Organic light emitting diode printing head

Abstract

The invention provides an organic light emitting diode printing head which comprises 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 comprises a displacement buffer, a driving circuit and an organic light-emitting diode. The displacement buffers are sequentially connected in series, so that the displacement output end of the displacement buffer at the front stage is coupled with the displacement input end of the displacement buffer at the rear stage. The actuation output end of each displacement buffer outputs an actuation output signal, and the actuation output signal is provided with an actuation pulse wave with a time point corresponding to the trigger pulse wave. The driving circuit is configured to store a brightness voltage corresponding to the brightness signal in the driving capacitor in response to a trigger pulse wave of the scanning signal. When both the first switch and the second switch are turned on, a driving current related to the brightness voltage is obtained through the driving path.

Description

Technical Field

[0001] The present invention relates to the technical field of organic light emitting diode print heads, and in particular to an organic light emitting diode print head having a light emitting unit made of a thin film transistor and an organic light emitting diode. Background Art

[0002] LED Print Head (LPH) is a light-emitting technology for printer heads. It mainly uses gallium arsenide semiconductor process to manufacture multiple light-emitting modules. Each light-emitting module has multiple light-emitting components and their driving circuits. Each light-emitting module is a die. These light-emitting modules are fixed and arranged on the printed circuit board using die bonding technology. Therefore, in order to manufacture the above-mentioned print head, complicated processes such as wafer cutting and die bonding are required. Summary of the invention

[0003] In view of this, in some embodiments, an organic light emitting diode print head is provided, comprising 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 comprises a displacement register, a driving circuit and an organic light emitting diode. Each displacement register comprises a displacement input terminal, an actuation output terminal and a displacement output terminal. These displacement registers are sequentially connected in series so that the displacement output terminal of the displacement register of the previous stage is coupled to the displacement input terminal of the displacement register of the next stage. The displacement input terminal of the displacement register of the first stage receives and shifts the start signal and outputs a scanning signal having a trigger pulse through the displacement output terminal. The remaining displacement registers respectively receive and shift the scanning signal outputted by the displacement output terminal of the displacement register of the previous stage and output a scanning signal having a shifted trigger pulse through the displacement output terminal, and the actuation output terminal of each displacement register outputs an actuation output signal, and the actuation output signal has a trigger pulse corresponding to the time point of the trigger pulse. The driving circuit comprises a driving capacitor, a first switch and a second switch, and is 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 is controlled by a brightness voltage, and the second switch is controlled by an actuation output signal. The organic light emitting diode is coupled to the first switch. The first switch and the second switch are located on a driving path of the organic light emitting diode. An upstream end of the driving path has a working voltage. When the first switch and the second switch are both turned on, the organic light emitting diode obtains a driving current related to the brightness voltage through the driving path.

[0004] In some embodiments, an organic light emitting diode print head is provided, including a control unit and a plurality of light emitting units. The control unit is configured to output a plurality of scanning signals, actuation signals and brightness signals. The scanning signals respectively have asynchronous trigger pulses. The light emitting units are coupled to the control unit. Each light emitting unit includes a synchronization circuit, a driving circuit and an organic light emitting diode. Each synchronization circuit 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 scanning signals one-to-one. The signal input terminals of the synchronization circuits receive the actuation signal. The actuation output terminals of each synchronization circuit output an actuation output signal according to the trigger pulse, so that the actuation output signal has an actuation pulse corresponding to the trigger pulse at a time point. The driving circuit includes a driving capacitor, a first switch and a second switch. It is 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 is controlled by the brightness voltage, and the second switch is controlled by the actuation output signal. The organic light emitting diode is coupled to the first switch, and the first switch and the second switch are located on the driving path of the organic light emitting diode. The upstream end of the driving path has a working voltage. When the first switch and the second switch are both turned on, the organic light emitting diode obtains a driving current related to the brightness voltage through the driving path.

[0005] In summary, according to some embodiments of the organic light emitting diode print head of the present invention, the light emitting unit made of the conductive thin film transistor, the organic light emitting diode and its driving circuit can be directly made on the substrate, which can simplify the manufacturing steps. On the other hand, the driving capacitor of the light emitting unit stores the brightness voltage corresponding to the brightness signal, and will not discharge the voltage to a low potential, which can ensure that the charging and discharging voltage changes of the capacitor will not fluctuate too much, speed up the response time of the light emitting unit (under the brightness signal with a short cycle time, the light emitting unit can quickly perform continuous actions of lighting and extinguishing), and protect the components from damage, thereby extending the service life.

