TWI549109B - Pmoled display with uniform brightness controller and driving method thereof - Google Patents

Description

Passive matrix organic light emitting diode display with balanced display brightness function and driving method thereof

A passive matrix organic light emitting diode display, in particular, a passive matrix organic light emitting diode display with balanced display brightness function.

Compared with traditional flat panel displays, organic light-emitting diode displays have many advantages such as wide viewing angle, fast response time, high brightness, low operating voltage, self-illumination, etc., and have become an indispensable display technology for today's and future displays. The organic light-emitting diode can be classified into an active matrix (AM) and a passive matrix (PM) according to different driving modes, wherein the passively driven organic light-emitting diode display has a low manufacturing cost and a good yield. Higher than many advantages, it is generally used for consumer or industrial electronic products.

Referring to FIG. 7, one of the passively driven OLED display 80 includes a plurality of display units 81 arranged in an array, and each display unit 81 of each column corresponds to the same scan electrode (COM_1, COM_2, ... or COM_n). ), each display unit 81 of each row corresponds to the same data electrode (SEG_1, SEG_2, ... or SEG_n). When driving, a driving chip (not shown) drives each scanning electrode (COM_1, COM_2, ... or COM_n) one by one and simultaneously inputs a data signal (SEG_1, SEG_2, ... or SEG_n) to each display unit 81. Produces a light output screen.

Referring to FIG. 8 , since the brightness of the light output that can be generated by each display unit 81 of the conventional passively driven organic light emitting diode display 80 is related to the current magnitude, when the passively driven organic light emitting diode display 80 corresponds to the same scan. When the electrodes and the display units 81B exhibiting a light output state are relatively large, since the display units 81 required to be driven in the same column are relatively large, the current obtained by each display unit 81 is relatively lower than that of the other columns. The unit 81A further causes unevenness in the brightness of the displayed picture, and this uneven brightness phenomenon is more significantly deteriorated when the resolution of the passively driven organic light emitting diode display 80 is increased.

In order to solve the problem that the existing passive-driven organic light-emitting diode display has a relatively large number of light outputs simultaneously generated by the display unit corresponding to each scan electrode, the brightness is lowered to cause uneven brightness of the display screen, and the present invention proposes The length of the driving time of the scan electrode and the data electrode or the voltage difference between the scan electrode and the data electrode can be matched according to the number of the light output states of each display unit corresponding to each scan electrode, so that the same scan line is generated and the light output is generated. Each of the display units having a relatively large number has a relatively long display time or a required voltage difference, thereby making up for the problem of uneven brightness and achieving the technical effect of equalizing the brightness display.

The invention relates to a passive matrix organic light emitting diode display with balanced display brightness function, which is suitable for continuously receiving a display signal, wherein the display signal comprises a plurality of picture information, and each picture information comprises a plurality of display unit information, the display The method comprises: a display unit matrix, comprising a plurality of scan electrodes, a plurality of data electrodes and a plurality of display units, each display unit corresponding to one scan electrode and one data electrode, wherein each display unit information is correspondingly displayed on each display unit; The driving control device is electrically connected to each scanning electrode and each data electrode, and determines the total number of display units corresponding to the same scanning electrode and to be driven according to each frame information, and adjusts the driving time length of the corresponding scanning electrode in a positive correlation manner. And a driving time length of the corresponding data electrode, or adjusting a voltage difference between the scan electrode and the data electrode received by the corresponding display unit in a positive correlation manner to equalize display units corresponding to the scan electrodes in the matrix of the display unit Brightness.

The driving control device determines the total number of display units corresponding to the same scan electrode and is to be driven according to each screen information, and adjusts the driving time length of the corresponding scan electrode and the driving time length of the corresponding data electrode in a look-up manner.

