Display

Abstract

To display an image while preventing a user from becoming aware of a screen area of a display that is installed behind mask means.SOLUTION: A display comprises: display means (14) that displays an image on a screen; and mask means that is arranged on the front of the screen and prevents a user from easily visually recognizing the boundary between the inside and outside of the screen when the image is not displayed on the screen. The display means (14) performs display (G) to prevent the user from easily recognizing the boundary between the inside and outside of the screen when the image is displayed on the screen.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a display device that makes it difficult to recognize the boundary between the inside and outside of the screen of a display means arranged behind mask means.

Background Art

[0002] In recent years, with the spread of car navigation systems (so-called car navi) and the development of car audio, the number of cases where a display device (hereinafter referred to as an in-vehicle monitor) is installed inside a vehicle has been increasing. In addition, the number of automobiles equipped with a camera (hereinafter referred to as a back camera) at the rear of the vehicle and displaying an image of the rear on the in-vehicle monitor when the vehicle is reversing is also increasing. On the other hand, the installation forms of in-vehicle monitors have also become diversified. For example, there are those fixedly installed on the dashboard, those incorporated into the dashboard, those incorporated into the headrests of the driver's or passenger's seats for rear seats, and those incorporating a liquid crystal display device into the rearview mirror for rear visibility. Here, the one incorporating a liquid crystal display device into the rearview mirror is hereinafter referred to as a rearview mirror monitor.

[0003] The rearview mirror monitor includes a liquid crystal display device on the back surface of the rearview mirror, and by making the mirror portion corresponding to the screen area of the liquid crystal display device a half mirror, the image displayed on the liquid crystal display device can be visually recognized through the mirror surface. That is, when an image is displayed on the above-described liquid crystal display device, the light of the screen passes through the area of the half mirror, so that the user can visually recognize the displayed image.

[0004] On the other hand, when nothing is displayed on the liquid crystal display device, there is no light passing through the half mirror area, and the half mirror area will solely reflect external light. For this reason, the half mirror area functions as a mirror, and the rearview mirror monitor appears to be no different from an ordinary rearview mirror at first glance when nothing is displayed on the liquid crystal display device. Therefore, the rearview mirror portion with the half mirror area can also be said to be mask means that makes it difficult to visually recognize the boundary between the inside and outside of the screen of the liquid crystal display device.

[0005] In Patent Document 1, as the structure of a conventional backlight for a liquid crystal display device, while forming a resin composition having optical functions such as diffusion, light collection, and refraction in a certain direction with respect to transmitted light on the upper surface of a transparent base material layer, on the lower surface of the base material layer, a light streak prevention layer is proposed to be formed by performing gradation printing with various inks in a light streak generation band such as the outer edge portion on the lamp side. This light streak prevention layer consists of a solid coating area and a gradation area, and the gradation area can blur the boundary line of the light streak prevention layer and make it difficult to visually recognize the light streak prevention layer on the liquid crystal screen.

[0006] In Patent Document 2, in a video display device capable of displaying a video signal with an aspect ratio different from that of the display screen, in order to make the blank area added when converting the video signal in accordance with the aspect ratio of the display screen more tasteful, it has been proposed to perform gradation display on the blank area around the video area.

[0007] Furthermore, in Patent Document 3, when displaying HD content with an aspect ratio of 16:9 including SD content with an aspect ratio of 4:3, in order to avoid image burn-in occurring at the boundary between the SD content display area and the band areas on both the left and right sides, a television receiver has been proposed that performs gradation processing to gradually change the luminance of the band image so that the difference from the luminance of the SD image is within a predetermined range.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] As described above, when no image is displayed on the liquid crystal display device in the conventional rearview mirror monitor, the screen of the liquid crystal display device is difficult to visually recognize from the outside by the mask means, so it is difficult to distinguish it from an ordinary rearview mirror. However, when an image such as an image from a car navigation or a rear camera is displayed on the screen of the liquid crystal display device, the edge of the screen may be made apparent by the displayed image. In such a case, the viewer is made aware of the screen area of the liquid crystal display device, and as a result, the image seen through the rearview mirror gives an obvious impression that it is a display by a liquid crystal display device retrofitted to the rearview mirror, which may wake up the viewer.

[0010] The present invention has been made in view of the above problems, and an object of the present invention is to provide a display device that can give an impression as if the entire area of the mask means is the screen of the display device by displaying an image so as not to make the viewer aware of the screen area of the display device installed behind the mask means.

Means for Solving the Problems

[0011] In order to solve the above-described problems, the present invention provides the following. (1) Display means for displaying an image on a screen, A display device comprising mask means disposed in front of the screen and making it difficult to visually recognize the boundary between the inside and the outside of the screen when no image is displayed on the screen, The display means is characterized in that it performs a display that makes it difficult to recognize the boundary between the inside and the outside of the screen when an image is displayed on the screen.

[0012] Here, the "display means" may be anything that can display an image. For example, a CRT, a liquid crystal display device, an organic EL display, a plasma display, etc. fall under this category. Also, the "mask means" may be, for example, a region consisting of a half-mirror region or a mirror region and a half-mirror region in the back mirror portion of a back mirror monitor, or a transparent member with a reduced light transmittance like smoked glass.

[0013] According to the invention described in (1) above, when the "display means" displays an image on the screen, in order to perform a display that makes it difficult to recognize the boundary between the inside and outside of the screen, the screen area of the "display means" installed behind the "mask means" can be made difficult to perceive not only when no image is being displayed on the screen as in the prior art, but also when an image is being displayed on the screen. That is, the screen area can always be made difficult to perceive. As a result, it is possible to give the person viewing the image the impression that the entire area of the mask means is the screen of the display device. Also, it is possible to always give the impression that the entire area of the mask means is the screen of the display device.

[0014] In particular, the mask means may be configured to make it difficult to visually recognize the boundary over the entire area of the boundary between the inside and outside of the screen of the display means. For example, when the screen of the display means is a rectangular screen, it may be configured to make it difficult to visually recognize the boundary over the entire four sides. Also, the mask means may be configured to make it difficult to visually recognize the boundary over the entire area of the boundary between the inside and outside of the screen, and further have a predetermined area extending from the above-mentioned boundary to the outside of the screen. Furthermore, the mask means may also be configured to have an area covering the entire area inside the screen together with these configurations.

[0015] (2) The display device according to (1) above, wherein the display means performs a display that makes it difficult to generate a subjective contour recognized as the boundary between the inside and outside of the screen.

[0016] Here, the "subjective contour" is a contour that is subjectively recognized by those who see it, even though it does not physically exist. For example, it refers to an optical illusion in which a contour line is perceived even though there is no change in luminance or color along the contour line.

[0017] According to the invention described in (2) above, in order to perform a display that makes it difficult to generate a subjective contour recognized as the boundary between the inside and outside of the screen, it is possible to reduce the possibility of generating an optical illusion as if such a boundary exists at a position where there is originally no boundary between the inside and outside of the screen. As the display that makes it difficult to generate the subjective contour recognized as the boundary between the inside and outside of the screen, it is preferably configured in the same way as the "display that makes it difficult to recognize the boundary" described in (3) and subsequent paragraphs. In particular, a configuration having the component in (7) is effective, and a configuration having the component in (8) is the most effective.

[0018] (3) The display means is characterized in that, as a display that makes it difficult to recognize the boundary, it is a gradation display that gradually decreases the brightness of the image displayed on the screen in the direction outside the screen, according to the display device described in (1) or (2) above.

[0019] Here, the gradation display may start uniformly from a point at a certain distance from the boundary of the screen, or the starting point (distance from the boundary of the screen) of the gradation display may be changed according to the display color of the image displayed on the screen. For example, for colors that are easily perceived by the human eye, the gradation display may start from a point farther from the boundary of the screen, and for colors that are difficult to be perceived by the human eye, the gradation display may start from a point closer to the boundary of the screen.