[0006] The detailed features and advantages of the present invention are described in detail in the following embodiments, and the contents are sufficient to enable any person skilled in the art to understand the technical content of the present invention and implement it accordingly. Moreover, based on the contents, claims and drawings disclosed in this specification, any person skilled in the art can easily understand the relevant purposes and advantages of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a feeder 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 Detailed feeding diagram of multiple light-emitting units in the first embodiment of the present invention.

[0009] Figure 3FIG. 1 is a signal timing diagram of an organic light emitting diode print head in the first embodiment of the present invention.

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

[0011] Figure 5 FIG. 1 is a circuit diagram of a shift register in a first embodiment of the present invention.

[0012] Figure 6 This is a feeder 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 FIG. 4 is a circuit diagram of a light emitting unit in a second embodiment of the present invention.

[0014] Figure 8 FIG. 1 is a signal timing diagram of an organic light emitting diode print head in the second embodiment of the present invention.

[0015] Fig. 9 FIG. 4 is a schematic plan view of an organic light emitting diode print head in some embodiments of the present invention.

[0016] Description of reference numerals:

[0017] 10, 20: organic light emitting diode print head;

[0018] 102, 202: control unit; 104, 204: light emitting unit; 106: start signal generating circuit; 106a: start signal output terminal; 108, 230: brightness signal generating 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 receiving terminal; 112, 208: driving circuit; 114, 210: organic light emitting diode; 116, 232: group; 116a: first group; 116b: second group; 118, 218: driving 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 end;

[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: actuation capacitor; 140: substrate;

[0023] 206: synchronization circuit; 212: synchronization signal input terminal; 226: scanning signal generating circuit; 226a: scanning signal output terminal; 228: actuation signal generating 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; 2 38a, 238b: third input terminal; 238c: third output terminal; 240: fourth NAND gate; 240a, 240b: fourth input terminal; 240c: fourth output terminal; 242: first NAND gate; 242a: fifth input terminal; 242b: fifth output terminal; 244: AND gate; 244a, 244b: sixth input terminal; 244c: sixth output terminal; 246: second NAND gate; 246a: seventh input terminal; 246b: seventh output terminal;

[0024] CK: frequency signal; E: signal to be displaced; EP: starting signal; I: actuation signal; L: axis; P1: driving path; S1: scanning signal; S11: trigger pulse wave; S2: actuation output signal; S21: trigger pulse wave; 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 DESCRIPTION

[0028] See also Figure 1 and Figure 2 . Figure 1 FIG. 1 is a feeder 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 FIG. 1 is a detailed feed line diagram of a plurality of light emitting units 104 in the first embodiment of the present invention. Figure 1 and Figure 2As shown, the organic light emitting diode print head 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. The light emitting unit 104 includes a light emitting component made of conductive thin film technology and a driving circuit thereof, so that it can be arranged on a substrate (see Fig. 9 The light emitting units 104 are formed on a substrate 140. The control unit 102 is configured to output a clock signal CK, an activation signal I, a start signal EP, and a brightness signal S3. In some embodiments, the 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 feeder diagrams of the plurality of light emitting units 104 are detailed feeder diagrams of the light emitting units 104 in the same group 116 .

[0029] In some embodiments, the control unit 102 includes a start signal generating circuit 106 and a brightness signal generating circuit 108. The start signal generating circuit 106 is configured to output a start signal EP. The start signal generating 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 generating circuit 108 is configured to output a brightness signal S3 to each light-emitting unit 104 to control the light brightness of each light-emitting unit 104. It is understood that the control unit 102 also includes other signal generating circuits that respectively output the frequency signal CK and the actuation signal I. To avoid the drawings being too complicated, Figure 1 Not drawn.