The driving control device includes a power supply unit electrically connected to each other, a data storage memory, a time compensation unit, a time control unit, a scan driving component and a data driving component, and the power supply unit provides the driving control device The data storage memory stores the display signal and a comparison table; the time compensation unit determines the total number of display units corresponding to the same scan electrode and is to be driven according to each frame information, and determines corresponding corresponding by referring to the comparison table. The length of the driving time of the scan electrode and the length of the driving time of the corresponding data electrode are output to the time control unit; the time control unit outputs a driving information to the scan driving component according to the display signal and the length of the driving time. The data driving component; the scan driving component and the data driving component are electrically connected to each of the scan electrodes and the data electrodes, respectively, and drive the matrix of the display cells.

Wherein, the driving control device defines, in a method, the driving time length of each scanning electrode is equal to a base time multiplied by a weight coefficient corresponding to the scanning electrode.

Wherein, the driving control device defines, in a method, the driving time length of each scanning electrode is equal to a base time multiplied by a weight coefficient corresponding to the scanning electrode and then divided by the total weight coefficient.

The time compensation unit includes a sequence of an adder circuit and a comparison circuit array in sequence, and the adder circuit array receives display unit information corresponding to the same scan electrode, and the time compensation unit is based on the output of the comparison circuit array, and refers to The comparison table determines the length of the driving time of the corresponding scan electrode and the length of the driving time of the corresponding data electrode.

The passive matrix organic light emitting diode display with balanced display brightness function determines the total number of display units corresponding to the same scan electrode to be driven according to each frame information, and adjusts the driving voltage of the corresponding scan electrode in a look-up manner. Or the corresponding driving voltage of the data electrode.

The present invention further provides a display method of a passive matrix organic light emitting diode display having a balanced display brightness function, the method comprising: capturing and displaying a display signal from the outside, the display signal comprising a plurality of screen information, each of which The screen information includes a plurality of display unit information; analyzes each screen information, and calculates a total number of display units corresponding to the same scan electrode and is to be driven; determining a driving time length of the corresponding scan electrode and corresponding data according to the total number in a positive correlation manner The driving time length of the electrode or the voltage difference corresponding to the display unit; and outputting driving information according to the driving time length or the voltage difference to equalize the overall brightness of the display.

The display method of the passive matrix organic light emitting diode display with the function of equalizing the display brightness determines the driving time length of the corresponding scanning electrode and the driving time length of the corresponding data electrode according to the total number in a look-up manner.

The driving information correspondingly displays one of the screen information and the display period is not fixed.

Based on the foregoing description, the present invention is:

1. Changing the driving time length of the scanning driving period Von of each display unit, compensating for the difference in brightness caused by simultaneously driving a relatively large number of display units, thereby significantly improving the overall display effect.

2. Using the look-up table method can greatly reduce the time required for calculation, thereby improving the response speed of the display, achieving a simplified calculation process and reducing the manufacturing cost.

3. The display period can be unfixed or fixed, making the control method more diverse and suitable for displays with multiple resolutions.

4. The voltage difference can be adjusted according to the number of display units, so that the driving voltage varies with different display unit numbers, thereby achieving the technical effect of balancing the brightness display.

As shown in FIGS. 1, 2 and 3, it is a passive matrix organic light emitting diode display with balanced display brightness function, comprising a display unit matrix 10 and a driving control device 20. The display unit matrix 10 includes a plurality of scan electrodes (COM) and a plurality of data electrodes (SEG) and a plurality of display units 11. Each of the scan electrodes and the data electrodes are alternately arranged at intervals. Each display unit 11 is formed at an interlaced position between each scan electrode and each data electrode, and generates a light output when a sufficient potential difference is formed between the corresponding scan electrode and the data electrode. The drive control device 20 is electrically connected to each of the scan electrodes and the data electrodes.

The driving control device 20 continuously receives an external display signal and temporarily stores the plurality of frame information (frame 1, frame 2...) included in the display signal, and each frame information includes a plurality of display unit information (pixel) Each display unit information is correspondingly displayed on each display unit 11. The drive control device 20 inputs a scan signal (COM_1~COM_m) to each scan electrode according to the content of each screen information, and inputs a data signal (SEG_1~SEG_n) to each data electrode to make each display unit to be driven. A sufficient potential difference is generated between the corresponding scan electrode and the data electrode, and each display unit 11 generates a light output screen corresponding to the frame information.

