GB2324945A - Horizontal deflection driving circuit in a multi-mode monitor has deflection frequency-dependent power supply - Google Patents

Horizontal deflection driving circuit in a multi-mode monitor has deflection frequency-dependent power supply Download PDF

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Publication number
GB2324945A
GB2324945A GB9809302A GB9809302A GB2324945A GB 2324945 A GB2324945 A GB 2324945A GB 9809302 A GB9809302 A GB 9809302A GB 9809302 A GB9809302 A GB 9809302A GB 2324945 A GB2324945 A GB 2324945A
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horizontal
driving
transistor
terminal
horizontal driving
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GB9809302D0 (en
GB2324945B (en
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Yong-Deog Shim
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WiniaDaewoo Co Ltd
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Daewoo Electronics Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/18—Generation of supply voltages, in combination with electron beam deflecting
    • H04N3/185—Maintaining dc voltage constant
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/27—Circuits special to multi-standard receivers
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G1/00—Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of data
    • G09G1/04—Deflection circuits ; Constructional details not otherwise provided for

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Details Of Television Scanning (AREA)

Abstract

In a horizontal deflection arrangement for a multi-mode monitor the voltage provided to the primary winding of a horizontal driving transformer HDT depends on the selected mode of the multi-mode monitor. In the multi-mode monitor the frequency of the horizontal driving signal changes with the video mode. The higher the frequency of the horizontal driving signal, the more current passes through the collector terminal of the horizontal driving transistor. Varied driving voltage depending on each video mode is provided by a driving power varying part 140 having voltage dividing circuits, each of which consists of a switching transistor and a resistor, parallel connected to each other to a primary side of the horizontal driving transformer. The current excited by the varied driving voltage compensates the variation of the driving current passing through the collector terminal of the horizontal driving transistor. Therefore, the constant current is excited at a secondary side of the horizontal driving transformer.