[0030] like Figure 2As shown, each light-emitting unit 104 includes a displacement register 110, a driving circuit 112 and an organic light-emitting diode 114. In some embodiments, each displacement register 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 the frequency signal CK output by the control unit 102, so that each displacement register 110 operates according to the frequency signal CK. These displacement registers 110 are connected in series in sequence so that the displacement output terminal 110c of the displacement register 110 of the previous stage is coupled to the displacement input terminal 110a of the displacement register 110 of the next stage. The displacement output terminal 110c is configured to output a scan signal S1, which is the result of shifting the signal received by the displacement input terminal 110a. Specifically, the displacement register 110 of the first stage receives the start signal EP via the displacement input terminal 110a, and shifts the start signal EP and outputs the scan signal S1 via the displacement output terminal 110c. The remaining displacement registers 110 receive the scanning signal S1 outputted from the displacement output terminal 110c of the displacement register 110 of the previous stage through the displacement input terminal 110a, and shift the received scanning signal S1 and output it through the displacement output terminal 110c. The actuation input terminal 110d receives the actuation signal I outputted by the control unit 102. In response to the actuation signal I, the actuation output terminal 110b of the displacement register 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 present invention is not limited thereto, and may be, for example, 64, 256, or other numbers. Here, the serial numbers of the light-emitting units 104 in these groups 116 are not uniformly restricted to start from the same side. That is, the serial numbers may start from one side of the light-emitting unit 104, or may start from the other side of the light-emitting unit 104. For example, the start signal generating circuit 106 is coupled to the first light-emitting unit 104 on the left side of some groups 116 and the first light-emitting unit 104 on the right side of some groups 116.

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

[0033] The brightness signal generating circuit 108 includes a plurality of brightness signal output terminals 108a. These brightness signal output terminals 108a are configured to output brightness signals S3. These brightness signal output terminals 108a are coupled to these groups 116 one by one, and each brightness signal output terminal 108a is coupled to all the light-emitting units 104 in the same group 116. Therefore, all the light-emitting units 104 in the same group 116 will receive the same brightness signal S3. A light-emitting unit 104 in each group 116 is designated at a time point by the scanning signal S1, so that only the designated light-emitting unit 104 performs the action corresponding to the brightness signal S3 at this time point. On the other hand, the light-emitting units 104 that are not designated will not perform the action corresponding to the brightness signal S3. In addition, the brightness signals S3 output by each brightness signal output terminal 108a are independent of each other and are not affected, so the designated light-emitting unit 104 in each group 116 can be independently controlled as needed.

[0034] In some embodiments, if the resolution of the organic light emitting diode print head 10 is expected to reach 600 DPI (Dots Per Inch), about 5120 light emitting units 104 are required. According to the aforementioned 128 light emitting units 104 in each group 116, 40 groups 116 are required. It should be noted that the number of signal lines for the control unit 102 to output the actuation signal I and the frequency signal CK is 40. The number of signal lines (also referred to as the brightness signal output terminal 108a) for the control unit 102 to output the brightness signal S3 is 40. Therefore, the brightness signal S3 is serialized data, and 128 signals are required to indicate the actions that the corresponding 128 light emitting units 104 should perform.

[0035] In some embodiments, the other signal generating circuits that respectively output the frequency signal CK and the activation signal I are the same as the brightness signal generating circuit 108, and have a plurality of signal output terminals, and these signal output terminals are respectively coupled to these groups 116 one-to-one, 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 activation 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 signals CK received by different groups 116 are the same; the signal output terminal that outputs the activation signal I outputs a synchronized activation signal I, but the activation signals I received by different groups 116 may be the same or different (determined by the light-emitting timing of each light-emitting unit 104).

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

[0037] See also Figure 2 and Figure 3 . Figure 3 1 is a signal timing diagram of the organic light emitting diode print head 10 in the first embodiment of the present invention. After the displacement input terminal 110a of the first-stage displacement register 110 receives the signal E to be shifted (here, the signal E to be shifted is the start signal EP), the state of the displacement input terminal 110a is shifted to the displacement output terminal 110c of the first-stage displacement register 110 for output (forming the trigger pulse S11 of the scan signal S1) in the next cycle of the clock signal CK. Similarly, after the displacement input terminal 110a of the second-stage displacement register 110 receives the signal E to be shifted (here, the signal E to be shifted is the scan signal S1 of the first-stage displacement register 110), the state of the displacement input terminal 110a is shifted to the displacement output terminal 110c of the second-stage displacement register 110 for output (forming the trigger pulse S11 of the scan signal S1) in the next cycle of the clock signal CK. Thus, the pulse of the start signal EP is shifted according to each stage of the displacement register 110 in turn according to the cycle of the clock signal CK. The shift output terminals 110c of the shift registers 110 are coupled to the corresponding light emitting units 104 one-to-one, so that the light emitting units 104 are designated to perform actions in response to the trigger pulse S11 of the corresponding scan signal S1 at different time points. Figure 3 As shown, the actuation output signal S2 has a trigger pulse S21 whose time point corresponds to the trigger pulse S11.