[0020] According to the invention of (3) described above, since the information displayed on the screen is displayed such that the brightness gradually decreases toward the outside of the screen, it is possible to approach a state where no image is displayed at the boundary between the inside and the outside of the screen. As a result, even when an image is displayed on the screen of the display device, the "masking means" can make it difficult to recognize the boundary between the inside and the outside of the screen, giving an impression as if the entire area of the "masking means" is the screen of the display device.

[0021] (4) The screen of the display means is configured as a dot matrix display, The display means, as a display that makes it difficult to recognize the boundary, is characterized in that the brightness of at least some of the dots in the peripheral portion of the screen where the image is displayed among the dots constituting the screen is decreased, according to the display device described in (3) above.

[0022] According to the invention of (4) described above, when an image is displayed on the screen, since the brightness near the boundary of the screen decreases, it is possible to approach a state where no display is made at the boundary between the inside and the outside of the screen. As a result, even when a display is made on the screen of the display device, the "masking means" can make it difficult to recognize the boundary between the inside and the outside of the screen, giving an impression as if the entire area of the "masking means" is the screen of the display device.

[0023] (5) The display means is characterized by having brightness adjustment means for adjusting the brightness of the image in the peripheral portion of the screen among the images displayed on the screen, according to the display device described in (4) above.

[0024] According to the invention of (5) described above, by adjusting the brightness of the image displayed in the peripheral portion of the screen by the "brightness adjustment means", even when an image is displayed on the screen of the display device, the "masking means" can make it difficult to recognize the boundary between the inside and the outside of the screen. Also, since the brightness can be adjusted, it is possible to appropriately perform the adjustment for making it difficult to recognize the boundary between the inside and the outside of the screen.

[0025] (6) The brightness adjustment means, when displaying the peripheral portion of the screen based on the image data representing the content displayed on the screen, reduces the brightness of the display of the peripheral portion of the screen to be lower than the brightness indicated by the image data and performs the display. The display device according to (5) above is characterized in this.

[0026] Here, "image data" corresponds to anything as long as it indicates the content displayed on the screen. For example, in addition to image data representing photos and graphics, text data indicating the characters to be displayed and its attribute data (such as the color, size, and font of the characters) are also included in "image data".

[0027] As a specific aspect of the brightness adjustment means, for example, it is preferable to adopt a configuration in which the brightness of the display of the peripheral portion of the screen is reduced by software processing when performing display control based on "image data". Thereby, without changing the hardware configuration, it is possible to make it difficult to recognize the boundary between the inside and the outside of the screen by the "mask means", so that while suppressing costs, an impression can be given as if the entire area of the "mask means" is the screen of the display device.

[0028] (7) The brightness adjustment means changes the position of the dot at which the gradation display starts, or the gradient of the gradation when performing the gradation display. The display device according to (6) above is characterized in this.

[0029] According to the invention of (7) described above, since the width of the gradation area added to the image to be displayed, or the inclination of the brightness change in the image displayed within the gradation area is not uniform, it is possible to make it difficult to generate a subjective contour recognized as the boundary between the inside and the outside of the screen.

[0030] (8) The brightness adjustment means changes the position of the dot at which the gradation display starts, or the gradient of the gradation when performing the gradation display, at a predetermined timing. The display device according to (7) above is characterized in this.

[0031] According to the invention of (8) described above, since the width of the gradation area added to the image to be displayed or the inclination of the brightness change in the image displayed in the gradation area changes at a predetermined timing, it is possible to make it more difficult to generate a subjective contour recognized as the boundary between the inside and outside of the screen.

[0032] (9) The display means storage means having a storage area corresponding to each dot of the dot matrix display; display data writing means for writing, based on the image data, display data regarding display at the corresponding dot into each storage area of the storage means; image display means for displaying an image on the dot matrix display based on the display data written in each storage area of the storage means, and comprising: The data writing means writes, into the storage area corresponding to the dot at the peripheral portion of the screen among the respective storage areas, display data having a brightness lower than the brightness specified by the image data for the display at the dot. The display device according to any one of (6) to (8) above, characterized in that.

[0033] According to the invention of (9) described above, when performing image display control based on image data, it is possible to lower the brightness of the image displayed at the peripheral portion of the screen only by changing only the writing process of the display data for each dot based on the image data. As a result, without changing the hardware configuration, it is possible to make it difficult to recognize the boundary between the inside and outside of the screen by the "mask means", so that while suppressing the cost, it is possible to give an impression that the entire area of the "mask means" is like the screen of the display device.

[0034] (10) When the data writing means writes the display data into each storage area of the storage means in order to display an object on the screen based on the image data, the data writing means changes the display data so that the peripheral portion of the object is displayed in gradation. The display device according to (9) above, characterized in that.

[0035] According to the invention of (10) described above, not only does the brightness of the peripheral portion of the screen decrease, but also the peripheral portion of the image representing the object is displayed in gradation. As a result, for example, when the shape of the object to be displayed is a polygon composed of straight lines, and one of its sides is a straight line parallel to the boundary between the inside and outside of the screen, there is a possibility that one side forming the outer shape of the object may appear to be the boundary between the inside and outside of the screen. Therefore, in order to avoid such misrecognition, by also displaying the peripheral portion of the object in gradation, it is possible to reduce the possibility of making the user aware of the screen area of the display device, and it is possible to give an impression as if the entire area of the mask means is the screen of the display device.

[0036] (11) The data writing means judges whether or not the entire object to be displayed within the screen is displayed, When it is determined that a part of the display of the object is not displayed within the screen, for the storage area corresponding to the dot at the peripheral portion of the screen in the object displayed within the screen, display data having a lower brightness than the brightness specified by the image data for the display at the dot is written. The display device according to (9) above, characterized in that.

[0037] According to the invention of (11) described above, when the entire image of the object to be displayed does not fit within the screen and a part of the object is cut off at the peripheral edge of the screen, the display of the object at the peripheral portion of the screen is displayed in gradation. As a result, it is possible to reduce the possibility of making the viewer of the object aware of the screen area of the display device due to a part of the object being cut off at the peripheral edge of the screen.

[0038] (12) The data writing means When there are a plurality of objects that are not entirely displayed within the screen, the gradation display at the peripheral portion of the screen for each of those objects is made different from each other when there are a plurality of objects that are not entirely displayed within the screen. The display device according to (9) above, characterized in that.

[0039] According to the invention of (12) described above, in the image to be displayed, when there are a plurality of objects displayed up to the periphery of the screen, in each of those objects, since the gradation display at the peripheral portion of the screen is different from each other, the ends of each object do not align linearly along the periphery of the screen, and it is possible to make it difficult to generate a subjective contour recognized as the boundary between the inside and outside of the screen.

[0040] (13) The display means is provided with a transmittance reducing means for reducing the light transmittance on the front surface side and the peripheral portion of the screen, and the display device according to (4) above, characterized in that.

[0041] According to the invention of (13) described above, by providing "transmittance reducing means" at the periphery of the screen, the brightness of the image displayed near the boundary of the screen is reduced, so that even when an image is being displayed on the screen of the display device, it is possible to make it difficult to recognize the boundary between the inside and outside of the screen by the "mask means". Therefore, by adding a simple configuration, it is possible to give the impression that the entire area of the "mask means" is like the screen of the display device.

[0042] (14) The display means includes an illumination means for illuminating the screen from the back side to make the image displayed on the screen visible, and a light dimming means provided on the back side and the peripheral portion of the screen for dimming the light from the illumination means, and the display device according to (4) above, characterized in that.

[0043] According to the invention of (14) described above, among the light from the "lighting means" that illuminates the back side of the screen of the "display means", the light for the peripheral portion of the screen is dimmed by the "light dimming means". Therefore, even when an image is being displayed on the screen of the display device, it is possible to make it difficult to recognize the boundary between the inside and the outside of the screen by the "mask means". For this reason, with a simple configuration, it is possible to give the impression that the entire area of the "mask means" is like the screen of the display device.

[0044] (15) The display means includes lighting means for illuminating the screen from the back side to make the image displayed on the screen visible. The lighting means has a central lighting portion for illuminating the central portion of the screen and a peripheral lighting portion for illuminating the peripheral portion, and the light amount of the peripheral lighting portion is made less than the light amount of the central lighting portion. The display device according to (4) above is characterized in this regard.