Description

HORIZONTAL DEFLECTION DRIVING CIRCUIT IN A MULTI-MODE MONITOR BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal deflection driving circuit in a monitor, and more particularly to a horizontal deflection driving circuit in a muiti-mode monitor which changes a voltage provided to a horizontal driving transformer depending on a mode of a video card.
2. Description of the Prior Art Generally, the monitor is a display apparatus in which a video signal and a synchronizing signal are received from the video card of a computer display on a picture tube screen. The monitor is composed of a video system for processing the video signal, a deflection system with a high voltage supply to produce scanning rasters on the picture tube screen, and a power system for supplying a driving power to the monitor. The deflection system has a vertical deflection block for generating a sawtooth current in vertical coils of a deflection yoke and a horizontal deflection block for generating a sawtooth current in horizontal coils of the deflection yoke and a rectified deflection voltage for boosted B+. A horizontal deflection oscillator, a horizontal deflection driver, and a power amplifier in the output stage for horizontal scanning are included in the horizontal deflection block.
The video card is classified by several modes according to the resolution to be realized. The classification of the video modes according to the resolution to be realized is shown in table 1.
[TABLE 1] Classification of the video modes
VIDEO MODE HORIZONTAL VERTICAL RESOLUTION FREQUENCY FREQUENCY (H*V) (KHz) (KHz) CGA 15.75 60 640 * 200 EGA 21.8 60 640 * 350 VGA 31.5 60 / 70 720 * 350 640 * 480 SVGA 35 - 37 INTERLACE 1024 * 768 HIGH 1024 * 768 RESOLUTION 64 - 75 60 - 70 1280 * 1024 MODE As shown in table 1, the horizontal frequency and the vertical frequency are changed according to the resolution to be realized, i.e., video modes. It has been desired to provide a monitor having a high resolution so that it can display increased amounts of data simultaneously in a computer terminal. In order to realize the display device having such a high resolution, it is necessary to carry out the horizontal deflection operation at high speeds maintaining large outputs(i.e., at a high horizontal scan frequency while a large horizontal deflection current flows into the horizontal deflection yoke). The more the horizontal frequency is increased, the more the flicker of the picture tube screen is prevented. Therefore, eye strain can be reduced.
The multi-mode monitor can realize at least two video modes, and is capable of altering a picture size and a picture position depending on the various horizontal frequencies(about 30 - 92KHz) generated from the video card according to each video mode, is capable of horizontal and vertical synchronization, is capable of optimizing the deflection system, and is capable of controlling the deflection correction circuit.
Before describing the horizontal deflection driving circuit in the multi-mode monitor, the deflection theory of the conventional monitor will be described below. An electron beam radiated from a cathode of the monitor is accelerated through a grid of the monitor, and is deflected by an electromagnetic force generated from a magnetic field of the deflection yoke. Therefore, a luminous point on the fluorescent plate is moved.
To achieve the above deflection operation the conventional monitor uses the electric deflection theory in which the deflection distance of the electron beam is proportional to a strength of the magnetic field, and the strength of the magnetic field is proportional to a current of the deflection yoke. Under the electromagnetic influence of the deflection yoke, the electron beam(s) are deflected vertically and horizontally simultaneously to produce scanning lines that slope slightly downward to the right. The deflection system of the conventional monitor has the horizontal deflection coil which forces the luminous point on the picture tube screen to move from left to right, i.e., a horizontal direction and a vertical deflection coil, which moves the luminous point from an upper side to a bottom side, i.e., a vertical direction to scan the electron beam from the left side of the picture tube screen to the right side of the picture tube screen at constant velocity and to return the electric beam to the left side of the picture tube screen at high velocity. The sawtooth waveform current as shown in FIG.
1 travels to the deflection yoke. The sawtooth waveform current for deflection provides linear scanning. The linear rise on the sawtooth is the trace part; the sharp drop in amplitude is for the retrace or flyback. Both trace and retrace are included in one cycle. At point E of the sawtooth waveform current in FIG. 1 the deflection force deflects the electron beam to the left side in largest angle, and at point F of the sawtooth waveform current the electron beam goes straight on because amplitude of the sawtooth waveform current is zero. From point F to point G of the sawtooth waveform current the current to deflect the electron beam toward the right side is gradually increased, and then the electron beam is deflected to the right side in largest angle at point G.
After that, the current is abruptly decreased and the above process is repeated from point E'.
FIG. 2 shows the conventional horizontal deflection circuit of the monitor. In FIG. 2, the horizontal synchronizing signal generated from the video card(unshown) is converted to a horizontal driving signal(H.drive) in a horizontal oscillating part(unshown), and then the horizontal driving signal(H.drive) is provided to a horizontal driving transistor TR1. When the horizontal driving signal(H.drive) turns on the horizontal driving transistor TR1, a driving power source Vcc and the horizontal driving transistor TR1 are conducted therethrough, and then an input current I1 is provided to a primary side of a horizontal driving transformer HDT. An output current I2 excited from a secondary side of the horizontal driving transformer HDT is provided to a base terminal of a horizontal output transistor TR2 for turning on the horizontal output transistor TR2. When the horizontal output transistor TR2 is turned on, a B+ power current of a flyback transformer(unshown) travels to the horizontal output transistor TR2 through the horizontal deflection yoke HDY. A period that the horizontal output transistor TR2 is turned on corresponds to a second half of an effective scanning period of the sawtooth waveform current(e. g., from point F to point G in FIG.1).
