OPTOELECTRONIC LIGHTING DEVICE WITH A PWM TRANSISTOR AND METHOD FOR MAKING OR CONTROLLING AN OPTOELECTRONIC LIGHTING DEVICE

Abstract

Optoelectronic lighting device (10, 20, 30, 40, 41, 42), with: an optoelectronic semiconductor device (11) configured to generate light, a power source (12) designed to generate a current, and a PWM transistor (13) controlled by a pulse-width modulated signal, which assumes a first state or a second state depending on the pulse-width modulated signal and which is configured to supply the optoelectronic semiconductor device (11) with the current generated by the current source (12) in the first state and to decouple it from the current generated by the current source (12) in the second state, wherein the current source (12) is manufactured using a first technology and the PWM transistor (13) is manufactured using a second technology, wherein the optoelectronic semiconductor device (11) and the PWM transistor (13) are arranged in a first circuit branch (31) and a second circuit branch (32) is connected in parallel to the first circuit branch (31), and wherein the second circuit branch (32) is configured such that the current generated by the current source (12) flows through the second circuit branch (32) when the PWM transistor (13) is in the second state.

Description

[0001] The present invention relates to an optoelectronic lighting device with a PWM transistor, a method for manufacturing an optoelectronic lighting device and a method for controlling an optoelectronic lighting device.

[0002] Conventional LED (light-emitting diode) displays operate using pulse-width modulation (PWM), also known as pulse duration modulation or pulse length modulation. With a shortest PWM pulse duration of, for example, 10 ns, a dynamic range of approximately 20 bits can be represented at 60 Hz, encompassing the bits for grayscale, dimming, calibration, and white point. This may be insufficient for some applications. Additional analog current dimming of the LEDs is only possible to a limited extent using conventional methods. Furthermore, pulses with a duration of 10 ns are not achievable with conventional TFT (thin-film transistor) technology.

[0003] Various control circuits for light-emitting diodes are known from the state of the art.

[0004] DE 10 2008 018 236 A1 discloses a circuit for operating a lighting unit, in which a power source serves to supply the lighting unit and a downstream pulse width modulation unit is provided for brightness control.

[0005] US 2008 / 0258695 A1 describes a light-emitting component in which a switching element is integrated on the same substrate as a light-emitting diode and connected in parallel to it to divert the current from the light-emitting diode and short-circuit it.

[0006] US Patent 2001 / 0052606 A1 discloses a display device with a matrix of pixels, in which the pixel control circuit includes a current source for adjusting the gray value. A common switch is provided for the simultaneous control of a plurality of LEDs, in order to supply the LEDs with current for a short period of time.

[0007] Furthermore, US 2018 / 0182286 A1 discloses a digital pixel driver circuit for µLED displays which converts an input voltage into a linearly dependent output current, whereby the grayscale control can be achieved by means of pulse width modulation (PWM).

[0008] US patent 2018 / 0247586 A1 discloses a hybrid driver architecture for µLED displays, in which circuit components are implemented on a backplane, while driver logic for generating PWM signals is housed in a separate microdriver IC.

[0009] The present invention is based, among other things, on the objective of creating an advantageous optoelectronic lighting device, particularly with a large dynamic range, which can be implemented cost-effectively. Furthermore, a display with an optoelectronic lighting device, a method for controlling an optoelectronic lighting device, and a method for manufacturing an optoelectronic lighting device are to be disclosed.

[0010] One object of the invention is achieved by an optoelectronic lighting device with the features of claim 1. Another object of the invention is achieved by a display with the features of claim 13. Furthermore, another object of the invention is achieved by a method for controlling an optoelectronic lighting device with the features of claim 14 and a method for manufacturing an optoelectronic lighting device with the features of claim 15. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0011] An optoelectronic lighting device comprises an optoelectronic semiconductor component, a current source, and a PWM transistor. The optoelectronic semiconductor component is configured to generate light. The current source is configured to generate a current. The PWM transistor can be controlled by, or is controlled by, a pulse-width modulated signal. Depending on the pulse-width modulated signal, the PWM transistor can assume a first state or a second state. When the PWM transistor is in the first state, the optoelectronic semiconductor component is supplied with the current generated by the current source. In the second state of the PWM transistor, the optoelectronic semiconductor component is decoupled from the current generated by the current source.

[0012] The power source is manufactured or implemented using a first technology, while the PWM transistor is manufactured or implemented using a second technology that differs from the first technology.

[0013] This makes it possible to implement only the PWM transistor in a technology that allows a high dynamic range, and to implement the power source and, in particular, other parts of the optoelectronic lighting device in a more cost-effective technology.

[0014] The power source can include transistors that are implemented in the first technology.

