Organic light emitting diode print head

Abstract

An organic light emitting diode print head includes a control unit and a plurality of light emitting units. The control unit is configured to output a start signal and a brightness signal. Each light emitting unit includes a shift register, a drive circuit, and an organic light emitting diode. The shift registers are connected in series such that a shift output terminal of a preceding shift register is coupled to a shift input terminal of a succeeding shift register. An actuation output terminal of each shift register outputs an actuation output signal having an actuation pulse corresponding to a time point of a trigger pulse of the scan signal. The drive circuit is configured to store a brightness voltage corresponding to the brightness signal on a drive capacitor in response to the trigger pulse of the scan signal. A drive current corresponding to the brightness voltage is obtained via a drive path when both a first switch and a second switch are open.

Description

Technical Field

[0001] This invention relates to the field of organic light-emitting diode (OLED) printhead technology, and particularly to an OLED printhead having a light-emitting unit made of a thin-film transistor and an OLED. Background Technology

[0002] An LED printhead (LPH) is a type of printhead that uses a light-emitting technology. It primarily utilizes gallium arsenide (GaAs) semiconductor manufacturing processes to create multiple light-emitting modules, each containing multiple light-emitting components and their driving circuitry. Each light-emitting module is a die. These modules are fixedly arranged on a printed circuit board using die bonding technology. Therefore, manufacturing such a printhead requires complex processes such as wafer dicing and die bonding. Summary of the Invention

[0003] In view of this, in some embodiments, an organic light-emitting diode (OLED) printhead is provided, including a control unit and a plurality of light-emitting units. The control unit is configured to output a start signal and a brightness signal. The plurality of light-emitting units are coupled to the control unit, and each light-emitting unit includes a displacement buffer, a driving circuit, and an OLED. Each displacement buffer includes a displacement input terminal, an actuation output terminal, and a displacement output terminal. These displacement buffers are connected in series such that the displacement output terminal of a preceding displacement buffer is coupled to the displacement input terminal of a subsequent displacement buffer. The displacement input terminal of a first-stage displacement buffer receives and displaces the start signal and outputs a scan signal with a trigger pulse via its displacement output terminal. The remaining displacement buffers respectively receive and displace the scan signal output by the displacement output terminal of the preceding displacement buffer and output scan signals with displaced trigger pulses via their displacement output terminals. The actuation output terminal of each displacement buffer outputs an actuation output signal having an actuation pulse with a timing point corresponding to the trigger pulse. The driving circuit includes a driving capacitor, a first switch, and a second switch, configured to store a brightness voltage corresponding to the brightness signal in the driving capacitor in response to the trigger pulse of the scan signal. The first switch is controlled by a brightness voltage, and the second switch is controlled by an actuation output signal. An organic light-emitting diode (OLED) is coupled to the first switch. The first and second switches are located on the drive path of the OLED. The upstream end of the drive path has an operating voltage. When both the first and second switches are turned on, the OLED receives a drive current related to the brightness voltage through the drive path.

[0004] In some embodiments, an organic light-emitting diode (OLED) printhead includes a control unit and a plurality of light-emitting units. The control unit is configured to output a plurality of scan signals, actuation signals, and brightness signals. These scan signals each have an asynchronous trigger pulse. The light-emitting units are coupled to the control unit. Each light-emitting unit includes a synchronization circuit, a driving circuit, and an OLED. Each synchronization circuit includes a synchronization signal input, an actuation input, and an actuation output. The synchronization signal inputs of these synchronization circuits receive the scan signals one-to-one. The signal inputs of these synchronization circuits receive the actuation signals. The actuation output of each synchronization circuit outputs an actuation output signal according to the trigger pulse, such that the actuation output signal has an actuation pulse with a timing point corresponding to the trigger pulse. The driving circuit includes a driving capacitor, a first switch, and a second switch. A brightness voltage corresponding to the brightness signal is stored in the driving capacitor in response to the trigger pulse of the scan signal. The first switch is controlled by the brightness voltage, and the second switch is controlled by the actuation output signal. The OLED is coupled to the first switch, and the first and second switches are located on the driving path of the OLED. An operating voltage is present upstream of the driving path. When both the first and second switches are turned on, the organic light-emitting diode receives a driving current related to the brightness voltage through the driving path.

[0005] In summary, the organic light-emitting diode (OLED) printhead according to some embodiments of the present invention, with its light-emitting unit made from a conductive thin-film transistor, an OLED, and its driving circuit, can be directly fabricated on a substrate, simplifying the fabrication process. Furthermore, the driving capacitor of the light-emitting unit stores the brightness voltage corresponding to the brightness signal and does not discharge the voltage to a low potential, ensuring that the charging and discharging voltage changes of the capacitor do not fluctuate too much. This accelerates the response time of the light-emitting unit (under brightness signals with short cycle times, the light-emitting unit can quickly perform continuous actions of emitting and extinguishing light), and protects the components from damage, extending their service life.

[0006] The following detailed description of the features and advantages of the present invention in the embodiments is sufficient to enable any person skilled in the art to understand the technical content of the present invention and to implement it accordingly. Based on the content disclosed in this specification, the claims and drawings, any person skilled in the art can easily understand the related objects and advantages of the present invention. Attached Figure Description

[0007] Figure 1 This is a feed diagram of the light-emitting unit in the first embodiment of the present invention, showing the connection relationship between the control unit and the light-emitting unit.

[0008] Figure 2 This is a detailed feed line diagram of multiple light-emitting units in the first embodiment of the present invention.

[0009] Figure 3This is a signal timing diagram of the organic light-emitting diode printhead in the first embodiment of the present invention.

[0010] Figure 4 This is a circuit diagram of the driving circuit of the light-emitting unit in the first embodiment of the present invention.

[0011] Figure 5 The circuit diagram of the displacement buffer in the first embodiment of the present invention is shown.

[0012] Figure 6 This is a feed diagram of the light-emitting unit in the second embodiment of the present invention, showing the connection relationship between the control unit and the light-emitting unit.

[0013] Figure 7 This is a circuit diagram of the light-emitting unit in the second embodiment of the present invention.

[0014] Figure 8 This is a signal timing diagram of the organic light-emitting diode printhead in the second embodiment of the present invention.