When the horizontal output transistor TR2 is abruptly turned off depending on the periodic output current I2, a retrace capacitor REC is charged by the charged current of the horizontal deflection yoke HDY. When the retrace capacitor REC is fully charged, the retrace capacitor REC is discharged to the horizontal deflection yoke HDY, and thus the horizontal deflection yoke HDY is re-charged by the charged current of the retrace capacitor REC. At this time, the retrace period(from point G to point E' in FIG. 1) is the total period that the retrace capacitor is charged and discharged. Also, when the horizontal deflection yoke HDY is charged fully with energy and then a damper diode DD is forward biased by the deflection yoke voltage, the damper diode DD is conductive and then the current traveling through the horizontal deflection yoke HDY drops to zero. The period that the current travels through the damper diode DD as described above corresponds to a first half of the effective scanning period(that is, from point E to point F in FIG.1). At the time that the current traveling through the horizontal deflection yoke HDY drops to zero, the horizontal output transistor TR2 is turned on again by the horizontal driving signal (H.drive), and the above process is repeated. Thus, the sawtooth waveform current travels through the horizontal deflection yoke HDY and then the electron beam achieves the horizontal deflection.
If, however, the conventional horizontal deflection circuit is employed in the multi-mode monitor, the horizontal driving transformer HDT always receives the constant driving power Vcc irrelevant to the frequency change of the horizontal driving signal (H.drive). Therefore, when the frequency of the horizontal driving signal(H.drive) is changed from high to low according to each video mode, the output current I2 at the secondary side of the horizontal driving transformer HDT is increased, and thus the base current of the horizontal output transistor TR2 is also increased.
That is, the output current I2 excited from the secondary side of the horizontal driving transformer HDT is varied because the horizontal frequency is changed depending on each video mode, and then the base current of the horizontal output transistor TR2 is changed. Thus, the power consumption of the secondary side of the horizontal driving transformer HDT is varied. Therefore, the design of the horizontal deflection circuit is complicated. Further, we hardly expect that the horizontal output transistor TR2 is stably switched due to the change of the base current of the horizontal output transistor TR2. Therefore, there is a problem that the optimization of the horizontal deflection circuit is difficult to realize according to each video mode.
SUMMARY OF THE INVENTION Therefore, the present invention is developed to solve the above problems.
An object of the present invention is to provide a horizontal deflection driving circuit in a multi-mode monitor in which, in one embodiment, a constant base current is always provided to a base terminal of the horizontal output transistor by varying the voltage provided to the primary side of the horizontal driving transformer in each video mode.
Another object of the present invention is to provide a horizontal deflection driving circuit in a multi-mode monitor which, in one embodiment, compensates a change of the current travelling through the horizontal driving transistor depending on a frequency variation of a horizontal driving signal by varying the voltage provided to the primary side of the horizontal driving transformer in each video mode.
To accomplish the above objects, the horizontal deflection driving circuit in the multi-mode monitor according to the present invention has: a driving power varying portion which receives a driving power and video mode information signals corresponding to each video mode and for varying a magnitude of the driving power depending on the video mode information signals; a horizontal driving transistor which has a collector terminal connected to the driving power varying portion through a resistor in parallel and is switched by a horizontal driving signal that is varied depending on video modes and is provided to a base terminal thereof; a horizontal driving transformer having one end of a primary side thereof serially connected to an output terminal of the driving power varying portion and the other end of the primary side thereof serially connected to the collector terminal of the horizontal driving transistor, and which receives a driving signal from the driving power varying portion by a switching operation of the horizontal driving transistor at a primary side thereof and then excites an output current at a secondary side thereof; a horizontal output transistor switched by the output signal generated from the secondary side of the horizontal driving transformer, and in which a base terminal receives the output signal excited from the secondary side of the horizontal driving transformer and an emitter terminal is grounded; and a sawtooth waveform generating portion having a damper diode and a retrace capacitor and for generating a deflecting current with a sawtooth waveform from a deflection voltage depending on an switching operation of the horizontal output transistor, the damper diode having an anode connected to a collector terminal of the horizontal output transistor in parallel, a grounded cathode, and a horizontal deflection yoke connected to the retrace capacitor in parallel, the retrace capacitor connected to the anode of the damper diode in parallel.