[0015] To supply the optoelectronic semiconductor device with the current generated by the current source in the first state of the PWM transistor and decouple it from the current generated by the current source in the second state, the PWM transistor can be designed such that its current-carrying path is low-resistance (i.e., electrically conductive) in one of the two states and high-resistance (i.e., electrically non-conductive) in the other. The PWM transistor can, for example, be designed as a field-effect transistor (FET). In this case, the drain-source path is the current-carrying path of the PWM transistor.

[0016] The optoelectronic semiconductor device can be configured, for example, as a light-emitting diode (LED), an organic light-emitting diode (OLED), a light-emitting transistor, or an organic light-emitting transistor. The optoelectronic semiconductor device can be part of an integrated circuit in various configurations.

[0017] The optoelectronic semiconductor component can be implemented in particular as an optoelectronic semiconductor chip.

[0018] In addition to the optoelectronic semiconductor component, the power source and the PWM transistor, the optoelectronic lighting device may also contain other semiconductor components and / or other components.

[0019] The optoelectronic lighting device can comprise one or more optoelectronic semiconductor components. Each of the optoelectronic semiconductor components may be assigned a current source and a PWM transistor.

[0020] Each of the optoelectronic semiconductor components can form a subpixel of a pixel. For example, a single pixel can contain three subpixels for the colors red, green, and blue.

[0021] The second technology used to manufacture the PWM transistor can exhibit higher charge carrier mobility than the first technology. This makes it possible to create a transistor that can be modulated more quickly.

[0022] Furthermore, the first technology can be TFT technology. The characteristic that the power source is manufactured using TFT technology can be understood to mean that the transistors of the power source are TFT transistors, i.e., thin-film transistors. For example, the TFT transistors can be IGZO (indium gallium zinc oxide) or LTPS (low-temperature polycrystalline silicon) transistors.

[0023] The second technology could be c-Si technology. The PWM transistor could be made of crystalline silicon.

[0024] According to one embodiment, the optoelectronic semiconductor device, the current source, and the PWM transistor, or rather the current-carrying path of the PWM transistor, are connected in series. In this case, the current-carrying path in the first state of the PWM transistor has a low resistance in order to supply the optoelectronic semiconductor device with the current generated by the current source.

[0025] There are several ways to connect the optoelectronic semiconductor device, the power source, and the PWM transistor in series. For example, the optoelectronic semiconductor device can be connected between the power source and the PWM transistor, or the power source can be connected between the optoelectronic semiconductor device and the PWM transistor, or the PWM transistor can be connected between the optoelectronic semiconductor device and the power source.

[0026] According to a further embodiment, the optoelectronic semiconductor device and the PWM transistor can be connected in parallel. The PWM transistor can be connected to the optoelectronic semiconductor device in such a way that the PWM transistor short-circuits the optoelectronic semiconductor device when the PWM transistor is in the second state.

[0027] The PWM transistor can be an integrated circuit (IC), in particular an application-specific integrated circuit (ASIC), or be integrated into an IC or an ASIC.

[0028] In particular, the PWM transistor can be a micro-injection chip (µIC) or integrated into a micro-injection chip (µIC). A micro-injection chip has a very thin substrate or no substrate at all, which allows it to be manufactured with small lateral dimensions.

[0029] The PWM transistor can also be implemented as a hybrid, for example as a printable µtransistor, i.e. micro-transistor, or can be manufactured locally using a laser beam as a recrystallized single transistor.

[0030] The optoelectronic semiconductor device can be a µLED, i.e., a micro-LED. Similar to a µIC, a µLED has a very thin substrate or no substrate at all.

[0031] The PWM transistor can be integrated into the µLED as an active substrate, thus reducing the assembly effort.

[0032] The optoelectronic lighting device can comprise several optoelectronic semiconductor devices, each associated with a current source and a PWM transistor controlled by a pulse-width modulated signal. The optoelectronic semiconductor devices, the current sources, and the PWM transistors can have the features described above. The optoelectronic semiconductor devices can be arranged in rows and columns, and the control inputs, particularly the gate terminals, of the PWM transistors arranged in a row can be interconnected. This enables row-synchronous control of the PWM transistors.

[0033] The power source can include at least one first transistor for generating the current and a capacitor for controlling the at least one first transistor with the capacitor voltage. The optoelectronic semiconductor device and the at least one first transistor, in particular its current-carrying path, can be connected in series. The current flow through the optoelectronic semiconductor device, and thus its brightness, can be controlled by means of the at least one first transistor. One terminal of the capacitor can be connected to a control terminal of the at least one first transistor. The second terminal of the capacitor can be connected to a reference potential, in particular a supply or ground potential, or can be connected to the reference potential via a suitable switch or transistor.

