This application claims priority of Taiwanese Patent Application No. 108111062, filed on Mar. 28, 2019.
The disclosure relates to display techniques, and more particularly to a display system and a shared driving circuit thereof.
Referring to
As the resolution of the conventional display system increases (for example, to the FHD resolution of 1920×1080 pixels, or even to the 4K UHD resolution of 3840×2160 pixels), the number of the driving circuits 11 increases significantly, resulting in significant increase of power consumption of the conventional display system. However, as the number of the driving circuits 11 increases, it becomes difficult to fabricate the driving circuits 11 on a single chip. In addition, a printed circuit board with many layers is required to carry a large amount of traces of the conventional display system, resulting in significant increase of total cost of the conventional display system.
Therefore, an object of the disclosure is to provide a display system and a shared driving circuit thereof. The display system can alleviate at least one drawback of the prior art.
According to an aspect of the disclosure, the display system includes a number (M) of scan line units, a number (N) of channel line units, a number (R) of light emitting arrays and a number (L) of shared driving circuits, where M≥1, where N≥1, where R≥1, and where L is equal to a maximum of M and N when M≠N, and is equal to M otherwise. Each of the light emitting arrays is connected to a corresponding one of the scan line units and a corresponding one of the channel line units. Each of the shared driving circuits includes a control circuit, a scan driver and a channel driver. The control circuit is for receiving an enable control output, and generates a scan enable signal and a channel enable signal based on the enable control output. The scan driver is connected to the control circuit for receiving the scan enable signal therefrom, and is operable to generate or not to generate a scan driving output based on the scan enable signal. The channel driver is connected to the control circuit for receiving the channel enable signal therefrom, and is operable to generate or not to generate a channel driving output based on the channel enable signal. The scan driver of each of a number (M) of the shared driving circuits is further connected to a respective one of the scan line units for providing the scan driving output thereto. The channel driver of each of a number (N) of the shared driving circuits is further connected to a respective one of the channel line units for providing the channel driving output thereto.
According to another aspect of the disclosure, the shared driving circuit is to be used in a display system. The display system includes at least one scan line unit, at least one channel line unit, and at least one light emitting array that is connected to the at least one scan line unit and the at least one channel line unit. The shared driving circuit includes a control circuit, a scan driver and a channel driver. The control circuit is for receiving an enable control output, and generates a scan enable signal and a channel enable signal based on the enable control output. The scan driver is connected to the control circuit for receiving the scan enable signal therefrom, and is operable to generate or not to generate a scan driving output based on the scan enable signal. The channel driver is connected to the control circuit for receiving the channel enable signal therefrom, and is operable to generate or not to generate a channel driving output based on the channel enable signal. The scan driver is further connected to one of the at least one scan line unit for providing the scan driving output thereto. The channel driver is further connected to one of the at least one channel line unit for providing the channel driving output thereto.
Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which:
Before the disclosure is described in greater detail, it should be noted that where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics.
Referring to
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In this embodiment, the signal processor 22 includes a controller 221, an input/output (I/O) interface 222, a configuration register 223, a pulse width modulator 224 and an error detector 225.
The controller 221 is connected to the clock generator 21 for receiving the internal global clock signal (IGCLK) therefrom, and is for further receiving the external global clock signal (EGCLK) and the data clock signal (DCLK) from the central control system. The controller 221 generates a channel clock signal (CCLK), a scan clock signal (SCLK) and an enable clock signal (ECLK) in synchrony with one of the internal global clock signal (IGCLK) and the external global clock signal (EGCLK), and generates a configuration clock signal (RCLK) in synchrony with the data clock signal (DCLK).