[0015] Figure 9 This is a planar schematic diagram of an organic light-emitting diode printhead in some embodiments of the present invention.

[0016] Explanation of reference numerals in the attached figures:

[0017] 10, 20: Organic light-emitting diode printhead;

[0018] 102, 202: Control unit; 104, 204: Light-emitting unit; 106: Start signal generation circuit; 106a: Start signal output terminal; 108, 230: Brightness signal generation circuit; 108a, 230a: Brightness signal output terminal; 110: Displacement buffer; 110a: Displacement input terminal; 110b, 216: Actuation output terminal; 110c: Displacement output terminal; 110d, 214: Actuation input terminal; 110e: Frequency receiver; 112, 208: Drive circuit; 114, 210: Organic light-emitting diode; 116, 232: Group; 116a: First group; 116b: Second group; 118, 218: Drive capacitor; 120, 220: First switch;

[0019] 120a, 122a, 124a, 126a, 128a, 130a, 132a, 134a, 136a, 220a, 222a, 224a: First end;

[0020] 120b, 122b, 124b, 126b, 128b, 130b, 132b, 134b, 136b, 220b, 222b, 224b: Second end;

[0021] 120c, 122c, 124c, 126c, 128c, 130c, 132c, 134c, 136c, 220c, 222c, 224c: Control terminal;

[0022] 122, 222: Second switch; 124, 224: Third switch; 126: Fourth switch; 128: Fifth switch; 130: Sixth switch; 132: Seventh switch; 134: Eighth switch; 136: Ninth switch; 138: Actuating capacitor; 140: Substrate;

[0023] 206: Synchronization circuit; 212: Synchronization signal input terminal; 226: Scan signal generation circuit; 226a: Scan signal output terminal; 228: Actuation signal generation circuit; 228a: Actuation signal output terminal; 234: First NAND gate; 234a, 234b: First input terminal; 234c: First output terminal; 236: Second NAND gate; 236a, 236b: Second input terminal; 236c: Second output terminal; 238: Third NAND gate; 38a, 238b: Third input; 238c: Third output; 240: Fourth NAND gate; 240a, 240b: Fourth input; 240c: Fourth output; 242: First NOT gate; 242a: Fifth input; 242b: Fifth output; 244: AND gate; 244a, 244b: Sixth input; 244c: Sixth output; 246: Second NOT gate; 246a: Seventh input; 246b: Seventh output;

[0024] CK: Frequency signal; E: Displacement signal; EP: Start signal; I: Actuation signal; L: Axis; P1: Drive path; S1: Scan signal; S11: Trigger pulse; S2: Actuation output signal; S21: Actuation pulse; S3: Brightness signal;

[0025] t1, t2, t3, t4, t5, t6, t7, t8: time points;

[0026] N1: First node; N2: Second node;

[0027] VDD: Operating voltage; VSS: Ground voltage. Detailed Implementation

[0028] Please see Figure 1 and Figure 2 . Figure 1 This is a feed diagram of the light-emitting unit 104 in the first embodiment of the present invention, showing the connection relationship between the control unit 102 and the light-emitting unit 104. Figure 2 This is a detailed feed line diagram of the plurality of light-emitting units 104 in the first embodiment of the present invention. (See attached diagram.) Figure 1 and Figure 2As shown, the organic light-emitting diode (OLED) printhead 10 includes a control unit 102 and a plurality of light-emitting units 104. Each light-emitting unit 104 is coupled to the control unit 102. Each light-emitting unit 104 includes a light-emitting component made of conductive thin-film technology and its driving circuitry, thus allowing it to be laid out according to a predetermined pattern on a substrate (see Figure 104). Figure 9 These light-emitting units 104 are formed on the substrate 140. The control unit 102 is configured to output a frequency signal CK, an actuation signal I, a start signal EP, and a brightness signal S3. In some embodiments, these light-emitting units 104 are divided into a plurality of groups 116. Each group 116 includes a plurality of light-emitting units 104. Figure 2 The detailed feed line diagram of the multiple light-emitting units 104 shown is a detailed feed line diagram of the light-emitting units 104 in the same group 116.

[0029] In some embodiments, the control unit 102 includes a start signal generation circuit 106 and a brightness signal generation circuit 108. The start signal generation circuit 106 is configured to output a start signal EP. The start signal generation circuit 106 is coupled to each light-emitting unit 104 to input the start signal EP to the first light-emitting unit 104 of each group 116. The brightness signal generation circuit 108 is configured to output a brightness signal S3 to each light-emitting unit 104 to control the brightness of each light-emitting unit 104. It is understood that the control unit 102 also includes other signal generation circuits that respectively output a frequency signal CK and an actuation signal I. To avoid making the figures overly complex, Figure 1 It was not drawn.

[0030] like Figure 2As shown, each light-emitting unit 104 includes a displacement buffer 110, a driving circuit 112, and an organic light-emitting diode 114. In some embodiments, each displacement buffer 110 includes a displacement input terminal 110a, an actuation output terminal 110b, a displacement output terminal 110c, an actuation input terminal 110d, and a frequency receiving terminal 110e. The frequency receiving terminal 110e receives a frequency signal CK output by the control unit 102, causing each displacement buffer 110 to operate according to the frequency signal CK. These displacement buffers 110 are connected in series such that the displacement output terminal 110c of the preceding displacement buffer 110 is coupled to the displacement input terminal 110a of the following displacement buffer 110. The displacement output terminal 110c is configured to output a scan signal S1, which is the result of shifting the signal received at the displacement input terminal 110a. Specifically, the first-stage displacement buffer 110 receives a start signal EP via the displacement input terminal 110a, shifts the start signal EP, and outputs the scan signal S1 via the displacement output terminal 110c. The remaining displacement buffers 110 receive the scan signal S1 output from the displacement output terminal 110c of the preceding displacement buffer 110 via the displacement input terminal 110a, and output the received scan signal S1 after displacement via the displacement output terminal 110c. The actuation input terminal 110d receives the actuation signal I output by the control unit 102. In response to the actuation signal I, the actuation output terminal 110b of the displacement buffer 110 outputs the actuation output signal S2.