The horizontal deflection driving circuit in the multimode monitor according to the present invention as described above provides the driving signal, which is excited from the driving power varying portion depending on each video mode, to the primary side of the horizontal driving transformer. The the driving power varying portion compensates the change of the driving signal due to the frequency change of the horizontal driving signal depending on each video mode.
Therefore, at the secondary side of the horizontal driving transformer the constant signal is excited in each video mode.
In result, the optimization of the horizontal deflection circuit can be easily realized in the multi-mode monitor according to each video mode.
BRIEF DESCRIPTION OF THE DRAWINGS Examples of embodiments of the present invention will now be described with reference to the-drawings, in which: - FIG. 1 is a graph showing a deflection current with a sawtooth waveform; FIG. 2 shows the conventional horizontal deflection circuit of the monitor; and FIG. 3 shows a horizontal deflection driving circuit in the multi-mode monitor according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A description will be given below in detail with reference to the accompanying drawings of an embodiment of the present invention.
FIG. 3 is the horizontal deflection driving circuit in the multi-mode monitor according to the embodiment of the present invention. As shown in FIG. 3, the horizontal deflection driving circuit in the multi-mode monitor according to the embodiment of the present invention has a driving power varying portion 100 connected to a driving power Vcc and which varies the magnitude of the driving power Vcc depending on video mode information signals from the micom(unshown). An output terminal of the driving power varying portion 100 is connected to a collector terminal of a horizontal driving transistor TR1 through a resistor in parallel. An emitter terminal of the horizontal driving transistor TR1 is grounded.
The horizontal driving transistor TR1 receives a varied horizontal driving signal depending on video modes through a base terminal thereof and then is switched by the horizontal driving signal. One end of a primary side of a horizontal driving transformer HDT is serially connected to the output terminal of the driving power varying portion 100, and the other end thereof is serially connected to a collector terminal of the horizontal driving transistor TR1. The horizontal driving transformer HDT receives a varied driving signal from the driving power varying portion 100 depending on the switching operation of the horizontal driving transistor TRl and excites an output signal at a secondary side thereof.
A base terminal of a horizontal output transistor TR2 is serially connected to the secondary side of the horizontal driving transformer HDT. The horizontal output transistor TR2 has a grounded emitter terminal and is switched by the output signal of the horizontal driving transformer HDT. A collector terminal of the horizontal output transistor TR2 is parallel connected to an anode terminal of a damper diode DD. A cathode terminal of the damper diode DD is grounded. The anode terminal of the damper diode DD is connected to a retrace capacitor REC in parallel. The retrace capacitor REC is connected to a horizontal deflection yoke HDY in parallel. A sawtooth waveform generating portion consists of the damper diode DD, the retrace capacitor REC, and the horizontal deflection yoke HDY. The sawtooth waveform generating portion generates a deflection current with a sawtooth waveform from a horizontal deflection voltage depending on a switching operation of the horizontal output transistor TR2.
The driving power varying portion 100 consists of a varied power generating part 140 and a varied power path 180.
Input terminals of the varied power generating part 140 are connected to the driving power Vcc and output terminals for the video mode information signals of the micom. An output terminal of the varied power generating part 140 is connected to the varied power path 180. The varied power generating path 180 consists of n switching members, which are parallel connected to each other and each of which is switched by the corresponding video mode information signal, and n dividing resistors, each of which is serially connected to the corresponding switching member. The dividing resistors are connected to the driving power Vcc through a path resistor.
The dividing resistors and the path resistor divide the driving power according to the switching operation of the switching members. The varied power path 180 is connected to the driving power Vcc and the varied power generating portion 140 parallel with the path resistor. The varied power path 180 is a path in which the varied power depending on the video mode information signals is provided to the horizontal driving transformer HDT therethrough.
The number of the output terminals for video mode information signals is decided by the number of the video modes to realize. In this embodiment, we will describe the multi-mode monitor that uses two video mode information signals, e.g., CS0 and CS1.
The varied power generating part 140 has a first transistor Q1 and a second transistor Q2, each base terminal of which is connected to the video mode information signal terminal CS0 or CSl of the micom. A collector terminal of the first transistor Q1 is connected to the driving power Vcc through a first dividing resistor R1 and a second dividing resistor R2 which are serially connected there between. An emitter terminal of the first transistor Q1 is grounded. The second transistor Q2 has a collector terminal parallel connected to the second dividing resistor R2 through the third dividing resistor R3 and a grounded emitter terminal.