[0045] According to the invention of (15) described above, since the illumination that illuminates the back side of the screen is darker at the peripheral portion of the screen than at the central portion of the screen, even when a display is being made on the screen of the display device, it is possible to make it difficult to recognize the boundary between the inside and the outside of the screen by the "mask means". For this reason, without using additional means other than the "lighting means", it is possible to give the impression that the entire area of the "mask means" is like the screen of the display device.

Effect of the Invention

[0046] As described above, according to the present invention, by performing a display that does not make the user aware of the screen area of the display device installed behind the mask means, it is possible to give the impression that the entire area of the mask means is like the screen of the display device.

Brief Description of the Drawings

[0047]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0048] Hereinafter, a display device according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment described below, first, the overall configuration of the present display device will be described.

[0049] <Overall Configuration of Radar Detector> FIGS. 1(a) and (b) show the appearance of a radar detector including an embodiment of the display device of the present invention. The radar detector 10 includes various mechanisms shown in FIG. 2 inside and outside a rectangular parallelepiped housing 11 serving as a main body, and the radar detector 10 is fixed by sandwiching a rearview mirror (not shown) provided in the vehicle from above and below by fixing tools 12a and 12b provided on the back surface of the housing 11.

[0050] As shown in Fig. 1(a), on the front surface of the housing 11 (the surface facing the driver), a rectangular mirror member 13, which is a mirror for reflecting the rear of the vehicle, is provided. On the right rear surface of the mirror member 13, a display unit 14 (hereinafter also referred to as "screen 14" according to the description) as display means is provided. In the present embodiment, a 2.8-inch small liquid crystal display is used as the display unit 14. In the mirror surface of the mirror member 13, the region (region HM shown by a broken line in Fig. 1(a)) facing the screen of the display unit 14 is a half mirror. Hereinafter, in Fig. 1(a), the region shown by the broken line is referred to as the half mirror region HM. Also, the region other than the half mirror region HM is referred to as the mirror region M. The region composed of this half mirror region HM and the mirror region M corresponds to mask means, and thereby, when an image of some kind is displayed on the screen of the display unit 14, the image can be visually recognized through the half mirror region HM. Also, when the display unit 14 is not displaying any image (when the screen is completely dark), the surrounding scenery is reflected in the half mirror region HM, and the screen of the display unit 14 provided on the back thereof becomes in a state that is extremely difficult to visually recognize. Above the half mirror region HM, an infrared light receiving unit 15 for receiving the infrared signal of the remote control 28 (see Fig. 2) is provided.

[0051] As shown in Fig. 1(b), on the right side in the figure on the back surface of the housing 11 (the surface facing the front window), a sound emission hole 18 for passing the sound output from the speaker 17 as sound output means to the outside is formed. Also, on the upper side approximately in the center in the figure on the back surface of the housing 11, an insertion hole 19 for a DC power jack is formed. Although not shown, in the present embodiment, the power supply on the main body side of the radar detection device 10 is obtained from a cigarette socket (that is, a secondary battery which is the vehicle battery) via a cigarette plug cord that electrically connects this DC jack and the cigarette socket of the vehicle. Further, a microwave receiver 22 and a wireless receiver 23 are built in below the insertion hole 19, and a GPS receiver 21 is built in on the right side of the microwave receiver 22 and the wireless receiver 23.

[0052] On the left side surface of the housing 11 shown in FIG. 1(b), a slot 20 is formed for inserting a memory card 25 as a storage medium into a memory card reader 24 (both are shown in FIG. 2). The memory card reader 24 can take in the data stored in the memory card 25 or write the contents of the memory of the database 27 and the control unit 26 shown in FIG. 2 into the memory card 25. More specifically, when there is updated information about the data stored in the memory card 25, such as new warning target information (position information including longitude and latitude, type information, etc.), the control unit 26 stores (downloads) the updated information in the database 27 built into the device and updates the data in the database 27.

[0053] In FIG. 2, the database 27 is a non-volatile memory (for example, EEPROM) built into or externally attached to the microcomputer which is the control unit 26. In the database 27, information about certain warning targets at the time of shipment is registered, and new warning target information and the like added later can be updated as described above.

[0054] The wireless receiver 23 receives wireless signals of a predetermined frequency. The infrared light receiving unit 15 performs data communication with a remote control (portable device: slave unit) 28 by infrared rays and performs various settings for this device. The remote control 28 is provided with a standby switching button, a first setting button, a second setting button, a selection button, a cancel button, a decision button, and cross buttons for up, down, left, and right (the above are not shown).

[0055] In addition, the control unit 26 is a microcomputer including a CPU 260, a ROM 262, a RAM 264, a VRAM 266, I / O, etc. (not shown in the figure). It executes predetermined processing based on the information input from the above various input devices and outputs predetermined warnings, messages, and information using the output devices. It is assumed that a storage area corresponding to each pixel constituting the screen of the display unit 14 is defined in the VRAM 266. Also, for these basic configurations, those similar to the conventional ones can basically be used.

[0056] The functions of the radar detector 10 in this embodiment are stored as a program on the EEPROM of the control unit 26, and are realized by the CPU of the control unit 26 executing this program. The functions executed by the CPU according to the program include a GPS logging function, a standby screen display function, a radar scope display function, a GPS warning function, a radar wave warning function, a wireless warning function, etc. The warning means in the present invention is embodied as a function of the CPU of the control unit 26.

[0057] The GPS logging function is a function in which the control unit 26 stores the current position detected by the GPS receiver 21 every second as a position history in a non-volatile memory in association with the detected time and speed (vehicle speed). This position history is, for example, a function of recording in the NMEA (National Marine Electronics Association) format.

[0058] The standby screen display function is a function of displaying the speed 141, latitude 142, and longitude 143 of the host vehicle detected by the GPS receiver 21 on the display unit 14 as shown in FIG. 3(a).

[0059] Here, the screen display area 140 of the display unit 14 when the standby screen display function, the GPS warning function, the radar wave warning function, and the wireless warning function are being executed is divided into a main display area 140A and an icon display area 140B, and the information related to each function is exclusively displayed in the main display area 140A. On the other hand, in the icon display area 140B, a compass icon 144, a road selection icon 145, a radar reception sensitivity mode icon 146, and a mode selection icon 147 are displayed. Further, the current time 148 is displayed at the right end of the icon display area 140B in the figure.

[0060] As shown in Fig. 3(b), the radar scope display function searches for warning targets within a predetermined range (for example, within a range of about 1 km) from the current position detected by the GPS receiver 21 based on the position information stored in the database 27, and displays the relative positional relationship between the own vehicle and the warning targets on the display unit 14. Note that the diagrams shown in Figs. 3(a) and (b) are for explaining the contents displayed during the execution of each function, and how these contents are specifically displayed will be described in detail later.

[0061] During the execution of the radar scope display function, a map 151 based on the map information stored in the database 27 is displayed in the main display area 140A, and an arrow-shaped own vehicle icon 152 indicating the position of the own vehicle is displayed on this map 151. Also, when an event occurs (when a predetermined condition for giving an alarm is satisfied) during the execution of the radar scope display function, a warning target icon 153 having characters such as "L", "RD", "P", "N", etc. is displayed on the map 151 to indicate the type and position of the warning target. Further, during the execution of the radar scope display function, the legal speed 154 of the road on which the own vehicle is traveling and the current speed 155 of the own vehicle are displayed in the lower right of the diagram in the main display area 140A.

[0062] When the control unit 26 detects the pressing of the standby switching button provided on the remote control 17 during the execution of the standby screen display function shown in Fig. 3(a), it switches to the radar scope display function shown in Fig. 3(b). Also, when the pressing of the standby switching button provided on the remote control 17 is detected during the execution of the radar scope display function, a process of switching to the standby screen display function is performed.

[0063] When an event occurs during the execution of the standby screen display function or the radar scope display function (hereinafter, these functions are collectively referred to as the standby function), the control unit 26 executes processes for realizing each function of the GPS warning function, the radar wave warning function, and the wireless warning function. The priority order of each function is set in the order of the radar wave warning function, the wireless warning function, and the GPS warning function from the highest.

