High-contrast liquid crystal projection system circuit capable of automatically adjusting brightness

Abstract

The utility model discloses a high-contrast liquid crystal projection system circuit capable of automatically adjusting brightness. The high-contrast liquid crystal projection system circuit comprises a liquid crystal projection LCD, and a brightness automatic adjusting circuit and a communication isolation circuit which are respectively connected with the liquid crystal projection LCD through LCD interfaces. The brightness automatic adjusting circuit comprises an environment brightness acquisition circuit and an LED brightness control circuit connected with the environment brightness acquisition circuit, wherein the environment brightness acquisition circuit and the LED brightness control circuit are arranged in series. Voltage compatibility and low power consumption functions are realized through an integrated block U3 and a matched circuit, and external serial port data are processed through a triode Q1, a triode Q2 and the matched circuit; ambient brightness data is collected through a photoresistor LDR1; automatic brightness adjustment is realized through a triode Q3, a triode Q4 and a matched circuit; through the LCD in the BTN mode, static driving is adopted, and the effect of high contrast of the projection system is achieved.

Description

Technical Field

[0001] The utility model relates to a liquid crystal projection system circuit, in particular to a high-contrast liquid crystal projection system circuit capable of automatically adjusting brightness. Background Art

[0002] Projection products do not require a specific carrier and are small in size, so they are widely used in advertising, home appliance display and other fields. At present, traditional projectors are expensive and large in size; advertising projection products can only display a single icon and cannot switch the display content at any time. At the same time, the single brightness does not meet the actual use needs, affects the product life, and the contrast is not high. The above restricts the widespread application of segment LCD projection systems. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a high-contrast liquid crystal projection system circuit with automatic brightness adjustment, realize voltage compatibility and low power consumption functions through integrated block U3 and supporting circuits, realize processing of external serial port data through transistor Q1, transistor Q2 and supporting circuits; collect environmental brightness data through photoresistor LDR1; realize automatic brightness adjustment through transistor Q3, transistor Q4 and supporting circuits; and realize high-contrast effect of the projection system through BTN mode LCD and static drive.

[0004] In order to solve the above technical problems, the technical solution of the utility model is: a high-contrast liquid crystal projection system circuit with automatic brightness adjustment, and its innovation lies in: the high-contrast liquid crystal projection system circuit with automatic brightness adjustment includes a liquid crystal projection LCD, an automatic brightness adjustment circuit and a communication isolation circuit respectively connected to the liquid crystal projection LCD through an LCD interface, and the automatic brightness adjustment circuit includes an ambient brightness acquisition circuit arranged in series and an LED brightness control circuit connected to the ambient brightness acquisition circuit.

[0005] Preferably, the liquid crystal projection LCD is statically driven in a BTN negative display mode, and the driving chip of the liquid crystal projection LCD is UC1507;

[0006] The liquid crystal projection LCD is provided with a VLCD pin, a VSS pin, a VDD pin, an SCL pin and an SDA pin connected to the display module, the communication isolation circuit, the ambient brightness acquisition circuit and the LED brightness control circuit.

[0007] Preferably, a voltage compatible circuit is provided on the liquid crystal projection LCD, and the voltage compatible circuit is connected between the VSS pin and the VDD pin, and includes a capacitor C1 and an integrated block U3 which are mutually connected in parallel between the VSS pin and the VDD pin, and the integrated block U3 includes pin 1, pin 2 and pin 3, and the pin 1 of the integrated block U3 and the pin 3 of the integrated block U3 are connected in parallel to both ends of the capacitor C1, and the pin 2 of the integrated block U3 is VDD3.3, and outputs a low voltage of 3.3v;

[0008] The communication isolation circuit is arranged between pin 2 and pin 3 on the integrated block U3.

[0009] Preferably, capacitors C2 and C3 connected in parallel are provided at both ends of pin 1 and pin 2 on the integrated block U3.