[0034] The optoelectronic lighting device may further include at least one second transistor for electrically coupling the capacitor to a programming line. This second transistor may be connected between the programming line and the first terminal of the capacitor. If the second transistor is configured such that its current-carrying path has a low resistance, the capacitor is connected to the programming line and can be programmed, i.e., charged to a specific voltage.

[0035] The at least one first transistor and the at least one second transistor are implemented using the first technology. Specifically, the first and second transistors are TFT transistors.

[0036] It can be provided that the optoelectronic semiconductor device and the PWM transistor are connected in a first circuit branch, and a second circuit branch is connected in parallel to the first circuit branch. The second circuit branch can be configured such that the current generated by the current source flows through the second circuit branch when the PWM transistor is in the second state. The second circuit branch can include a diode, in particular a semiconductor diode with a pn junction, and one or more transistors. Furthermore, the second circuit branch, or at least a part of it, can be implemented using the second technology, in particular c-Si technology.

[0037] During the period in which the current generated by the power source does not flow through the first circuit branch containing the optoelectronic semiconductor device, the current flows through the second circuit branch. Consequently, there is no change in current, but rather a rerouting of the current, which means that the current-driving transistor does not contribute to the slew rate. Furthermore, with a suitable design of the second current branch, the drain-source voltage of the power transistor remains constant, so that no capacitive coupling to the capacitor occurs.

[0038] The optoelectronic lighting device may further include a control unit designed to control the PWM transistor with the pulse-width modulated signal.

[0039] The optoelectronic light source can be used, for example, in any type of display, i.e., optical display device, particularly in automotive applications, such as dashboard displays. Such a display can incorporate one or more of the optoelectronic light sources described above. Furthermore, the optoelectronic light source can be used in other suitable applications.

[0040] A method is designed for controlling an optoelectronic lighting device. The optoelectronic lighting device comprises an optoelectronic semiconductor device for generating light, a current source for generating current, and a PWM transistor. The PWM transistor is driven by a pulse-width modulated signal and assumes a first state or a second state depending on the pulse-width modulated signal. In the first state, the PWM transistor supplies the optoelectronic semiconductor device with the current generated by the current source, and in the second state, it decouples the optoelectronic semiconductor device from the current generated by the current source. The current source is implemented using a first technology, while the PWM transistor is implemented using a second technology.

[0041] Another method is used to manufacture an optoelectronic lighting device. The optoelectronic lighting device comprises an optoelectronic semiconductor component for generating light, a current source for generating current, and a PWM transistor controlled by a pulse-width modulated signal. Depending on the pulse-width modulated signal, the PWM transistor assumes a first state or a second state. Furthermore, the PWM transistor is configured to supply the optoelectronic semiconductor component with the current generated by the current source in the first state and to decouple it from the current generated by the current source in the second state. The current source is manufactured using a first technology, and the PWM transistor is manufactured using a second technology.

[0042] The method for controlling an optoelectronic lighting device and the method for manufacturing an optoelectronic lighting device can have the configurations of the optoelectronic lighting device described above.

[0043] Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawings. These schematically show: Fig. 1 a schematic circuit diagram of an optoelectronic lighting device; Fig. 2 a representation of a PWM signal; Fig. 3 a circuit diagram of a circuit for the realization of an optoelectronic lighting device; Fig. 4. A representation of the time course of the programming of a cell and a PWM cycle; Fig. 5 Representations of the current and voltage across an LED during a rising edge of a PWM pulse for an optoelectronic lighting device manufactured using TFT technology; Fig. 6. A representation of the current through an LED during successive cycles for an optoelectronic lighting device manufactured using TFT technology; Fig. 7 Representations of the current and voltage across an LED during a rising edge of a PWM pulse for an optoelectronic lighting device with a c-Si PWM transistor; Fig. 8 A representation of the current through an LED during successive cycles for an optoelectronic lighting device with a c-Si PWM transistor; Fig. 9 a circuit diagram of a circuit according to the invention for the realization of an optoelectronic lighting device; Fig. 10 a representation of the current through an LED during a rising edge of a PWM pulse for the optoelectronic lighting device according to Fig. 9; Fig. 11 a representation of the current through the LED during successive cycles for the optoelectronic lighting device according to Fig. 9; Fig. 12 a circuit diagram of another circuit for the realization of an optoelectronic lighting device with an LED; Fig. 13 a circuit diagram of another circuit for the realization of an optoelectronic lighting device with several LEDs; Fig. 14 a representation of the temporal course of the control of the optoelectronic lighting devices according to Fig. 12 and Fig. 13; Fig. 15 to 19 illustrations of circuit variants from Fig. 12; Fig. 20 different variants of a component with a microLED and a PWM transistor; and Fig. 21 and Fig. 22 different variations of a circuit with an RGB trip LED.

