JP2006030595A - Video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized and lightweight video display device having the small total of signal lines while provided with a plurality of video display elements. <P>SOLUTION: The video display device (2) includes the two video display elements (11L and 11R) for displaying videos provided to right and left eyes, a display element drive part (20) for supplying a drive signal and a pixel signal to the video display elements (11L and 11R), a drive signal line (31) for transmitting the drive signal, and pixel signal lines (32L and 32R) for transmitting the pixel signal. There are provided two sets of the pixel signal lines (32L and 32R), the same number as the video display elements (11L and 11R), to which the pixel signals are individually given. There is provided only one set of the drive signal line (31), and the same drive signals are given to the video display elements (11L and 11R) to be collectively driven. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a video display device including a plurality of video display elements.

  In recent years, with the development of electronics technology and video technology, portable video display devices that display various video information have come to be widely used. Applications of portable video display devices include: TV broadcast reception display, movie, theater and other caption display, navigation information display, work support information display, explanation display in exhibition halls such as museums, art museums, amusement parks , Various displays such as attraction video and guidance display in the theme park.

  In such a portable video display device, two images with parallax are displayed for the left eye and the right eye to provide a stereoscopic image with a high sense of presence, or to provide a video to be provided to the left and right eyes. The interval is also changed according to the user's eye width. In particular, the head-mounted video display device has an advantage that the video is presented only to the wearer and thus has high secrecy and that both hands can be used freely.

  The portable video display device is desirably small and light, and is generally configured by a small video display element and an observation optical system that provides an enlarged image displayed by the video display element. As such an image display element, a liquid crystal display (LCD) element or an electroluminescence (EL) display element is suitable.

  Although these display elements generate light representing an image by modulating the illumination light given by the former, and the latter directly emits light representing the image, a large number of two-dimensionally arranged pixels are used. And each pixel represents one point of the image, and a set of pixels represents the entire image. These display elements are supplied with a pixel signal representing an image to be displayed, that is, specifying a state of each pixel, in addition to a drive signal necessary for driving. The drive signal and the pixel signal are supplied from a drive unit provided separately from the video display element.

  There is not one kind of driving signal necessary for driving the liquid crystal display element or the electroluminescence display element. Therefore, the number of driving signal lines for transmitting the driving signal to the video display element is, for example, ten, Provided. There may be a plurality of pixel signal lines for transmitting pixel signals to the video display element. In a video display element having two video display elements to provide different images to the left and right eyes, a set of drive signal lines and a set of pixel signal lines are arranged between the drive unit and each video display element. Has been.

  In the case of a head-mounted image display device, the image display element is arranged in front of the eyes, near the forehead or near the cheek, but when only the front portion of the device becomes heavy, the feeling of wearing becomes worse. Therefore, it is preferable to dispose the drive unit that supplies the drive signal and the video signal to the video display element, for example, near the back of the head or other than the head. In such an arrangement, it is necessary to lengthen the drive signal line and the pixel signal line.

  However, in a video display device having a plurality of video display elements, when each video display device is individually connected to a drive unit, a set number of drive signal lines equal to the number of video display devices between the drive unit and the video display element are provided. Pixel signal lines are provided, and the total number of signal lines increases. As the number of signal lines increases, the weight of the apparatus increases, and the space occupied by the signal lines increases, making it difficult to reduce the size. Furthermore, even if the signal lines are bundled to make a single cable for easy handling, the cable becomes thick and difficult to bend, and it is difficult to achieve the purpose.

  The above problem caused by the signal line becomes more prominent as the number of video display elements increases. Although this problem can occur in any portable video display device, a head-mounted video display device is particularly undesirable because it causes a reduction in wearing feeling.

  The plurality of video display elements are provided so that a plurality of videos, particularly different videos, can be displayed at the same time. Therefore, the number of pixel signal lines needs to be equal to the number of video display elements. On the other hand, it is not always necessary to individually drive a plurality of video display elements, and it is also possible to drive them collectively. Even if a plurality of video display elements are driven together, it is possible to simultaneously display a plurality of the same or different videos.