The varied power path 180 consists of a third transistor Q3, a fourth transistor Q4, and a diode. The third transistor Q3 has a collector terminal connected to the driving power Vcc parallel with the first dividing resistor Rl, a base terminal parallel connected to the second dividing resistor R2, and an emitter terminal connected to the base terminal of the fourth transistor Q4. The fourth transistor Q4 has a collector terminal connected to the collector terminal of the third transistor QB in parallel and an emitter terminal connected to the base terminal of the fourth transistor Q4 through the diode.
The emitter terminal of the fourth transistor Q4 is connected to one end of a primary side of a horizontal driving transformer HDT. The other end of the primary side of the horizontal driving transformer HDT is connected to a collector terminal of a horizontal driving transistor TR1. The horizontal driving transistor TR1 is switched by a horizontal driving signal(H.drive) received through the base terminal thereof. Depending on the switching operation of the horizontal driving transistor TRl an induced current is excited at a secondary side of the horizontal driving transformer HDT. The induced current switches a horizontal output transistor TR2. A collector terminal of the horizontal output transistor TR2 is connected to an anode of a damper diode DD in parallel. A cathode of the damper diode DD is grounded. A retrace capacitor REC is connected to the anode of the damper diode DD in parallel. The retrace capacitor REC is connected to a horizontal deflection yoke HDY in parallel.
In this embodiment of the present invention, the magnitudes of the first, second, and third dividing resistors R1, R2, R3 are selected to meet the requirements that the higher the resolution of each video mode, the lower the driving voltage is provided to the primary side of the horizontal driving transformer HDT.
Hereinbelow, operation and effects of the horizontal deflection driving circuit in the multi-mode monitor according to an embodiment of the present invention will be described according to logical values of the video mode information signals CS0, CS1.
Table 2 shows the logical values of the video mode information signals corresponding to the video modes.
[TABLE 2] Logical values of the video mode information signals
N CSO CSl MODE 1 LOW LOW MODE 2 LOW HIGH MODE 3 HIGH LOW R MODE 4 HIGH HIGH Here, CS0 is a first mode information signal, and CSl is a second mode information signal. The higher the mode number, the higher the horizontal driving frequencytH.drive) is used in. That is, the resolution of mode 4 is higher than the resolution of mode 1.
MODE 1 > When the video mode information signals CS0, CSI have 'low' levels, the first transistor Q1 and the second transistor Q2 are turned off, and thus no current travels through the second and third dividing resistors R2, R3. That is, the driving power Vcc is provided to the horizontal driving transformer HDT through the common base transistors Q3, Q4 after a reduced voltage through the first dividing resistor R1 is provided to the base terminal of the third transistor Q3. That is, a first driving voltage VA1 of the horizontal driving transformer HDT is equal to the driving power Vcc. The horizontal driving transistor TR1 provides a periodic pulse signal to the primary side of the horizontal driving transformer HDT by a first horizontal driving signal received through the base terminal thereof, and thus the output current is excited at the secondary side of the horizontal driving transformer HDT. When the horizontal output transistor TR2 is turned on by the output current, the B+ power current of a flyback transformer(unshown) travels to the horizontal output transistor TR2 through the horizontal deflection yoke HDY.
When the horizontal output transistor TR2 is abruptly turned off depending on the periodic output current, a retrace capacitor REC is charged by the charged current of the horizontal deflection yoke HDY. When the retrace capacitor REC is fully charged, the retrace capacitor REC is discharged to the horizontal deflection yoke HDY, and thus the horizontal deflection yoke HDY is re-charged by the charged current of the retrace capacitor REC.
Also, when the horizontal deflection yoke HDY is charged full with energy and then a damper diode DD is forward biased by the deflection yoke voltage, the damper diode DD is conductive and thus the current traveling through the horizontal deflection yoke HDY drops to zero. At the time that the current traveling through the horizontal deflection yoke HDY drops to zero, the horizontal output transistor TR2 is turned on again by the horizontal driving signal (H.drive), and the above process is repeated. Thus, the sawtooth waveform current travels through the horizontal deflection yoke HDY, and then the electron beam achieves the horizontal deflection.
MODE 2 > When the first video mode information signal CS0 has a 'low' level, and the second video mode information signal CS1 has a 'high' level, the first transistor Q1 is turned off and the second transistor Q2 is turned on. Thus the current travels to the first dividing resistor R1 and the third dividing resistor R3 connected to the driving power Vcc. As the driving power Vcc is divided by the first dividing resistor R1 and the third dividing resistor R3, the third transistor Q3 and the fourth transistor Q4 are turned on, and a second driving voltage VA2 at A-point provided to the horizontal driving transformer HDT is shown in the expression 1.
R3 VA2 = w - x Vcc (1) R1+R3 Here, VA2 is a voltage provided to the primary side of the horizontal driving transformer HDT in mode 2.