[0044] The following detailed description refers to the accompanying drawings, which form part of this description and show specific embodiments in which the invention can be implemented. Since components of embodiments can be positioned in a number of different orientations, the directional terminology serves only for illustration and is in no way restrictive. It is understood that other embodiments may be used and structural or logical modifications may be made without affecting the scope of protection. It is understood that the features of the various embodiments described herein may be combined with one another unless specifically stated otherwise. Therefore, the following detailed description should not be interpreted as restrictive.In the figures, identical or similar elements are provided with identical reference symbols, insofar as this is expedient.

[0045] Fig. Figure 1 shows a schematic circuit diagram of an optoelectronic lighting device 10. The optoelectronic lighting device 10 contains an optoelectronic semiconductor component, designed as an LED 11, in particular as a microLED, for generating light. The optoelectronic lighting device 10 can also contain further LEDs or microLEDs and can be integrated into a display.

[0046] Furthermore, the optoelectronic lighting device 10 includes a controllable current source 12 for generating a current and a PWM transistor 13. The current source 12 and the PWM transistor 13 are controlled by a control unit 14.

[0047] Data words 15 are entered into an input of the control unit 14. The control unit 14 controls the current source 12 by means of a control signal 16 and the PWM transistor 13 by means of a control signal 17 such that a data word 15 entered into the control unit 14 is converted into a brightness value of the light produced by the LED 11.

[0048] The control signal 17 for controlling the PWM transistor 13 is a pulse-width modulated signal. Depending on the pulse-width modulated signal, the PWM transistor 13 assumes a first state or a second state. In the first state of the PWM transistor 13, the LED 11 is supplied with the current generated by the current source 12, while in the second state of the PWM transistor 13, the LED 11 is decoupled from the current generated by the current source 12, i.e., it is not supplied with current.

[0049] In the present embodiment, the PWM transistor 13 is designed as a field-effect transistor. The gate terminal of the PWM transistor 13 is driven by the control signal 17. The drain-source path of the PWM transistor 13 is connected between the LED 11 and the current source 12. In the first state of the PWM transistor 13, the drain-source path has a low resistance, and in the second state, it has a high resistance.

[0050] Alternative circuits for the LED 11, the current source 12, and the PWM transistor 13 are described below. In particular, the PWM transistor 13 can also be arranged in parallel with the LED 11.

[0051] The current source 12, or the transistors contained in the current source 12, are manufactured using a first technology, while the PWM transistor is manufactured using a second technology that has a higher charge carrier mobility than the first technology.

[0052] An example is a control signal 17 plotted against time t, i.e. a pulse-width modulated signal with which the gate terminal of the PWM transistor is applied, in Fig. Figure 2 shows that the control signal 17 can assume two discrete values, i.e., a first value 18 and a second value 19. During the period in which the control signal 17 assumes the first value 18, a rectangular pulse with a pulse width t1 is generated. The pulse is repeated periodically with a period T. When the control signal 17 assumes the first value 18, i.e., during the duration t1 of the pulse, the drain-source path of the PWM transistor 13 is low-impedance. Otherwise, the drain-source path is high-impedance. The control unit 14 can, in particular, control the pulse width t1 of the pulse.

[0053] Fig. Figure 3 shows a schematic circuit diagram of a circuit 20, with which the in Fig. The optoelectronic lighting device 10 shown in Figure 1 can be implemented. The circuit 20 serves to control the LED 11. Of course, further LEDs can be provided, which are arranged, for example, in rows and columns and controlled by means of analogous circuits.

[0054] Circuit 10 comprises a controllable current source configured as a 3T1C cell, which includes three transistors 21, 22, 23, configured as field-effect transistors, and a capacitor 24. Circuit 20 also includes the PWM transistor 13. Circuit 20 can therefore also be referred to as a 4T1C cell.

[0055] The current-carrying paths, i.e., the drain-source paths, of transistors 21, 22, 23 are connected in parallel. LED 11, the drain-source path of PWM transistor 13, and the transistor array consisting of transistors 21, 22, 23 are connected in series.

[0056] In the present embodiment, the anode terminal of LED 11 is supplied with a supply potential VDD.

[0057] The gate terminal of the PWM transistor 13 is controlled by a signal S1.

[0058] One terminal of capacitor 24 is connected to the gate terminals of transistors 21, 22, 23. A second terminal of capacitor 24 is connected to ground (GND).

