathode electrode voltage Vcat, and the number of reverse bias applications can be minimized. Thereby, it is possible to suppress adverse effects on the panel including the organic EL element OLED as compared with the binary driving method (FIG. 12D).

(B-3) Example of Driving Operation of Organic EL Panel Module Hereinafter, an example of driving operation of the organic EL panel module will be described based on FIG. 13A shows the potential waveform of the signal line DTL, and FIG. 13B shows the drive waveform of the write control line WSL. FIG. 13C shows a driving waveform of the power supply line DSL. FIG. 13D shows a potential waveform of the gate potential Vg of the driving transistor N2. FIG. 13E shows a potential waveform of the source potential Vs of the driving transistor N2.

  First, the initialization operation will be described. The initialization operation is an operation for initializing the holding potential of the holding capacitor Cs. This operation is executed by switching the power supply line DSL from the drive power supply VH to the drive power supply VSS while the write control line WSL is at the L level. At this time, the power supply line DSL is lowered to the drive power supply VSS, so that the source potential Vs of the drive transistor N2 is lowered to the drive power supply VSS. Of course, the organic EL element OLED is turned off because a reverse bias is applied.

At this time, the driving transistor N2 operates in a floating state. Therefore, as the source potential Vs of the driving transistor N2 is lowered, the potential of the gate electrode (gate potential Vg) coupled through the storage capacitor Cs is also lowered. This operation is an initialization operation.
This operation state continues until immediately before the start of the variation correction operation (threshold correction operation) of the threshold voltage Vth of the drive transistor N2.

In the case of this embodiment, as shown in FIG. 13B, the write control line WSL is switched from the L level to the H level immediately before the start of the threshold value correction operation. When the write control line WSL becomes H level, the sampling transistor N1 is turned on, and the gate potential Vg of the drive transistor N2 is set to the offset potential Vofs. This operation is a correction preparation operation.
Thereafter, the threshold value correcting operation is started by switching the power supply line DSL from the drive power supply VSS to the drive power supply VH.

  When the threshold correction operation starts, the drive transistor N2 is turned on, and the source potential Vs starts to rise. On the other hand, since the gate potential Vg of the drive transistor N2 is fixed to the offset potential Vofs, the gate-source voltage Vgs of the drive transistor N2 gradually decreases. FIG. 14 shows an enlarged view of the potential change of the source potential Vs of the drive transistor N2 during the threshold correction operation.

  As shown in FIG. 14, the increase in the source potential Vs of the drive transistor N2 is automatically stopped when the gate-source voltage Vgs of the drive transistor N2 reaches the threshold voltage Vth. This operation is a threshold correction operation, and the variation in the threshold voltage Vth of the drive transistor N2 is cancelled. Note that the potential of the write control line WSL is controlled to be switched from the H level to the L level after waiting for a timing set in consideration of variations in time required for the threshold value correction operation.

Thereafter, the potential of the signal line DTL is switched to the signal potential Vsig. Of course, the signal potential Vsig is a potential corresponding to the pixel gradation of the sub-pixel 23 to be written. The signal potential Vsig
Is written to the signal line DTL before the write control line WSL is switched to the H level. This is because writing is started in a state in which the potential of the signal line DTL has changed to the signal potential Vsig.

As described above, the signal potential Vsig is applied to the signal line DTL, the write control line WSL is controlled to be switched to the H level while the drive power supply VH is applied to the power supply line DSL, and the signal potential Vsig is written. Be started.
As the signal potential Vsig is written, the gate potential Vg of the drive transistor N2 rises and the drive transistor N2 is turned on.

  When the driving transistor N2 is turned on, a current having a magnitude corresponding to Vgs−Vth is drawn from the power supply line DSL, and a capacitance component parasitic on the organic EL element OLED is charged. By charging the parasitic capacitance, the anode potential of the organic EL element OLED (the source potential Vs of the drive transistor N2) rises. However, the organic EL element OLED does not emit light unless the anode potential of the organic EL element OLED becomes higher than the cathode potential by a threshold voltage Vth (oled) or more.

  The current flowing at this time depends on the mobility μ of the driving transistor N2. FIG. 15 shows the difference in the rising speed of the source potential Vs due to the difference in mobility μ. As shown in FIG. 15, as the mobility μ increases, the amount of current increases and the source potential Vs also rises faster. This means that even when the same signal potential Vsig is applied, the gate-source voltage Vgs of the driving transistor N2 having a high mobility μ is equal to the gate-source voltage Vgs of the driving transistor N2 having a relatively low mobility μ. Means smaller than.