[0064] The GPS warning function is a process that is executed at a predetermined time interval (1-second interval) by an event from a timer in the control unit 26. Based on the latitude and longitude of the warning target stored in the database 27 and the current latitude and longitude of the own vehicle detected by the GPS receiver 21, the distance between the two is calculated. When the calculated distance reaches a predetermined approach distance (for example, within 2 km), a warning is displayed on the display unit 14, and a warning sound such as an effect sound, BGM, or voice is output from the speaker 17.

[0065] Examples of warning targets for the GPS warning function include speed measurement devices (loop coil, LH system, H system, radar-type orbis, etc.), mouse trap areas, moving orbis areas, following-up enforcement areas, temporary stop enforcement areas, intersection enforcement areas, other enforcement areas, seat belt inspection areas, drunk driving inspection areas, mobile phone inspection areas, other inspection areas, intersection monitoring points, signal violation suppression systems, highway traffic police teams, N systems, traffic monitoring systems, police stations, accident-prone areas, service areas, parking areas, highway oases, highway lengths / continuous tunnels, highway radio reception areas, road stations, viewpoint parking lots, parking lots, public toilets, etc. The database 27 stores the type information of these warning targets, the latitude and longitude information indicating their positions, the data of schematic diagrams or photos to be displayed on the display unit 14, and the voice data in association with each other.

[0066] The radar wave warning function is a warning function that displays a warning on the display unit 14 and outputs a warning sound from the speaker 17 when an electric wave corresponding to a microwave in a predetermined frequency band emitted from a speed measurement device is detected by the microwave receiver 22. For example, when a microwave in a predetermined frequency band emitted from a speed measurement device is detected by the microwave receiver 22, a schematic diagram or photo of the radar stored in the database 27 is displayed on the display unit 14 as a warning, and the voice data stored in the database 27 is read out and a voice saying "There is a radar. Caution for speed" is output from the speaker 17.

[0067] The wireless warning function is a function that issues a warning by the wireless receiver 23 when receiving radio waves emitted by an emergency vehicle or the like so as not to interfere with its running or the like. In the wireless warning function, frequencies such as regulatory radio, car audio radio, digital radio, very small radio, police activity radio, police telephone, police activity radio, radar radio, helicopter radio, fire helicopter radio, fire radio, emergency radio, highway radio, security radio, etc. are scanned. When wireless is received at the scanned frequency, a schematic diagram indicating that the wireless corresponding to that frequency stored for each wireless type in the database 27 has been received is displayed on the display unit 14 as a warning screen, and the voice data stored for each wireless type in the database 27 is read out, and a warning voice indicating the type of that wireless is output from the speaker 17. For example, when receiving regulatory radio, a voice such as "This is regulatory radio. Caution for speed" is output.

[0068] Here, in the radar scope display function, the GPS warning function, the radar wave warning function, and the wireless warning function, as described above, a plurality of different types of warning targets are set, and a priority order corresponding to the type of each warning target is determined. The priority order of each warning target is visualized, for example, by classifying the colors of the warning target icons 153 shown in FIG. 3(b) into groups of "red", "yellow", "blue", or "green" in descending order of priority. And, for example, for the warning target belonging to the "red" group with the highest priority, a warning is notified in the characteristic display mode of the present embodiment described below, and for the warning target belonging to the "yellow", "blue", or "green" group with the second or lower priority, a warning is notified in the same general display mode as the conventional one (not shown).

[0069] <Display mode of the image on the screen of the display device> Next, the display mode of the image displayed on the screen of the display device in the present embodiment will be described with reference to FIG. 4. The display mode shown in FIG. 4 is obtained by applying the display mode of the display device in the present embodiment to the image displayed during the execution of the radar scope display function shown in FIG. 3(b). Further, the display mode shown in FIG. 4 illustrates the mode of being displayed on the screen of the display unit 14, and does not illustrate the display mode visually recognized through the half mirror region HM of the mirror member 13.

[0070] As shown in FIG. 4, in the image displayed on the display device of the present embodiment, there is a gradation region G with a constant width W that gradually brightens from the outermost periphery (hereinafter also referred to as the edge) of the screen of the display unit 14 toward the inside of the screen. At the boundary of the gradation region G indicated by the broken line in the figure, the original brightness of the displayed image is obtained. In other words, within the gradation region G, the displayed image becomes darker as it goes from the boundary to the outside (the peripheral side of the screen), and when reaching the outermost periphery of the screen of the display unit 14, it becomes a completely dark state where nothing is displayed. This gradation region G corresponds to the "peripheral portion of the display region". Further, hereinafter, the region of the screen of the display unit 14 that is not the gradation region G (the region within the broken line in FIG. 4) is referred to as the normal region N.

[0071] It goes without saying that in FIG. 4, the broken line indicating the boundary of the gradation region G is not displayed on the screen of the display unit 14. Further, the shape and position of the gradation region G are constant. For example, even when the display of the own vehicle icon 152 moves or the display of the map 151 scrolls due to the vehicle equipped with the radar detector 10 traveling, the gradation region G does not move or deform accordingly.

[0072] The width of the gradation region G refers to the length in the vertical direction with respect to the edge of the screen. Also, the width of the gradation region G and the degree of change in brightness in the direction of the width W (hereinafter also referred to as the brightness gradient) may be appropriately determined according to the size of the half-mirror region HM in the mirror member 13 with respect to the size of the screen of the display unit 14, the light transmittance in the half-mirror region HM, and the specifications regarding the image display of the display unit 14. That is, the gradation region G may be determined so that when the image displayed across the entire screen of the display unit 14 is viewed through the half-mirror region HM of the mirror unit 13, the edge of the screen is difficult to visually recognize.

[0073] (Function and Effect) Thus, by adding the gradation region G as shown in FIG. 4 to the image to be displayed, the following function and effect are achieved. First, in the front view of the radar detector 10 shown in FIG. 1(a), when no image is displayed on the screen of the display unit 14, it is difficult to distinguish between the half-mirror region HM and the mirror region M, and the front of the mirror member 13 appears like a uniform mirror. For this reason, it is difficult to visually recognize the boundary between the inside and outside of the screen of the display unit 14. In this state, for example, assume that an image is displayed on the screen of the display unit 14 in which the image portion to be displayed is bright and the other background portion is dark. When this image is viewed through the half-mirror region HM of the mirror member 13, the image portion to be displayed can be clearly visually recognized, but for the background portion, the light transmitted through the half-mirror region HM (excluding the image portion to be displayed) is weak and the reflected light becomes dominant, so it appears like a mirror. As a result, in the mirror member 13, it appears as if only the image portion to be displayed is floating in the mirror.

[0074] On the other hand, when a bright image is displayed across the entire screen of the display unit 14 as in the prior art, there will be a place where the brightness contrast becomes prominent between the inside and the outside of the edge of the screen of the display unit 14. Therefore, when such an image is viewed through the half-mirror region HM, the shape of the screen of the display unit 14 (usually rectangular) will be clearly recognized. Also, for example, when a road is drawn up to the edge of the screen of the display unit 14, the viewer will feel that the road extending outside the screen has its display cut off at the edge of the screen. Thus, when an image reaches the edge of the screen and there is a part of the image that is felt to continue outside the screen (for example, an image where a part of an object having a predetermined form as a whole is displayed), if the image is cut off at the edge of the screen, the shape of the screen of the display unit 14 will be recognized. Therefore, instead of looking at the image floating in the mirror of the mirror member 13, it is once again realized that one is merely looking at the screen of the display unit 14 provided on the back side of the mirror member 13, which may make the viewer feel awakened or bored.

[0075] Therefore, in the present embodiment, a gradation region G with a constant width W is provided from the peripheral edge of the screen of the display unit 14, and the image displayed near the peripheral edge of the screen of the display unit 14 is gradually shifted from "bright" to "dark" as it approaches the peripheral edge of the screen. This makes the edge of the screen of the display unit 14 less noticeable when viewing the image through the half-mirror region HM. As a result, in both cases when no image is displayed on the screen of the display unit 14 and when an image is displayed, it is possible to always make it difficult to recognize the shape of the screen of the display unit 14, and the possibility of making the viewer of the displayed image feel awakened or bored is reduced.