The second driving voltage VA2 provided to the primary side of the horizontal driving transformer HDT is lower than the first driving voltage VA1 in mode 1. The current excited by the second driving voltage at the primary side of the horizontal driving transformer HDT is less than the current excited by the first driving voltage in mode 1. However, the current excited by a second horizontal driving signal at the primary side of the horizontal driving transformer HDT is more than the current excited by the first horizontal driving signal in mode 1 because the second horizontal driving signal having a frequency higher than the frequency of the first horizontal driving signal in mode 1 is provided to the horizontal driving transistor TR1. That is, the driving power varying portion 100 in mode 2 provides the second driving voltage lower than the first driving voltage to the primary side of the horizontal driving transformer HDT, but the resolution in mode 2 is higher than the resolution in mode 1, i.e., the second horizontal driving frequency in mode 2 is higher than the first horizontal driving frequency in mode 1.
The current excited at the primary side of the horizontal driving transformer HDT consists of the current excited by the second driving voltage and the current excited by the second horizontal driving signal. As the second driving voltage provided to the primary side of the horizontal driving transformer HDT is decreased, the strength of the current excited by the second driving voltage is decreased. However, as the second horizontal driving frequency is increased, the strength of the current excited by the second horizontal driving signal is increased. In result, the current with the same magnitude as mode 1 travels through the primary side of the horizontal driving transformer HDT in mode 2 by compensating the frequency change of the horizontal driving signal with the change of the driving voltage. Therefore, the output current excited at the secondary side of the horizontal driving transformer HDT in mode 2 has the same magnitude as the output current in mode 1.
MODE 3 > When the first video mode information signal CS0 has a 'high' level, and the second video mode information signal CS1 has a 'low' level, the first transistor Q1 is turned on and the second transistor Q2 is turned off. Thus the current travels through the first dividing resistor R1 and the second dividing resistor R2 connected to the driving power Vcc. That is, a third driving voltage VA3 provided to A-point of the primary side of the horizontal driving transformer HDT is shown in the expression 2.
R2 VA3 = ------- x Voc (2) R1+R2 Here, VA3 is a voltage provided to the primary side of the horizontal driving transformer HDT in mode 3.
As the third driving voltage VA3 in mode 3 is lower than the second driving voltage VA2 in mode 2, the strength of the current excited by the third driving voltage is less than the current excited by the second driving voltage. As a third horizontal driving frequency in mode 3 is higher than the second horizontal driving frequency in mode 2, the strength of the current excited by the third horizontal driving frequency is more than the current excited by the second horizontal driving frequency. In result, the current with the same magnitude as mode 2 travels through the primary side of the horizontal driving transformer HDT in mode 3 by compensating the frequency change of the horizontal driving signal with the voltage change of the driving voltage. Therefore, the output current excited at the secondary side of the horizontal driving transformer HDT in mode 3 has the same magnitude as the output current in mode 1 or 2.
MODE 4 > When the first video mode information signal CSO and the second video mode information signal CS1 have 'high' levels, the first transistor Q1 and the second transistor Q2 are turned on. After that, the driving voltage Vcc is divided by the first dividing resistor R1, the second dividing resistor R2, and the third dividing resistor R3. The divided driving power is provided to the horizontal driving transformer HDT through the common base transistors Q3, Q4.
A fourth driving voltage VA4 provided to A-point in the primary side of the horizontal driving transformer HD to the fourth horizontal driving signal with the frequency higher than the frequency in mode 3 but the strength of the fourth driving voltage lower than the strength of the third driving voltage.
As described above, the horizontal deflection driving circuit in the multi-mode monitor decreases the driving voltage provided to the primary side of the horizontal driving transformer HDT when the horizontal driving frequency obtained from the video card is increased. That is, when the frequency of the horizontal driving signal is increased, the current traveling through the collector terminal of the horizontal driving transistor switched by the horizontal driving signal is also increased. Even if the video mode is changed, constant current can be provided to the primary side of the horizontal driving transformer by compensating the increment of the current excited by the horizontal driving signal with the decrement of the current excited by the decreased voltage at the primary side of the horizontal driving transformer, and thus the magnitude of the current obtained from the secondary side of the horizontal driving transformer is constant. In result, even if the video mode is changed, the horizontal deflection driving circuit in the multi-mode monitor can make constant the amount of the current excited at the secondary side of the horizontal driving transformer, i.e., the amount of the base current of the horizontal output transistor.
Therefore, the optimized horizontal deflection circuit is easily realized in the multi-mode monitor. Further, the horizontal deflection circuit can be operated stably.
In the above, the present invention is described in detail by using the preferred embodiment, but the invention is not limited in the above embodiment. It should be obvious to people skilled in the conventional art that modifications can be made to the invention as described above without departing from the the scope of the invention.