In one of the screen information display period frame 1 (please refer to FIG. 1), each scan signal includes a scan driving period Von and a non-driving period Voff. The length of time of the scan driving period Von is the length of time that the corresponding display unit 11 can generate light output according to the voltage state of the scanning signal. The time length adjustment mode of the scan driving cycle Von is: the driving control device 20 first calculates, in each frame information, each display unit 11 that is to be in a light output state and corresponds to each scanning electrode in each display period. The total number of times, and then the length of the scan driving period is adjusted in a positive correlation manner according to the total number. The time length adjustment mode of the scan driving cycle Von can determine the extension time of the scan driving cycle Von by selecting the most appropriate positive correlation mode or table lookup mode after the experience and the visual experience test. In practice, a correspondence between the result of the experience and the visual experience test and the voltage can be formed into a table, and the optimum voltage combination is found by using the look-up table during driving, and the aforementioned driving is performed.

As shown in FIG. 3 , in the screen information, five display units 11A corresponding to the same scan electrode are required to exhibit a light output state, and the scan drive period Von time of the scan signal is increased by the above adjustment. The display unit 11A is visually made to compensate for the brightness, that is, the brightness is increased, because of the increase in display time, thereby achieving the technical effect of uniform brightness.

It is worth noting that, as the scan driving period Von is extended, in order to achieve a correct display result, the data signal must also be extended in accordance with the extension of the scan driving period Von. As shown in FIG. 1, the corresponding scan signal is located in the scan driving period Von and the corresponding data signal is located in a data driving period Vhigh, so that the display unit 11 to be driven generates a correct display result.

Further, please refer to FIG. 6a and FIG. 6b. In addition to the time period of extending the scan driving period, the voltage level of the scan signal COM and/or the data signal SEG can be adjusted by adjusting the technical effects of the present invention. Achieve the technical effect of displaying brightness matching balance. In FIG. 6a, when a relatively large number of display units 11A are driven during the same scan driving period, the differential pressure corresponding to the data signal SEG is adjusted by adjusting the same scanning signal COM in the same display screen. The display unit 11A having a relatively large number of displays may have a relatively large voltage difference to compensate for the aforementioned problem of insufficient/unbalanced brightness. Thus, in the same picture driving, the display unit 11B corresponding to the same scan driving period. Compared with the display unit 11A having a relatively small number of display units, in order to balance the problem that the display units 11A may be insufficient in brightness, the data driving signal voltage Vs can be reduced by reducing the data signal to achieve the present invention. Balance the display. As shown in the actual example, please refer to FIG. 6a. When driving correspondingly a relatively large number of the display units 11A, the voltage level of the corresponding data signal SEG can be pulled up, for example, to 4 volts (V), until the next display. When the display unit 11B is driven by a relatively small period, the corresponding data signal SEG is reduced to a lower voltage (ie, Vs) such as 2.5V, so that the technical effect of the balanced display can be achieved. Alternatively, as shown in FIG. 6b, when the same scanning signal COM corresponds to the relatively large number of display units 11A to be displayed, the voltage Vc of the scanning driving period can be reduced, so as to achieve relatively large display units. 11A produces a relatively large voltage difference and achieves the effect of balanced display. As shown in the actual example, when a relatively large number of the display units 11A are driven, the voltage difference of the corresponding driving display units 11A can be increased by reducing the voltage of the scanning signal COM, for example, driving relatively more. The voltage difference of the display unit 11A is 4V, and the voltage difference of the display unit 11B is relatively small to be 2.5V, thereby achieving the effect of compensating the display effect.