[0031] like Figure 1 As shown. In some embodiments, each group 116 includes the same number of light-emitting units 104. As an example, the number of light-emitting units 104 is 128, but the invention is not limited to this; for example, it can be 64, 256, or other numbers. Here, the numbering of the light-emitting units 104 in these groups 116 is not uniformly restricted to starting from the same side. That is, the numbering can start from one side of the light-emitting unit 104 or from the other side of the light-emitting unit 104. For example, the start signal generation circuit 106 is coupled to the first light-emitting unit 104 on the left in some groups 116 and the first light-emitting unit 104 on the right in some groups 116.

[0032] The start signal generation circuit 106 includes a plurality of start signal output terminals 106a. These start signal output terminals 106a are configured to output a start signal EP. These start signal output terminals 106a are each coupled one-to-one to the groups 116, and each start signal output terminal 106a is coupled to a first-stage displacement buffer 110 in the same group 116. Therefore, when the start signals EP of the various start signal output terminals 106a are synchronized with each other, the first-stage displacement buffers 110 in each group 116 are actuated in response to the start signal EP at the same time point, and the subsequent stages of these displacement buffers 110 are actuated sequentially.

[0033] The luminance signal generation circuit 108 includes a plurality of luminance signal output terminals 108a. These luminance signal output terminals 108a are configured to output luminance signals S3. These luminance signal output terminals 108a are each coupled one-to-one to the groups 116, and each luminance signal output terminal 108a is coupled to all light-emitting units 104 in the same group 116. Therefore, all light-emitting units 104 in the same group 116 will receive the same luminance signal S3. By using a scan signal S1 to specify one light-emitting unit 104 in each group 116 at a certain time, only the specified light-emitting unit 104 performs the action corresponding to the luminance signal S3 at that time. On the other hand, the light-emitting units 104 that are not specified will not perform the action corresponding to the luminance signal S3. Furthermore, the luminance signals S3 output by each luminance signal output terminal 108a are independent of each other and do not affect each other, so the specified light-emitting units 104 in each group 116 can be controlled independently as needed.

[0034] In some embodiments, if the resolution of the organic light-emitting diode printhead 10 is expected to reach 600 DPI (Dots Per Inch), approximately 5120 light-emitting units 104 are required. Since each group 116 has 128 light-emitting units 104, 40 groups 116 are needed. It should be noted that the control unit 102 outputs 40 signal lines for the actuation signal I and the frequency signal CK. The control unit 102 also outputs 40 signal lines for the brightness signal S3 (which can also refer to the brightness signal output terminal 108a). Therefore, the brightness signal S3 is serialized data, requiring 128 signals to respectively indicate the actions that the corresponding 128 light-emitting units 104 should perform.

[0035] In some embodiments, the other signal generation circuits that output the frequency signal CK and the actuation signal I are the same as the brightness signal generation circuit 108, and have multiple signal output terminals. These signal output terminals are coupled one-to-one to the groups 116, and each signal output terminal is coupled to all the light-emitting units 104 in the same group 116. Therefore, each light-emitting unit 104 in the same group 116 receives the same frequency signal CK and the same actuation signal I. In some embodiments, the signal output terminal that outputs the frequency signal CK outputs a synchronized frequency signal CK, so that the frequency signal CK received by different groups 116 is the same; the signal output terminal that outputs the actuation signal I outputs a synchronized actuation signal I, but the actuation signal I received by different groups 116 may be the same or different (determined by the light emission timing of each light-emitting unit 104).

[0036] In some embodiments, the signal generating circuit for outputting the frequency signal CK has a separate signal output terminal coupled to all light-emitting units 104 to provide a synchronized frequency signal CK to each light-emitting unit 104. In some embodiments, the signal generating circuit for outputting the actuation signal I has a separate signal output terminal coupled to all light-emitting units 104 to provide a synchronized actuation signal I to each light-emitting unit 104.

[0037] Please see Figure 2 and Figure 3 . Figure 3 This is a signal timing diagram of the organic light-emitting diode printhead 10 in the first embodiment of the present invention. After the displacement input terminal 110a of the first-stage displacement buffer 110 receives the signal to be displaced E (here, the signal to be displaced E is the start signal EP), in the next cycle of the frequency signal CK, the state of the displacement input terminal 110a is shifted to the displacement output terminal 110c of the first-stage displacement buffer 110 for output (forming the trigger pulse S11 of the scan signal S1). Similarly, after the displacement input terminal 110a of the second-stage displacement buffer 110 receives the signal to be displaced E (here, the signal to be displaced E is the scan signal S1 of the first-stage displacement buffer 110), in the next cycle of the frequency signal CK, the state of the displacement input terminal 110a is shifted to the displacement output terminal 110c of the second-stage displacement buffer 110 for output (forming the trigger pulse S11 of the scan signal S1). Thus, the pulse of the start signal EP will be shifted sequentially according to the cycle of the frequency signal CK based on each stage of the displacement buffer 110. The displacement output terminals 110c of these displacement buffers 110 are each coupled one-to-one to the corresponding light-emitting units 104. Therefore, these light-emitting units 104 are designated to perform actions at different time points in response to the trigger pulse S11 of the corresponding scan signal S1. Figure 3 As shown, the actuation output signal S2 has an actuation pulse S21 corresponding to the trigger pulse S11 at a time point.

[0038] Figure 4 This is a circuit diagram of the driving circuit 112 for the light-emitting unit 104 in the first embodiment of the present invention. Figure 4As shown, the driving circuit 112 includes a driving capacitor 118, a first switch 120, and a second switch 122. The driving circuit 112 is configured to store a brightness voltage corresponding to a brightness signal S3 in the driving capacitor 118 in response to a trigger pulse S11 of the scan signal S1. The first switch 120 is controlled by the brightness voltage, and the second switch 122 is controlled by an actuation pulse S21 of the actuation output signal S2. An organic light-emitting diode (OLED) 114 is coupled to the first switch 120. The first switch 120 and the second switch 122 are located on the driving path P1 of the OLED 114. The upstream end of the driving path P1 has an operating voltage VDD. When both the first switch 120 and the second switch 122 are turned on, the OLED 114 receives a driving current related to the brightness voltage via the driving path P1, thereby emitting light. Thus, each OLED 114 can receive a corresponding driving current based on the brightness voltage, emitting light with consistent brightness as the driving current changes.