Japanese Patent Laid-Open No. 8-47000 discloses that a plurality of cameras have a common clock signal to synchronize imaging operations. However, it has not been proposed so far to drive a plurality of video display elements together and to display a plurality of videos.
JP-A-8-47000

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a small and lightweight video display device having a plurality of video display elements and a small total number of signal lines.

  In order to achieve the above object, in the present invention, a video display device including a plurality of video display elements each having a plurality of pixels and displaying a part of a video with each pixel outputs pixel signals to the plurality of video display elements. A plurality of sets of pixel signal lines that are individually transmitted and a set of drive signal lines that transmit drive signals to a plurality of video display elements, and a plurality of video display elements are driven together by a set of drive signal lines. A plurality of images are displayed.

  Although this video display device includes a plurality of video display elements, only one set of drive signal lines is provided as in the case of a device including only one video display element. Therefore, an increase in weight and a required space due to the drive signal line can be suppressed, and the size and weight can be reduced. On the other hand, the number of pixel signal lines is the same as that of video display elements, and pixel signals can be individually transmitted to each video display element, so that different videos can be displayed simultaneously.

  The video display element includes a mounting member for mounting on a user's head and an optical system for enlarging and providing images displayed by the plurality of video display elements to the user wearing the head. be able to.

  The plurality of video display elements can be liquid crystal display elements or electroluminescence display elements.

  A drive unit that supplies pixel signals and drive signals to a plurality of video display elements via the pixel signal lines and drive signal lines, and the distance between the drive unit and the one closest to the drive unit among the plurality of video display elements, It may be configured to be longer than the shortest distance between the plurality of video display elements. If it does in this way, a weight will be disperse | distributed and it will become a well-balanced apparatus suitable for head mounting type.

  At least a part of the pixel signal line and the drive signal line is a conductor line covered with an insulating material, and can be configured to be bundled to form one cable. Even in this case, since the total number of signal lines is small, the cable does not become so thick and handling is easy.

  A structure in which at least a part of the pixel signal line and the drive signal line is provided on the flexible substrate may be employed. If it does in this way, it will become a still smaller device.

  Since the video display device of the present invention includes only one set of the minimum number of drive signal lines, an increase in weight and a necessary space due to the drive signal lines can be suppressed, and the size and weight can be reduced. On the other hand, pixel signals can be individually transmitted to each image display element, so that different images can be displayed simultaneously.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a circuit configuration of the video display device 1 according to the first embodiment. The video display device 1 provides the same video to the left and right eyes of the user at the same time. The video display device 11L displays a video image for the left eye and the video display device 11R displays a video image for the right eye. And a display element driving unit 20 for supplying drive signals and pixel signals to the video display elements 11L and 11R.

  The video display elements 11L and 11R are liquid crystal display elements, each having a large number of pixels arranged two-dimensionally. Each pixel represents one point of the video, and a set of pixels represents the entire video. The liquid crystal layer of each pixel of the video display elements 11L and 11R takes a state in which the illumination light to be applied is a video light representing video (one point) and an unnecessary light other than the video light, and the display element driving unit 20 The state is switched according to the pixel signal given from. Note that the image display elements 11L and 11R include a polarizing plate (not shown) that transmits only image light out of image light and unnecessary light having different polarization directions.

  The video display elements 11 </ b> L and 11 </ b> R are operated by a drive signal supplied from the display element driving unit 20. For example, the timing for switching the state of each pixel is indicated by a drive signal.

  The display element driving unit 20 includes a decoder 21, a frame buffer 22, a frame buffer controller 23, a timing generator 24, and a video processing unit 25. The decoder 21 extracts video data representing video from a video signal given from the outside. The frame buffer 22 stores the video data extracted by the decoder 21 for each frame. The frame buffer controller 23 controls input / output of the frame buffer 22.

  The timing generator 24 generates a drive signal to be supplied to the video display elements 11L and 11R. There are a variety of drive signals, including, for example, signals such as system clock, horizontal clock, vertical clock, horizontal synchronization, vertical synchronization, and video display enable.