[0010] Preferably, the communication isolation circuit includes a transistor Q1 and a transistor Q2 connected to the VDD pin through a resistor R4 and a resistor R3 respectively, the transistor Q1 is connected to pin 2 of the integrated block U3 through the resistor R2, the transistor Q2 is connected to pin 2 of the integrated block U3 through the resistor R1, and the resistor R4 and the resistor R3 are pull-up resistors of the external serial port signals SCL / IN and SDA / IN respectively.

[0011] Preferably, the ambient brightness collection circuit is a transistor Q4 connected to the VDD pin, a resistor RA1 is connected in series between the source of the transistor Q4 and the VDD pin, a photoresistor LDR1 and a resistor RA2 connected in parallel to each other are arranged between the base of the transistor Q4 and the VDD pin, and the gate of the transistor Q4 is connected to the VSS pin through the LED brightness control circuit.

[0012] Preferably, the LED brightness control circuit includes a transistor Q3 arranged between a VDD pin and a VSS pin, a gate of the transistor Q3 is connected to the VSS pin, a base of the transistor Q3 is connected to the gate of the transistor Q4 through a resistor RA4, a capacitor CA1 and a resistor RA3 are arranged in parallel between the base of the transistor Q3 and the gate of the transistor Q3, and a source of the transistor Q3 is connected to the VDD pin.

[0013] Preferably, an LED driving circuit is arranged between the source of the transistor Q3 and the VDD pin, and the LED driving circuit comprises a diode D1, and a resistor RL1 and a resistor RL2 which are connected in series with the diode D1 and in parallel with each other.

[0014] The utility model has the advantages of realizing voltage compatibility and low power consumption functions through integrated block U3 and supporting circuits, realizing processing of external serial port data through transistor Q1, transistor Q2 and supporting circuits; collecting environmental brightness data through photoresistor LDR1; realizing automatic brightness adjustment through transistor Q3, transistor Q4 and supporting circuits; and realizing high contrast effect of projection system through BTN mode LCD and static drive.

[0015] By adopting the above circuit, the LCD projection system can automatically adjust the brightness, greatly improve the contrast, and can be widely used in various occasions; it can realize the automatic processing of different voltage systems and different level data, and at the same time realize the characteristics of projection display, thereby increasing the service life of the segment code LCD projection system and greatly improving the versatility and application range of the segment code LCD projection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0017] Figure 1 The utility model is a principle block diagram of a high-contrast liquid crystal projection system circuit with automatic brightness adjustment.

[0018] Figure 2 The utility model discloses a circuit diagram of a high-contrast liquid crystal projection system circuit capable of automatically adjusting brightness.

[0019] Figure 3 The utility model is a schematic diagram of a liquid crystal projection LCD and an LCD interface in a high-contrast liquid crystal projection system circuit with automatic brightness adjustment.

[0020] Figure 4 The utility model is a schematic diagram of a voltage compatible circuit in a high-contrast liquid crystal projection system circuit with automatic brightness adjustment.

[0021] Figure 5 The utility model is a schematic diagram of a communication isolation circuit in a high-contrast liquid crystal projection system circuit with automatic brightness adjustment.

[0022] Figure 6 The utility model is a schematic diagram of an automatic brightness adjustment circuit in a high-contrast liquid crystal projection system circuit which can automatically adjust brightness.

[0023] In the figure: 1-LCD interface, 2-communication isolation circuit, 3-ambient brightness acquisition circuit, 4-LED brightness control circuit, 5-LED drive circuit, 6-voltage compatibility circuit. DETAILED DESCRIPTION

[0024] The high contrast liquid crystal projection system circuit with automatic brightness adjustment of the utility model comprises a liquid crystal projection LCD, a brightness automatic adjustment circuit and a communication isolation circuit 2 respectively connected to the liquid crystal projection LCD through an LCD interface 1, and the brightness automatic adjustment circuit comprises an ambient brightness acquisition circuit 3 arranged in series, and an LED brightness control circuit 4 connected to the ambient brightness acquisition circuit 3. The voltage compatibility and low power consumption functions are realized through the integrated block U3 and the supporting circuit, the external serial port data is processed through the transistor Q1, the transistor Q2 and the supporting circuit; the ambient brightness data is collected through the photoresistor LDR1; the brightness is automatically adjusted through the transistor Q3, the transistor Q4 and the supporting circuit; and the high contrast effect of the projection system is realized through the LCD in BTN mode and static drive.