The preferred value of the driving voltage Vc and the data driving signal voltage Vs can be obtained by an empirical formula or a data calculation method. For example, the driving control unit 20 can be provided by a built-in comparison table of the number of display units and the voltage. In the same screen display process, when a relatively large number of the display units 11A are displayed correspondingly, the voltage difference is increased, and the voltage difference is reduced during the period in which the display unit 11B is relatively small, and the display brightness balance is achieved. In other words, the present invention achieves the aforementioned effect of brightness balance by a technique of time compensation (adjusting the driving period) or voltage compensation (adjusting the driving voltage difference). In an implementation, the time compensating unit 24 and the time control unit 25 can be replaced by a voltage control unit 25, and the voltage control unit 25 obtains a voltage value corresponding to the number of driving display units 11 according to the comparison table 23, The output voltage of the data driving unit 27 and the scan driving unit 26 is driven. In other words, the data driving unit 27 and the scan driving unit 26 can provide multi-level driving elements.

Referring to FIG. 4, as the scan driving period Von is changed by driving a different number of the display units 11, the display period (t _frame ) of each frame information of the present invention may be a fixed value or a non-determined value. The method in which the drive control device 20 calculates the display period (t _frame ) may be, for example, the following two types. The first method defines that the driving time length (t ₁ ~ t _n ) of the scan driving period Von of each scan electrode is equal to a preset one base time (T _base ) multiplied by a weight coefficient corresponding to the scan electrode ( ω ₁ ~ω _n ), as follows: [Math 1] t ₁ = T _base * ω ₁ [Math 2] t ₂ = T _base * ω ₂ [Math 3] t ₃ = T _base * ω ₃ : [Math 4] t _n = T _base * ω _n

The second method defines that the driving time length (t ₁ ~ t _n ) of each scan electrode is equal to the base time (T _base ) multiplied by a weight coefficient (ω ₁ ~ ω _n ) corresponding to the scan electrode and then divided by all The sum of the weight coefficients is as follows: [Math 5] t ₁ = T _base * ω ₁ / ∑ ω [Math 6] t ₂ = T _base * ω ₂ / ∑ ω [Math 7] t ₃ = T _base * ω ₃ / ∑ω : [Math 8] t _n = T _base * ω _n / ∑ω

The calculation method of the weight coefficient (ω ₁ ~ ω _n ) is obtained by judging the total number of the display units 11 corresponding to the same scan electrode and being driven according to each frame information. The setting of the base time (T _base ) can be determined according to factors such as the reaction time of the circuit, the total number of the display units 11, the reaction time of the driving elements used, the empirical formula, and the visual experience, thereby being applicable to different A resolution and size display.

The driving control device 20 of the embodiment includes a power supply unit 21 electrically connected to each other, a data storage memory 22, a time compensation unit 24, a time control unit 25, a scan driving component 26 and a data driving component 27. A comparison table 23 is stored in the data storage memory 22.

The power supply unit 21 provides the power required by the drive control device 20, and the type thereof is not limited, and may be a plurality of sets of DC/DC conversion circuits for providing each circuit unit in the drive control device 20 or The power of the modules with different or identical voltage requirements, for example, provides 3.3V and 5V for operating the circuitry inside the drive control device 20. In the present embodiment, the power supply unit 21 includes a conversion circuit for supplying power to the AC 120V to DC5V of the time compensation unit 24, and an AC 120V for supplying power to the scan driving element 26 and the data driving element 27. Switch to DC8V conversion circuit. Since the various conversion circuits described above are circuit elements that are common in the art, detailed descriptions thereof will not be repeated herein.

The data storage memory 22 receives information such as the display signal and the driving required parameters from the outside and temporarily stores the information, and the type thereof is not limited, such as a flash memory or a static random access memory (SRAM). Or Dynamic Random Access Memory (DRAM). In this embodiment, the data storage memory 22 is a flash memory. Since the various memory devices described above are circuit components that are common in the art, detailed descriptions thereof will not be repeated herein.

