JP3655344B2 - Color display device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a color display device that displays a desired color by arranging a color display body, which is divided into a plurality of colors, on a dot matrix, and rotating and stopping it with a motor. The present invention relates to information that can display video information from a still image to a moving image and that is used in the fields of advertisement display devices, wall surface video display devices, and the like.
[0002]
[Prior art]
As a pulse method for driving the color display motor, the applicant of the present invention has disclosed a motor driving pulse as an acceleration pulse and a braking pulse, or an acceleration pulse according to Japanese Patent Application Laid-Open Nos. 5-297812 and 5-303338. Although a method comprising a deceleration pulse and a braking pulse has been proposed, the same waveform is used for the braking pulse when moving from the moving image screen to the still screen. In other words, the drive pulse is configured to finish all within one frame period. When a dot defect occurs due to a malfunction, the dot defect remains if the same display color continues for two or more frames. The effect of preventing this was not given. As a result, in the last frame period of the moving image plane, the state of each dot is displayed as a still screen, and if there is a dot defect on that screen, the dot defect will be displayed as long as the still screen continues. there were.
[0003]
In Japanese Patent Laid-Open No. 5-297811, each color display element constituting the screen, that is, display color data transmitted in the current frame for each dot and display color data of the previous frame are displayed. If the two are different, the above motor is driven and a new screen is displayed. However, in the proposed method, a motor that does not change the display color has a power-saving effect without giving a drive pulse, while it does not drive with the same display color. At times, the state of dot defects continues, causing inconvenience.
[0004]
[Problems to be solved by the invention]
In general, since the same screen is displayed continuously for still images, dot defects on the screen that do not bother you on the video screen stand out, and once the dot defects are displayed, the color changes, There was a problem that the state was displayed indefinitely until it became a new image. On the other hand, there are some variations due to the manufacturing process due to the characteristics of the motor. For example, in order to avoid any dot defects on the entire screen, braking pulses must be applied for a longer period than necessary. There was a problem in terms of quick frame switching. The present invention provides means for reducing dot defects in a still image without reducing the frame speed of the moving image.
[0005]
[Means for Solving the Problems]
In the present invention, when the color display element is rotated, the period of the braking pulse which is a part of the driving pulse used on the moving image plane is extended, regenerated, or changed in shape, so that the dot defect is stationary. The device is designed to minimize the amount of images brought into the picture. The moving image plane and the still screen here mean a case where the color of each dot constituting the screen changes or does not change in the next frame period. In this embodiment, the display of the first frame period is performed. When the color data and the display color data of the second frame period are the same, when the display color data does not change from the period of the second frame or the first frame period and several frames continue, the nth frame indicating an arbitrary frame period Until the period, the braking pulse having the same polarity as that of the period of the first frame is extended or regenerated to measure the operation stability of the dot.
[0006]
【Example】
FIG. 6 is an exploded perspective view of a color display element in a conventional color display device. The color display elements used in this embodiment are the same as those used in Japanese Patent Application Laid-Open Nos. 5-297812 and 5-303338. The four yokes 112 press-fitted into the magnetic material base plate 111 are wound with coils 117, 118, 119, and 120, respectively. The coils 117, 118, 119, and 120 facing each other are connected in series. Thus, two sets of coils are formed, and the color display body 128 is rotated by applying drive pulses to the coil terminals 121 and 122 and 123 and 124, respectively. A stator 113 is coupled to the upper end of each yoke 112, and a magnet 116 is disposed at the center. The magnet gap 114 is a gap between the stator 113 and the magnet 116, and the stator gap 115 is four gaps between the stators 113. A magnet 116 is fixed to the rotating shaft 125, the upper end of the rotating shaft 125 protrudes through the bearing hole 127 of the stator frame 126, and the upper end of the rotating shaft 125 is center hole 129 on the upper end surface of the color display body 128. , The rotary shaft 125 and the color display body 128 are coupled. The lower end of the rotating shaft 125 is rotatably supported by a shaft hole provided in the main plate 111. The cylindrical surface of the color display body 128 is divided into, for example, four colors parallel to the cylinder axis, and rotates integrally with the magnet 116, so that it switches to four colors when viewed from the side. The stator frame 126 is a plastic frame that positions and holds the four stators 113. For the sake of clarity, the stator frame 126 and the color display 128 are drawn upward in FIG. Then, the stator frame 126 covers the stator 113, the magnet 116 is immediately below the stator frame 126, and the electromagnet part in which the coils 117 to 120 are wound around the stator frame 126 and the yoke 112 is the color display body 128. It is housed in the motor.
