KR200147281Y1 - Synchronized signal polarity discrimination circuit for projector - Google Patents

Abstract

The present invention is a projection type image display system in which a polarity discrimination signal for discriminating the polarity of a synchronization signal according to the external image signal has a continuous output level when displaying a composite image signal from the outside of the projection image display system. A synchronization signal polarity discrimination circuit is provided.

Accordingly, the present invention is a projection type image display system which receives a composite image signal from the outside and forms a projection image on a screen screen, and receives the synchronization signal SYNC according to the composite image signal and receives the synchronization signal SYNC. The first flip-flop 10 for generating an output pulse whose polarity is inverted at each pulse input of the signal), the inverting element 12 for inverting the signal level of the synchronous signal SYNC, and the inverting element 12 through the inverting element 12. The second flip-flop 14, the first flip-flop 10, and the second flip-flop (14) for receiving an inputted synchronization signal SYNC and generating an output pulse whose polarity is inverted at every pulse input of the synchronization signal SYNC. A first logic element 16 for generating a synchronous output signal for receiving the output pulses from the circuit 14 and performing logic processing to generate a synchronous pulse, and the synchronous signal SYNC and the first logic element 16; Processing the synchronous output signal from And a second logic element 18 for generating a polarity discrimination signal having a continuous level corresponding to the polarity of the synchronization signal SYNC, which not only ensures a stable polarity discrimination operation but also has a continuous level. The polarity discrimination signal is generated to facilitate polarity discrimination.

Description

Synchronization signal polarity discrimination circuit of projection image display system

The present invention relates to a synchronization signal polarity discrimination circuit of a projection image display system, and more particularly, to a synchronization signal polarity discrimination circuit of a projection image display system for discriminating whether the synchronization signal from the outside is positive or negative. .

As is well known, the image display device is roughly divided into a direct type display device represented as a CRT device and a projection display device represented as an LCD device, among which a CRT device as a direct display device is used on a fluorescent panel. When a fluorescent point is formed and the electron beam is focused on the R, G, B fluorescent point, the corresponding fluorescent point is emitted to enable display of a color image. However, in such a CRT apparatus, the R, G, B fluorescent point is formed for one pixel. In addition, the screen is not limited to the enlargement of the screen, and the manufacturing cost is increased due to the complicated manufacturing process.

On the other hand, in the LCD device which is a projection display device, a target image is displayed by applying a voltage corresponding to an image signal from the uniform arrangement of liquid crystals as a liquid crystal driving voltage and adjusting the arrangement direction of the liquid crystals with a polarizing plate, thereby making it a relatively light weight. Although thinning is possible, such LCD device has the disadvantage that the light loss is increased by the polarizing plate for adjusting the amount of light emitted relative to the total amount of incident light.

In view of this, in recent years, a projection image display system using AMA (Actuated mirror array) has been proposed to display color images. The projection image display system using the AMA is a state in which AMA is arranged in one dimension. It is composed of a one-dimensional structure in which M × 1 light beams are prescanned using a scanning mirror, or a two-dimensional structure in which M × N light beams are projected to represent an image having an array of M × N pixels.

As such an AMA device has been proposed and put into practical use, a video signal of a television or a video tape recorder or a PC (Personal Computer) is implemented as an AMA projector instead of a dedicated monitor. Synchronization signals of video devices (e.g. TV, VCR, etc.) are negative polarity, but in the case of a PC, the synchronization polarity is different depending on the screen mode and the supported video card.

Therefore, the projection type image display system using AMA recognizes the polarity of the input synchronization and converts it to the synchronization polarity used in the system for signal processing.

That is, when an external composite video signal having a positive polarity signal or a negative polarity signal is input to the synchronous separation circuit, it is converted into a horizontal synchronous signal and a vertical synchronous signal by an operation in the synchronous separation circuit. In this case, the polarity of the output synchronization signal is, for example, after the positive or negative polarity is recognized by the counting result from the counter counting the number of clocks in the high pulse period. Is output as it is, and the negative synchronization signal is converted to positive polarity and then output.