  The drive signal is transmitted from the timing generator 24 to the video display elements 11L and 11R via the drive signal line 31. As many drive signal lines 31 as the number of drive signals are provided. However, only one set of the drive signal lines 31 is provided, and branches near the video display elements 11L and 11R and is connected to the video display element 11L and the video display element 11R. Therefore, the video display elements 11L and 11R are given the same drive signal and are driven together.

  The timing generator 24 also gives a trigger signal that instructs the frame buffer controller 23 to output video data.

  The video processing unit 25 processes video data output from the frame buffer 22 via the frame buffer controller 23 to generate pixel signals to be supplied to the video display elements 11L and 11R. The timing generator 24 outputs the trigger signal in synchronization with the drive signal, and the pixel signal output from the video processing unit 25 and the drive signal output from the timing generator 24 are synchronized.

  The pixel signal is transmitted from the video processing unit 25 to the video display elements 11L and 11R via the pixel signal line. While the drive signal line 31 is one set, the pixel signal line is provided with the same number of sets (that is, two sets) as the number of the video display elements 11L and 11R, and the pixel signal for the video display element 11L is a pixel. The pixel signals for the video display element 11R are individually transmitted through the pixel signal line 32R through the signal line 32L.

  The pixel signal may be a digital signal or an analog signal. In the case of a digital signal, the gradation of one point of the video is represented by a plurality of bits, so that there are a plurality of signals. In order to increase the transmission efficiency to the video display elements 11L and 11R, these signals are output simultaneously. desirable. However, it is also possible to transmit each signal at different times. In the case of an analog signal, one point of the video can be represented by one signal, but a plurality of signals can be transmitted simultaneously in order to increase transmission efficiency. That is, whether the pixel signal is a digital signal or an analog signal, each of the pixel signal lines 32L and 32R can be either singular or plural.

  In the video display device 1, pixel signals are individually transmitted to the video display elements 11L and 11R through the two sets of pixel signal lines 32L and 32R, but the pixel signals transmitted by the pixel signal lines 32L and 32R are the same. Therefore, the images displayed by the image display elements 11L and 11R are the same. This configuration is suitable for displaying planar objects such as characters as images.

  A circuit configuration of the video display device 2 of the second embodiment is schematically shown in FIG. The video display device 2 is a modification of the video display device 1 so that different videos are simultaneously provided to the left and right eyes of the user. Therefore, the two decoders 21L and 21R that extract video data from the video signal for the left eye and the video signal for the right eye, respectively, and the two frame buffers 22L that store the video data extracted by the decoders 21L and 21R for each one frame. 22R, and two frame buffer controllers 23L and 23R that control input / output of the frame buffers 22L and 22R.

  Further, the timing generator 24 gives a trigger signal for instructing output of video data to both the frame buffer controllers 23L and 23R. Further, the video processing unit 25 processes the video data output from the frame buffer 22L via the frame buffer controller 23L, generates a pixel signal to be supplied to the video display element 11L, and receives the frame via the frame buffer controller 23R. The video data output from the buffer 22R is processed to generate a pixel signal to be supplied to the video display element 11R.

  Similar to the video display device 1, a pair of drive signal lines 31 is provided and the same number of video signal lines 32L and 32R as the number of video display elements 11L and 11R (that is, two sets) is provided. is there.

  In the video display device 2, it is possible to provide completely different videos to the left and right eyes, or to provide a video with parallax to the left and right eyes so that the images can be observed stereoscopically. Of course, the same image can be provided to the left and right eyes.

  FIG. 3 shows the appearance of the video display devices 1 and 2 of the above embodiments. The video display devices 1 and 2 guide the light from the casings 51L and 51R and the video display elements 11L and 11R, which accommodate the video display elements 11L and 11R, respectively, to the left and right eyes, and display the video display elements 11L and 11R. Observation optical systems 40L and 40R for providing magnified images of the image, bridge 52 connecting observation optical systems 40L and 40R, temples 53L and 53R attached to observation optical systems 40L and 40R, and nose pads attached to bridge 52 54L, 54R, and a control box 59 that houses the display element driving unit 20 and a power source (battery). Except for the control box 59, the control box 59 has a shape like glasses and is mounted on the user's head.