[0025] The above-mentioned liquid crystal projection LCD adopts BTN negative display mode static drive, and the driving chip of the liquid crystal projection LCD is UC1507. The liquid crystal projection LCD is provided with VLCD pin, VSS pin, VDD pin, SCL pin and SDA pin connected to the display module, the communication isolation circuit 2, the ambient brightness acquisition circuit 3 and the LED brightness control circuit 4.

[0026] The above-mentioned liquid crystal projection LCD is provided with a voltage compatible circuit 6, which is connected between the VSS pin and the VDD pin, and includes a capacitor C1 and an integrated block U3 which are mutually connected in parallel between the VSS pin and the VDD pin, the integrated block U3 includes pin 1, pin 2 and pin 3, the pin 1 of the integrated block U3 and the pin 3 of the integrated block U3 are connected in parallel at both ends of the capacitor C1, the pin 2 of the integrated block U3 is VDD3.3, and outputs a 3.3v low voltage; the communication isolation circuit 2 is provided between pin 2 and pin 3 on the integrated block U3, and the capacitor C2 and the capacitor C3 are provided at both ends of the pin 1 and the pin 2 on the integrated block U3. The external voltage below 12V is fixed to 3.3V output through the integrated block U3, the capacitor C1 filters the input voltage to prevent external interference, and the capacitors C2 and C3 filter the 3.3V voltage.

[0027] The communication isolation circuit 2 of the utility model includes a transistor Q1 and a transistor Q2 connected to the VDD pin through a resistor R4 and a resistor R3 respectively, the transistor Q1 is connected to the pin 2 of the integrated block U3 through the resistor R2, the transistor Q2 is connected to the pin 2 of the integrated block U3 through the resistor R1, and the resistor R4 and the resistor R3 are pull-up resistors of the external serial port signals SCL / IN and SDA / IN respectively. The level is determined by the transistor Q1 and the transistor Q2, and the resistor R1 and the resistor R2 are externally connected to a 3.3V voltage to convert the RX / IN and TX / IN from the external level to the 3.3V level.

[0028] The above-mentioned environment brightness acquisition circuit 3 is a transistor Q4 connected to the VDD pin, a resistor RA1 is connected in series between the source of the transistor Q4 and the VDD pin, a photoresistor LDR1 and a resistor RA2 are arranged in parallel between the base of the transistor Q4 and the VDD pin, and the gate of the transistor Q4 is connected to the VSS pin through the LED brightness control circuit 4. The LED brightness control circuit 4 includes a transistor Q3 arranged between the VDD pin and the VSS pin, the gate of the transistor Q3 is connected to the VSS pin, the base of the transistor Q3 is connected to the gate of the transistor Q4 through the resistor RA4, a capacitor CA1 and a resistor RA3 are arranged in parallel between the base of the transistor Q3 and the gate of the transistor Q3, and the source of the transistor Q3 is connected to the VDD pin. An LED driving circuit 5 is arranged between the source of the transistor Q3 and the VDD pin, and the LED driving circuit 5 includes a diode D1, and resistors RL1 and RL2 that are connected in series with the diode D1 and arranged in parallel with each other.

[0029] The intensity of the external light source is sensed by the photoresistor LDR1. When the external light source becomes brighter, the resistance of the photoresistor LDR1 becomes smaller, the base current of the transistor Q4 becomes larger, the voltage across the capacitor CA1 and the resistor RA3 increases, the gate voltage of the transistor Q3 connected to the resistor RA4 gradually increases, the current of the transistor Q3 gradually increases, the current of the diode D1 gradually increases, and the brightness gradually increases. When the external light source becomes darker, the resistance of the photoresistor LDR1 increases, the base current of the transistor Q4 decreases, the resistor RA3 continues to consume the voltage across the capacitor CA1, the voltage across the capacitor CA1 and the resistor RA3 gradually decreases, the gate voltage of the transistor Q3 connected to the resistor RA4 gradually decreases, the current of the transistor Q3 gradually decreases, the current of the diode D1 decreases synchronously, and the brightness gradually decreases.