In this case, the self-determination of the polarity of the synchronization signal included in the composite video signal from the outside should be preceded. The polarity discrimination circuit for determining the polarity of the synchronization signal is separated from the synchronization as shown in FIG. The synchronous signal separated by the circuit (not shown) is integrated into the DC component by the integrating element composed of the resistor R1 and the capacitor C1 and converted into digital data by the ADC (Analog-Digital Converter). It is determined whether the corresponding synchronization signal is positive or negative.

In addition, another polarity discrimination circuit for determining the polarity of the synchronization signal counts the synchronization signal separated based on the clock pulse through the counter 4 as shown in FIG. 2 to determine whether the synchronization signal is positive or negative. The signal to be discriminated can be output.

However, the polarity discrimination circuit using the integrating element and ADC 2 shown in FIG. 1 has a disadvantage in that the circuit configuration for polarity discrimination of the sync signal is complicated, and the polarity of the sync signal using the counter shown in FIG. Since the discrimination circuit has a different frequency according to the mode of the synchronization signal input from the outside, there is a disadvantage that there is a possibility of error occurrence in the counting operation due to the clock pulse, and that the stable polarity discrimination operation cannot be guaranteed. However, since the polarity discrimination output output through the conventional polarity discrimination circuit has a pulse period similar to or the same as that of the input synchronization signal, it is not possible to easily perform polarity discrimination in subsequent signal processing means.

Accordingly, the present invention has been made in view of the above circumstances, and in the case of displaying a composite video signal from the outside of the projection image display system on the screen, a polarity discrimination signal for discriminating the polarity of the synchronization signal according to the external video signal is provided. It is an object of the present invention to provide a synchronization signal polarity discrimination circuit of a projection type image display system in which the power supply has a continuous output level.

According to the synchronization signal polarity discrimination circuit of the projection type image display system according to the present invention to achieve the above object, in the projection type image display system for receiving a composite image signal from the outside to form a projection image on the screen screen, A first flip-flop that receives a sync signal according to a composite video signal and generates an output pulse whose polarity is inverted at every pulse input of the sync signal, an inverting device for inverting the signal level of the sync signal, and inverting through the inverting device A second flip-flop that generates an output pulse whose polarity is reversed every time a pulse input of the sync signal is received, and the output pulses from the first flip-flop and the second flip-flop are received and logically processed. A first logic element for generating a synchronous output signal having a constant polarity and from the synchronous signal and the first logic element A synchronization signal polarity discrimination circuit of a projection type image display system comprising a second logic element for logic processing a synchronous output signal and generating a polarity discrimination signal having a continuous level corresponding to the polarity of the synchronous signal.

According to the present invention configured as described above, in the case of determining the polarity of the composite video signal applied from the external image reproducing apparatus in the projection type image display system, the level of the signal according to the polarity discrimination result is continuously maintained, thereby making it easier to Make polarity discrimination possible.

1 and 2 are circuit configuration diagrams showing a conventional general synchronous polarity discrimination circuit,

3 is a circuit diagram showing a synchronization signal polarity discrimination circuit of a projection image display system according to the present invention;

4 is a signal waveform diagram illustrating a polarity discrimination operation for an external synchronization signal according to a preferred embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10 --- first flip-flop, 12 --- inverter,

14 --- second flip-flop, 16 --- first exclusive oragate,

18 --- Second Exclusive Oagate.

Hereinafter, the present invention configured as described above will be described in detail with reference to the accompanying drawings.

That is, Fig. 3 is a circuit diagram showing a synchronization signal polarity discrimination circuit of the projection type image display system according to the present invention. In the apparatus of the present invention, reference numeral 10 denotes that the T terminal is connected to a power supply terminal (Vcc) and the clock terminal thereof. The signal level is maintained from the rising edge of the corresponding synchronizing signal SYNC to the subsequent rising edge while the synchronization signal SYNC of the composite video signal inputted from the outside is maintained, and from the subsequent rising edge to the next rising edge. A first flip-flop, for example a T-flop flop, in which the signal level is kept inverted is shown.