[0007]
FIG. 7 is a waveform diagram of a conventional drive pulse for driving the motor of FIG. This drive pulse is composed of an acceleration pulse 10, a deceleration pulse 12, and a braking pulse 30. Levels H and L in the figure indicate the direction of the coil current, and level Z means that no coil current flows. This drive pulse is used only for moving images and is not used for still images. The acceleration pulse 10 is a voltage waveform for rotating the magnet 116 in FIG. 6 from the start position A to the stop position B, for example, and is applied to the two sets of coils. The deceleration pulse 12 is a voltage waveform applied so as to be pulled back to the start position A when the magnet 116 rotates from the start position A to the stop position B, and is applied to the magnet 116 and the color display 128 by the acceleration pulse 10. Has the function of removing the inertial force. Therefore, when the magnet 116 reaches the stop position B, the inertial force of the color display body 128 is almost zero. The braking pulse 30 is a voltage waveform applied so that the magnet 116 can stop at the stop position B. The braking pulse 30 stops the magnet 116 at a stable point. However, since the inertial force cannot be completely removed due to the manufacturing variation of the motor, the magnet 116 actually stops at the stop position B in the form of damped vibration even when the braking pulse 30 is applied.
[0008]
FIG. 8 is an explanatory view of the operation of the magnet and the stator of the color display element of FIG. In FIG. 8A, among the four stators 113a, 113b, 113c, and 113d around the magnet 116, the stators 113a and 113b are excited so as to have an S pole, and the stators 113c and 113d have an N pole. The magnet 116 stops at the position where it is placed, and the stable state is maintained. FIG. 8B is a diagram when the magnet 116 of FIG. 8A is rotated 90 ° counterclockwise, and excitation is performed so that the stators 113b and 113c have S poles and the stators 113a and 113d have N poles. By doing so, the magnet 116 stops at a position rotated 90 ° counterclockwise.
[0009]
A rotation state when the coil is excited by the drive pulse of FIG. 7 in order to rotate 90 ° counterclockwise from FIG. 8A and stop at the position of FIG. 8B will be described. When the stators 113 a to 113 d are excited as shown in FIG. 8B by the acceleration pulse 10 of FIG. 7, the N pole of the magnet 116 starts to rotate from the position 131 toward the position 133. Next, the stators 113a to 113d are excited as shown in FIG. 8A by the deceleration pulse 12 shown in FIG. 7, so that the magnet 116 reaches the position 133 shown in FIG. 8B while being decelerated. Wrap around. Next, the stators 113a to 113d are excited again as shown in FIG. 8B by the braking pulse 30 in FIG. 7, so that the magnet 116 is braked, and the positions 132, 134 ′, 132 ′ centered on the position 133 and the damping vibration. Then stop at position 133. If the braking pulse 30 in FIG. 7 has ended before the end of the damped vibration, the magnet 116 may stop at a place other than the normal stop point and display a dot defect. Then, some of the large number of dots of the large display device remain as dot defects when the screen is still.
[0010]
FIG. 1 is a waveform diagram of a drive pulse according to the present invention. Levels H and L in FIG. 1 indicate the direction of the coil current, and level Z indicates a state in which no coil current flows. This drive pulse is a pulse for preventing a dot defect when a frame in which the color does not change is continued after the color is switched in the first frame period. The first frame period includes an acceleration pulse 10, a deceleration pulse 12, and a first braking pulse 14, and is the same drive pulse as the drive pulse in FIG. In the second frame period, the second braking pulse 16 is formed by extending the first braking pulse 14, and braking can be performed until the above-described damped oscillation is completely completed. The second braking pulse 16 can be set to an arbitrary period (possible up to the middle of the frame period) according to the manufacturing variation of the motor, but FIG. 1 illustrates the end of the second frame period as an example. is there. In the case of a television image, the period of one frame is set to 30 milliseconds, and if it is applied until the damped vibration is terminated by the second braking pulse 16 in FIG. 1, a moving image display at the same speed as the television image is also possible. It becomes possible.
[0011]
Further, the method of extending the second braking pulse 16 in FIG. 1 is naturally not applicable if the second frame period is a moving image. That is, the display color is switched in the first frame period, and can be applied only in the second frame period when the still image state is entered. As described above, the inconvenience that the dot defect generated in the still image cannot be corrected indefinitely can be solved. . The display color data will not be the same for more than two frame periods. That is, when the moving image frame period is continuously displayed, even if a dot defect occurs in the middle, it is hardly noticeable, so it is out of scope.
