Display device

0001The present invention relates to a display device that is capable of shifting different display contents on the identical display surface of the display device.

0002A display device of this kind is disclosed in Japanese patent laying-open publication No. 2001 - 100679. This display device has a first printed area through which only blue light can pass and a second printed area through which only green light can pass, the other printed area forming a lightproof background, the printed areas being formed by printing on a rear surface of a transparent sheet that is illuminated from a rear side of the sheet by a first light source of blue light and a second light source of green light.

0003The above known conventional display device, however, encounters a problem that a display device requires a high-precession printing process, resulting in a high manufacturing cost, because all the areas are printed on one side of the sheet and the three printed areas are formed adjacently to one another. In addition, in a case that the adjacent printed areas are overlapped with each other, their overlapping area parts stand out to impair display, while in a case that the adjacent areas have a gap between them, the light from the light sources passes through the gap, resulting in deterioration of display quality.

0004It is, therefore, an object of the present invention to provide a display device which overcomes the foregoing drawbacks and can obtain high display quality at a lower manufacturing cost and prevent light leakage without using a high-precession printing process.

0005According to a first aspect of the present invention there is provided a display device that selectively provides a first display and a second display, the display device comprising: a first light source to emit first light; a second light source to emit second light having a peak wavelength different from a peak wavelength of the first light; and a translucent sheet that is hit selectively by one of the first and second lights, wherein the translucent sheet has a first surface and a second surface opposite to the first surface, and the translucent sheet having first printed area parts formed on the first surface of the translucent sheet to pass only the first light for providing the first display, second printed area parts formed on the first surface to pass only the second light for providing the second display, third printed area parts formed on the first surface to prevent transmittance of the first and second lights, and printed dimmer area parts formed on the second surface at areas corresponding to overlapped area parts of the first and second displays so as to suppress the first and second lights.

0006Therefore, this display device can obtain high display quality at a lower manufacturing cost and prevent light leakage without using a high-precession printing process.

0007The objects, features and advantages of the present invention will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: <ul id="ul0001" list-style="none"><li>FIG. 1 is a cross sectional side view of a switch with a display device of a first embodiment according to the present invention;</li><li>FIG. 2 is a plain view of a color filter with printed area parts used in the display device shown in FIG. 1;</li><li>FIG. 3 is a rear view of the color filter with printed dimmer area parts;</li><li>FIG. 4 is a cross-sectional view, taken on line A - A of FIG. 2, of the color filter with the printed area parts;</li><li>FIG. 5 is a fragmentary enlarged cross-sectional view, indicated in a circle B in FIG. 4, of the color filter with the printed area parts in a state that light enters the color filter;</li><li>FIG 6 is a characteristic diagram showing a relationship of luminous intensity of a first and second light sources used in the display device and transmission efficiency of the color filter with respect to wavelength of light;</li><li>FIG 7A is a fragmentary diagram showing a dot pattern in the printed dimmer area parts shown in FIGS. 3 to 5, and FIG. 7B is a fragmentary diagram showing a gradated dot pattern used in the printed dimmer area parts;</li><li>FIG 8A is a plain view of the display device shown in FIG 1 in a state that the display device provides a first display, and FIG 8B is a plain view of the display device in a state that the display device provides a second display;</li><li>FIG 9A is a fragmentary diagram showing a modified dot pattern in the printed dimmer area parts shown in FIG. 7A, and FIG 9B is a fragmentary diagram showing a modified dot pattern used in the printed dimmer area parts shown in FIG. 7B;</li><li>FIG 10A is a plain view of a color filter used in a display device of a second embodiment according to the present invention, and FIG 10B is a rear view of the color filter;</li><li>FIG. 11 is a cross-sectional view, taken on line C - C of FIG. 10A, of a color filter with printed area parts used in a display device of a second embodiment according to the present invention;</li><li>FIG 12 is a fragmentary diagram showing a dot pattern having dots with different diameter and pitch in the printed dimmer area parts shown in FIG 11;</li><li>FIG 13 is a characteristic diagram showing a relationship of luminous intensity of a first and second light sources and transmission efficiency of the color filter, which are used in a display device of the second embodiment, with respect to wavelength of light;</li><li>FIG 14 is a cross-sectional view of a color filter with printed area parts used in a display device of a third embodiment according to the present invention; and</li><li>FIG 15 is a cross-sectional view of a color filter with printed area parts used in a display device of a fourth embodiment according to the present invention.</li></ul>

0008Throughout the following detailed description, similar reference characters and numbers refer to similar elements in all figures of the drawings, and their descriptions are omitted for eliminating duplication.

0009Referring to FIGS. 1 to 9 of the drawings, there is shown a first preferred embodiment of a display device according to the present invention. In this embodiment, a switch has a display device capable of providing different displays.