In addition, reference numeral 12 denotes an inverter which inverts the signal level for the synchronization signal SYNC in the positive or negative state, and 14 denotes the inverter 12 having its T terminal connected to a power supply terminal Vcc. Receives the synchronization signal SYNC inverted by the clock terminal and maintains the signal level from the rising edge of the corresponding synchronization signal SYNC to the subsequent rising edge, and the signal level is increased from the subsequent rising edge to the next rising edge. A second flip flop consisting of, for example, a T-flip flop that is kept inverted.

Reference numeral 16 denotes an exclusive OR of the output pulse signal from the first flip-flop 10 and the output pulse signal from the second flip-flop 14 to always generate a synchronous output signal having a positive pulse. A first exclusive oragate is shown, and 18 is a polarity having a continuous low level or a high level by receiving an exclusive OR by receiving the synchronization signal SYNC and the synchronization output signal from the first exclusive oragate 16. A second exclusive orifice that generates a discrimination signal is shown.

Next, the operation of the present invention made as described above will be described in detail with reference to the accompanying drawings.

First, in the projection type image display system, the polarity of the synchronization signal SYNC according to the composite image signal in the state of receiving the composite image signal from an external image reproducing apparatus such as a television, a video tape recorder or a PC to reproduce the image on the screen. In the case of this positive polarity, the first flip-flop 10 causes the pulse to be maintained from the rising edge of the positive synchronization signal SYNC to the subsequent rising edge and the signal level is increased from the subsequent rising edge to the next rising edge. While generating an inverted output pulse, the second flip-flop 14 receives the sync signal SYNC whose signal level is inverted by the inverter 12 and subsequently rises at the rising edge of the sync signal SYNC. It generates an output pulse that keeps the pulse up to the edge.

As a result, the first exclusive oragate 16 receives the output pulse from the first flip-flop 10 and the output pulse from the second flip-flop 14 to perform an exclusive OR. As shown in FIG. 4, a synchronous output signal having positive polarity is generated.

At this time, the second exclusive orifice 18 receives the synchronous signal SYNC and the synchronous output signal from the first exclusive oragate 16 and performs exclusive OR processing as shown in FIG. 4. As described above, a polarity discrimination signal having a low level is generated.

On the other hand, when the polarity of the composite video signal from the outside is negative, the second flip-flop (receiving the output pulse from the first flip-flop 10 and the synchronization signal SYNC inverted by the inverter 12) As shown in FIG. 4, the first exclusive oragate 16 having received the output pulse from 14 generates a synchronous output signal having positive polarity.

Accordingly, the second exclusive orifice 18 receives an exclusive logic sum by receiving a synchronization signal SYNC having the negative polarity and an output pulse signal having the positive polarity from the first exclusive oragate 16. Processing will generate a polarity discrimination signal having a constant high level as shown in FIG.

According to the present invention made as described above, in the projection type image display system, it is possible to form a polarity discrimination signal having a constant level at the time of polarity discrimination against a synchronization signal from the outside, thereby not only to ensure a stable polarity discrimination operation at all times. Therefore, the polarity discrimination signal having the continuous level can be generated, so that the polarity discrimination can be made more easily.

Claims (2)

In the projection type image display system for receiving a composite image signal from the outside to form a projection image on the screen screen, A first flip-flop 10 which receives the sync signal SYNC according to the composite video signal and generates an output pulse whose polarity is inverted every time the pulse of the sync signal SYNC is input; An inverting element 12 which inverts the signal level of the synchronization signal SYNC, A second flip-flop 14 which receives the inverted sync signal SYNC through the inverting element 12 and generates an output pulse whose polarity is inverted at every pulse input of the sync signal SYNC; A first logic element 16 which receives the output pulses from the first flip-flop 10 and the second flip-flop 14 and performs a logic process to generate a synchronous output signal such that the sync pulse has a certain polarity; A second logic element for logic processing the sync signal SYNC and the sync output signal from the first logic element 16 to generate a polarity discrimination signal having a continuous level corresponding to the polarity of the sync signal SYNC; 18. A synchronization signal polarity discrimination circuit of a projection type image display system, comprising: 2. The synchronization signal polarity discrimination circuit according to claim 1, wherein the first logic element (16) and the second logic element (18) are made of an exclusive oragate.