[0038] Figure 4 FIG. 1 is a circuit diagram of the driving circuit 112 of 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 the brightness signal S3 in the driving capacitor 118 in response to the trigger pulse S11 of the scanning signal S1. The first switch 120 is controlled by the brightness voltage, and the second switch 122 is controlled by the trigger pulse S21 of the actuation output signal S2. The organic light emitting diode 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 organic light emitting diode 114. The upstream end of the driving path P1 has a working voltage VDD. When the first switch 120 and the second switch 122 are both turned on, the organic light emitting diode 114 obtains a driving current related to the brightness voltage through the driving path P1, thereby emitting light. Therefore, each organic light emitting diode 114 can obtain a corresponding driving current according to the brightness voltage, so as to emit 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 coupled in sequence along the flow 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 working voltage VDD. The second terminal 122b of the second switch 122 is coupled to the first terminal 120a of the first switch 120, the second terminal 120b of the first switch 120 is coupled to the anode of the organic light emitting diode 114, and 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, so that the second switch 122 is turned on in response to the actuation pulse S21 of the actuation output signal S2. Here, the first switch 120 and the second switch 122 are NMOS transistors, the first terminal (120a, 122a) is a drain, the second terminal (120b, 122b) is a source, and the control terminal (120c, 122c) is a 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 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, the first terminal 124a is a drain, the second terminal 124b is a source, and the control terminal 124c is a gate.

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

[0042] See also Figure 3 and Figure 4 . The third switch 124 is turned on in response to the trigger pulse S11 of the scan signal S1, that is, the first end 124a of the third switch 124 and the second end 124b of the third switch 124 are turned on, so that the driving capacitor 118 receives the brightness signal S3 through the third switch 124 and is charged to the brightness voltage. In addition, due to process errors, the characteristics of the transistors in each light-emitting unit 104 and the organic light-emitting diodes 114 may be inconsistent, resulting in inconsistent light brightness of the organic light-emitting diodes 114 of these light-emitting units 104. Therefore, a suitable brightness voltage value is given to each corresponding light-emitting unit 104 through the brightness signal S3 to adjust the driving current given to the corresponding organic light-emitting diode 114, so that each organic light-emitting diode 114 can emit light with consistent brightness (when light emission is required). It should be particularly noted that, depending on whether the corresponding organic light-emitting diode 114 is to be made to emit light, the brightness signal S3 during the trigger pulse S11 period is a high potential (light emission) or a low potential (no light emission). Furthermore, the voltage level (ie, voltage value) of the high potential can be slightly adjusted according to the demand to adjust the drain-source current demand (for example, if the brightness needs to be reduced, the brightness voltage is reduced to reduce the drain-source current; otherwise, the brightness voltage is increased).

[0043] The time length of the trigger pulse S11 is sufficient to allow the driving capacitor 118 to be charged to the brightness voltage. It should be noted that the time length of the trigger pulse S11 depends on the printing speed. For example, if the printing speed is 600 PPM (Pages per Minute, PPM), the time length of the arterial wave S21 is greater than the trigger pulse S1 at a printing speed of 1200 PPM. 1 time length.

[0044] See also Figure 3 and Figure 5 . Figure 5FIG. 1 is a circuit diagram of the shift register 110 in the first embodiment of the present invention. Figure 5 As shown, in some embodiments, each shift register 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 actuation capacitor 138. The fourth switch 126 has a first end 126a, a second end 126b and a control end 126c. The fifth switch 128 has a first end 128a, a second end 128b and a control end 128c. The sixth switch 130 has a first end 130a, a second end 130b and a control end 130c. The seventh switch 132 has a first end 132a, a second end 132b and a control end 132c. The eighth switch 134 has a first end 134a, a second end 134b and a control end 134c. The ninth switch 136 has a first end 136a, a second end 136b and a control end 136c. Here, each of the switches (126, 128, 130, 132, 134, 136) of the shift register 110 is an NMOS transistor, the first end (126a, 128a, 130a, 132a, 134a, 136a) is a drain, the second end (126b, 128b, 130b, 132b, 134b, 136b) is a source, and the control end (126c, 128c, 130c, 132c, 134c, 136c) is a gate.