The I/O interface 222 includes a first serial I/O pin (SIO1), a second serial I/O pin (SIO2), and a 16-bit bi-directional shift register (not shown) that is connected between the first and second serial I/O pins (SIO1, SIO2). The I/O interface 222 is for receiving the data clock signal (DCLK) from the central control system, and is for further receiving, from the central control system or the I/O interface 222 of the shared driving circuit at the previous stage, the display data and a plurality of control settings one bit at a time at the first serial I/O pin (SIO1) in synchrony with the data clock signal (DCLK). The I/O interface 222 outputs the display data and the control settings sixteen bits at a time, and further outputs the display data and the control settings one bit at a time at the second serial I/O pin (SIO2) for receipt by the I/O interface 222 of the shared driving circuit at the next stage, if any.
The configuration register 223 is connected to the controller 221 for receiving the configuration clock signal (RCLK) therefrom, and is further connected to the I/O interface 222 for receiving and storing the control settings therefrom sixteen bits at a time in synchrony with the configuration clock signal (RCLK). In this embodiment, the configuration register 223 includes a plurality of 16-bit fields for storing the control settings; and the control settings include the source control setting (SET1), an enable control setting (SET2), a current gain control setting (SET3), a reference voltage control setting (SET4), a scan control setting (SET5) and an error detection control setting (SET6). The configuration register 223 is further connected to the clock generator 21 for providing the source control setting (SET1) thereto.
The pulse width modulator 224 includes a storage element 226 and a pulse width modulation (PWM) engine 227. The storage element 226 is connected to the I/O interface 222 for receiving and storing the display data therefrom sixteen bits at a time. The storage element 226 may be a static random access memory (SRAM), a dynamic random access memory (DRAM), a register file that includes a plurality of D flip-flops, or the like. In this embodiment, the display data contains forty-eight-by-thirty-two 16-bit grey scale values that respectively correspond to the LEDs 321-323 (see
The channel control output includes the first to third PWM signals (PWMr1-PWMr16, PWMg1-PWMg16, PWMb1-PWMb16) that are generated by the PWM engine 227, and the current gain control setting (SET3) and the reference voltage control setting (SET4) that are stored in the configuration register 223. The scan control output includes the scan clock signal (SCLK) that is generated by the controller 221, and the scan control setting (SET5) that is stored in the configuration register 223. The enable control output includes the enable clock signal (ECLK) that is generated by the controller 221, and the enable control setting (SET2) that is stored in the configuration register 223.
In this embodiment, the control circuit 25 is connected to the controller 221 and the configuration register 223 for receiving the enable clock signal (ECLK) and the enable control setting (SET2) respectively therefrom, and generates the channel enable signal (SD) and the scan enable signal (SS) based on the enable control setting (SET2) in synchrony with the enable clock signal (ECLK). Each of the channel enable signal (SD) and the scan enable signal (SS) is switchable between an active state (e.g., being at a logic “1” level) and an inactive state (e.g., being at a logic “0” level). The control circuit 25 may be implemented using a counter, a finite-state machine, a register circuit and a combinational logic circuit.
Referring to
The control generator 234 is connected to the control circuit 25 (see
The current gain controller 231 is connected to the configuration register 223 (see
The current provider 232 is connected to the current gain controller 231 for receiving the first to third current gain control signals therefrom, is adapted to be further connected to a first power rail 91 for receiving therefrom a first supply voltage (VLEDr) with a magnitude that falls within a range of 2.4V to 4.5V, and is adapted to be further connected to a second power rail 92 for receiving therefrom a second supply voltage (VLEDgb) with a magnitude that falls within a range of 3.2V to 4.5V. The current provider 232 provides forty-eight driving currents that are divided into sixteen first driving currents, sixteen second driving currents and sixteen third driving currents. The first driving currents are sourced from the first power rail 91. The second and third driving currents are sourced from the second power rail 92. The current provider 232 further adjusts magnitudes of the first driving currents based on the first current gain control signal, adjusts magnitudes of the second driving currents based on the second current gain control signal, and adjusts magnitudes of the third driving currents based on the third current gain control signal.