The comparison table 23 records the relationship of "the time extended by the driving time length (t ₁ to t _n ) of the scanning driving period Von when driving the different number of display units 11", so the comparison table 23 provides the relationship. The drive control device 20 calculates the aforementioned method for the fastest driving time length, which not only can greatly reduce the computational load of the hardware, but also can speed up the reaction speed and reduce the display delay problem caused by the calculation speed being too slow. The comparison table 23 may include a relationship of "the number of driving the display unit 11 and the driving time length (t ₁ ~ t _n ) of the scanning driving period Von", and the relationship may depend on the material type of the display unit 11 used. The visual response time, the resolution of the display unit matrix 10, and the like are adjusted so that different display unit matrices 10 and the display unit 11 can achieve an optimum display effect (display reaction speed, uniform display brightness, etc.).

The time compensating unit 24 determines the scan driving period Von by the relationship between the number of driving the display unit 11 and the driving time length (t ₁ to t _n ) of the scanning driving period Von recorded in the comparison table 23 This data drives the length of the period Vhigh. In this embodiment, the time compensation unit 24 is a circuit as shown in FIG. 5, which is an adder circuit array 242 connected in series with a comparison circuit array 244, and an input data is display unit information corresponding to the same scan electrode. In the example, the bit width of the display unit information is 10 bits, and the input data is input to the input terminal data of the adding circuit array 242. The output of one of the comparison circuit arrays 244 (T1, T2 or T3) is a time length option of the scan drive period Von of one of the column scan electrodes corresponding to one frame of picture information. If it is necessary to drive seven display units 11 or more, T1 is 1, and T2 and T3 are 0, which represents the driving period of a column display unit 11 as T1. If a column needs to drive between 6 and 4 display units 11, T2 is 1, and T1 and T3 are 0, indicating that the driving period of this particular column is T2. If another column needs to drive less than 3 display units 11, T3 is 1, and T1 and T2 are 0, indicating that the driving period of the column is T3. The time compensation unit 24 further determines, according to the output (T1, T2 or T3) of the comparison circuit array 244, the length of the driving time of the scan driving period Von and the length of the data driving period Vhigh in a table lookup manner.

The scan driving component 26 and the data driving component 27 are electrically connected to the scan electrodes and the data electrodes, respectively, and output the scan signal and the data signal to the scan electrodes and the data electrodes respectively to provide the display units 11 to be generated. The appropriate electrical signal required for light output. In this embodiment, the scan driving component 26 and the data driving component 27 are both driving circuits composed of a boosting circuit and a buffering component. Since the boosting circuit and the buffering component are circuit components that are common in the art, detailed descriptions thereof will not be repeated herein.

The time control unit 25 stores the frame information in the data storage memory 22 according to the driving time of the display signal, the driving time period (t ₁ ~ t _n ) of the scanning driving cycle Von, and the driving time of the data driving cycle Vhigh. The length outputs a drive information to the scan driving element 26 and the data driving element 27, so that the scan driving element 26 and the data driving element 27 adjust the light output time of each display unit 11 and cause the display unit matrix 10 to perform display. jobs.

Referring to FIG. 6, the driving control device 20 can perform a driving method for equalizing the display brightness, and adjusting the driving time length of the scanning signal and the data signal according to the content of the display signal. The driving method includes the following steps:

1. Capture and display a display signal from the outside, the display signal includes a plurality of screen information, and each screen information includes a plurality of display unit information;

2. Analyze each frame information and calculate the total number of display units corresponding to the same scan electrode and to be driven;

3. determining the driving time length of the corresponding scan electrode and the driving time length of the corresponding data electrode according to the total number of display units in a positive correlation manner (table lookup method);

4. Output a drive message based on the length of the drive time to equalize the overall brightness of the display. The driving information correspondingly displays one of the screen information and the display period is not fixed.

Based on the foregoing description, the present embodiment has the following features:

1. Changing the driving time length of the scanning driving period Von of each display unit, compensating for the difference in brightness caused by simultaneously driving a relatively large number of display units, thereby significantly improving the overall display effect.

2. Using the look-up table method can greatly reduce the time required for calculation, thereby improving the response speed of the display, achieving a simplified calculation process and reducing the manufacturing cost.

3. The display period can be unfixed or fixed, making the control method more diverse and suitable for displays with multiple resolutions.

4. The voltage difference can be adjusted according to the number of display units, so that the driving voltage varies with different display unit numbers, thereby achieving the technical effect of balancing the brightness display.