[0045] The first terminal 126a of the fourth switch 126 is coupled to the control terminal 126c to form the aforementioned shift 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 working voltage VDD, and the second terminal 130b is coupled to the first terminal 132a of the seventh switch 132, and 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, which receives 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, and the displacement output terminal 110c is located between the two terminals. 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 actuation capacitor 138 is coupled between the second terminal 134b and the control terminal 134c of the eighth switch 134. In other words, one terminal (the first node N1) of the actuation capacitor 138 is coupled to the second terminal 126b of the fourth switch 126; the other terminal of the actuation capacitor 138 is coupled to the displacement output terminal 110c.

[0046] Again Figure 3 and Figure 5 As shown below, Figure 3 The signal action timings of the first-level and second-level shift registers 110 are used as examples for explanation.

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

[0048] At time point t3 (the scanning generation point of the first-stage shift register 110): in the first-stage shift register 110, the frequency signal CK received by the frequency receiving terminal 110e changes from a low potential to a high potential, and the shift output terminal 110c of the first-stage shift register 110 outputs a high potential, i.e., a trigger pulse S11 is generated. Since the shift input terminal 110a of the second-stage shift register 110 is coupled to the shift output terminal 110c of the first-stage shift register 110, the scanning signal S1 outputted via the shift output terminal 110c of the first-stage shift register 110 is inputted to the shift input terminal 110a of the second-stage shift register 110 to serve as the waiting shift signal E of the second-stage shift register 110 (at this moment, the second-stage shift register 110 enters the start point).

[0049] At time point t4 (the scanning end point of the first-stage shift register 110): in these shift registers 110, the frequency signal CK received by the frequency receiving terminal 110e becomes low and the trigger pulse S11 ends, and the actuation signal I received by the actuation input terminal 110d turns high. The fourth switch 126, the seventh switch 132 and the eighth switch 134 of the first-stage shift register 110 are closed, and the fifth switch 128, the sixth switch 130 and the ninth switch 136 are opened. Therefore, the first node N1 of the first-stage shift register 110 is low, and the second node N2 is high. The scanning of the first-stage shift register 110 ends. At this time, the trigger pulse S21 is high, and the actuation output terminal 110b is connected to the control terminal 122C of the light-emitting unit 104, and the second switch 122 is opened.

[0050] At time point t5: the displacement output terminal 110c of the second-stage displacement register 110 outputs a high potential and generates a trigger pulse S11 (the second-stage displacement register 110 enters the scan generation point). Since the displacement input terminal 110a of the third-stage displacement register 110 is coupled to the displacement output terminal 110c of the second-stage displacement register 110 (see Figure 2 ), therefore, the scan signal S1 outputted via the second-stage shift output terminal 110c is inputted into the shift input terminal 110a of the third-stage shift register 110 to serve as the to-be-shifted signal E of the third-stage shift register 110 (the third-stage shift register 110 enters the start point).

[0051] At time point t6: the activation input terminal 110d receives the second high-level activation signal I, so that the second node N2 of the second-level shift register 110 turns to a high level (the scanning of the second-level shift register 110 ends).

[0052] At time point t7: the third level shift register 110 enters the scan generation point ( Figure 3 not shown).

[0053] Therefore, the number of the shift registers 110 can be expanded according to the number of the light-emitting units 104, and each shift register 110 can use the scan signal S1 output by the previous stage as the signal to be shifted E, and after the shift register 110 receives the scan signal S1 of the previous stage, the shift output terminal 110c of the shift register 110 outputs the trigger pulse S11, so that the brightness signal S3 charges the driving capacitor 118 to the brightness voltage.