[0076] <Embodiment for Adding a Gradation Region to an Image> Next, each embodiment for adding the gradation region G shown in FIG. 4 to the image displayed on the display unit 14 will be described.

[0077] (First Embodiment) First, the first embodiment will be described. In the first embodiment, the gradation region G as shown in FIG. 4 is added by image processing performed when an image is displayed on the screen of the display unit 14. Hereinafter, this image processing is referred to as gradation addition processing, and its content will be described below.

[0078] First, the CPU 260 determines display data for one pixel in a predetermined order based on the image data to be displayed among the image data stored in the database 27 shown in FIG. 2.

[0079] Here, the "predetermined order" is, for example, assuming that each pixel constituting the screen of the display unit 14 is arranged in an m×n matrix, for each pixel row from the first row to the mth row in order, and for each pixel row, in order from the pixel in the first column to the pixel in the nth column. That is, the order is the pixels of (the first row, the first column) to (the first row, the nth column), then the pixels of (the second row, the first column) to (the second row, the nth column), then the pixels of (the third row, the first column) to (the third row, the nth column),..., and finally the pixels of (the mth row, the first column) to (the mth row, the nth column). Also, the "display data" is data that specifies the display color for each pixel, and is, for example, data indicating the gradation (0 to 255) in each of the three primary colors (RGB).

[0080] Next, the CPU 260 refers to the gradation data stored in the ROM 262 shown in FIG. 2, and recognizes a predetermined lightness coefficient (hereinafter referred to as the lightness coefficient) for the pixels for which the display data has been determined based on the image data. This gradation data defines the above-described lightness coefficients for the individual pixels constituting the screen of the display unit 14. This lightness coefficient takes a value in the range from 0 to 1. "0" means that the lightness is "0" (i.e., black), and "1" means the lightness of the determined display data as it is. A value that exceeds "0" and is less than "1" indicates the ratio of reducing the lightness with respect to the lightness of the determined display data.

[0081] From this, the CPU 260 multiplies the recognized value of the lightness coefficient by the display data determined above, that is, the values indicating the gradations in each of the RGB colors, and uses the result as the display data (hereinafter referred to as the converted display data) for actual display. Then, after storing the converted display data for one calculated pixel in the storage area corresponding to that pixel in the VRAM 266 (see FIG. 2), the converted display data for the next pixel is calculated according to the predetermined order described above. In this way, when the converted display data is obtained for all the pixels constituting the screen of the display unit 14, the CPU 260 drives each pixel constituting the screen of the display unit 14 according to the converted display data stored in the VRAM 266 to display an image.

[0082] Next, the content of the gradation data stored in the above-described ROM 262 will be described. As described above, the gradation data is constituted by the lightness coefficients for each pixel constituting the screen of the display unit 14. The value of this lightness coefficient is, for example, "1" for the pixels included in the normal region N in the screen shown in FIG. 4. Also, for the pixels at the outermost periphery of the screen of the display unit 14 (that is, the pixels of the first to nth columns in the first and mth rows, and the pixels of the first to mth rows in the first and nth columns), the value is "0". Further, from the boundary B (shown by a broken line in FIG. 4) between the normal region N and the gradation region G to the outermost periphery of the screen, the value of the lightness coefficient for the pixels gradually decreases so as to approach "0" from "1". Here, the inclination of the change until the value of the lightness coefficient decreases from "1" to "0" may be a straight line or a curve.

[0083] Here, when the width W of the gradation region G is constant and the inclination of the value of the lightness coefficient for each pixel in the gradation region G in the gradation data is uniform, the subjective contour is likely to be recognized due to the human cognitive characteristics. Here, the "subjective contour" refers to an optical illusion in which the contour line is perceived even though there is no change in luminance or color along the contour line. Note that the "subjective contour" that is a problem in the present embodiment is the edge of the screen that should not exist and is perceived by the person viewing the image due to changes in the luminance and color of the image viewed through the half mirror region of the mirror member 13. Therefore, when simply referred to as the "subjective contour" hereinafter, it means "the edge of the screen that should not exist and is perceived by the person viewing the image".

[0084] Note that the "subjective contour" may be more easily recognized depending on the content of the displayed image. For example, in the icon display area 140B shown in FIG. 3, four square icons (azimuth compass icon 144, road selection icon 145, radar reception sensitivity mode icon 146, mode selection icon 147) are arranged in a horizontal row on the left side of the figure, and the current time is displayed on the right side of the figure. When such a display is made, there is a possibility that a subjective contour may be recognized by the lower sides of the four icons and the lines connecting the bottoms of the characters and numbers of the current time.

[0085] Also, in the map 151 of FIG. 6, since three roads reach the left edge portion of the screen, it is felt that the display of the road that should originally continue further is cut off there, so it becomes easier to recognize that there is an edge of the screen at that portion. Moreover, the line connecting the ends of these three roads in a certain direction (for example, upward) in order is recognized as a subjective contour line. Since this line coincides with the left edge of the screen, ultimately, the edge of the screen is also recognized as a subjective contour. Therefore, as described above, by applying a gradient with a certain width w, it is possible to make it difficult to recognize the ends of the roads, and by suppressing the feeling that the display of the roads is cut off, it is possible to make it difficult to recognize the edge of the screen.

[0086] For example, in order to make the above-mentioned "subjective contour" difficult to recognize, the gradation data stored in the ROM 262 may be set to the content as shown in FIG. 5. That is, as shown in FIG. 4, in order to give a gradation with a certain width w, the value of the lightness coefficient for each pixel is set to uniformly decrease from "1" to "0" from the pixel located on the boundary B shown in FIG. 5 toward the pixel located at the edge of the screen. Here, the pixels located on the boundary B are the pixels located on the straight line connecting the four pixels of the w-th row and w-th column, the w-th row and the (n - w)-th column, the (m - w)-th row and w-th column, and the (m - w)-th row and the (n - w)-th column. That is, the shape of the boundary B is rectangular (shown by the thin broken line in FIG. 5), and the lightness coefficient is uniformly decreased from the pixels located on each boundary B toward the pixels located at the edge of the screen. In the following, for example, when referring to the pixel of the w-th row and w-th column, it is expressed as the pixel of (w, w).

[0087] However, if the shape of the boundary B is made similar to the shape of the edge of the screen, there remains a possibility that the edge of the screen is recognized as a subjective contour. Therefore, further, in order to make the "subjective contour" difficult to recognize, the shape of the boundary B is deformed into an arbitrary curve instead of a rectangle, as shown by the thick broken line B' in FIG. 5, for example, and the gradation data is set so that the value of the lightness coefficient for each pixel decreases from "1" to "0" from the pixel located on the deformed boundary B' toward the pixel located at the edge of the screen. How to deform the boundary B may be determined as appropriate. For example, based on the pixels located on the boundary B, at the positions of these pixels, within the range of the predetermined maximum movement width, after moving an arbitrary number of pixels in the row direction or column direction, the pixels after the movement are set as the pixels located on the boundary B'.

[0088] For example, as described above, the pixels located on the boundary B are the pixels located on the straight line connecting the four pixels of (w, w), (w, n - w), (m - w, w), and (m - w, n - w). For the pixels located on the line connecting (w, w) and (w, n - w) and on the line connecting (m - w, w) and (m - w, n - w), the column values are arbitrarily increased or decreased within a predetermined numerical range (for example, ±30). Also, for the pixels located on the line connecting (w, w) and (m - w, w) and on the line connecting (w, n - w) and (m - w, n - w), the row values are arbitrarily increased or decreased within a predetermined numerical range (for example, ±30). After determining the pixels located on the boundary B' in this way, the gradation data is set so that the value of the lightness coefficient for each pixel decreases from "1" to "0" from each of these pixels toward the pixels located at the edge of the screen.