[0059] The circuit further comprises 20 transistors 25 and 26. One terminal of each transistor 25 and 26 is connected between transistors 21, 22, 23 and the PWM transistor 13. The other terminal of the drain-source path of transistor 26 is connected to a programming line and carries a sense signal. The other terminal of the drain-source path of transistor 25 is connected to the first terminal of capacitor 24.

[0060] The gate terminals of transistors 25, 26 are controlled by a signal ProgEn.

[0061] In Fig. Figure 3 shows two distinct areas 27 and 28 of the circuit 20, indicated by dashed lines. Area 27 was fabricated using the first technology, and area 28 was fabricated using the second technology. In this embodiment, the first technology is a TFT technology, and the second technology is a c-Si technology. Consequently, transistors 21, 22, 23, 25, and 26 are thin-film transistors (TFTs). The PWM transistor 13 is fabricated from crystalline silicon. For example, the PWM transistor 13 can be a micro-injection chip (µIC). Furthermore, the PWM transistor 13 can be fabricated as a printable µtransistor or locally as a recrystallized single transistor using a laser beam.

[0062] The actual current driver in circuit 20 consists of transistors 21, 22, 23. When, in the state ProgEn = VDD and S1 = GND, the drain-source paths of transistors 25, 26 are low-impedance and the drain-source path of the PWM transistor 13 is high-impedance, a current can be impressed via the programming line. Since the PWM transistor 13 is closed, this current charges or programs capacitor 24 and generates exactly the gate-source voltage at the transistor array consisting of transistors 21, 22, 23 that is necessary to drive the desired rated current.

[0063] When ProgEn = GND and S1 = VDD, the drain-source paths of transistors 25 and 26 are high-impedance and the drain-source path of transistor 13 is low-impedance, the corresponding current flows through LED 11, determined by the voltage across capacitor 24. This current can be modulated by the signal S1, which controls PWM transistor 13, in the sense of a PWM signal.

[0064] In Fig. 4 are the signals S1 and ProgEn as well as the current I flowing through the LED 11. LED plotted against time t. First, the system is switched to the state ProgEn = VDD and S1 = GND to program cell or capacitor 24. Then, the PWM cycle is performed, in which ProgEn is at GND and the PWM signal S1, with a predefined pulse width, drives the PWM transistor 13.

[0065] In Fig. 5 and Fig. Figure 6 shows measurement curves for circuit 20, where in this case both areas 27 and 28 were produced using TFT technology. Fig. 5 are the current I LED and the voltage V LED The maximum rise time, i.e., the time between the two peaks in the LED 11, is displayed during a rising edge of a PWM pulse. Fig. The 5 dashed lines shown represent approximately 10 ns, which shows that circuit 20 is fundamentally suitable for PWM dimming.

[0066] Fig. Figure 6 shows the decrease in current I LED due to the switching of PWM transistor 13 during successive cycles. The reason for the decrease in current I LED The charge injection into capacitor 24 occurs with each PWM pulse. The current I LED However, the charge decreases only slightly over the 500 cycles shown, during which capacitor 24 is not recharged. Consequently, the effect of the switching pulses in the load path on the charge of capacitor 24 can be neglected.

[0067] For the in Fig. The same measurements were taken for the curves shown in figures 7 and 8 as for the Fig. 5 or 6 were carried out, however in this case area 27 of circuit 20 was manufactured using TFT technology, while area 28 was manufactured using c-Si technology.

[0068] Fig. Figure 7 shows that the rise time could be significantly reduced by using crystalline silicon for the PWM transistor 13. The maximum rise time is now only about 5 ns. Furthermore, there is virtually no change in the current I. LED over several cycles, as Fig. 8 shows.

[0069] Fig. Figure 9 shows a schematic circuit diagram of a circuit 30, which is based on the in Fig. The circuit shown in section 3 is based on 20.

[0070] The section 28 of circuit 30, produced using the second technology, has a first circuit branch 31 and a second circuit branch 32 connected in parallel to the first circuit branch 31. The first circuit branch 31 comprises the LED 11 and the PWM transistor 13.

[0071] The second circuit branch 32 contains a pn diode 33 and transistors 34 and 35, which are designed as field-effect transistors. The drain-source paths of transistors 34 and 35 are connected in series with the pn diode 33. The gate terminal of transistor 34 is driven by the signal S1. The gate terminal of transistor 35 is driven by the signal ProgEn.

[0072] Transistors 34 and 35 are designed as p-channel transistors, whereas transistors 13, 25, and 26 are designed as n-channel transistors.

[0073] The current generated by transistors 21, 22, 23 flows through the second circuit branch 32 when the drain-source path of the PWM transistor 13 is high impedance.