[0054] See also Figure 6 , Figure 7 and Figure 8 . Figure 6 FIG. 2 is a feeder 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 FIG. 2 is a circuit diagram of the light emitting unit 204 in the second embodiment of the present invention. Figure 8 1 is a signal timing diagram of an organic light emitting diode print head 20 in a second embodiment of the present invention. The organic light emitting diode print head 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, an actuation signal I, and a brightness signal S3. The 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, wherein the synchronization signal input terminals 212 of these synchronization circuits 206 receive these scanning signals S1 one-to-one, and these actuation input terminals 214 receive the actuation signal 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 a trigger pulse S21 whose time point corresponds 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 the brightness signal S3 in the driving capacitor 218 in response to the trigger pulse S11 of the scanning signal S1. The first switch 220 is controlled by the brightness voltage, and the second switch 222 is controlled by the trigger pulse S21 of the actuation output signal S2. The organic light emitting diode 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 organic light emitting diode 210. The upstream end of the driving path P1 has a working voltage VDD. When the first switch 220 and the second switch 222 are both turned on, the organic light emitting diode 210 obtains a driving current related to the brightness voltage through the driving path P1, thereby emitting light. Therefore, each organic light emitting diode 210 can obtain 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 end 220a, a second end 220b, and a control end 220c. The second switch 222 includes a first terminal 222a, a second terminal 222b, and a control terminal 222c.

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

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

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

[0059] Again Figure 7As shown, in some embodiments, the synchronization circuit 206 refers to a logic circuit, which includes 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. The AND gate 244 has a sixth input terminal (244a, 244b) and a sixth output terminal 244c. The second NOT gate 246 has a seventh input terminal 246a and a seventh output terminal 246b.

[0060] The first input terminal 234a of the first NAND gate 234 is coupled to the activation 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 NAND 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 activation 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 the present invention is not limited thereto. Any circuit that can implement 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 (TFT).

[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 NAND gate 242 form a D-type latch. Therefore, when the scan signal S1 generates a trigger pulse S11 (i.e., the scan signal S1 turns to a high level), the third output terminal 238c of the third NAND gate 238 outputs a signal that is consistent with the activation signal I currently at the first input terminal 234a of the first NAND gate 234 to the sixth input terminal 244a of the NAND gate 244. During the period when the scan signal S1 is not in the trigger pulse S11 (i.e., the scan signal S1 turns to a low level), the third output terminal 238c of the third NAND gate 238 maintains outputting the signal. On the other hand, during the period of the trigger pulse S11, the control terminal 224c of the third switch 224 is turned on, so that the driving capacitor 218 receives the brightness signal S3 through the third switch 224 and is charged to the brightness voltage (as in the operation of the first embodiment described above, which will not be repeated here). In addition, the sixth input terminal 244b of the AND gate 244 receives the scanning signal S1 inverted by the second NOT gate 246, so that when the trigger pulse S11 ends (from a high potential to a low potential, at which time the third switch 224 is closed), the sixth output terminal 244c of the AND gate 244 transmits the signal of the third output terminal 238c of the third NAND gate 238 (i.e., the actuation output signal S2 having the actuation pulse S21 (high potential)) to the second switch 222. Therefore, the starting time point of the actuation output signal S2 having the actuation pulse S21 received by the second switch 222 is when the trigger pulse S11 ends (e.g., when the trigger pulse S11 ends). Figure 3 Thus, when the trigger pulse S11 ends, the second switch 222 on the driving path P1 is turned on, and the first switch 220 is turned on or off according to the brightness voltage of the driving capacitor 218, thereby determining whether the organic light emitting diode 210 emits light and its brightness.