[0012]
In order to determine whether or not the second braking pulse 16 can be used in the second frame period, it is necessary to detect whether it is a moving image or a still image. The present applicant has proposed the detection means in Japanese Patent Laid-Open No. 5-297811, and as a method, the display color data of the first frame and the display color data of the second frame of the dot at the same position are compared. If the two are the same, the motor rotation command is not issued, and the second frame is disclosed as means for saving power consumption as a stationary dot. By using this method, it is easy to know whether the second frame period of the present invention is a moving image or a still image.
[0013]
The size of the color display body is large and small. However, when displaying a video with a large color display body, the weight of the color display body increases, so the period of damped vibration tends to increase. In the same period as the driving pulse for rotating the small color display, dot defects are likely to occur. That is, it is necessary to lengthen the drive pulse period. The drive pulse has a period required for rotation depending on the size of the color display body. In the case of FIG. 1, the drive pulse for the period required for rotation and a single image of a moving image are displayed. One frame period is the same period. If the display speed of the moving image is reduced without changing the size of the color display body, one frame period for displaying one image becomes longer, but the drive pulse period is determined by the size of the display body as described above. Therefore, it is possible to finish faster than one frame period. In such a case, the period until switching to the next color, that is, the period until the end of one frame period is vacant without bothering after the second frame and applying a braking pulse. The braking pulse may be extended and it is not necessary to use the second frame period of FIG. However, means for extending the braking pulse and absorbing the damped vibration can be used as well for safety.
[0014]
FIG. 2 is a waveform diagram of a braking pulse showing another embodiment of the present invention. As described above, this method is naturally not applicable if the second frame period or later is a moving image. The period until the middle of the second frame period and the third frame period in FIG. 2 is constituted by the second braking pulse 18 having a voltage waveform lower than the voltage waveform of the first braking pulse 14 in the first frame period. Has been. In the second frame period, as described with reference to FIG. 8B, the damping vibration is considerably absorbed by the first frame period. Therefore, in the second frame period, the same voltage as the first braking pulse 16 is It is unnecessary. Therefore, in the second frame period, the second braking pulse 18 having a voltage lower than that of the first braking pulse 14 is used in order to enhance the effect of low power consumption. There is no problem even if it extends over the third frame period as long as it is a still image period. The second braking pulse 18 can be arbitrarily set as long as it is lower than the voltage waveform of the first braking pulse 14 and the braking effect is within a sufficient range. In addition to the second braking pulse 18 of FIG. 2, as a method for enhancing the effect of low power consumption in the second frame period, the same effect can be obtained with a chopper-type braking pulse in which a braking voltage is intermittently applied. Each of the above-described means has an effect that the capacity of the power source used in this apparatus can be reduced.
[0015]
FIG. 3 is a waveform diagram of drive pulses showing still another embodiment of the present invention. In FIG. 3, the frame period in which the display color is switched is defined as the first frame period, and when the same display color continues for a considerable period thereafter, the frame period in which the second braking pulse starts to be applied is defined as the nth frame period. It is as section 20. The driving pulse in the first frame period is the same as the voltage waveform in FIG. The second braking pulse 22 having the same polarity as the first braking pulse 14 may be applied immediately after the first frame period in the second frame period. However, the second braking pulse 22 is added after n frames as shown in FIG. Even if is added, the same effect can be obtained. The period of the stop section 20 represents a period until the second braking pulse 22 is applied, and can be arbitrarily set as necessary. The case where the period of the second braking pulse 22 extends over the n-th frame and the (n + 1) -th frame period is exemplified, but the effect can be obtained even within one frame. However, since the display color of the dot defect cannot be specified, the period of the second braking pulse 22 is usually set to a long period so that the display color of the dot defect can be changed to the correct display color. Moreover, even if most of the dot defects can be eliminated by adding the second braking pulse 22, for the sake of safety, a third braking pulse 24 or a third braking pulse (not shown) may be added. Periodic application of a plurality of braking pulses after 24 is also effective for dot defects. Similar to the second braking pulse 22, these are added automatically or by an operation command after the stop sections 20 and 23, and dot defects can be reliably eliminated.
[0016]
FIG. 4 is a timing waveform diagram for generating the drive pulse of FIG. Here, description will be given with display color data. As shown, each frame period begins with a drive signal (DR) that represents display color data as a display color by rotation of the motor. In the first frame period, the display color data is determined by the drive signal (DR). When the display color data is determined to be blue, the coil is excited by the illustrated drive pulse to display blue. However, it is assumed that the display color was not blue in the previous frame period of the first frame period. When the next display color data is determined to be white in the second frame period, the coil is excited by the illustrated driving pulse to display white. Next, when the next display color data is determined to be white in the third frame period, the motor is not rotated in the third frame period, and a still image is obtained. Since the third frame period is the same as the display color data of the second frame period, the drive pulse of the second frame period is extended to the third frame period as shown in FIG. That's fine. The display color data is determined again in the fourth frame period, and if the dot defect disappears in the third frame period even if it is determined to be white, that is, a still image, it is not necessary to extend the drive pulse again. Various methods of extending the braking pulse are conceivable. Here, the driving pulse of FIG. 1 is used as an embodiment. Next, when the display color data is determined to be red in the fifth frame period, another driving pulse shown in the figure is generated to display red in order to rotate the motor from white to red.