The channel switches (SWr1-SWr16, SWg1-SWg16, SWb1-SWb16) are divided into sixteen first channel switches (SWr1-SWr16) that respectively correspond to the first driving current signals, sixteen second channel switches (SWg1-SWg16) that respectively correspond to the second driving current signals, and sixteen third channel switches (SWb1-SWb16) that respectively correspond to the third driving current signals. Each of the first to third channel switches (SWr1-SWr16, SWg1-SWg16, SWb1-SWb16) has a first terminal that is connected to the current provider 232, a second terminal that is for providing the respective one of the first to third driving current signals, and a control terminal that is connected to the control generator 234 for receiving therefrom one of the first to third channel control signals (CCr1-CCr16, CCg1-CCg16, CCb1-CCb16) which corresponds to the respective one of the first to third driving current signals. Each of the first channel switches (SWr1-SWr16) permits a respective one of the first driving currents to flow therethrough when conducting. Each of the second channel switches (SWg1-SWg16) permits a respective one of the second driving currents to flow therethrough when conducting. Each of the third channel switches (SWb1-SWb16) permits a respective one of the third driving currents to flow therethrough when conducting.
Therefore, when the channel enable signal (SD) is in the active state, the first to third channel switches (SWr1-SWr16, SWg1-SWg16, SWb1-SWb16) transition between conduction and non-conduction, the first to third driving current signals are generated, and a magnitude of each of the first to third driving current signals is equal to the magnitude of a corresponding one of the first to third driving currents in a case where a corresponding one of the first to third channel switches (SWr1-SWr16, SWg1-SWg16, SWb1-SWb16) conducts, and is zero otherwise. When the channel enable signal (SD) is in the inactive state, none of the first to third channel switches (SWr1-SWr16, SWg1-SWg16, SWb1-SWb16) conducts, and the first to third driving current signals are not generated.
The amplifier unit 233 is connected to the second terminals of the first to third channel switches (SWr1-SWr16, SWg1-SWg16, SWb1-SWb16), is further connected to the configuration register 223 (see
Referring to
The scan controller 241 is connected to the controller 221 (see
The multiplexer unit 247 is connected to the scan controller 241 for receiving the scan control signals therefrom, is adapted to be further connected to a third power rail 93 for receiving a ground voltage therefrom, is for further receiving thirty-two indication signals that respectively correspond to the scan driving signals, and generates thirty-two switch control signals that respectively correspond to the scan driving signals. For each of the scan driving signals, the multiplexer unit 247 outputs one of the ground voltage and the scan control signal corresponding to the scan driving signal based on the indication signal corresponding to the scan driving signal to serve as the switch control signal corresponding to the scan driving signal.
Each of the scan switches (SW1-SW32) (e.g., an N-type power semiconductor transistor) has a first terminal (e.g., a drain terminal) that is for providing a respective one of the scan driving signals, a second terminal (e.g., a source terminal) that is adapted to be connected to the third power rail 93 for receiving the ground voltage therefrom, and a control terminal (e.g., a gate terminal) that is connected to the multiplexer unit 247 for receiving therefrom one of the switch control signals which corresponds to the respective one of the scan driving signals.
Each of the amplifiers 248 is connected to the first terminal of a respective one of the scan switches (SW1-SW32), and is further connected to the multiplexer unit 247 for receiving therefrom one of the switch control signals that is received by the respective one of the scan switches (SW1-SW32). Each of the amplifiers 248 adjusts a magnitude of a voltage at the first terminal of the respective one of the scan switches (SW1-SW32) to a predetermined reference voltage value when the one of the switch control signals causes the respective one of the scan switches (SW1-SW32) to not conduct. As a consequence, upper ghosting can be eliminated.