[0039] like Figure 4 As shown, in some embodiments, the second switch 122, the first switch 120, and the organic light-emitting diode 114 are sequentially coupled along the direction of the driving current. Specifically, the first switch 120 includes a first terminal 120a, a second terminal 120b, and a control terminal 120c. The second switch 122 includes a first terminal 122a, a second terminal 122b, and a control terminal 122c. The first terminal 122a of the second switch 122 receives the operating voltage VDD. The second terminal 122b of the second switch 122 is coupled to the first terminal 120a of the first switch 120, and the second terminal 120b of the first switch 120 is coupled to the anode of the organic light-emitting diode 114. The cathode of the organic light-emitting diode 114 receives the ground voltage VSS. The control terminal 120c of the first switch 120 is coupled to the driving capacitor 118 to turn on or off in response to the brightness voltage of the driving capacitor 118. The control terminal 122c of the second switch 122 receives the actuation output signal S2, causing the second switch 122 to turn on in response to the actuation wave S21 of the actuation output signal S2. Here, the first switch 120 and the second switch 122 are NMOS transistors, with the first terminal (120a, 122a) being the drain, the second terminal (120b, 122b) being the source, and the control terminals (120c, 122c) being the gate.

[0040] like Figure 4As shown, in some embodiments, the driving circuit 112 further includes a third switch 124. The third switch 124 includes a first terminal 124a, a second terminal 124b, and a control terminal 124c. The first terminal 124a of the third switch 124 receives the brightness signal S3. The second terminal 124b of the third switch 124 is coupled to the driving capacitor 118. The control terminal 124c of the third switch 124 receives the scan signal S1. Therefore, the on / off state of the third switch 124 is determined by the trigger pulse S11 of the scan signal S1. Here, the third switch 124 is an NMOS transistor, with the first terminal 124a as the drain, the second terminal 124b as the source, and the control terminal 124c as the gate.

[0041] The aforementioned transistors (such as the aforementioned switches 120, 122, 124, 126, 128, 130, 132, 134, and 136) are thin-film transistors (TFTs).

[0042] See Figure 3 and Figure 4 The third switch 124 is activated in response to the trigger pulse S11 of the scan signal S1, meaning that the first terminal 124a and the second terminal 124b of the third switch 124 are connected, allowing the driving capacitor 118 to receive the brightness signal S3 via the third switch 124 and be charged to the brightness voltage. Furthermore, due to process errors, the transistors and organic light-emitting diodes 114 in each light-emitting unit 104 may have inconsistent characteristics, resulting in inconsistent brightness of the organic light-emitting diodes 114 in these light-emitting units 104. Therefore, a suitable brightness voltage value is provided to each corresponding light-emitting unit 104 via the brightness signal S3 to adjust the driving current supplied to the corresponding organic light-emitting diode 114, enabling each organic light-emitting diode 114 to emit light with consistent brightness (when illumination is required). It should be noted that the brightness signal S3 during the trigger pulse S11 is either high (illuminating) or low (not illuminating) depending on whether the corresponding organic light-emitting diode 114 needs to be illuminated. Furthermore, the voltage level (i.e., voltage value) at the high potential can be slightly adjusted as needed to adjust the demand for the source-drain current (if brightness needs to be reduced, the brightness voltage is reduced to decrease the source-drain current; conversely, the brightness voltage is increased).

[0043] The duration of the aforementioned trigger pulse S11 is sufficient to charge the driving capacitor 118 to the brightness voltage. It should be noted that the duration of the trigger pulse S11 depends on the printing speed; for example, a printing speed of 600 PPM (Pages per minute)... At a print speed of 1200 PPM, the duration of the arterial pulse S21 is greater than that of the trigger pulse S1 at a print speed of 1200 PPM. 1. The length of time.

[0044] Please see Figure 3 and Figure 5 . Figure 5This is a circuit diagram of the displacement buffer 110 in the first embodiment of the present invention. Figure 5 As shown, in some embodiments, each displacement buffer 110 includes a fourth switch 126, a fifth switch 128, a sixth switch 130, a seventh switch 132, an eighth switch 134, a ninth switch 136, and an actuating capacitor 138. The fourth switch 126 has a first terminal 126a, a second terminal 126b, and a control terminal 126c. The fifth switch 128 has a first terminal 128a, a second terminal 128b, and a control terminal 128c. The sixth switch 130 has a first terminal 130a, a second terminal 130b, and a control terminal 130c. The seventh switch 132 has a first terminal 132a, a second terminal 132b, and a control terminal 132c. The eighth switch 134 has a first terminal 134a, a second terminal 134b, and a control terminal 134c. The ninth switch 136 has a first terminal 136a, a second terminal 136b, and a control terminal 136c. Here, the switches (126, 128, 130, 132, 134, 136) of each shift register 110 are NMOS transistors, with the first terminal (126a, 128a, 130a, 132a, 134a, 136a) being the drain, the second terminal (126b, 128b, 130b, 132b, 134b, 136b) being the source, and the control terminal (126c, 128c, 130c, 132c, 134c, 136c) being the gate.

[0045] The first terminal 126a of the fourth switch 126 is coupled to the control terminal 126c to form the aforementioned displacement input terminal 110a. The first terminal 128a of the fifth switch 128 is coupled to the second terminal 126b of the fourth switch 126 and the actuation capacitor 138. The second terminal 128b of the fifth switch 128 receives the ground voltage VSS, and the control terminal 128c of the fifth switch 128 is the aforementioned actuation input terminal 110d. The first terminal 130a and the control terminal 130c of the sixth switch 130 receive the operating voltage VDD, and the second terminal 130b is coupled to the first terminal 132a of the seventh switch 132. The second terminal 132b of the seventh switch 132 receives the ground voltage VSS. The control terminal 132c of the seventh switch 132 is coupled to the second terminal 126b of the fourth switch 126. The first terminal 134a of the eighth switch 134 is the aforementioned frequency receiving terminal 110e, receiving the aforementioned frequency signal CK. The second terminal 134b of the eighth switch 134 is coupled to the first terminal 136a of the ninth switch 136, with the aforementioned displacement output terminal 110c located between them. The second terminal 136b of the ninth switch 136 receives the ground voltage VSS. The control terminal 134c of the eighth switch 134 is coupled to the second terminal 126b of the fourth switch 126, and the control terminal 136c of the ninth switch 136 is coupled to the second node N2. The actuating capacitor 138 is coupled between the second terminal 134b and the control terminal 134c of the eighth switch 134. That is, one end of the actuating capacitor 138 (the first node N1) is coupled to the second terminal 126b of the fourth switch 126; the other end of the actuating capacitor 138 is coupled to the aforementioned displacement output terminal 110c.