That is, the amount of current flowing through the drive transistor N2 having a high mobility μ is smaller than the amount of current flowing through the drive transistor N2 having a relatively low mobility μ. As a result, if the signal potential Vsig is the same regardless of the variation in the magnitude of the mobility μ, the current having the same magnitude is corrected to flow through the organic EL element OLED. This operation is a mobility correction operation.
Note that when the mobility correction operation is completed, the anode potential of the organic EL element OLED also becomes higher than the threshold voltage Vth (oled), and the organic EL element OLED is turned on. This ON operation starts light emission of the organic EL element OLED.

Further, after the signal potential Vsig is written, the sampling transistor N1 is controlled to be off, and the driving transistor N2 operates in a floating state. For this reason, as the anode potential increases due to the ON operation of the organic EL element OLED, the gate potential Vg of the drive transistor N2 also increases due to the bootstrap operation.
Thereafter, light emission by the drive power source VH and light emission by the drive power source VM set in accordance with the frame average luminance are repeatedly executed as described above.

  Note that the drive power supply VM changes in the range from the cathode electrode voltage Vcat to the drive power supply VH according to the frame average luminance. At this time, the peak luminance level is variable depending on the ratio of the period length from the start end to the end end of the drive power supply VH to the frame period length and the ratio of the total output period length of the drive power supply VH and the total output period length of the drive power supply VM. Can be controlled. Moreover, the period length from the start point to the end point of the light emission period can be fixed while variably controlling the peak luminance level.

(B-4) Summary As described above. In the case of this embodiment, the peak luminance level can be controlled by variable control of the drive power source VM. At this time, no processing is performed on the pixel data. Therefore, in controlling the peak luminance level, the display performance of gradation expression is not impaired.

  In the case of this embodiment, the period length from the start time of the first output period of the drive power supply VH to the end time of the fifth output period is fixed. That is, even if the peak luminance level is varied, the ratio between the light emission period length and the non-light emission period length is fixed. For this reason, it is possible to prevent the moving image display performance from changing due to the variable control of the peak luminance level.

  In the case of this embodiment, the drive power supply VH is divided into five output periods, and an output period of the drive power supply VM that is a variable drive power supply is arranged between the output periods. For this reason, the shape of the luminance distribution accompanying the variable control of the peak luminance level can be adjusted smoothly. Note that by dividing the luminance power supply VH into five periods, the frequency of the light emission period can be increased, and flicker can be hardly recognized. Of course, fine control of the compatibility between the moving image characteristics and the flicker characteristics can be realized by the change in the luminance distribution accompanying the adjustment of the drive power supply VM which is a variable drive power supply.

(C) Form example 2
(C-1) System Configuration Example FIG. 16 shows a system configuration example of the organic EL panel module 51 according to this embodiment. In FIG. 16, the same reference numerals are given to the portions corresponding to those in FIG. 4.
The organic EL panel module 51 has a configuration in which a pixel array unit 13, a signal line drive unit 15, a write control line drive unit 17, a power supply line drive unit 19, and a drive power generation unit 53 are arranged on a glass substrate. have.

  Below, only the drive power generation part 53 which is a new configuration will be described. The drive power generator 53 in this embodiment also generates drive power to be applied to the power supply line DSL corresponding to each row. However, in generating the drive power, the illuminance value around the panel detected by the illuminance sensor 55 is referred to as shown in FIG. In FIG. 17, the same reference numerals are given to the portions corresponding to FIG. 7.

Incidentally, the illuminance sensor 55 is arranged on the surface of the housing so that the illuminance around the panel can be accurately detected. For the illuminance sensor 55, for example, a phototransistor, a photodiode, or a photo IC (photodiode + amplifier circuit) is used.
As shown in FIG. 17, the drive power generator 53 includes a variable drive power generator 57 and a drive timing generator 35.

The variable drive power generation unit 57 is a circuit device that generates a drive power VM having a magnitude corresponding to the detected ambient illuminance. FIG. 18 shows a circuit configuration example of the variable drive power generation unit 57. In FIG. 18, parts corresponding to those in FIG.
The variable drive power supply generation unit 57 includes a variable drive power supply value setting unit 59, a digital / analog conversion circuit 43, and a level shift buffer circuit 45.