[0074] Fig. 10 shows analogous to Fig. 7 the current I LED through LED 11 of circuit 30 during a rising edge of a PWM pulse. The maximum rise time, i.e., the time between the two in Fig. The distance between the 10 dashed lines shown is only about 2 ns.

[0075] Fig. Figure 11 shows the size of the current I LED during successive cycles for circuit 30. The change in current I LED is only very slight.

[0076] Fig. Figure 12 shows a schematic circuit diagram of circuit 40, which is a simplified version of circuit 20. Circuit 40 contains only transistor 21 as the current-driving transistor. Capacitor 24 is programmed via transistor 25. Furthermore, the PWM transistor 13, manufactured using c-Si technology, is connected between the supply potential VDD and LED 11.

[0077] Fig. Figure 13 shows several LEDs 11 arranged in a row of a display, each facing from the Fig. The circuit 40 is controlled by the known circuit 12. The gate terminals of the PWM transistors 13 arranged in the same row are connected to each other and are controlled by the signal S1. Furthermore, the gate terminals of the transistors 25 arranged in the same row are controlled by the signal ProgEn.

[0078] Fig. Figure 14 shows the timing of the control process. The top line of Fig. Figure 14 shows the signal S1, which is applied to the gate terminals of the PWM transistors 13. In the middle row of Fig. 14 is the gate-source voltage V GS one of the transistors 21 is shown and in the bottom row of Fig. Figure 14 shows the ProgEn signal, which is applied to the gate terminals of transistors 25.

[0079] To program the capacitors 24, the ProgEn signal is switched on so that the drain-source paths of the transistors 25 are low-impedance and the capacitors 24 can be charged to a respective voltage using the Sense 1, Sense 2, ... Sense n signals. This applies the desired gate-source voltages V to the transistors 21. GS generated. These voltages then determine the current I. LED through the respective LED 11.

[0080] After the capacitors 24 are programmed, the gate terminals of the PWM transistors 13 are supplied with the pulse-width modulated signal S1. The pulse-width modulated signal S1 switches the current I LED The respective LED 11 simply switches the device on and off.

[0081] The line-synchronous signal S1 serves as the global dimming signal. Grayscale levels and calibration are implemented by the TFT section, which can also be described as slow PWM (compared to the fast PWM using the PWM transistors 13).

[0082] An alternative solution involves switching the entire voltage V LED Using LED 11 is not preferred for power stability reasons.

[0083] In contrast, switching the PWM transistors 13 requires only a few µA and can therefore easily be implemented in parallel with switching the gate signal ProgEn.

[0084] If the line-synchronous signal S1 is used as a global dimming signal, signal S1 can be shifted to the next line using a shift register, analogous to the ProgEn signal. This can be implemented with minimal effort.

[0085] Since the signal S1 only has an on / off function, i.e., it does not control the current I LED Since the control is simple, no complex designs regarding temperature, drift, or other compensations are necessary. Consequently, only the PWM transistor 13 needs to switch between an on and an off state at high speed. In Fig. Figure 13 shows a so-called common-anode arrangement, in which the supply potential VDD is applied to the anode terminals of the LEDs 11. Alternatively, the LEDs 11 can also be arranged in a so-called common-cathode arrangement, in which the cathode terminals of the LEDs 11 are connected to ground potential GND.

[0086] Fig. Figures 15 to 19 show variants of the in Fig. Circuit 40 shown in 12.

[0087] In the in the Fig. 15 and Fig. In circuits 41 and 42 shown in Figure 16, the fast PWM transistor 13 is connected in parallel to the LED 11, with the circuits in Fig. 15 and Fig. 16 are configured as a common-cathode arrangement or common-anode arrangement. Instead of the current I LED To interrupt the current I by LED 11 LED in Fig. 15 and Fig. 16 is short-circuited by the PWM transistor 13. This short-circuits the slower TFT transistor 21, which is configured as a PMOS in Fig. 15 or as NMOS in Fig. The circuit, designed as shown in section 16, is not significantly involved in modulating the LED cross-current. Only the rapid change in voltage V has an effect. DSThe current change caused by transistor 21, motivated by the finite internal resistance of the current source represented by transistor 21, must be carried by the slower transistor.

[0088] However, in circuits 41 and 42, the maximum LED current is drawn for a longer period even with small pulse widths. To reduce power consumption, the slow TFT transistor 21 can be switched off after short-circuiting LED 11.

[0089] The in Fig. The circuit shown in 17 differs from the one in Fig. The circuit shown in 12 is characterized by the fact that the PWM transistor 13 is arranged between the transistor 21 and the ground potential GND.