[0089] The gradation data as described above may be stored in advance in the ROM262 shown in FIG. 2, or may be generated by the CPU260 based on a function or the like. For example, information for identifying the pixels located on the reference boundary B is stored in the ROM262, and the CPU260 determines the boundary B' shown in FIG. 5 based on that information. Next, the CPU260 obtains gradation data in which the value of the lightness coefficient decreases from the pixels located on the determined boundary B' toward the pixels located at the edge of the screen. Then, the gradation data obtained by this process is stored in the database 27 shown in FIG. 2. Thereby, when the CPU260 displays the image shown in FIG. 4, the CPU260 performs gradation addition based on the gradation data stored in the database 27.

[0090] The above-mentioned gradation data is such that the width of the gradation region can be arbitrarily changed by arbitrarily changing the shape of the boundary B. As another method, when decreasing the value of the lightness coefficient for each pixel from each pixel located on the rectangular boundary B toward the pixel located at the edge of the screen from "1" to "0", the slope of the value of the lightness coefficient may be arbitrarily changed. For example, from the position on the rectangular boundary B to the position of the edge of the screen, the value of the lightness coefficient linearly changes from "1" to "0", the value of the lightness coefficient becomes "0" at a position closer to the boundary B than the edge of the screen from the position on the boundary B, the slope of the change becomes steep, the value of the lightness coefficient changes in a curved manner (convex curve or concave curve), and so on, showing various modes of change. Hereinafter, the slope of the change of the lightness coefficient is referred to as the lightness gradient.

[0091] In this way, by changing the lightness gradient in the gradation data, the mode of the gradation added to the image can be arbitrarily changed, so that it is possible to make it difficult for the viewer of the screen to recognize the "subjective contour". Also in this method, gradation data with a changed lightness gradient may be stored in the ROM 262 in advance, or information capable of specifying the pixels located on the boundary B may be stored in the ROM 262, and the CPU 260 arbitrarily changes the lightness gradient from each pixel to the image located at the edge of the screen based on the information, and the obtained gradation data may be stored in the database 27. Furthermore, the above two methods may be combined, first, a deformed boundary B' is determined, and then the lightness gradient from each pixel located on the boundary B' to the pixel located at the edge of the screen may be arbitrarily changed.

[0092] In addition, when the CPU 260 determines the gradation data, it is more preferable to update the gradation data at a predetermined timing. As this predetermined timing, for example, when the power of the radar detector 10 is turned on, when a predetermined number of days have elapsed, when a predetermined time has elapsed, when the displayed screen is switched, etc. may be used. By doing so, not only the subjective contours that coincide with or approximate the edges of the screen, but also the generation of subjective contours that may be caused by the boundary B and the gradation pattern can be suppressed.

[0093] Furthermore, in order to make it difficult for the viewer of the screen to recognize the "subjective contour", it is preferable to eliminate as much as possible the display that makes it easy to recognize the subjective contour. For example, as described above, in the icon display area 140B shown in FIG. 3, four square icons are arranged in a horizontal row on the left side in the figure, and the current time is displayed on the right side in the figure. Therefore, the subjective contour is easily recognized by the line connecting the lower side of each icon and the bottom of the characters and numbers representing the current time.

[0094] Therefore, in the figure, the display positions in the vertical direction may be appropriately shifted so that the four icons and the display positions of the current time are not aligned in a straight line, or the shape of the icons may be changed so that the contour of each icon does not become a line parallel to the edge of the screen. As a shape of an icon that makes it difficult to recognize the subjective contour, for example, a shape in which the contour line of the icon is composed of an oblique straight line or a curve so as not to be parallel to the edge of the screen, or an icon without a contour line can be considered. Also, when displaying characters, the characters may be displayed in color, but the periphery of the characters should be all black.

[0095] As described above, the control unit 26 that performs the above-described gradation addition process when displaying an image can be said to correspond to the "brightness adjustment means". Also, the above-described VRAM corresponds to the "storage means", and it can be said that the control unit 26 also corresponds to the "data writing means" and the "image display means".

[0096] (Modification of the First Embodiment) As a method of adding the gradation region G, as described above, instead of writing display data that is darker than the actual brightness into the storage area corresponding to each pixel of the VRAM based on the image data, the number of pixels for displaying the image may be gradually decreased. That is, instead of writing the display data for originally displaying the map 151 into the storage area corresponding to each pixel of the VRAM, the same display data as the background image (for example, black) is written, and the number of such pixels is gradually increased from the boundary between the normal region N and the gradation region G toward the periphery of the screen.

[0097] Specifically, as the above-described gradation data, for the pixels included in the gradation region G, data indicating whether to use the display data determined in step S10 of FIG. 5 or the same display data as the background image (hereinafter referred to as conversion specification data) is determined. Then, when the CPU 260 performs the process of step S14 as a result of the determination process in step S12 of FIG. 5, according to the conversion specification data corresponding to the pixel, the display data determined in step S10 of FIG. 5 or the same display data as the background image is stored in the corresponding storage area of the VRAM.

[0098] Therefore, in the gradation data in this modified example, as approaching the periphery of the screen, among a plurality of pixels within a certain area, the ratio of the pixels performing the same display as the background image increases, and as a result, a gradation region G as shown in FIG. 4 is added. Note that the ratio of the pixels performing the same display as the background image by the above-described conversion specification data can be made less likely to recognize the subjective contour by changing it so that the boundary between the normal region N and the gradation region G becomes the boundary B' shown in FIG. 5 or so that the change in the ratio of the pixels performing the same display as the background image does not become uniform as approaching the periphery of the screen, similar to the gradation data specifying the lightness coefficient.

[0099] (Application Example 1 of the First Embodiment) As described above, in the present embodiment, the display data for each pixel in the gradation region G is converted into display data having a darkness corresponding to the position of each pixel rather than the original brightness. Therefore, by changing the pixels to be the target of the above-described conversion of the display data, the gradation region within the screen of the display unit 14 can be changed.

[0100] For example, when the map 151 and the own vehicle icon 152 shown in FIG. 3(b) are three-dimensionally displayed (3D display), as shown in FIG. 6(a), the display position of the horizon H parallel to the long side of the screen is fixed, and the background image (the region corresponding to the sky) BG in the region above the horizon H in the figure is displayed uniformly darker than the display of the map 151. Assuming that the gradation region G shown in FIG. 4 is added to such an image, the brightness gradient in the gradation region G is reflected in the image of the map 151 near the left and right sides and the lower side of the screen, but the brightness gradient in the gradation region G is not reflected in the image of the map 151 near the horizon H. Therefore, the contrast between the image of the map 151 and the background image BG becomes prominent with the horizontal line H as the boundary, and when such an image is viewed through the half mirror region HM of the mirror member 13, the horizon H of the map 151 may be clearly recognized and may be recognized as if it were the edge of the screen.

[0101] Therefore, as in the gradation region G' shown in FIG. 6(b), in addition to the gradation regions of a constant width W from the left and right sides and the lower side of the screen, for the gradation region of the upper side, the conversion of the display data in the present embodiment or its modification may be performed such that a gradation region of a constant width W is added downward from the horizon H. In this way, even for a location that is not originally the edge of the screen, depending on the content of the image to be displayed, by performing the conversion of the display data such that a gradation region is added to a location that may be recognized as if it were the edge of the screen, it is possible to prevent the screen region of the display unit 14 from being recognized based on misrecognition.

[0102] In order to add the gradation as described above, first, gradation data for adding the gradation area G shown in FIG. 4 and gradation data for adding the gradation area G' shown in FIG. 6(b) are stored in advance in the ROM 262 of FIG. 2. Then, when stereoscopically displaying the map 151 or the like, it is preferable to perform the processes of steps S12 to S16 in FIG. 5 based on the latter gradation data.

[0103] (Application Example 2 of the First Embodiment) In Application Example 1 described above, the position or range of the gradation area G within the screen was changed according to the image to be displayed. In contrast, Application Example 2 changes the width of the gradation area for each object (hereinafter referred to as an object) to be displayed as an image.