  At the time of wearing, the temples 53L and 53R are supported by the temporal region, the nose pads 54L and 54R are supported by the side portions of the nose, and the observation optical systems 40L and 40R are positioned immediately in front of the left and right eyes, respectively. , 51R are positioned above the observation optical systems 40L, 40R. The control box 59 is attached to a part other than the user's head, for example, the waist. It is also possible to accommodate the control box 59 in a pocket of clothes.

  The observation optical systems 40L and 40R include transparent plates 41L and 41R and holographic elements (HOE) 42L and 42R. The casings 51L and 51R are fixed to the upper ends of the transparent plates 41L and 41R.

  Further, a cable 55 is provided between the control box 59 and the casing 51R, and a cable 56 is also provided between the casing 51R and the casing 51L. The cable 55 is a bundle of drive signal lines 31 and pixel signal lines 32L and 32R each covered with an insulating material and a power supply line, and the cable 56 is connected to the drive signal lines 31 each covered with an insulating material. The pixel signal line 32L and the power supply line are bundled into one. The drive signal line 31 is branched in the housing 51R.

  FIG. 4 shows a cross section of the inside of the casing 51R and the observation optical system 40R. In addition to the image display element 11R, the housing 51R includes a light source 12R that emits illumination light for illuminating the image display element 11R that is a liquid crystal display, and an illumination that guides the illumination light from the light source 12R to the image display element 11R. The optical system 13R is accommodated. The light source 12R is, for example, a light emitting diode, and the illumination optical system 13R is, for example, a convex lens. The light source 12R and the illumination optical system 13R form part of the display unit 10.

  The rear surface (surface close to the eye) of the transparent plate 41R of the observation optical system 40R is a flat surface, and the front surface (surface far from the eye) of the transparent plate 41R is also a flat surface except for the upper end portion. These two planes are parallel, and the transparent plate 41R is a parallel plate except for the upper end. The vicinity of the upper end of the front surface is further away from the rear surface as it approaches the upper end, and the upper end of the transparent plate 41R has a wedge shape. The casing 51 is attached to the upper end portion.

  The transparent plate 41R is produced by joining a member 41a that is long in the up-down direction and a member 41b having a shape surrounding the member 41a from the left and right and from below. These members 41a and 41b are made of the same material, and there is no difference in optical characteristics such as refractive index. The lower end surface of the member 41a is inclined with respect to the rear surface and the front surface, and a holographic element 42R is provided on the lower end surface. That is, the holographic element 42R is sandwiched between the two members 41a and 41b.

  The light from the image display element 11R passes through the upper end surface of the transparent plate 41R and enters the transparent plate 41R. The image display element 11R, the light source 12R, and the illumination optical system 13R are set so that the light that has entered the transparent plate 41R is totally reflected on the rear surface of the transparent plate 41R, and enters the transparent plate 41R. The light travels downward while being totally reflected by the rear surface and the front surface, and reaches the holographic element 42R.

  The holographic element 42R diffracts and reflects the light from the image display element 11R incident through the transparent plate 41R and emits it from the rear surface, and an enlarged virtual image of the image displayed by the image display element 11R is displayed at the exit pupil ER. It is set so that it can be observed. The distance from the exit pupil ER to the virtual image is, for example, 1 m. Since the transparent plate 41R transmits light from the outside world, the user wearing the video display device 1 can also observe the outside world, and the video (virtual image) is observed to overlap with a part of the outside world.

  Here, the configuration for providing video to the right eye has been described, but the configuration for providing video to the left eye is the same. In addition, the optical axes of the observation optical systems 40L and 40R are set so that two images (virtual images) provided to the left and right eyes overlap each other, so that the user can observe the images without feeling uncomfortable. Congestion is realized.

  The cable 55 that connects the control box 59 and the casing 51R is several tens of centimeters long, but is light, thin, and easily bent because there is only one set of the drive signal lines 31. Therefore, the image display devices 1 and 2 have a good feeling on the head, and the control box 59 can be attached not only to a specific part of the body but also to any part.