  The variable drive power supply value setting unit 59 is a circuit device that sets a variable drive power supply value corresponding to the detected ambient illuminance. In the case of this embodiment, the variable drive power supply value setting unit 59 uses a lookup table having input / output characteristics shown in FIG. That is, the variable drive power supply value setting unit 59 uses the illuminance as an input value and the variable drive power supply value as an output value.

In FIG. 19, the horizontal axis represents illuminance [lx], and the vertical axis represents voltage. As shown in FIG. 19, it is assumed that the cathode electrode potential Vcat is assigned to the assumed minimum value of illuminance, and the drive power supply VH is assigned to the assumed maximum value of illuminance. The assumed minimum and maximum illuminance values are set assuming the use environment.
Incidentally, the operations of the digital / analog conversion circuit 43 and the level shift buffer circuit 45 are the same as those of the above-described embodiment.

(C-2) Summary In the case of this embodiment, when the ambient illuminance is bright, the peak luminance level is increased to improve visibility, while when the ambient illuminance is dark, the peak luminance level is decreased to prevent black floating. be able to.
Of course, since the moving image characteristic and the flicker characteristic can be compatible, the display quality can be improved as compared with the prior art.

(D) Other Embodiments (D-1) Other Generation Methods of Variable Drive Power Supply In the case of the above-described embodiment, the voltage value of the drive power supply VM can be varied according to the average frame brightness and the ambient illuminance. The case of setting to is described.

However, the drive power source VM can be set with reference to other information. For example, the voltage value of the drive power source VM may be variably set based on the ambient temperature of the organic EL panel module or the environmental temperature. For example, when the temperature is low, the voltage value of the drive power supply VM may be set high, and when the temperature is high, the voltage value of the drive power supply VM may be set low. In addition, what is necessary is just to use a known temperature sensor for the measurement of ambient temperature or environmental temperature.
Further, the voltage value of the drive power supply VM may be variably set by combining the plurality of conditions described above.

(D-2) Number of Arrangements of Variable Drive Power Supply In the case of the above-described embodiment, the case where four drive power VMs that are variable drive power supplies are arranged in the light emission period has been described.
However, this number is not limited to four and may be one or more.

(D-3) Other Power Lines to be Driven In the case of the embodiment described above, the case where the cathode electrode potential of the organic EL element OLED is fixed and the drive power on the anode side is variably controlled has been described.
However, the same operation may be performed by fixing the potential on the anode electrode side of the organic EL element OLED and variably controlling the potential on the cathode electrode side.

  FIG. 20 shows a correspondence relationship between the sub-pixel 23 and the drive circuit. In FIG. 20, the same reference numerals are assigned to the corresponding parts to those in FIG. In the sub-pixel 23 shown in FIG. 20, the anode electrode side of the organic EL element OLED is set to the drive power supply VH common to all the sub-pixels 23. On the other hand, the power supply line DSL is connected to the cathode electrode of the organic EL element OLED in units of rows. In the case of this embodiment, any one of the drive power supplies VSS, VM, and VH-Vcat is applied to the power supply line DSL line-sequentially.

FIG. 21 shows the relationship between the variable range of the drive power source VM, which is a variable drive power source, and the variable range of the peak luminance level. In FIG. 21, the horizontal axis represents voltage, and the vertical axis represents luminance [nit]. This relationship is the relationship shown upside down in the relationship shown in FIG. The reason why the maximum value of the drive power source VM is VH−Vcat is to prevent a reverse bias from being applied to the organic EL element OLED.
FIG. 22 shows a setting example of the drive power source VM in the case of this embodiment. FIG. 22 shows input / output characteristics of a look-up table used for setting the drive power source VM. The horizontal axis in FIG. 22 is the average luminance level, and the vertical axis is the voltage.

(D-4) Other circuit configurations of subpixels Other circuit configurations of the subpixels are also conceivable. FIG. 23 shows another circuit configuration example of the sub-pixel 71. In the case of the sub-pixel 71, the driving transistor N2 is a P-channel type thin film transistor. In the case of the sub-pixel 71, one electrode of the storage capacitor Cs is connected to a fixed power source. Of course, pixel circuits having other circuit configurations are also conceivable.

(D-5) Drive power supply of common power supply In the case of the first and second embodiments, the drive power supply for controlling the organic EL element OLED to the non-light emitting state is set to VSS lower than the cathode electrode potential Vcat. explained. That is, the reverse bias was applied to the organic EL element OLED.
However, the drive power supply controlled to the non-light emitting state may be set to the cathode electrode potential Vcat.