[0046] Again Figure 3 and Figure 5 As shown below, Figure 3 The signal action timing of the first and second stage displacement buffers 110 is illustrated as an example.

[0047] At time t1 (the start point of the first-stage displacement buffer 110): In the first-stage displacement buffer 110, the frequency signal CK received by the frequency receiver 110e is at a high potential, the start signal EP received by the displacement input 110a is at a high potential, and the actuation signal I received by the actuation input 110d is at a low potential. The fourth switch 126, the sixth switch 130, the seventh switch 132, and the eighth switch 134 of the first-stage displacement buffer 110 are turned on, while the fifth switch 128 and the ninth switch 136 are turned off. At this time, the first node N1 of the first-stage displacement buffer 110 is at a high potential, and the second node N2 of the first-stage displacement buffer 110 is at a low potential. The voltage output by the displacement output 110c is at a low potential.

[0048] At time t3 (the scan generation point of the first-stage displacement buffer 110): In the first-stage displacement buffer 110, the frequency signal CK received by the frequency receiving end 110e changes from a low potential to a high potential, and the displacement output end 110c of the first-stage displacement buffer 110 outputs a high potential, that is, a trigger pulse S11 is generated. Since the displacement input end 110a of the second-stage displacement buffer 110 is coupled to the displacement output end 110c of the first-stage displacement buffer 110, the scan signal S1 output through the displacement output end 110c of the first-stage displacement buffer 110 will be input to the displacement input end 110a of the second-stage displacement buffer 110 as the displacement signal E to be displaced by the second-stage displacement buffer 110 (at this moment, the second-stage displacement buffer 110 enters the start point).

[0049] At time t4 (the end of the scan of the first-stage displacement buffer 110): In these displacement buffers 110, the frequency signal CK received by the frequency receiver 110e becomes low and the trigger pulse S11 ends, while the actuation signal I received by the actuation input 110d becomes high. This causes the fourth switch 126, the seventh switch 132, and the eighth switch 134 of the first-stage displacement buffer 110 to close, and its fifth switch 128, the sixth switch 130, and the ninth switch 136 to open. Therefore, the first node N1 of the first-stage displacement buffer 110 is low and its second node N2 is high, the scan of the first-stage displacement buffer 110 ends, and at this time the actuation pulse S21 is high, which is connected from the actuation output 110b to the control terminal 122C of the light-emitting unit 104, turning on the second switch 122.

[0050] At time t5: the displacement output terminal 110c of the second-stage displacement buffer 110 outputs a high potential and generates a trigger pulse S11 (the second-stage displacement buffer 110 enters the scan generation point). Since the displacement input terminal 110a of the third-stage displacement buffer 110 is coupled to the displacement output terminal 110c of the second-stage displacement buffer 110 (see... Figure 2 Therefore, the scan signal S1 output through the second-stage displacement output terminal 110c will be input to the displacement input terminal 110a of the third-stage displacement buffer 110 as the displacement signal E to be displaced by the third-stage displacement buffer 110 (the third-stage displacement buffer 110 enters the start point).

[0051] At time t6: the actuation input terminal 110d receives the second high-potential actuation signal I. This causes the second node N2 of the second-stage displacement buffer 110 to go high (the second-stage displacement buffer 110 finishes scanning).

[0052] At time t7: the third-level displacement buffer 110 enters the scan generation point ( Figure 3 (Not shown in the image).

[0053] Therefore, the number of displacement buffers 110 can be increased according to the number of light-emitting units 104, and each displacement buffer 110 can use the scan signal S1 output from the previous stage as the signal to be displaced E. After receiving the scan signal S1 from the previous stage, the displacement output terminal 110c of the displacement buffer 110 outputs a trigger pulse S11, so that the brightness signal S3 charges the driving capacitor 118 to the brightness voltage.

[0054] Please see Figure 6 , Figure 7 and Figure 8 . Figure 6 The following is a feed diagram of the light-emitting unit 204 in the second embodiment of the present invention, showing the connection relationship between the control unit 202 and the light-emitting unit 204. Figure 7 This is a circuit diagram of the light-emitting unit 204 in the second embodiment of the present invention. Figure 8 This is a signal timing diagram of the organic light-emitting diode (OLED) printhead 20 in a second embodiment of the present invention. The OLED printhead 20 includes a control unit 202 and a plurality of light-emitting units 204. The control unit 202 is configured to output a plurality of scan signals S1, actuation signals I, and brightness signals S3. These scan signals S1 each have an asynchronous trigger pulse S11. The plurality of light-emitting units 204 are coupled to the control unit 202, and each light-emitting unit 204 includes a synchronization circuit 206, a driving circuit 208, and an organic light-emitting diode 210. Each synchronization circuit 206 includes a synchronization signal input terminal 212, an actuation input terminal 214, and an actuation output terminal 216. The synchronization signal input terminals 212 of these synchronization circuits 206 respectively receive the scanning signals S1 one-to-one, and the actuation input terminals 214 receive the actuation signals I. The actuation output terminal 216 of each synchronization circuit 206 outputs an actuation output signal S2 according to the trigger pulse S11, so that the actuation output signal S2 has an actuation pulse S21 with a time point corresponding to the trigger pulse S11.