Referring to
Therefore, when the scan enable signal (SS) is in the active state, the at least some of the scan switches (SW1-SW32) transition between conduction and non-conduction, the scan driving signals are generated, and each of the scan driving signals ties the first terminal of a corresponding one of the scan switches (SW1-SW32) to the ground voltage in a case where the corresponding one of the scan switches (SW1-SW32) conducts, and does not tie the first terminal of the corresponding one of the scan switches (SW1-SW32) to the ground voltage otherwise. When the scan enable signal (SS) is in the inactive state, none of the scan switches (SW1-SW32) conducts, and the scan driving signals are not generated.
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In the first mode, the scan enable signal (SS) and the channel enable signal (SD) of the shared driving circuit 21 are in the active state for a predetermined time period, and the scan enable signals (SS) and the channel enable signals (SD) of the shared driving circuits 22, 23 are in the inactive state, so the light emitting array 31,1 is driven by the scan driving output and the channel driving output from the shared driving circuit 21 to emit light for the predetermined time period.
In the second mode, the scan enable signal (SS) of the shared driving circuit 21 and the channel enable signal (SD) of the shared driving circuit 22 are in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 22, 23 and the channel enable signals (SD) of the shared driving circuits 21, 23 are in the inactive state, so the light emitting array 31,2 is driven by the scan driving output from the shared driving circuit 21 and the channel driving output from the shared driving circuit 22 to emit light for the predetermined time period.
In the third mode, the scan enable signal (SS) of the shared driving circuit 21 and the channel enable signal (SD) of the shared driving circuit 23 are in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 22, 23 and the channel enable signals (SD) of the shared driving circuits 21, 22 are in the inactive state, so the light emitting array 31,3 is driven by the scan driving output from the shared driving circuit 21 and the channel driving output from the shared driving circuit 23 to emit light for the predetermined time period.
In the fourth mode, the scan enable signal (SS) of the shared driving circuit 22 and the channel enable signal (SD) of the shared driving circuit 21 are in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 21, 23 and the channel enable signals (SD) of the shared driving circuits 22, 23 are in the inactive state, so the light emitting array 32,1 is driven by the scan driving output from the shared driving circuit 22 and the channel driving output from the shared driving circuit 21 to emit light for the predetermined time period.
In the fifth mode, the scan enable signal (SS) and the channel enable signal (SD) of the shared driving circuit 22 are in the active state for the predetermined time period, and the scan enable signals (SS) and the channel enable signals (SD) of the shared driving circuits 21, 23 are in the inactive state, so the light emitting array 32,2 is driven by the scan driving output and the channel driving output from the shared driving circuit 22 to emit light for the predetermined time period.
In the sixth mode, the scan enable signal (SS) of the shared driving circuit 22 and the channel enable signal (SD) of the shared driving circuit 23 are in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 21, 23 and the channel enable signals (SD) of the shared driving circuits 21, 22 are in the inactive state, so the light emitting array 32,3 is driven by the scan driving output from the shared driving circuit 22 and the channel driving output from the shared driving circuit 23 to emit light for the predetermined time period.
In the seventh mode, the scan enable signal (SS) of the shared driving circuit 23 and the channel enable signal (SD) of the shared driving circuit 21 are in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 21, 22 and the channel enable signals (SD) of the shared driving circuits 22, 23 are in the inactive state, so the light emitting array 33,1 is driven by the scan driving output from the shared driving circuit 23 and the channel driving output from the shared driving circuit 21 to emit light for the predetermined time period.
In the eighth mode, the scan enable signal (SS) of the shared driving circuit 23 and the channel enable signal (SD) of the shared driving circuit 22 are in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 21, 22 and the channel enable signals (SD) of the shared driving circuits 21, 23 are in the inactive state, so the light emitting array 33,2 is driven by the scan driving output from the shared driving circuit 23 and the channel driving output from the shared driving circuit 22 to emit light for the predetermined time period.
In the ninth mode, the scan enable signal (SS) and the channel enable signal (SD) of the shared driving circuit 23 are in the active state for the predetermined time period, and the scan enable signals (SS) and the channel enable signals (SD) of the shared driving circuits 21, 22 are in the inactive state, so the light emitting array 33,3 is driven by the scan driving output and the channel driving output from the shared driving circuit 23 to emit light for the predetermined time period.