[0017]
In the actual operation of the color display body, the drive pulse is a pulse configuration such as an acceleration pulse, a deceleration pulse, a braking pulse, etc. within one frame period, and the time distribution depends on what color is changed from what color. The polarity to be excited in the coil is reversed without changing, but in each of FIGS. 1, 2, 3, 4, and 7, the drive pulse is schematically shown in order to simplify the explanation. Represents.
[0018]
FIG. 5 is a block diagram of a circuit that generates the drive pulses of FIGS. 1, 2, 3, and 7. FIG. A conventional circuit for generating the drive pulse of FIG. 7 will be described. Display color data is given from a signal source (not shown), and a new display color data is stored in the new data latch 50 and a previous display color data is stored in the old data latch by a drive signal (DR) instructing rotation start of the color display body. 52, the motor rotates based on the result, and the new display color data is displayed. Next, when the drive signal (DR) is transmitted again, the display color data latched in the new data latch 50 becomes the previous display color data and is latched in the old data latch 52, and the next new display color data. Is latched in the new data latch 50. The time when new display color data different from the previous display color data is latched is the starting point of the waveform of FIG. Next, the display color data latched by the new data latch 50 and the old data latch 52 are transmitted to the drive waveform generation circuit 54. The drive waveform generation circuit 54 determines a display color change based on the display color data of the new data latch 50 and the old data latch 52, and uses a drive clock (CP) transmitted from a signal source (not shown). A drive pulse to be applied to the coil is generated and transmitted to the drive circuit 56. The drive circuit 56 applies the drive pulse to the coil of the motor 57 to rotate the display body. In the drive waveform generation circuit 54, when there is no change in the display color data of the new data latch 50 and the old data latch 52, the drive pulse is not required and is not generated as described above. The drive signal (DR) is at the starting point of each frame, and the drive waveform is generated in the same frame period while switching between the old and new data latches, counting up the number of frames, etc. 57 is displayed.
[0019]
The circuit for generating the drive pulse of FIG. 1 of the present invention will be described. Until the driving pulse of the first frame period is applied to the coil, the driving pulse is the same as the conventional driving pulse shown in FIG. When the next drive signal (DR) is transmitted, the display color data of the new data latch 50 is transmitted to the old data latch 52, and the new display color data is latched in the new data latch 50. Display color data of the new data latch 50 and the old data latch 52 are transmitted to the comparison circuit 58. The circuit of FIG. 5 is configured so that the drive pulses of FIGS. 1, 2, and 3 can be generated. Therefore, the pulse setting 60 sets which drive pulse is used. As the pulse setting 60, it is assumed that the driving pulse of FIG. 1 is set. The comparison circuit 58 compares the display color data of the new data latch 50 and the old data latch 52, and if they match, a match signal is transmitted to the second braking pulse generation circuit 62. The second braking pulse generation circuit 62 has a second braking pulse period that can be arbitrarily set. During the period set by counting the driving clock (CP) from the signal source, the driving waveform generation circuit 54 A second braking pulse is transmitted. That is, the second braking pulse generation circuit 62 determines the polarity of the second braking pulse from the display color data of the new data latch 50, and the waveform that continuously extends the braking pulse in the first frame period is the driving waveform generation circuit. 54 is generated and transmitted to the drive circuit 56, and the motor 57 is rotated.
[0020]
Next, the circuit for generating the drive pulse of FIG. 2 of the present invention will be described. Until the driving pulse of the first frame period is applied to the coil, the driving pulse is the same as the conventional driving pulse shown in FIG. When the next drive signal (DR) is transmitted, the display color data of the new data latch 50 moves to the old data latch 52, and the new display color data is latched in the new data latch 50. If the drive pulse of FIG. 2 is set by the pulse setting 60, the display color data of the new data latch 50 and the old data latch 52 are transmitted to the comparison circuit 58. It is transmitted to the braking pulse generation circuit 62. In the second braking pulse generation circuit 62, the second braking pulse 18 having the same polarity as the display color data of the new data latch 50 is generated and transmitted to the drive waveform generation circuit 54, as in the case of FIG. The second braking pulse 18 is generated as a part of the previously generated driving pulse, that is, a waveform that continuously extends the first braking pulse 14 in the first frame period, and is transmitted to the driving circuit 56. . Further, the period of the second braking pulse 18 generated by the second braking pulse generation circuit 62 is transmitted to the voltage switching circuit 64 as a voltage switching signal. When the second braking pulse 18 is applied to the coil by the driving circuit 56, the voltage switching circuit 64 sets the voltage to 3V lower than the usual 6V by the voltage switching signal from the second braking pulse generating circuit 62, By sending it to the drive circuit 56, a voltage of 3V is applied to the coil.