[0055] like Figure 7As shown, the driving circuit 208 includes a driving capacitor 218, a first switch 220, and a second switch 222. The driving circuit 208 is configured to store a brightness voltage corresponding to a brightness signal S3 in the driving capacitor 218 in response to a trigger pulse S11 of the scan signal S1. The first switch 220 is controlled by the brightness voltage, and the second switch 222 is controlled by an actuation pulse S21 of the actuation output signal S2. An organic light-emitting diode (OLED) 210 is coupled to the first switch 220, and the first switch 220 and the second switch 222 are located on the driving path P1 of the OLED 210. The upstream end of the driving path P1 has an operating voltage VDD. When both the first switch 220 and the second switch 222 are turned on, the OLED 210 receives a driving current related to the brightness voltage via the driving path P1, and thus emits light. Therefore, each OLED 210 can receive a corresponding driving current according to the brightness voltage, so as to emit light with consistent brightness as the driving current changes. The first switch 220 includes a first terminal 220a, a second terminal 220b, and a control terminal 220c. The second switch 222 includes a first terminal 222a, a second terminal 222b, and a control terminal 222c.

[0056] The driving circuit 208 also includes a third switch 224. The third switch 224 includes a first terminal 224a, a second terminal 224b, and a control terminal 224c. The first terminal 224a of the third switch 224 receives the brightness signal S3. The second terminal 224b of the third switch 224 is coupled to the driving capacitor 218, and the control terminal 224c of the third switch 224 receives the scan signal S1. Therefore, the open state of the third switch 224 is determined by the trigger pulse S11 of the scan signal S1. Here, the third switch 224 is an NMOS transistor, with the first terminal 224a as the drain, the second terminal 224b as the source, and the control terminal 224c as the gate. It should be noted that in the second embodiment, the operation of the driving circuit 208 after receiving the actuation output signal S2, the scan signal S1, and the brightness signal S3 is the same as in the first embodiment. Please refer to the description of the first embodiment; it will not be repeated here.

[0057] like Figure 6 and Figure 7As shown, in some embodiments, the control unit 202 includes a scan signal generation circuit 226, an actuation signal generation circuit 228, and a brightness signal generation circuit 230. The scan signal generation circuit 226 includes a plurality of scan signal output terminals 226a. The scan signal generation circuit 226 is configured to output scan signals S1 via these scan signal output terminals 226a. The actuation signal generation circuit 228 includes a plurality of actuation signal output terminals 228a. The actuation signal generation circuit 228 is configured to output actuation signals I via these actuation signal output terminals 228a. The brightness signal generation circuit 230 includes a plurality of brightness signal output terminals 230a. The brightness signal generation circuit 230 is configured to output brightness signals S3 via these brightness signal output terminals 230a.

[0058] like Figure 6 As shown, in some embodiments, these light-emitting units 204 are divided into a plurality of groups 232. Each scan signal output terminal 226a is coupled to the light-emitting unit 204 in these groups 232 with the same sequence number as the scan signal output terminal 226a. These actuation signal output terminals 228a are coupled one-to-one to these groups 232, and each actuation signal output terminal 228a is coupled to all light-emitting units 204 in the same group 232. These brightness signal output terminals 230a are coupled one-to-one to these groups 232, and each brightness signal output terminal 230a is coupled to all light-emitting units 204 in the same group 232. Therefore, all light-emitting units 204 in the same group 232 will receive the same actuation signal I. However, since only one light-emitting unit 204 in the same group 232 is designated (receives trigger pulse S11) at any given time, only the designated light-emitting unit 204 performs the corresponding action according to the actuation signal I it receives; the light-emitting units 204 that do not receive trigger pulse S11 will not perform the corresponding action. Furthermore, the brightness signals S3 output by each brightness signal output terminal 230a are independent of each other and are not affected by each other, so the light-emitting units 204 specified in each group 232 can be controlled independently as needed.

[0059] Again Figure 7As shown, in some embodiments, the synchronization circuit 206 refers to a logic circuit including a first NAND gate 234, a second NAND gate 236, a third NAND gate 238, a fourth NAND gate 240, a first NOT gate 242, an AND gate 244, and a second NOT gate 246. Specifically, the first NAND gate 234 has a first input terminal (234a, 234b) and a first output terminal 234c. The second NAND gate 236 has a second input terminal (236a, 236b) and a second output terminal 236c. The third NAND gate 238 has a third input terminal (238a, 238b) and a third output terminal 238c. The fourth NAND gate 240 has a fourth input terminal (240a, 240b) and a fourth output terminal 240c. The first NOT gate 242 has a fifth input terminal 242a and a fifth output terminal 242b. AND gate 244 has a sixth input (244a, 244b) and a sixth output 244c. Second NOT gate 246 has a seventh input 246a and a seventh output 246b.

[0060] The first input terminal 234a of the first NAND gate 234 is coupled to the actuation signal output terminal 228a. The first input terminal 234b is coupled to the scan signal output terminal 226a. The first output terminal 234c is coupled to the third input terminal 238a of the third NAND gate 238. The second input terminal 236b of the second NAND gate 236 is coupled to the scan signal output terminal 226a. The second input terminal 236a of the second NAND gate 236 is coupled to the fifth output terminal 242b of the first NOT gate 242. The second output terminal 236c of the second NAND gate 236 is coupled to the fourth input terminal 240a of the fourth NAND gate 240. The third input terminal 238b of the third NAND gate 238 is coupled to the fourth output terminal 240c of the fourth NAND gate 240. The third output terminal 238c of the third NAND gate 238 is coupled to the fourth input terminal 240b of the fourth NAND gate 240. The fifth input terminal 242a of the first NOT gate 242 is coupled to the actuation signal output terminal 228a. The sixth input terminal 244b of the AND gate 244 is coupled to the seventh output terminal 246b of the second NOT gate 246. The sixth output terminal 244c of the AND gate 244 is coupled to the control terminal 222c of the second switch 222. The seventh input terminal 246a of the second NOT gate 246 is coupled to the scan signal output terminal 226a and the control terminal 224c of the third switch 224.

[0061] In some embodiments, the first NAND gate 234, the second NAND gate 236, the third NAND gate 238, the fourth NAND gate 240, the first NOT gate 242, the AND gate 244, and the second NOT gate 246 in the synchronization circuit 206 may be implemented by thin-film transistors (TFTs), but this is not a limitation. Any circuit capable of implementing the aforementioned logic components may be implemented.

[0062] In some embodiments, the aforementioned transistors (such as the aforementioned switches 220, 222, 224) are thin-film transistors (TFTs).