0010A switch 1 has a switch finisher 2, a guide member 7 fixed to a lower and inner part of the switch finisher 2, and a slider 8 arranged inside the switch finisher 8 and capable of sliding rearward and forward.

0011The switch finisher 2 is shaped like a square-tube, and the guide member 7 is shaped like a square-tube smaller than the switch finisher 2 to be fixed in an inner part of the switch finisher 2 at this rear side.

0012The guide member 7 is formed on at least two facing inner surfaces thereof with rail portions 7a that extend in a back and front direction to receive projections 8d formed on outer side-wall surfaces of the slider 8.

0013The switch finisher 2 and the guide member 7 are fixed at their rear portions by a base plate 6 so that their rear openings are closed up. The base plate 7 is provided with a first light source 3, a second light source 4, a tact switch 5, and a not-shown electronic circuit on its front surface.

0014The first light source 3 is constructed so as to cast first light having a peak wavelength of about 500 nm as indicated by a line 24 in FIG. 6, and the second light source 4 is constructed so as to cast second light having a peak wavelength of about 600 nm as indicated by a line 22 in FIG 6. These light sources 3 and 4 are made of different-color light emitting diodes (LEDs), which are preferable for a low cost and easy maintenance. The light sources 3 and 4 may be made of other devices.

0015The slider 8 has a side-wall portion 8a to form a square tube, and an inner slanted wall portion 8b arranged inside of and integrally formed with the side-wall portion 8a. The inner slanted wall portion 8a is shaped like a quadrangular-pyramid tube so that its opening becomes narrower from its front end toward its rear end. The rear end opening of the inner slanted wall portion 8b is formed so that the light sources 3 and 4 are positioned in the rear end opening, while the tact switch 5 is positioned out of the rear end opening and between the inner slanted wall portion 8b and the side-wall portion 8a.

0016The slider 8 is fixed at its front edge side and inside thereof with a color filter 10 with printed area parts, which will be described in detail later. A smoked lens 11 is arranged on a front surface of the color filter 10 to cover it. The smoked lens 11 has a low translucency in its whole area so that he or she can not see printed patterns of the printed area parts provided on the color filter 10 through the smoked lens 11 in an outside light at lights-out time.

0017The tact switch 5 is switchable between ON and OFF according to backward and forward movement of the slider 8. Specifically, the tact switch 5 is kept in contact with a projecting portion 8c projected rearward from an outer surface of the inner slanted wall portion 8b for switching. When a user presses a front surface of the smoked lens 11, the slider 8 moves back together with the smoked lens 11 and the color filter 10 along the rail portions 7a of the guide member 7. This causes the projecting portion 8c of the slider 8 to press the tact switch 5. Then, when the user releases the smoked lens 11 from being pressed, the tact switch 5 pushes forward and moves the slider 8 to its original position by reaction force of the tact switch 5.

0018As shown in FIGS. 2 to 4, the color filter 10 is made of a translucent light-diffusion sheet 10a with printed area parts 10b, 10c, 10e, and 10f for providing a first display 12 of a graphic symbol indicated by a circle as shown in FIG. 8A and a second display 13 of a graphic symbol indicated by a letter "X" as shown in FIG 8B. The translucent light-diffusion sheet 10a corresponds to a translucent sheet of the present invention.

0019As shown in FIG 2, first printed area parts 10b are printed on a front surface of the diffusion sheet 10a correspondingly to the circle of the first display 12 excluding overlapped area parts 10d of the circle of the first display 12 and the letter "X" of the second display 13. The first printed area parts 10b are colored blue to pass blue light therethrough, and have transmission efficiency, with respect to wavelength, indicated by a dotted line 23 in FIG 6. The front surface of the diffusion sheet 10a corresponds to a first surface of the present invention and a rear surface of the diffusion sheet 10a corresponds to a second surface of the present invention.

0020Second printed area parts 10c are printed on the front surface of the diffusion sheet 10 correspondingly to the letter "X" of the second display 13 excluding the overlapped area parts 10d of the circle of the first display 12 and the letter "X" of the first display 3. The second printed area parts 10c are colored red to pass red light therethrough, and have transmission efficiency, with respect to wavelength, indicated by a dotted line 21 in FIG 6.

0021The first and second printed area parts 10b and 10c are printed on the front surface of the diffusion sheet 10a in a manner that they have printed area wider than the first and second displays 12 and 13 so as to protrude from outer edges of the first and second displays 12 and 13. Then, printed background area parts 10e is printed in black on edge portions of the first and second printed area parts 10b and 10c so that they define outer edges of the first and second displays 12 and 13b by masking excessive portions of the first and second printed area parts 10b and 10c as shown in FIG 4. This printed background area parts 10e are made from material that prevents light-transmittance, while the overlapped area parts 10d are not printed so as to transmit light. The printed background area parts 10e correspond to third printed area parts of the present invention.