10‧‧‧Display unit matrix
11‧‧‧Display unit
20‧‧‧Drive Control Unit
21‧‧‧Power unit
22‧‧‧Data storage memory
23‧‧‧ comparison table
24‧‧‧Time Compensation Unit
25‧‧‧Time Control Unit
26‧‧‧Scan drive components
27‧‧‧Data Driven Components

1 is a preferred embodiment of the present invention and its corresponding signals. 2 is a block diagram of a system in accordance with a preferred embodiment of the present invention. FIG. 3 is a schematic diagram of correspondence between driving signals and display brightness according to a preferred embodiment of the present invention. 4 is a schematic diagram showing a display period of a frame data according to a preferred embodiment of the present invention. FIG. 5 is a schematic circuit diagram of a time compensation unit according to a preferred embodiment of the present invention. FIG. 6 is a schematic diagram of a driving method according to a preferred embodiment of the present invention. Figure 6a is a schematic view of the driving of the second embodiment of the present invention. Figure 6b is a schematic view of the driving of the third embodiment of the present invention. Figure 7 shows an existing passively driven organic light emitting diode display and its corresponding signals. Figure 8 shows the drive display results of an existing passively driven organic light emitting diode display.

20‧‧‧Drive Control Unit

21‧‧‧Power unit

22‧‧‧Data storage memory

23‧‧‧ comparison table

24‧‧‧Time Compensation Unit

25‧‧‧Time Control Unit

26‧‧‧Scan drive components

27‧‧‧Data Driven Components

Claims (5)

A passive matrix organic light emitting diode display with balanced display brightness function is suitable for continuously receiving a display signal, wherein the display signal includes a plurality of screen information, and each of the screen information includes a plurality of display unit information, and the display comprises: The display unit matrix includes a plurality of scan electrodes, a plurality of data electrodes, and a plurality of display units, each display unit corresponding to one scan electrode and one data electrode, and each display unit information is correspondingly displayed on each display unit; and a driving control device And electrically connecting each scan electrode and each data electrode, and determining the total number of display units corresponding to the same scan electrode and being driven according to each frame information, adjusting the corresponding display unit received from the scan electrode in a positive correlation manner A voltage difference between the data electrodes to equalize the brightness of the display unit corresponding to each of the scan electrodes in the matrix of the display unit. The passive matrix organic light emitting diode display having the function of equalizing display brightness according to claim 1, wherein the driving control device comprises a power supply unit electrically connected to each other, a data storage memory, a voltage control unit, a scan driving component and a data driving component, wherein: the power supply unit provides power required by the driving control device; the data storage memory stores the display signal and a comparison table of the number and voltage of the display unit; the power control unit is based on The comparison table obtains a corresponding voltage value required to drive the number of display units, and then drives an output voltage of the data driving component and the scan driving component; and the scan driving component and the data driving component respectively correspond to each scan electrode and each data electrode Electrically connected and driving the display unit matrix. The passive matrix organic light emitting diode display with balanced display brightness function as described in claim 1 of the patent application determines that the same scan electrode will be driven according to each frame information. The total number of display units is adjusted in a look-up manner to the driving voltage of the corresponding scanning electrode or the driving voltage of the corresponding data electrode. A display method of a passive matrix organic light emitting diode display with a balanced display brightness function, comprising the steps of: capturing and displaying a display signal by an external image, wherein the display signal comprises a plurality of screen information, and each of the screen information comprises a plurality of Display unit information; analyze each frame information, and calculate the total number of display units corresponding to the same scan electrode and to be driven; determine the voltage difference between the corresponding scan electrode and the corresponding data electrode according to the total number; and This voltage difference magnitude equalizes the overall brightness of the display. A display method of a passive matrix organic light emitting diode display having an equalized display brightness function as described in claim 8 of the patent application, further comprising a comparison table of the number of display units and the voltage, according to the total number in a manner of looking up the table Determine the voltage difference between the corresponding scan electrode and the corresponding data electrode.