  The external appearance of the modification of the video display apparatuses 1 and 2 is shown in FIG. This is a control box 59 having a necessary minimum size and attached to the temple 53R. The control box 59 is disposed at a position where the distance to the casings 51L and 51R is longer than the distance between the casings 51L and 51R. With such an arrangement, the weight can be dispersed, and the control box 59 can be mounted on the head, but a device with a high mounting feeling can be obtained.

  FIG. 6 shows the external appearance of another modification of the video display devices 1 and 2, and FIG. This is provided on the flexible substrates 57 and 58 in place of the drive signal lines 31, the pixel signal lines 32L and 32R, and the power supply lines being conductor lines coated with an insulating material. The drive signal line 31 is branched in the housing 51R. The control box 59 is attached to the temple 53R in the same manner as that shown in FIG. 5, and most of the flexible board 57 that connects the control box 59 and the housing 51R is built in the temple 53R.

  Since there is only one set of drive signal lines 31, it is easy to make the flexible substrate 57 thinner, and as a result, such an arrangement can be achieved.

  In each of the above-described embodiments, an example in which a liquid crystal display element is used as the video display elements 11L and 11R is described. However, an electroluminescence display element can also be adopted. Employing an electroluminescence display element eliminates the need for illumination light and can provide a high-definition image with higher contrast. The configuration of the observation optical systems 40L and 40R is not limited, and instead of the optical system including the transparent plates 41L and 41R and the holographic elements 42L and 42R shown here, an optical system including a lens and a half mirror are included. An optical system is also possible.

  Further, here, a configuration is provided in which one video display element is provided for each of the left and right eyes, but a plurality of video display elements are provided for one eye, and different parts of the same video are displayed on each video display element. In other words, a so-called multi-view video display device can be provided. Even in this case, an increase in the total number of signal lines can be suppressed by providing only one set of drive signal lines and driving all the video display elements together.

The figure which shows typically the circuit structure of the video display apparatus of 1st Embodiment. The figure which shows typically the circuit structure of the video display apparatus of 2nd Embodiment. The figure which shows the external appearance of the video display apparatus of 1st, 2nd embodiment. Sectional drawing which shows typically the structure of the display part and observation optical system of the video display apparatus of 1st, 2nd embodiment. The figure which shows the external appearance of the modification of the video display apparatus of 1st, 2nd embodiment. The figure which shows the external appearance of another modification of the video display apparatus of 1st, 2nd embodiment. The figure which shows typically the structure for connecting the display element drive part and video display element in the modification of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Video display apparatus 10 Display part 11L, 11R Video display element 12R Light source 13R Illumination optical system 20 Display element drive part 21, 21L, 21R Decoder 22, 22L, 22R Frame buffer 23, 23L, 23R Frame buffer controller 24 Timing generator 25 Video processing unit 31 Drive signal line 32L, 32R Pixel signal line 40L, 40R Observation optical system 41L, 41R Transparent plate 42L, 42R Holographic element 51L, 51R Case 52 Bridge 53L, 53R Temple 54L, 54R Nose pad 55, 56 Cable 57, 58 Flexible substrate 59 Control box

Claims (6)

A video display device including a plurality of video display elements having a plurality of pixels and displaying a part of the video with each pixel,
A plurality of sets of pixel signal lines for individually transmitting pixel signals to a plurality of video display elements;
A set of drive signal lines for transmitting drive signals to a plurality of video display elements,
A video display device, wherein a plurality of video display elements are collectively driven by a set of drive signal lines to display a plurality of videos. A mounting member for mounting on the user's head;
The video display device according to claim 1, further comprising an optical system that enlarges and provides a video displayed by the video display elements to a user wearing the head.   The video display device according to claim 1, wherein the plurality of video display elements are liquid crystal display elements or electroluminescence display elements. A drive unit for supplying a pixel signal and a drive signal to a plurality of video display elements via the pixel signal line and the drive signal line;
The distance between the drive unit closest to the drive unit among the plurality of video display elements is longer than the shortest distance between the multiple video display elements. The video display device according to item.   5. The video display device according to claim 4, wherein at least a part of the pixel signal line and the drive signal line is a conductor line covered with an insulating material, and is bundled to form one cable. .   The video display device according to claim 4, wherein at least part of the pixel signal line and the drive signal line is provided on a flexible substrate.

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