0022Printed dimmer area parts 10f are printed on the rear surface of the diffusion sheet 10a at areas corresponding to the overlapped area parts 10d of the first and second printed area parts 10b and 10c. The printed dimmer area parts 10f have a dot pattern in which black rounded dots are arranged regularly and printed as shown in FIG 7A. The rounded dots are set in diameter and density so as to obtain optimum dimmer effect.

0023The printed dimmer area parts 10f are also formed to cover a projection area of the overlapped area parts 10d and have a printed area larger than the overlapped area parts 10d. This causes overlapped area portions D of the printed dimmer area parts 10f and the first printed area parts 10b and of the printed dimmer area parts 10f and the second printed area parts 10c as shown in FIG 4. The overlapped area portions D have a dot pattern in which black rounded dots are gradated to be smaller in diameter as shown in FIG. 7B.

0024The operation and advantages of the switch 1 of the first embodiment will be described.

0025In order to provide the first display 12, the first light source 3 is turned on to light up, while the second light source 4 is turned off. The red light is emitted from the first light source 3 in all directions, and travels forward directly and under reflection on an inner surface of the inner slanted wall portion 8b of the slider 8. This light hits the color filter 10 from its rear side, and enters the diffusion sheet 10a under restraining its brightness, which is determined by the area rate of black dots and remaining portions of the printed dimmer area parts 10f formed on the rear surface of the diffusion sheet 10a, because the light is prevented its transmittance through the black dots, but the remaining portions can transmit the light. This means that the amount LI of light inputted to the diffusion sheet 10a is expressed by the following equation:<maths id="math0001" num=""><math display="block"><mrow><mtext>LI=Ar/AD</mtext></mrow></math><img file="EP1575017A1_D0001.tif" /></maths>    where Ar is an area of the remaining portions (portions excluding the black dots) of the printed dimmer area parts 10f, and AD is an entire area of the printed dimmer area parts 10f.

0026Note that the light enters the diffusion sheet 10a except the printed dimmer area parts 10f without substantial impairment of brightness, and is diffused in the diffusion sheet 10a to travel forward as shown in FIG. 5. This diffusion of the light brings brightness difference to be small among the first printed area parts 10b, the second printed area parts 10c, and the printed dimmer area parts 10f.

0027Accordingly, the first printed area parts 10b pass the light to provide the first display 12 in bright, because the first light source 3 casts the blue light as indicated by the line 24 in FIG 6 and the first printed area parts 10b have the filter transmission efficiency indicated by the dot line 23 in FIG 6.

0028The brightness of an overlapping portion of the first light source 3 and the diffusion sheet 10a is suppressed by light-diffusion function of the diffusion sheet 10a, which brings the first display 12 to be uniformly provided. The printed dimmer area parts 10f decrease the brightness of the blue light passing through the overlapped area parts 10d, without changing its color.

0029In this case, the second printed area parts 10c prevent transmittance of the light emitted from the first light source 3, because the first light source 3 casts the blue light as indicated by the line 24 in FIG. 6 and the second printed area parts 10c have the filter transmission efficiency indicated by the dot line 21 in FIG. 6. In addition, the printed background area parts 10e prevent any light emitted from the first or second light sources 3 and 4 from passing therethrough. Accordingly, the circle of the first display 12 in blue is provided on the smoked lens 11 as shown in FIG. 8A, so that the user can see it.

0030In order to provide the second display 13, the second light source 4 is turned on to light up, while the first light source 3 is turned off.

0031The second printed area parts 10c pass red light emitted from the second light source 4 to provide the second display 13 in bright, because the second light source 4 casts the red light as indicated by the line 22 in FIG 6 and the second printed area parts 10c have the filter transmission efficiency indicated by the dot line 21 in FIG 6.

0032The printed dimmer area parts 10f decrease the brightness of the red light passing through the overlapped area parts 10d, without changing its color.

0033In this case, the first printed area parts 10b prevent transmittance of the light emitted from the second light source 4, because the second light source 4 casts the red light as indicated by the line 22 in FIG. 6 and the first printed area parts 10b have the filter transmission efficiency indicated by the dot line 23 in FIG. 6. In addition, the printed background area parts 10e prevent any light emitted from the first or second light sources 3 and 4 from passing therethrough. Accordingly, the letter "X" of the second display 13 in red is provided on the smoked lens 11 as shown in FIG 8B, so that the user can see it.

0034As described above, the switch 1 can selectively provide the first display 12 and the second display 13 through the smoked lens 11, which is pressed by the user for moving the slider 8 backward so as to press the tact switch 5. The electronic circuit on the base plate 6 acts to judge which of the first and second display 12 and 13 is provided and whether or not the tact switch 5 is pressed, which brings the switch 1 to be used for two operation inputs. This enables operation inputting in different modes by one switch.