Claims (4)

1. A horizontal deflection driving circuit of a multimode monitor comprising: a driving power varying portion which receives a driving power and video mode information signals corresponding to each video mode and for varying a magnitude of the driving power depending on the video mode information signals; a horizontal driving transistor which has a collector terminal connected to the driving power varying portion through a resistor in parallel and is switched by a horizontal driving signal that is varied depending on video modes and is provided to a base terminal thereof; a horizontal driving transformer having one end of a primary side thereof serially connected to an output terminal of the driving power varying portion and the other end of the primary side thereof serially connected to the collector terminal of the horizontal driving transistor, and which receives a driving signal from the driving power varying portion by a switching operation of the horizontal driving transistor at a primary side thereof and then excites an output current at a secondary side thereof; a horizontal output transistor switched by the output signal generated from the secondary side of the horizontal driving transformer, and in which a base terminal receives the output signal excited from the secondary side of the horizontal driving transformer and an emitter terminal is grounded; and a sawtooth waveform generating portion having a damper diode and a retrace capacitor and for generating a deflecting current with a sawtooth waveform from a deflection voltage depending on a switching operation of the horizontal output transistor, the damper diode having an anode connected to a collector terminal of the horizontal output transistor in parallel, a grounded cathode, and a horizontal deflection yoke connected to the retrace capacitor in parallel, the retrace capacitor connected to the anode of the damper diode in parallel.
2. A horizontal deflection driving circuit in the multimode monitor as claimed in claim 1, wherein said driving power varying portion 100 comprises: a varied power generating portion 140 having switching members, which are parallel connected to each other and are switched depending on the video mode information signals, and resistors, which are disposed between the driving power Vcc and the switching members and divide the driving power according to a switching operation of the switching members; and a varied power path 180 serially connected to the driving power Vcc and parallel connected to the varied power generating portion 140 and for providing the power varied by the video mode information signals to the horizontal driving transformer HDT.
3. The horizontal deflection driving circuit in the multi-mode monitor as claimed in claim 1, wherein said driving power varying portion 100 comprises: a first transistor Q1 and a second transistor Q2 switched by each of video mode information signals CS0, CS1, the first transistor Q1 having a collector terminal parallel connected to the driving power Vcc through a first dividing resistor R1 and a second diving resistor R2 and a grounded emitter terminal, the second transistor Q2 having a collector terminal parallel connected to the second dividing resistor R2 through a third dividing resistor R3 and a grounded emitter terminal; a varied power path having a third transistor Q3, a fourth transistor Q4, and a diode for providing the varied power to the horizontal driving transformer HDT, the third transistor Q3 having a collector terminal connected to the driving power Vcc parallel with the first dividing resistor R1, a base terminal parallel connected between the second dividing resistor R2 and the first dividing resistor Rl, and an emitter terminal connected to the base terminal of the fourth transistor Q4, the fourth transistor Q4 having a collector terminal parallel connected to the collector terminal of the third transistor Q3, a base terminal connected to an anode of the diode, and an emitter terminal connected to the cathode terminal of the diode.
4. A horizontal deflection driving circuit substantially as hereinbefore described with reference to and illustrated by Figure 3 of the drawings.
GB9809302A 1997-04-30 1998-04-30 Horizontal deflection driving circuit in a multi-mode monitor Expired - Fee Related GB2324945B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1019970016785A KR100221339B1 (en) 1997-04-30 1997-04-30 Horizontal deflection drive circuit in multi-mode monitor