[0021]
Next, the circuit for generating the drive pulse of FIG. 3 according to the present invention will be described. Until the driving pulse of the first frame period is applied to the coil, the driving pulse is the same as the conventional driving pulse shown in FIG. When the next drive signal (DR) is transmitted, the display color data of the new data latch 50 moves to the old data latch 52, and the new display color data is latched in the new data latch 50. 3 is set by the pulse setting 60, the display color data of the new data latch 50 and the old data latch 52 are transmitted to the comparison circuit 58. If they match, the coincidence signal is sent to the frame counter 66. Is transmitted. The frame counter 66 includes counters for the nth frame for generating the second braking pulse 22 and the n + nth frame for generating the third braking pulse 24. The drive signal (DR) is generated by the coincidence signal. To generate the stop section 20 of FIG. When the set count ends, the output is transmitted to the second braking pulse generation circuit 62. In the second braking pulse generation circuit 62, the period of the second braking pulse 22 that can be arbitrarily set is set as described above, and is set by counting the drive clock (CP) from the signal source following the stop period. During this period, the second braking pulse 22 transmitted to the driving waveform generating circuit 54 and generated by the second braking pulse generating circuit 62 is a part of the previously generated driving pulse, that is, the first frame period. A waveform having the same polarity as the braking pulse is generated, transmitted to the drive circuit 56, applied to the motor 57, and a dot causing a dot defect displays a normal color.
[0022]
Further, it is easy to generate not only the second braking pulse 22 but also the third braking pulse 24 by reusing the frame counter 66 by means similar to the second braking pulse. By repeating the above-described braking pulse as many times as is automatically or by an operation command, it is possible to reliably eliminate dot defects.
[0023]
【The invention's effect】
According to the present invention, it is possible to remove dot defects during a still image period almost completely only by partially changing the drive pulse of the motor. In addition, there is an advantage that the frame speed does not decrease and the capacity of the power source used does not increase.
[Brief description of the drawings]
FIG. 1 is a waveform diagram of a drive pulse of the present invention.
FIG. 2 is a waveform diagram of drive pulses showing another embodiment of the present invention.
FIG. 3 is a waveform diagram of drive pulses showing still another embodiment of the present invention.
4 is a timing waveform diagram for generating the drive pulse of FIG. 1; FIG.
FIG. 5 is a block diagram of a circuit that generates the drive pulses of FIGS. 1, 2, 3, and 7;
FIG. 6 is an exploded perspective view of a color display element in a conventional color display device.
FIG. 7 is a waveform diagram of a conventional driving pulse for driving the motor of FIG.
8 is an operation explanatory diagram of a magnet and a stator of the color display element of FIG. 6. FIG.
[Explanation of symbols]
112 Yoke 113a-d Stator 116 Magnet 117-120 Coil 128 Color display body 10 Acceleration pulse 12 Deceleration pulse 14 First braking pulse 16, 18, 22 Second braking pulse 20, 23 Stop zone 24 Third braking pulse

Claims (4)

A magnet and a color display that is separately applied in multiple colors are fixed to a rotating shaft, and a member that rotatably supports the rotating shaft, a stator that surrounds the magnet, and a yoke and a coil that change magnetic flux to the stator. In a color display device constituted by a motor,
A driving pulse for driving the motor to display one color during the first frame period is composed of at least an acceleration pulse and a braking pulse, and when the color of the first frame period is continued after the second frame period, A color display device comprising: a second braking pulse having the same polarity as the first braking pulse of the first frame during a plurality of subsequent frame periods including two frame periods. The color display device according to claim 1,
The second braking pulse extends the braking pulse of the first frame period over a plurality of frame periods following the first frame period, and ends at the middle or end of the extended last frame period. Color display device. The color display device according to claim 1,
The color display device, wherein the second braking pulse is configured by a voltage waveform lower than the voltage waveform of the first braking pulse in the first frame period. The color display device according to claim 1,
The color display device according to claim 1, wherein the second braking pulse includes one or a plurality of braking pulses extending over one or more frame periods across a stop section.

Images