[0063] In this embodiment, the first NAND gate 234, the second NAND gate 236, the third NAND gate 238, the fourth NAND gate 240, and the first NOT gate 242 form a D-type latch. Thus, when the scan signal S1 is triggered by the pulse S11 (i.e., the scan signal S1 goes high), the third output terminal 238c of the third NAND gate 238 outputs a signal that matches the actuation signal I at the first input terminal 234a of the first NAND gate 234, to the sixth input terminal 244a of the AND gate 244. During the period when the scan signal S1 is not under the trigger pulse S11 (i.e., the scan signal S1 goes low), the third output terminal 238c of the third NAND gate 238 continues to output this signal. On the other hand, during the trigger pulse S11, the control terminal 224c of the third switch 224 is turned on, causing the drive capacitor 218 to receive the brightness signal S3 via the third switch 224 and charge to the brightness voltage (as described in the first embodiment above, and will not be repeated here). Furthermore, the sixth input terminal 244b of AND gate 244 receives the scan signal S1 inverted by the second NOT gate 246, causing the trigger pulse S11 to end (from high potential to low potential, at which point the third switch 224 will close). Only then does the sixth output terminal 244c of AND gate 244 transmit the signal from the third output terminal 238c of the third NAND gate 238 (i.e., the actuation output signal S2 with the actuating pulse S21 (high potential)) to the second switch 222. Thus, the starting point of the actuating pulse S21 of the actuation output signal S2 received by the second switch 222 is at the end of the trigger pulse S11 (as shown in the image). Figure 3 (The corresponding relationship is shown). Thus, when the trigger pulse S11 ends, the second switch 222 on the drive path P1 is turned on, while the first switch 220 is turned on or off based on the brightness voltage of the drive capacitor 218, thereby determining whether the organic light-emitting diode 210 emits light and its brightness.

[0064] Please see Figure 7 and Figure 8 The first-stage light-emitting unit 204 receives the actuation output signal S2, the brightness signal S3, and the first-stage scan signal S1 transmitted by the control unit 202. At time point t2, the first-stage light-emitting unit 204 is designated to operate, and the brightness voltage charged to the driving capacitor 218 according to the corresponding brightness signal S3 determines whether the organic light-emitting diode 210 emits light and its brightness. Similarly, at time points t4 and t6, the second-stage and third-stage light-emitting units 204 are designated to operate, respectively. And so on. Please refer to [link to relevant documentation]. Figure 9 , Figure 9This is a plan view of an organic light-emitting diode (OLED) printhead 10 in some embodiments of the present invention. In some embodiments, the light-emitting units 104 are configured on a substrate 140 and distributed in a linear pattern. These light-emitting units 104 are divided into a plurality of groups 116, which include a plurality of first groups 116a and a plurality of second groups 116b. Each group 116 is located in one segment on the axis L of the substrate 140. These groups (116a, 116b) are arranged alternately and in a first light-emitting order (e.g., ...). Figure 9 The middle arrow indicates the direction from left to right) and the second emission sequence is opposite to the first emission sequence (e.g., Figure 9 The arrows point from right to left to illuminate the light-emitting units 104. In other words, the first group 116a and the second group 116b are arranged alternately (for example, the first group 116a has odd numbers and the second group 116b has even numbers, or vice versa), and the first group 116a illuminates the light-emitting units 104 according to the first light-emitting order, while the second group 116b illuminates the light-emitting units 104 according to the second light-emitting order. Thus, compared to the same-direction illumination method, the step difference between each printed line is less noticeable. It should be noted that although the symbol for the light-emitting unit 104 is based on the first embodiment, this arrangement is equally applicable in the second embodiment.

[0065] In some embodiments, the light-emitting units 104 and 204 are fabricated using conductive thin-film transistor technology. That is, the aforementioned organic light-emitting diodes 114 and 210 and driving circuits 112 and 208 are fabricated using transparent conductive thin-film transistors such as indium tin oxide (ITO) and indium zinc oxide (IZO), and encapsulated on a substrate 140 (e.g., a glass substrate). Therefore, the aforementioned plurality of light-emitting units 104 and 204 can be formed on the substrate 140 according to a predetermined layout, without the need for wafer dicing, die bonding, or other steps. Furthermore, the conductive film can also form wires, saving the wire bonding step. In some embodiments, the displacement buffer 110 is fabricated using conductive thin-film technology and encapsulated on the same substrate 140 as the light-emitting unit 104. The aforementioned transistors are thin-film transistors (TFTs). The organic light-emitting diodes 114 and 210 can be active-matrix organic light-emitting diodes (AMOLEDs), giving them advantages such as small size, self-illumination, and fast response speed.

[0066] In some embodiments, control units 102 and 202 are control circuits such as microprocessors, digital signal processors (DSPs), and application-specific integrated circuits (ASICs) that can output the aforementioned timing signals.

[0067] In summary, the organic light-emitting diode printheads (10, 20) according to some embodiments of the present invention, which are made of conductive thin-film transistors, organic light-emitting diodes (114, 210) and their driving circuits (112, 208), can directly fabricate light-emitting units (104, 204) on the substrate 140, simplifying the fabrication process. On the other hand, the driving capacitors (118, 218) of the light-emitting units (104, 204) store the brightness voltage corresponding to the brightness signal S3 and do not discharge the voltage to a low potential (i.e., limit the discharge change of the driving capacitors (118, 218)). This can speed up the response time of the light-emitting units (104, 204) to emit light (under the brightness signal S3 with a short period of time, the light-emitting units (104, 204) can quickly perform continuous actions of emitting and extinguishing light), and can ensure that the brightness voltage changes do not fluctuate excessively, thus preventing component damage and extending the service life.

[0068] Although the technical content of the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications and refinements made by those skilled in the art without departing from the spirit of the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims of this application.