(D-6) Product example (electronic equipment)
In the above description, the invention has been described by taking the organic EL panel module having the lighting period setting function according to the embodiment as an example. However, organic EL panel modules and other display panel modules equipped with this type of setting function are also distributed in product forms mounted on various electronic devices. Examples of mounting on electronic devices are shown below.

  FIG. 24 shows a conceptual configuration example of the electronic device 81. The electronic device 81 includes the organic EL panel module 83, the system control unit 85, and the operation input unit 87 described above. The processing content executed by the system control unit 85 differs depending on the product form of the electronic device 81. The operation input unit 87 is a device that receives an operation input to the system control unit 85. For the operation input unit 87, for example, a switch, a button, other mechanical interfaces, a graphic interface, or the like is used.

Note that the electronic device 81 is not limited to a device in a specific field as long as it has a function of displaying an image or video generated in the device or input from the outside.
FIG. 25 shows an example of an external appearance when the other electronic device is a television receiver. A display screen 97 including a front panel 93, a filter glass 95, and the like is disposed on the front surface of the television receiver 91. A portion of the display screen 97 corresponds to the organic EL panel module 83.

  Further, for example, a digital camera is assumed as this type of electronic apparatus 81. FIG. 26 shows an appearance example of the digital camera 101. FIG. 26A shows an example of the appearance on the front side (subject side), and FIG. 26B shows an example of the appearance on the back side (photographer side).

  The digital camera 101 includes a protective cover 103, an imaging lens unit 105, a display screen 107, a control switch 109, and a shutter button 111. Among these, the display screen 157 corresponds to the organic EL panel module 83.

For example, a video camera is assumed as this type of electronic device 81. FIG. 27 shows an example of the appearance of the video camera 121.
The video camera 121 includes an imaging lens 125 that images a subject in front of the main body 123, a shooting start / stop switch 127, and a display screen 129. Among these, the display screen 179 corresponds to the organic EL panel module 83.

  In addition, for example, a portable terminal device is assumed as this type of electronic device 81. FIG. 28 shows an example of the appearance of a mobile phone 131 as a mobile terminal device. A cellular phone 131 illustrated in FIG. 28 is a foldable type, and FIG. 28A illustrates an appearance example in a state where the housing is opened, and FIG. 28B illustrates an appearance example in a state where the housing is folded.

  The mobile phone 131 includes an upper housing 133, a lower housing 135, a connecting portion (in this example, a hinge portion) 137, a display screen 139, an auxiliary display screen 141, a picture light 143, and an imaging lens 145. Among these, the display screen 139 and the auxiliary display screen 141 correspond to the organic EL panel module 83.

Further, for example, a computer is assumed as this type of electronic device 81. FIG. 29 shows an example of the appearance of the notebook computer 151.
The notebook computer 151 includes a lower housing 153, an upper housing 155, a keyboard 157, and a display screen 159. Among these, the display screen 159 corresponds to the organic EL panel module 83.

  In addition to these, the electronic device 81 may be an audio playback device, a game machine, an electronic book, an electronic dictionary, or the like.

(D-7) Other Display Device Examples In the above-described embodiments, the case where the invention is applied to an organic EL panel module has been described.
However, the driving technique described above can also be applied to other self-luminous display panel modules. For example, the present invention can also be applied to a display device in which LEDs are arranged and other display devices in which light emitting elements having a diode structure are arranged on a screen. For example, the present invention can be applied to a display panel module in which inorganic EL elements are arranged in a matrix.

(D-8) Others Various modifications can be considered for the above-described embodiments within the scope of the gist of the invention. Various modifications and applications created or combined based on the description of the present specification are also conceivable.