Publications (3)

Publication Number Publication Date
GB9809302D0 GB9809302D0 (en) 1998-07-01
GB2324945A true GB2324945A (en) 1998-11-04
GB2324945B GB2324945B (en) 2001-05-23

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GB9809302A Expired - Fee Related GB2324945B (en) 1997-04-30 1998-04-30 Horizontal deflection driving circuit in a multi-mode monitor

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2340708A (en) * 1998-08-07 2000-02-23 Thomson Consumer Electronics Power supply for a deflection circuit operating at multi-scan frequencies

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4574224A (en) * 1983-08-17 1986-03-04 Zenith Electronics Corporation Variable rate horizontal deflection system for a video monitor
GB2192508A (en) * 1986-06-27 1988-01-13 Rca Corp Multi-scan rate monitor power supply
EP0254573A2 (en) * 1986-07-24 1988-01-27 Microvitec PLC Horizontal deflection stage
EP0510461A1 (en) * 1991-04-24 1992-10-28 Mitsubishi Denki Kabushiki Kaisha Auto scan horizontal deflection apparatus
US5212552A (en) * 1991-07-15 1993-05-18 Matsushita Electric Industrial Co., Ltd. Horizontal deflection circuit
US5614794A (en) * 1995-04-24 1997-03-25 Shamrock Technology Company Limited Horizontal deflection circuit for a multisync monitor

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4574224A (en) * 1983-08-17 1986-03-04 Zenith Electronics Corporation Variable rate horizontal deflection system for a video monitor
GB2192508A (en) * 1986-06-27 1988-01-13 Rca Corp Multi-scan rate monitor power supply
EP0254573A2 (en) * 1986-07-24 1988-01-27 Microvitec PLC Horizontal deflection stage
EP0510461A1 (en) * 1991-04-24 1992-10-28 Mitsubishi Denki Kabushiki Kaisha Auto scan horizontal deflection apparatus
US5212552A (en) * 1991-07-15 1993-05-18 Matsushita Electric Industrial Co., Ltd. Horizontal deflection circuit
US5614794A (en) * 1995-04-24 1997-03-25 Shamrock Technology Company Limited Horizontal deflection circuit for a multisync monitor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2340708A (en) * 1998-08-07 2000-02-23 Thomson Consumer Electronics Power supply for a deflection circuit operating at multi-scan frequencies
GB2340708B (en) * 1998-08-07 2003-01-08 Thomson Consumer Electronics A power supply for a deflection circuit operating at multi-scan frequencies

Also Published As

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GB9809302D0 (en) 1998-07-01
KR100221339B1 (en) 1999-09-15
KR19980079111A (en) 1998-11-25
GB2324945B (en) 2001-05-23

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