Claims

1. An organic light emitting diode print head characterized by, The application relates to a driving circuit of an organic light emitting diode (OLED) display, comprising: a control unit configured to output a start signal and a brightness signal; a plurality of light emitting units coupled to the control unit, each of the light emitting units comprising: a displacement buffer, each of the displacement buffers comprising a displacement input end, an actuation output end and a displacement output end, the displacement buffers being sequentially connected so that the displacement output end of a former stage displacement buffer is coupled to the displacement input end of a latter stage displacement buffer, wherein the displacement input end of the first stage displacement buffer receives and displaces the start signal to output a scanning signal with a trigger pulse via the displacement output end, and the displacement input end of each of the remaining displacement buffers receives and displaces the scanning signal output by the displacement output end of the former stage displacement buffer to output the scanning signal with a displaced trigger pulse via the displacement output end, and the actuation output end of each of the displacement buffers outputs an actuation output signal with an actuation pulse corresponding to the trigger pulse in time point; a driving circuit comprising a driving capacitor, a first switch and a second switch, configured to store a brightness voltage corresponding to the brightness signal in the driving capacitor in response to the trigger pulse of the scanning signal, the first switch being controlled by the brightness voltage, and the second switch being controlled by the actuation output signal; and an organic light emitting diode coupled to the first switch, the first switch and the second switch being located in a driving path of the organic light emitting diode, an upstream end of the driving path having an operating voltage, the organic light emitting diode obtaining a driving current related to the brightness voltage via the driving path when the first switch and the second switch are both turned on. In the application, the driving circuit further comprises a third switch, the first switch, the second switch and the third switch each comprising a first end, a second end and a control end, the first end of the third switch receiving the brightness signal, the control end of the third switch receiving the scanning signal, and the second end of the third switch being coupled to the driving capacitor, the third switch being turned on in response to the trigger pulse of the scanning signal so that the driving capacitor receives the brightness signal and is charged to the brightness voltage.

2. The organic light emitting diode print head of claim 1, wherein, In the application, the control end of the first switch is coupled to the driving capacitor, and the first switch is turned on or turned off in response to the brightness voltage.

3. The organic light emitting diode print head of claim 2, wherein, In the application, the first end of the second switch receives the operating voltage, the second end of the second switch is coupled to the first end of the first switch, the control end of the second switch receives the actuation output signal, and the second switch is turned on in response to the actuation pulse of the actuation output signal.

4. The organic light emitting diode print head of claim 3, wherein, In the application, the end time point of the trigger pulse of the scanning signal is the same as the start time point of the actuation pulse of the actuation output signal.

5. The organic light emitting diode print head of claim 4, wherein, In the application, the second switch, the first switch and the organic light emitting diode are sequentially coupled along the flow direction of the driving current.

6. The organic light emitting diode print head of claim 1, wherein, In the application, the control unit comprises: ​ 7. The organic light emitting diode print head of claim 1, wherein, ​ The luminance signal generation circuit includes a plurality of luminance signal output terminals configured to output the luminance signal via the luminance signal output terminals; The luminous units are divided into a plurality of groups, and the luminance signal output terminals are respectively one-to-one coupled to the groups and each of the luminance signal output terminals is coupled to all the luminous units in a same group.

8. The organic light emitting diode print head of claim 1, wherein, The luminous units are configured to be distributed in a linear shape, the luminous units are divided into a plurality of groups, each group is located in a section of the linear shape, the groups are staggered and respectively light up the luminous units in the group in a first light-up sequence and a second light-up sequence, and the first light-up sequence is opposite to the second light-up sequence.

9. An organic light emitting diode print head, characterized by, The control unit is configured to output a plurality of scan signals, actuation signals and luminance signals, the scan signals respectively have asynchronous trigger pulses; And A plurality of luminous units are coupled to the control unit, each of the luminous units includes: A synchronization circuit, each of the synchronization circuits includes a synchronization signal input terminal, an actuation input terminal and an actuation output terminal, the synchronization signal input terminals of the synchronization circuits respectively receive the scan signals one-to-one, the actuation input terminals of the synchronization circuits receive the actuation signals, and the actuation output terminals of each of the synchronization circuits output actuation output signals according to the trigger pulses, so that the actuation output signals have actuation pulses corresponding to the time points of the trigger pulses; A driving circuit including a driving capacitor, a first switch and a second switch, configured to store a luminance voltage corresponding to the luminance signal in the driving capacitor in response to the trigger pulses of the scan signals, the first switch is controlled by the luminance voltage, and the second switch is controlled by the actuation output signal; And An organic light-emitting diode coupled to the first switch, the first switch and the second switch are located in a driving path of the organic light-emitting diode, an upstream end of the driving path has an operating voltage, and the organic light-emitting diode obtains a driving current related to the luminance voltage via the driving path when the first switch and the second switch are both turned on. Wherein, 10. The organic light emitting diode print head of claim 9, wherein, The driving circuit further includes a third switch, the first switch, the second switch and the third switch respectively include a first end, a second end and a control end, the first end of the third switch receives the luminance signal, the control end of the third switch receives the scan signal, and the second end of the third switch is coupled to the driving capacitor, and the third switch is turned on in response to the trigger pulses of the scan signals, so that the driving capacitor receives the luminance signal and is charged to the luminance voltage. Wherein, 11. The organic light emitting diode print head of claim 10, wherein, The control end of the first switch is coupled to the driving capacitor, and the first switch is turned on or turned off in response to the luminance voltage. Wherein, 12. The organic light emitting diode print head of claim 11, wherein, ​ The first end of the second switch receives the operating voltage, the second end of the second switch is coupled to the first end of the first switch, the control end of the second switch receives the actuation output signal, and the second switch is turned on in response to the actuation pulse of the actuation output signal.

13. The organic light emitting diode print head of claim 12, wherein, wherein, The end time point of the trigger pulse of the scanning signal is the same as the start time point of the actuation pulse of the actuation output signal.

14. The organic light emitting diode print head of claim 9, wherein, wherein, The second switch, the first switch, and the organic light emitting diode are coupled in sequence along the flow direction of the driving current.

15. The organic light emitting diode print head of claim 9, wherein, The control unit comprises: a brightness signal generation circuit comprising a plurality of brightness signal output ends configured to output the brightness signal via the brightness signal output ends; wherein the light emitting units are divided into a plurality of groups, the brightness signal output ends are respectively and individually coupled to the groups, and each of the brightness signal output ends is coupled to all the light emitting units in the same group.

16. The organic light emitting diode print head of claim 9, wherein, The light emitting units are configured to be distributed in a linear shape, the light emitting units are divided into a plurality of groups, each of the groups is located in one section of the linear shape, the groups are staggered and arranged in a first light emitting sequence and a second light emitting sequence to light up the light emitting units thereof, and the first light emitting sequence is opposite to the second light emitting sequence.

Images