It is a figure which shows the relationship between 1 frame period and light emission period. It is a figure explaining the relationship between total light emission period length and a peak luminance level. It is a figure which shows the example of an external appearance of an organic electroluminescent panel module. It is a figure which shows the structural example of an organic electroluminescent panel module. It is a figure explaining the arrangement structure of the sub pixel which constitutes a pixel array part. It is a figure which shows the circuit structural example of a sub pixel. It is a figure explaining the structural example of a drive power generation part. It is a figure explaining the circuit structural example of a variable drive power generation part. It is a figure explaining the example of a setting of drive power supply VM according to an average luminance level. It is a figure which shows the relationship between drive power supply VM and a luminance level. It is a figure which shows the drive waveform example of a power wire. It is a figure explaining the change of the luminance distribution by variable control of drive power supply VM. It is a figure explaining the drive operation example of an organic electroluminescent panel module. It is a figure explaining threshold value correction operation. It is a figure explaining mobility correction operation. It is a figure which shows the structural example of the organic electroluminescent panel module which concerns on the example 2 of a form. It is a figure explaining the structural example of a drive power generation part. It is a figure explaining the circuit structural example of a variable drive power generation part. It is a figure explaining the example of a setting of drive power supply VM according to peripheral illumination intensity. It is a figure explaining the other drive system of a drive power supply. It is a figure which shows the other relationship between drive power supply VM and a luminance level. It is a figure explaining the other example of a setting of drive power supply VM according to an average luminance level. It is a figure which shows the other pixel circuit example of a sub pixel. It is a figure which shows the function structural example of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Organic EL panel module 13 Pixel array part 15 Signal line drive part 17 Write control line drive part 19 Power supply line drive part 21 Drive power supply generation part 33 Variable drive power supply generation part

Claims (7)

A power supply line driving circuit for driving a power supply line connected to each pixel arranged in a matrix on a self-luminous display panel,
In the light emission period of the self-light-emitting element, the first drive power supply that is fixedly set and the second drive power supply that is variably set within a range in which a forward voltage is applied to the self-light-emitting element are sequentially handled. Supply to the power line
A semiconductor integrated circuit having a power supply line drive circuit for supplying a third drive power supply for controlling the self light emitting element to a non-light emitting state to a power supply line during a non-emission period of the self light emitting element. The second drive power source is variably controlled such that the higher the average luminance level of the frame image is, the smaller the potential difference from the first drive power source is. The lower the average luminance level of the frame image is, the lower the first drive power source is. The semiconductor integrated circuit according to claim 1, wherein the semiconductor integrated circuit is variably controlled so that a potential difference with a driving power source is increased. The second drive power supply is variably controlled so that the higher the peripheral illuminance of the self light emitting display panel is, the smaller the potential difference from the first drive power supply is. The semiconductor integrated circuit according to claim 1, wherein the semiconductor integrated circuit is variably controlled so as to increase a potential difference with respect to one drive power source. The semiconductor integrated circuit according to claim 2, wherein the second drive power supply is output to the power supply line a plurality of times within one frame period. A pixel array unit having a pixel structure corresponding to an active matrix driving method;
A signal line driving circuit for driving the signal line;
A write control line drive circuit that controls writing of potentials to each pixel arranged in a matrix in the pixel array unit;
A power source line driving circuit for driving a power source line connected to each pixel arranged in a matrix on the pixel array unit, wherein a first driving power source fixedly set during a light emission period of the self light emitting element; The second drive power source variably set within the range in which the forward voltage is applied to the self-light emitting element is supplied to the corresponding power line in time sequence, and the self-light emitting element is turned off during the non-light emitting period of the self light emitting element. A self-luminous display panel module, comprising: a power line driving circuit that supplies a third driving power source controlled to a non-light emitting state to a power line. A pixel array unit having a pixel structure corresponding to an active matrix driving method;
A signal line driving circuit for driving the signal line;
A write control line drive circuit that controls writing of potentials to each pixel arranged in a matrix in the pixel array unit;
A power source line driving circuit for driving a power source line connected to each pixel arranged in a matrix on the pixel array unit, wherein a first driving power source fixedly set during a light emission period of the self light emitting element; The second drive power source variably set within the range in which the forward voltage is applied to the self-light emitting element is supplied to the corresponding power line in time sequence, and the self-light emitting element is turned off during the non-light emitting period of the self light emitting element. A power supply line drive circuit for supplying a third drive power supply for controlling to a non-light emitting state to the power supply line;
A system controller that controls the operation of the entire system;
An electronic device comprising: an operation input unit for the system control unit. In the light emission period of the self-light-emitting element, the first drive power supply that is fixedly set and the second drive power supply that is variably set within a range in which a forward voltage is applied to the self-light-emitting element are sequentially handled. Supplying power to the power line,
A method of driving a power supply line wired on the self-light-emitting display panel, comprising: supplying a third drive power source for controlling the self-light-emitting element to a non-light-emitting state to the power supply line during the non-light-emitting period of the self-light-emitting element.