[0104] FIG. 7(a) shows an example of the display mode of the image according to Application Example 2. The image shown in this figure basically has the same content as the image shown in FIG. 4, but the icon display area 140B is not shown in order to more clearly illustrate the features in Application Example 2. Also, in this figure, the same parts as those shown in FIG. 4 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. In FIG. 6, the roads, various icons (own vehicle icon 152, warning target icon 153), legal speed 154 and current speed 155 within the map 151, which are displayed as an image, as well as other numbers, characters, and lines are also treated as individual objects.

[0105] In Application Example 2, for an object to be displayed where the entire object cannot be contained within the screen and a part of its display is cut off at the edge of the screen, a gradation area is appropriately added to the object starting from the cut-off part. For example, in the object "road" displayed on the map 151 shown in FIG. 7(a), there are the following roads that reach the edge of the screen. That is, a thick road R1 extending vertically in the approximate center of the screen, a thick road R2 extending horizontally from the left side of the screen and hitting road R1, a thin road R3 branching off into two from road R2, a thin road R4 extending horizontally from the left side to the right side of the screen and intersecting road R1 slightly above road R2, a thin road R5 extending diagonally upward to the right from the upper left side of the screen, intersecting road R4, merging with road R1, and further reaching the upper part of the screen, and a thin road R6 extending obliquely upward to the left and intersecting road R5 above the approximate center of the screen.

[0106] And at the ends of the above-described roads R1 to R6, gradation areas having random widths w1 to w5, w5', w6 are added respectively starting from the edge part of the screen. As a result, for example, on the left side of the screen shown in FIG. 7(a), in the figure, the widths w4, w5, w2, w3 of the gradation areas at the ends of roads R4, R5, R2, R3 in order from the top are different from each other, so the positions where the ends of each road are difficult to visually recognize do not line up vertically in a straight line. Therefore, when such a screen is viewed through the half-mirror area of the mirror member 13, it is possible to make it difficult for the viewer to be aware of the edge of the screen.

[0107] In addition, since the positions of the ends of each road do not line up in a straight line parallel to the edge of the screen of the display unit 14 at the edge of the screen, it is also possible to prevent the generation of a subjective contour (coinciding with or parallel to the edge of the screen of the display unit 14) connecting the ends of each road, and it is possible to prevent the user from being conscious of the screen area of the display unit 14. In particular, when drawing a plurality of objects close to the edge of the screen, it is advisable to determine the positions of the ends of the objects so that a virtual line connecting the ends of the plurality of objects in order in a direction parallel to the edge of the screen is not parallel to the line of the edge of the screen. For example, it is advisable to set the positions randomly so that a line connecting in order the positions where the road completely disappears by gradation processing (for example, a virtual line connecting in order from X = 0 to X = m or a virtual line connecting in order from Y = 0 to Y = m) is not parallel to the four sides of the screen.

[0108] Also, the start position of the gradation may be set in the same way. That is, the start position of the gradation of the object may be determined so that a virtual line connecting in order the gradation start positions of the plurality of objects in a direction parallel to the edge of the screen is not parallel to the line of the edge of the screen. Furthermore, the gradation pattern (for example, how much darker at what distance) may be different for each object. By doing so, it is possible to prevent the generation of a subjective contour parallel to the edge of the screen and to make it difficult for the user to be conscious of the edge of the screen.

[0109] In Application Example 2, since the display of the road changes according to the movement of the host vehicle, the above-described gradation data cannot be determined in advance. Therefore, when the CPU 260 displays an object called a road, it specifies the road that reaches the edge of the screen, and for the road that reaches the edge, it arbitrarily determines the width of the gradation from the edge of the screen. Then, for each road, a process of adding a gradation with the determined width is performed. This process is a process of gradually decreasing the brightness as approaching the edge of the screen for the pixels related to the drawing of the road, or increasing the number of pixels that perform the same display as the background image, as described above.

[0110] In the above example, the object is "road", but the same processing may be performed for other objects (e.g., characters). For example, when displaying a certain character, the CPU 260 determines whether the entire character is displayed within the screen. If it is determined that the entire character is displayed within the screen, no gradation is added to the character. On the other hand, when it is determined that a part of the character is interrupted by the screen due to the movement of the host vehicle or the like, a gradation with an arbitrary width is added to the character.

[0111] (Application Example 3 of the First Embodiment) In Application Example 2 described above, the range of the gradation region G within the screen was changed for each object to be displayed as an image. In contrast, Application Example 3 changes the lightness gradient of the gradation for each display color of each object.

[0112] FIG. 7(b) shows an example of the display mode of the image according to Application Example 3. The image shown in this figure basically has the same content as the image shown in FIG. 4, but the icon display region 140B is not shown in order to more clearly illustrate the features in Application Example 3. Also, in this figure, the same parts as those shown in FIG. 4 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. Note that in FIG. 7(b), the roads within the map 151, various icons (host vehicle icon 152, warning target icon 153), legal speed 154, current speed 155, and other numbers and lines displayed as an image are treated as individual objects.

[0113] In the image of the map 151 shown in Fig. 7(b), the road GR extending vertically in the approximate center of the screen is generally displayed in green, which is a color (a color with high sensitivity) that is easily perceptible to the human eye. Also, the road BR extending horizontally from the left end to the center of the screen and hitting the above-described road GR is generally displayed in blue, which is a color (a color with low sensitivity) that is difficult to be perceived by the human eye. Further, it is assumed that the area other than the roads is displayed in a color with a sensitivity intermediate between green and blue (for example, orange).

[0114] As shown in Fig. 7(b), the width Wa of the gradation area (corresponding to the "peripheral part of the object") for the road GR, which is an object displayed in a color with high sensitivity, is wider than the width W of the gradation area G in the area other than the roads. This is because, since the road GR is displayed in a color that is easily perceptible to the human eye, by starting the gradation from a position farther from the edge of the screen, the change in apparent brightness in the road GR and the change in apparent brightness in the area other than the road GR are made to match each other.

[0115] Conversely, the width Wb of the gradation area (corresponding to the "peripheral part of the object") for the road BR, which is an object displayed in a color with low sensitivity, is narrower than the width W of the gradation area G in the area other than the roads. This is because, since the road BR is displayed in a color that is difficult to be perceived by the human eye, by starting the gradation from a position closer to the edge of the screen, the change in apparent brightness in the road BR and the change in apparent brightness in the area other than the road BR are made to match each other.

[0116] In this way, by adding gradations corresponding to the display colors to the "road" object on the map to be displayed, it becomes possible to adjust so that the change in the brightness of the image in the gradation area G becomes uniform when the entire screen is viewed.

[0117] (Second Embodiment) A second embodiment for adding a gradation region G to the displayed image is shown in FIG. 8. FIG. 8 shows a schematic exploded perspective view of the display unit 14. In this figure, the liquid crystal panel 50 is a well-known liquid crystal panel that constitutes a rectangular screen for displaying an image, and is composed of a liquid crystal layer, transparent electrodes, color filters, polarizing plates, and the like. The lighting means 51 illuminates the liquid crystal panel 50 from behind in order to make the image displayed on the liquid crystal panel 50 visible, and is composed of a rod-shaped cold cathode tube 52 and a rectangular light guide plate 53. The cold cathode tube 52 is provided along one short side of the light guide plate 53, and the light guide plate 53 takes in the light of the cold cathode tube 52 from the short side cross section on the side where the cold cathode tube 52 is provided and emits it from the surface on the liquid crystal panel 50 side, thereby illuminating the liquid crystal panel 50 from behind.

[0118] The gradation addition filter 54 is a sheet-like filter for adding the gradation region G shown in FIG. 4 to the image displayed on the liquid crystal panel 50, and its shape and dimensions match the image display region of the liquid crystal panel 50. In the region corresponding to the gradation region G shown in FIG. 4, the light transmittance of the gradation addition filter 54 gradually decreases from its boundary (shown by a broken line in FIG. 4) toward the periphery of the gradation addition filter 54, and it is formed to be in a light-shielding state when it reaches the periphery. In the gradation addition filter 54, it is desirable to make the light transmittance in the normal region N as high as possible. Also, for example, the portion of the normal region N may be cut out to form a rectangular frame-shaped sheet having a constant width W.