It should be noted that, in each of the first to ninth modes, the current gain controllers 231 (see
It should also be noted that, in a modification of this embodiment, the enable control setting received by the shared driving circuit 21 may indicate that there are first to third modes, that the scan driving output should be generated in the first mode, and that the channel driving output should be generated in the first to third modes. The enable control setting received by the shared driving circuit 22 may indicate that there are first to third modes, that the scan driving output should be generated in the second mode, and that the channel driving output should be generated in the first to third modes. The enable control setting received by the shared driving circuit 23 may indicate that there are first to third modes, that the scan driving output should be generated in the third modes, and that the channel driving output should be generated in the first to third modes. Based on these enable control settings, the display system may operate cyclically in the first to third modes. In the first mode, the scan enable signal (SS) of the shared driving circuit 21 and the channel enable signals (SD) of the shared driving circuits 21-23 may be in the active state for a predetermined time period, and the scan enable signals (SS) of the shared driving circuits 22, 23 may be in the inactive state, so the light emitting arrays 31,1-31,3 may be driven by the scan driving output from the shared driving circuit 21 and respectively by the channel driving outputs from the shared driving circuits 21-23 to emit light for the predetermined time period. In the second mode, the scan enable signal (SS) of the shared driving circuit 22 and the channel enable signals (SD) of the shared driving circuits 21-23 may be in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 21, 23 may be in the inactive state, so the light emitting arrays 32,1-32,3 may be driven by the scan driving output from the shared driving circuit 22 and respectively by the channel driving outputs from the shared driving circuits 21-23 to emit light for the predetermined time period. In the third mode, the scan enable signal (SS) of the shared driving circuit 23 and the channel enable signals (SD) of the shared driving circuits 21-23 may be in the active state for the predetermined time period, and the scan enable signals (SS) of the shared driving circuits 21, 22 may be in the inactive state, so the light emitting arrays 33,1-33,3 may be driven by the scan driving output from the shared driving circuit 23 and respectively by the channel driving outputs from the shared driving circuits 21-23 to emit light for the predetermined time period.
Referring to
In the second embodiment, in each of the light emitting arrays 31,1-33,3, for each of the columns of the light emitting elements 32, the cathodes of the red LEDs 321 of the light emitting elements 32 are connected to the respective one of the first channel lines (Cr1-Cr16) of the channel line unit corresponding to the light emitting array, the cathodes of the green LEDs 322 of the light emitting elements 32 are connected to the respective one of the second channel lines (Cg1-Cg16) of the channel line unit corresponding to the light emitting array, and the cathodes of the blue LEDs 323 of the light emitting elements 32 are connected to the respective one of the third channel lines (Cb1-Cb16) of the channel line unit corresponding to the light emitting array; and for each of the rows of the light emitting elements 32, the anodes of the LEDs 321-323 of the light emitting elements 32 are connected to the respective one of the scan lines (S1-S32) of the scan line unit corresponding to the light emitting array. In other words, each of the LED arrays 31,1-33,3 has a common anode configuration in this embodiment.
Referring to
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1. A number (L) of the shared driving circuits can be used to drive at most a number (L2) of the light emitting arrays. As a resolution of the display system increases, the number of the shared driving circuits increases slightly, resulting in low power consumption of the display system as compared to the conventional display system.
2. Since the number of the shared driving circuits is small, the shared driving circuits can be fabricated on a single chip, thereby reducing total cost of the display system.
3. Since the number of the shared driving circuits is small, the display system has a small amount of traces to be laid out on a printed circuit board, so a printed circuit board with a few layers can be used to carry the traces of the display system, thereby reducing the total cost of the display system.
In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects, and that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure.
While the disclosure has been described in connection with what are considered the exemplary embodiments, it is understood that the disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
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