[0030] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A high contrast liquid crystal projection system circuit with automatic brightness adjustment, characterized in that: The high-contrast liquid crystal projection system circuit with automatic brightness adjustment includes a liquid crystal projection LCD, an automatic brightness adjustment circuit and a communication isolation circuit respectively connected to the liquid crystal projection LCD through an LCD interface, and the automatic brightness adjustment circuit includes an ambient brightness collection circuit arranged in series and an LED brightness control circuit connected to the ambient brightness collection circuit.

2. A high contrast liquid crystal projection system circuit with automatic brightness adjustment as claimed in claim 1, characterized in that: The liquid crystal projection LCD is statically driven in a BTN negative display mode, and the driving chip of the liquid crystal projection LCD is UC1507; The liquid crystal projection LCD is provided with a VLCD pin, a VSS pin, a VDD pin, an SCL pin and an SDA pin connected to the display module, the communication isolation circuit, the ambient brightness acquisition circuit and the LED brightness control circuit.

3. A high contrast liquid crystal projection system circuit with automatic brightness adjustment as claimed in claim 2, characterized in that: The liquid crystal projection LCD is provided with a voltage compatible circuit, the voltage compatible circuit is connected between the VSS pin and the VDD pin, and includes a capacitor C1 and an integrated block U3 which are mutually connected in parallel between the VSS pin and the VDD pin, the integrated block U3 includes pin 1, pin 2 and pin 3, the pin 1 of the integrated block U3 and the pin 3 of the integrated block U3 are connected in parallel to the two ends of the capacitor C1, the pin 2 of the integrated block U3 is VDD3.3, and outputs a low voltage of 3.3v; The communication isolation circuit is arranged between pin 2 and pin 3 on the integrated block U3.

4. A high contrast liquid crystal projection system circuit with automatic brightness adjustment as claimed in claim 3, characterized in that: Capacitors C2 and C3 connected in parallel are disposed at both ends of pin 1 and pin 2 on the integrated block U3.

5. A high contrast liquid crystal projection system circuit with automatic brightness adjustment as claimed in claim 3, characterized in that: The communication isolation circuit includes a transistor Q1 and a transistor Q2 connected to the VDD pin through a resistor R4 and a resistor R3 respectively. The transistor Q1 is connected to pin 2 of the integrated block U3 through the resistor R2, and the transistor Q2 is connected to pin 2 of the integrated block U3 through the resistor R1. The resistor R4 and the resistor R3 are pull-up resistors for the external serial port signals SCL / IN and SDA / IN respectively.

6. A high contrast liquid crystal projection system circuit with automatic brightness adjustment as claimed in claim 2, characterized in that: The ambient brightness collection circuit is a transistor Q4 connected to the VDD pin, a resistor RA1 is connected in series between the source of the transistor Q4 and the VDD pin, a photoresistor LDR1 and a resistor RA2 are arranged in parallel between the base of the transistor Q4 and the VDD pin, and the gate of the transistor Q4 is connected to the VSS pin through the LED brightness control circuit.

7. A high contrast liquid crystal projection system circuit with automatic brightness adjustment as claimed in claim 6, characterized in that: The LED brightness control circuit includes a transistor Q3 arranged between a VDD pin and a VSS pin, a gate of the transistor Q3 being connected to the VSS pin, a base of the transistor Q3 being connected to the gate of the transistor Q4 via a resistor RA4, a capacitor CA1 and a resistor RA3 being arranged in parallel between the base of the transistor Q3 and the gate of the transistor Q3, and a source of the transistor Q3 being connected to the VDD pin.

8. A high contrast liquid crystal projection system circuit with automatic brightness adjustment as claimed in claim 7, characterized in that: An LED driving circuit is arranged between the source of the transistor Q3 and the VDD pin. The LED driving circuit includes a diode D1, and resistors RL1 and RL2 connected in series with the diode D1 and in parallel with each other.

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