[0090] In Fig. 18 and Fig. Terminal 19 is connected to the supply potential VDD of capacitor 24. Furthermore, in Fig. 18 The LED 11 is arranged between transistor 21 and PWM transistor 13. In Fig. 19 the transistor 21 is arranged between the PWM transistor 13 and the LED 11 and the cathode of the LED 11 is connected to the ground potential GND.

[0091] One advantage of the circuits described above is that a large part of the respective circuitry can be implemented using traditional TFT electronics, such as IGZO or LTPS. This includes, among other things, current dimming (e.g., 7 bits) and, additionally, simple PWM (e.g., 8 bits) with a shortest LTPS pulse width of, for example, > 1 µs.

[0092] High-speed PWM with ultra-short pulses, e.g., 10 ns, is achieved using c-Si, i.e., crystalline silicon. This high-speed PWM can be implemented, for example, with a Si-(µ) chip (a hybrid design) or with locally generated crystalline silicon, e.g., through laser recrystallization. Since the "fast" part of the circuit is spatially very limited (in the simplest case, for example, just a simple on / off FET), the additional costs (silicon area) are kept to a minimum. Furthermore, an external dimmer (combination of TFT + external dimmer) can be omitted. This saves component height or display height and increases efficiency.

[0093] The PWM transistor 13 can already be integrated into the microLED and, in this case, is supplied with the microLED component. This reduces, for example, the costs of externally placing / printing microtransistors or additionally recrystallizing a TFT transistor. This is technologically possible for all three colors: red, green, and blue. Since both GaAs and GaN have high charge carrier mobilities, fast PWM can be achieved. Because the PWM transistor 13 has a simple on / off functionality, the requirements are minimal.

[0094] The switching functionality can also be integrated into a submount, carrier, or interposer of the LED. For example, RGB trip LEDs can be mounted on an interposer containing the PWM transistor. This is advantageous because the PWM transistor has approximately the same geometry as the (µ)LED, thus requiring no additional surface area. Furthermore, only one additional pin or connection is needed for the shared PWM gate.

[0095] Fig. Figure 20 shows three different variants in which the PWM transistor 13 is integrated into the µLED. In one variant, the PWM transistor 13 is arranged in parallel with the LED 11. In the other two variants, the drain-source path of the PWM transistor 13 is connected to the cathode or anode of the PWM transistor 13, respectively. Each of the in Fig. The 20 components shown contain 3 connection pins.

[0096] If the c-Si PWM transistor 13 is implemented as a microcontroller (µIC), multiple PWM switches can be integrated into a single µIC. For example, if one µIC is designed for four RGB pixels (12 LEDs), this µIC would have, for instance, one PWM switch signal pad, 12 source / drain pads, and one VDD / GND pad, resulting in a total of, for example, 18 pads. Due to its simplicity, the system is scalable to, for example, 16 pixels. Since only one transistor is required per LED, high pixel densities can also be achieved.

[0097] Fig. 21 shows the from Fig. 13 known circuits, in which three LEDs 11 with the colors red, green and blue together with the associated PWM transistors 13 are integrated in a common substrate as an RGB trip LED, e.g. printable. The in Fig. 21 Component 45 shown with the three LEDs 11 and the three PWM transistors 13 has, for example, at least 5 connections.

[0098] Fig. Figure 22 shows a circuit with three LEDs 11 of the colors red, green, and blue. The driver circuits for the LEDs 11 correspond to the circuit from [reference missing]. Fig. 16. Alternatively, the driver circuits can also be implemented as a common-cathode arrangement. The three LEDs 11 and the associated PWM transistors 13 can be integrated into a common substrate as an RGB trip LED. Fig. Areas 46A, 46B, and 46C, which are encompassed by the common substrate, are labeled in Figure 22. For clarity, areas 46A, 46B, and 46C are shown separately. REFERENCE MARK LIST 10 optoelectronic lighting device 11 LED 12 Power source 13 PWM transistor 14 Control unit 15 data words 16 Control signal 17 Control signal 18 first value 19 second value 20 circuit 21 transistors 22 transistors 23 transistors 24 Capacitor 25 transistors 26 transistors 27 area 28 area 30 circuit 31 first circuit branch 32 second circuit branch 33 pn diode 34 transistors 35 transistors 40 circuit 41 Circuit 42 Circuit 45 components 46A area 46B area 46C area