[0119] Note that the gradation addition filter 54 corresponds to a "transmittance reduction means" that reduces the brightness of the image displayed on the liquid crystal panel 50 according to the light transmittance in its gradation region G.

[0120] (Modification of the Second Embodiment) In the configuration of the second embodiment shown in FIG. 8, the gradation addition filter 54 is arranged on the surface of the liquid crystal panel 50 (the surface facing the driver side). As a modification of this, the gradation addition filter 54 may be interposed between the liquid crystal panel 50 and the lighting means 51 (the back side of the screen). In this case, the gradation addition filter 54 functions as a "light attenuation means" for attenuating the light from the lighting means 51 according to the light transmittance in the gradation region G.

[0121] Alternatively, instead of providing the gradation addition filter 54 shown in FIG. 8, the light transmittance in the region corresponding to the gradation region G shown in FIG. 4 may be gradually changed in the half mirror region HM of the mirror member 13. Also, in the gradation addition filter 54, the boundary B between the normal region N and the gradation region G shown in FIG. 4 may be a curve that varies within a predetermined range, like the boundary B' shown in FIG. 5.

[0122] (Third Embodiment) FIG. 9 shows a third embodiment for adding a gradation region G. In the above-described second embodiment, the gradation addition filter 54 was added to the configuration of the display unit 14. However, in this embodiment, instead of adding the gradation addition filter 54, the lighting means 51 constituting the display unit 14 is given a feature. Here, FIG. 9 is a front view showing the appearance of the lighting means 51 (see FIG. 8) constituting the display unit 14. (a) schematically shows a general lighting means, and (b) schematically shows the lighting means in the second embodiment. In this figure, the same components as those shown in FIG. 8 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0123] First, the light guide plate 53a shown in Fig. 9(a) is used for a general lighting means 51 (for example, the lighting means shown in Fig. 8). On the surface of the light guide plate 53a opposite to the liquid crystal panel side (hereinafter referred to as the back surface), a large number of white dots WD are formed for reflecting the light incident from one short side of the light guide plate 53a toward the back surface of the liquid crystal panel. The white dots WD are formed, for example, by printing white ink on the back surface of the light guide plate 53a. In the present embodiment, their shape is circular. Also, in order to illuminate the back surface of the liquid crystal panel with as uniform brightness as possible, the size and density of the white dots WD are smaller and sparser the closer they are to the cold cathode tube 52 which is the light source, and larger and denser the farther away they are.

[0124] On the other hand, in the case of the light guide plate 53a in the third embodiment shown in Fig. 9(b), regarding the size and density of the white dots WD, in the normal region N within the broken line in the figure, it shows the same tendency as the general light guide plate 53a shown in Fig. 9(a). In contrast, in the gradation region G shown by hatching, compared with the white dots WD shown in Fig. 9(a), it shows a tendency to be smaller and sparser the closer it is to the periphery of the light guide plate 53b. By forming the white dots WD on the back surface of the light guide plate 53b in this way, in the image displayed in the gradation region G, it can be displayed to gradually become darker as it approaches the periphery of the screen.

[0125] That is, by forming the white dots WD in the "normal region N" corresponding to the "central lighting part" and the "gradation region G" corresponding to the "peripheral lighting part" as in the light guide plate 53b shown in Fig. 9(b), it is possible to "make the light quantity of the peripheral lighting part less than that of the central lighting part". In Fig. 9(b), the boundary B between the normal region N and the gradation region G is shown as a straight line, but the size and arrangement density of the white dots WD may be determined so as to be a curve that varies within a predetermined range like the boundary B' shown in Fig. 5.

[0126] (Modification of the Third Embodiment) The lighting means shown in Fig. 9 was mainly composed of a cold cathode tube and a light guide plate. However, different from this, for example, a substrate on which a plurality of white LEDs are arranged in a matrix is provided behind the liquid crystal panel, and the brightness of each white LED can be adjusted. Then, by adjusting so that the light quantity of each white LED arranged in the region corresponding to the gradation region G is less than the light quantity of each white LED arranged in the region corresponding to the normal region N, it may be possible to "make the light quantity of the peripheral illumination part less than the light quantity of the central illumination part".

[0127] This adjustment of brightness can be achieved by changing the current supplied to the LED, or by changing the time (pulse width) for which the current is supplied to the LED and the ratio (duty ratio) of the time for which the current is supplied to the LED to the time for which the current is not supplied, by pulse width modulation (PWM). In this way, the means for making the brightness of each white LED adjustable is included in the "brightness adjustment means".

[0128] <Other changes> Note that the "mask means" in the display device according to the present invention is not limited to the region composed of the mirror region M and the half-mirror region HM formed in the mirror member 13 that functions as an in-vehicle rearview mirror as in the above-described embodiment. For example, the entire area of the mirror may be configured as a half-mirror region with the mirror region M also being a half-mirror region. Also, in an instrument panel (so-called IP) of an automobile, a transparent member such as a smoked glass installed on the driver side of an image display device or various instruments, which has a reduced light transmittance, is also included in the "mask means" of the present invention. In this case, the smoked glass preferably has a configuration including a region facing the screen and having a predetermined width around that region. In this way, not only when no image is being displayed on the screen, but also when an image is being displayed on the screen, it is possible to make it difficult to sense the screen region. Thereby, it is possible to give the person viewing the image an impression as if the entire area of the mask means is the screen of the display device.

[0129] <Operation and effect> When the liquid crystal of the display unit 14 is turned off by the half mirror region HM and the mirror region M, it has the function of enhancing the integration of the mirror and the liquid crystal by making the boundary of the screen inconspicuous. However, in the conventional configuration, as soon as the liquid crystal of the display unit 14 is turned on, the boundary of the screen is recognized, and there is a problem that it looks as if a square photo or picture sticker is pasted on the mirror region M, which is uninteresting. One of the reasons for this is that the image is clearly displayed up to the square frame at the edge of the screen. According to the configuration of each of the above-described embodiments, when the screen is viewed through the half mirror region HM, the square liquid crystal frame at the edge of the screen cannot be felt, so that it looks as if an image, characters, etc. are floating on the mirror. That is, the mask means composed of the half mirror region HM and the mirror region M and the image can have a stronger sense of integration.

Explanation of Signs

[0130] 10 Radar detector 11 Housing 12a, 12b Fixture 13 Mirror member 14 Display unit 14 (display means) 15 Infrared light receiving part 17 Speaker 18 Sound emitting hole 19 Insertion hole for DC power jack 20 Slot 21 GPS receiver 22 Microwave receiver 23 Wireless receiver 24 Memory card reader 25 Memory card 26 Control unit (brightness adjustment means, storage means, data writing means, image display means) 27 Database 28 Remote control 50 Liquid crystal panel 51 Lighting means 52 Cold cathode tube 53 Light guide plate 54 Gradation addition filter (transmittance reduction means, dimming means) 140 Screen display area 140A Main display area 140B Icon display area 141 Speed 142 Latitude 143 Longitude 144 Compass icon 145 Road selection icon 146 Radar reception sensitivity mode icon 147 Mode selection icon 148 Current time 151 Map 152 Own vehicle icon 153 Alarm target icon 154 Legal speed 155 Current speed of own vehicle

Claims

1. A function of displaying, on a display screen, a first display area in which a predetermined image is displayed and a second display area in which a uniformly darker image than the predetermined image is displayed; a function of performing a gradation display in which, when the first display region and the second display region are displayed, a brightness of an area in the first display region adjacent to the second display region decreases toward the second display region; Equipped Display device.

2. The boundary of the area where the gradation display is performed on the opposite side to the second display area and the boundary between the first display area and the second display area have mutually different shapes. The display device according to claim 1 .

3. A masking means is provided for making the boundary between the inside and outside of the display screen less visible when no image is displayed on the display screen. The display device according to claim 1 .

4. A program for causing a computer to realize the functions of the display device according to any one of claims 1 to 3.

Images