[0064] See also Figure 7 and Figure 8 The first-level light-emitting unit 204 receives the actuation output signal S2, the brightness signal S3 and the first-level scanning signal S1 transmitted by the control unit 202. At time point t2, the first-level light-emitting unit 204 is designated to operate, and the brightness voltage charged by the driving capacitor 218 corresponding to the brightness signal S3 determines whether the organic light-emitting diode 210 emits light and its light brightness. Similarly, at time points t4 and t6, the second-level and third-level light-emitting units 204 are designated to operate respectively. And so on. Please refer to Fig. 9 , Fig. 9FIG. 1 is a schematic plan view of an organic light emitting diode print head 10 in some embodiments of the present invention. In some embodiments, the light emitting units 104 are arranged on a substrate 140 and are distributed in a linear manner. The light emitting units 104 are divided into a plurality of groups 116, and the groups 116 include a plurality of first groups 116a and a plurality of second groups 116b. Each group 116 is located in a section on the axis L of the substrate 140. The groups (116a, 116b) are arranged in a staggered manner and are arranged in a first light emitting sequence (such as Fig. 9 The direction of the arrow is from left to right) and a second light-emitting sequence opposite to the first light-emitting sequence (such as Fig. 9 In other words, the first group 116a and the second group 116b are arranged alternately (for example, the first group 116a is odd-numbered, and the second group 116b is even-numbered, or vice versa), and the first group 116a lights up the light-emitting units 104 according to the first light-emitting sequence, and the second group 116b lights up the light-emitting units 104 according to the second light-emitting sequence. Therefore, compared with the lighting method in the same direction, it is not easy to see the step difference of each printed line. It should be noted that although the symbols of the light-emitting units 104 are marked in the first embodiment, this arrangement and distribution is also applicable to the second embodiment.

[0065] In some embodiments, the light-emitting units 104 and 204 are made using conductive thin film transistor technology. That is, the organic light-emitting diodes 114 and 210 and the driving circuits 112 and 208 are made using transparent conductive thin film transistors such as indium tin oxide (ITO) and indium zinc oxide (IZO), and are packaged on a substrate 140 (e.g., a glass substrate). Therefore, the 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 cutting, die bonding, and other steps. The conductive film can also form a wire, which can save the wire bonding step. In some embodiments, the shift register 110 is made using conductive film technology and is packaged on the same substrate 140 as the light-emitting unit 104. The transistor is a thin film transistor (TFT). Among them, the organic light-emitting diodes 114 and 210 can be active-matrix organic light-emitting diodes (AMOLED), so that the organic light-emitting diodes 114 and 210 have the advantages of small size, self-luminescence, and fast response speed.

[0066] In some embodiments, the control unit 102, 202 is a control circuit such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), etc. that can output the aforementioned timing signal.

[0067] In summary, according to some embodiments of the organic light emitting diode printhead (10, 20) of the present invention, the light emitting unit (104, 204) made of the conductive thin film transistor, the organic light emitting diode (114, 210) and the driving circuit (112, 208) can be directly manufactured on the substrate 140, which can simplify the manufacturing steps. On the other hand, the driving capacitor (118, 218) of the light emitting unit (104, 204) stores the brightness voltage corresponding to the brightness signal S3, and will not discharge the voltage to a low potential (i.e., limit the discharge change of the driving capacitor (118, 218)), which can speed up the response time of the light emitting unit (104, 204) to emit light (under the brightness signal S3 with a shorter cycle time, the light emitting unit (104, 204) can quickly perform continuous actions of emitting light and extinguishing), and can ensure that the brightness voltage change will not fluctuate excessively to cause damage to the components, thereby extending the service life.

[0068] Although the technical contents of the present invention have been disclosed as above in the form of preferred embodiments, they are not intended to limit the present invention. Any slight changes and modifications made by any person skilled in the art without departing from the spirit of the present invention should be included in the scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of this application.

Claims

1. An organic light emitting diode print head, characterized in that: include: A control unit configured to output a start signal and a brightness signal; as well as A plurality of light emitting units are coupled to the control unit, each of the light emitting units comprising: a displacement register, each of which comprises a displacement input terminal, an actuation output terminal and a displacement output terminal, wherein the displacement registers are sequentially connected in series so that the displacement output terminal of the displacement register of the preceding stage is coupled to the displacement input terminal of the displacement register of the succeeding stage, wherein the displacement input terminal of the displacement register of the first stage receives and shifts the start signal and outputs a scanning signal having a trigger pulse through the displacement output terminal, and the remaining displacement registers respectively receive and shift the scanning signal outputted by the displacement output terminal of the displacement register of the preceding stage and output the scanning signal having the shifted trigger pulse through the displacement output terminal, and the actuation output terminal of each displacement register outputs an actuation output signal, wherein the actuation output signal has a trigger pulse corresponding to the time point of the trigger pulse; 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, wherein the first switch is controlled by the brightness voltage and the second switch is controlled by the actuation output signal; as well as An organic light emitting diode is coupled to the first switch, wherein the first switch and the second switch are located on a driving path of the organic light emitting diode, an upstream end of the driving path has a working voltage, and the organic light emitting diode obtains a driving current related to the brightness voltage through the driving path when the first switch and the second switch are both turned on.