Claims

[1] Optoelectronic lighting device (10, 20, 30, 40, 41, 42), comprising: an optoelectronic semiconductor device (11) configured to generate light, a power source (12) designed to generate a current, and a PWM transistor (13) controlled by a pulse-width modulated signal, which assumes a first state or a second state depending on the pulse-width modulated signal and which is configured to supply the optoelectronic semiconductor device (11) with the current generated by the current source (12) in the first state and to decouple it from the current generated by the current source (12) in the second state, wherein the current source (12) is manufactured using a first technology and the PWM transistor (13) is manufactured using a second technology, wherein the optoelectronic semiconductor device (11) and the PWM transistor (13) are arranged in a first circuit branch (31) and a second circuit branch (32) is connected in parallel to the first circuit branch (31), and wherein the second circuit branch (32) is configured such that the current generated by the current source (12) flows through the second circuit branch (32) when the PWM transistor (13) is in the second state. [2] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to claim 1, wherein the second technology has a higher charge carrier mobility than the first technology. [3] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to claim 1 or 2, wherein the first technology is a TFT technology and / or the second technology is a c-Si technology. [4] Optoelectronic lighting device (10, 20, 30, 40) according to one of the preceding claims, wherein the optoelectronic semiconductor device (11), the power source (12) and the PWM transistor (13) are connected in series. [5] Optoelectronic lighting device (41, 42) according to one of claims 1 to 3, wherein the optoelectronic semiconductor device (11) and the PWM transistor (13) are connected in parallel. [6] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to one of the preceding claims, wherein the PWM transistor (13) is an IC, in particular a µIC. [7] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to any of the preceding claims, wherein the optoelectronic semiconductor device is a µLED (11). [8] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to claim 7, wherein the PWM transistor (13) is integrated into the µLED (11). [9] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to one of the preceding claims, wherein the optoelectronic lighting device (10, 20, 30, 40, 41, 42) comprises several optoelectronic semiconductor devices (11), each of which is associated with a current source (12) and a PWM transistor (13) controlled by a pulse-width modulated signal, and wherein the optoelectronic semiconductor devices (11) are arranged in rows and columns and control inputs of the PWM transistors (13) arranged in a row are connected to each other. [10] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to one of the preceding claims, wherein the current source (12) has at least one first transistor (21, 22, 23) for generating the current and a capacitor (24) for controlling the at least one first transistor (21, 22, 23) with the capacitor voltage. [11] Optoelectronic lighting device (10, 20, 30, 40, 41, 42) according to claim 10, wherein the optoelectronic lighting device (11) has at least one second transistor (25, 26) for coupling the capacitor (24) to a programming line. [12] Optoelectronic lighting device (10) according to one of the preceding claims, wherein the optoelectronic lighting device (10) has a control unit (14) configured to control the PWM transistor (13) with the pulse width modulated signal. [13] Display with one or more optoelectronic lighting devices (10, 20, 30, 40, 41, 42) according to any of the preceding claims. [14] Method for controlling an optoelectronic lighting device (10, 20, 30, 40, 41, 42), wherein the optoelectronic lighting device (10, 20, 30, 40, 41, 42) comprises an optoelectronic semiconductor device (11) for generating light, a current source (12) for generating current and a PWM transistor (13), and wherein the PWM transistor (13) is driven by a pulse width modulated signal and the PWM transistor (13) assumes a first state or a second state depending on the pulse width modulated signal, wherein the PWM transistor (13) supplies the optoelectronic semiconductor device (11) with the current generated by the current source (12) in the first state and decouples it from the current generated by the current source (12) in the second state, wherein the current source (12) is manufactured using a first technology and the PWM transistor (13) is manufactured using a second technology, and wherein the optoelectronic semiconductor device (11) and the PWM transistor (13) are arranged in a first circuit branch (31) and a second circuit branch (32) is connected in parallel to the first circuit branch (31), and wherein the second circuit branch (32) is configured such that the current generated by the current source (12) flows through the second circuit branch (32) when the PWM transistor (13) is in the second state. [15] Method for manufacturing an optoelectronic lighting device (10, 20, 30, 40, 41, 42), wherein the optoelectronic lighting device (10, 20, 30, 40, 41, 42) comprises an optoelectronic semiconductor device (11) for generating light, a current source (12) for generating current and a PWM transistor (13) controlled by a pulse width modulated signal, wherein the PWM transistor (13) assumes a first state or a second state depending on the pulse width modulated signal and the PWM transistor (13) is configured to supply the optoelectronic semiconductor device (11) with the current generated by the current source (12) in the first state and to decouple it from the current generated by the current source (12) in the second state, wherein the current source (12) is manufactured using a first technology and the PWM transistor (13) is manufactured using a second technology, and wherein the optoelectronic semiconductor device (11) and the PWM transistor (13) are arranged in a first circuit branch (31) and a second circuit branch (32) is connected in parallel to the first circuit branch (31), and wherein the second circuit branch (32) is configured such that the current generated by the current source (12) flows through the second circuit branch (32) when the PWM transistor (13) is in the second state.

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