2. The organic light emitting diode print head according to claim 1, wherein: in, 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 brightness signal, the control end of the third switch receives the scanning signal, 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 pulse of the scanning signal, so that the driving capacitor receives the brightness signal and is charged to the brightness voltage.

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

4. The organic light emitting diode print head according to claim 3, wherein: in, The first end of the second switch receives the working 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 output signal.

5. The organic light emitting diode print head according to claim 4, wherein: in, The end time point of the trigger pulse wave of the scanning signal is the same as the start time point of the trigger pulse wave of the actuation output signal.

6. The organic light emitting diode print head according to claim 1, wherein: in, The second switch, the first switch and the organic light emitting diode are coupled in sequence along the flow direction of the driving current.

7. The organic light emitting diode print head according to claim 1, wherein: The control unit comprises: A brightness signal generating circuit, comprising a plurality of brightness signal output terminals, configured to output the brightness signal via the brightness signal output terminals; The light-emitting units are divided into a plurality of groups, the brightness signal output ends are coupled to the groups one by one, and each brightness signal output end is coupled to all the light-emitting units in the same group.

8. The organic light emitting diode print head according to claim 1, wherein: The light-emitting units are configured to be distributed in a line, and the light-emitting units are divided into a plurality of groups, each group is located in one of the sections of the line, and the groups are arranged in a staggered manner and light up their own light-emitting units in a first light-emitting sequence and a second light-emitting sequence respectively, wherein the first light-emitting sequence is opposite to the second light-emitting sequence.

9. An organic light emitting diode print head, characterized in that: include: A control unit configured to output a plurality of scanning signals, an actuation signal and a brightness signal, wherein the scanning signals respectively have asynchronous trigger pulses; as well as A plurality of light emitting units are coupled to the control unit, each of the light emitting units comprising: A synchronization circuit, each of which comprises a synchronization signal input terminal, an actuation input terminal and an actuation output terminal, wherein the synchronization signal input terminal of the synchronization circuit receives the scanning signal one-to-one, the actuation input terminal of the synchronization circuit receives the actuation signal, and the actuation output terminal of each synchronization circuit outputs an actuation output signal according to the trigger pulse wave, so that the actuation output signal has a trigger pulse wave at a time point corresponding to the trigger pulse wave; 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, wherein the first switch is controlled by the brightness voltage and the second switch is controlled by the actuation output signal; as well as An organic light emitting diode is coupled to the first switch, wherein the first switch and the second switch are located on a driving path of the organic light emitting diode, an upstream end of the driving path has a working voltage, and the organic light emitting diode obtains a driving current related to the brightness voltage through the driving path when the first switch and the second switch are both turned on.

10. The organic light emitting diode print head according to claim 9, wherein: in, The driving circuit also 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 brightness signal, the control end of the third switch receives the scanning signal, 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 pulse of the scanning signal, so that the driving capacitor receives the brightness signal and is charged to the brightness voltage.

11. The organic light emitting diode print head according to claim 10, wherein: in, The control end of the first switch is coupled to the driving capacitor, and the first switch is turned on or off in response to the brightness voltage.

12. The organic light emitting diode print head according to claim 11, wherein: in, 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 turns on the second switch in response to the actuation pulse of the actuation output signal.

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

14. The organic light emitting diode print head according to claim 9, wherein: in, 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 according to claim 9, wherein: The control unit comprises: A brightness signal generating circuit, comprising a plurality of brightness signal output terminals, configured to output the brightness signal via the brightness signal output terminals; The light-emitting units are divided into a plurality of groups, the brightness signal output ends are coupled to the groups one by one, and each brightness signal output end is coupled to all the light-emitting units in the same group.

16. The organic light emitting diode print head according to claim 9, wherein: The light-emitting units are configured to be distributed in a line, and the light-emitting units are divided into a plurality of groups, each of which is located in one of the sections of the line. The groups are arranged in a staggered manner and light up their own light-emitting units in a first light-emitting sequence and a second light-emitting sequence respectively, wherein the first light-emitting sequence is opposite to the second light-emitting sequence.

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