0035In this first embodiment, due to the printed dimmer parts 10f, no printing is necessary on the overlapped area parts 10d. The overlapped area parts 10d are display parts directly connecting the first printed area parts 10b and the second printed area parts 10c with each other. Gaps between them cause deterioration of display quality, and dislocating of the overlapped area parts 10d from the first or second printed area parts 10b and 10c causes light leakage. Avoidance of the above problem by printing the overlapped area parts 10d requires high precision printing. However, the display device of the first embodiment can be built at a low cost, because it removes printing, and therefore it does not need high precision printing.

0036Moreover, the display device of the switch 1 can provide high-quality displays without high precession printing, because the first display 12 and the second display 13 can be obtained by using positive printing in which the black background area parts 10e is printed so as to extract figurations corresponding to the first and second displays 12 and 13. The light leakage due to dislocating of the overlapped area parts 10d from the first or second printed area parts 10b and 10c can be prevented. Printing the printed dimmer area parts 10f larger than the overlapped parts 10d enables the display device to be built at low cost by removing high precession printing.

0037In this first embodiment, not-printing of the overlapped area parts 10d can avoid dislocating of components of the first and second displays 12 and 13, resulting in improvement in display quality.

0038The inner slanted wall portion 8b of the slider 8 reflects the lights emitted from the first and second light sources 3 and 4 and changes their direction to travel forward, which provides the first and second displays 12 and 13 with entirely high brightness. Accordingly, a user can see them easily at high brightness when they are displayed, and can not see the printed area parts 10b, 10c, 10e, and 10f that are subjected to sunlight but not displayed.

0039Providing the printed dimmer area parts 10f on the diffusion sheet 10a and not-printing of the overlapped area parts 10d decrease brightness difference among the overlapped area parts 10d, the first printed area parts 10b, and the second printed area parts 10c, making it possible to accommodate the brightness so that a user can identify its display. Accordingly, it can improve display quality.

0040The printed dimmer area parts 10f can be adjusted so as to surplus the brightness by changing the area rate of dot-printed areas and not-printed areas. This can be obtained by changing diameter of a dot, without increasing a manufacturing cost. The dots are arranged regularly to obtain uniform dimmer light, so that a user can not see these patterned dots through the diffusion sheet 10a. Black color of the dots can easily control the brightness to be suppressed certainly.

0041The gradation in the printed dimmer area parts 10f can decrease In stead of using the gradation shown in FIGS. 7A and 7B, a checkered pattern shown in FIG. 9A and a lattice pattern shown in FIG. 9B may be used, respectively.

0042The switch 1 with the display device can be selectively operated under two displays, which is suitable for adaptation to an instrument panel, increasing freedom of design.

0043Next, a display device of a second embodiment according to the present invention will be described with reference to the accompanying drawings of FIGS. 10 to 13.

0044A color filter 10 has a light-diffusion sheet 10a having printed area parts 10b, 10c, 10e, 10f, and 10g. The printed dimmer area parts 10g are printed on a rear surface of the diffusion sheet 10a at area corresponding to second printed area parts 10c in addition to the printed dimmer area parts 10f arranged at area corresponding to overlapped area parts 10d of first printed area parts 10b and the second printed area parts 10c. In this embodiment, the first printed area parts 10b have filter transmission efficiency as indicated by a dot line 25 in FIG 13 and the second printed area parts 10c have filter transmission efficiency as indicated by a dot line 21 in FIG. 13.

0045A first light source has luminous intensity as indicated by a line 24, and a second light source has luminous intensity as indicated by a line 22.

0046The printed dimmer area parts 10g have a dot pattern in which intensity of black dots arranged in the printed dimmer area parts 10g becomes lower than that of black dots arranged in the printed dimmer area parts 10f as shown in FIG 12.

0047The other parts are constructed similarly to those of the switch 1 with the display device of the first embodiment.

0048In this embodiment, the color filter 10 has the first and second printed area parts 10b and 10c, which causes a difference G of filter transmission efficiency between the first and second printed area parts 10b and 10c in some cases due to their characteristics as indicated a dot line 25 of the first printed area parts 10b and a dot line 21 of the second printed area parts 10c in FIG. 13. In this case, the brightness difference is notably large between a first display using light emitted from a first light source and a second display using a second light source, which results in deterioration of its display quality and appearance quality.

0049However, in this embodiment, the printed dimmer area parts 10g decrease the brightness of the second printed area parts 10c so as to be substantially equal to that of the first printed area parts 10b, which improves display quality of the display device of the second embodiment. This adjustment of the brightness is useful for providing two displays without priority.

0050Next, a switch with a display device of a third embodiment according to the present invention will be described with reference to the accompanying drawing of FIG. 14.

0051A color filter 10 has a light-diffusion sheet 10a having printed area parts 10b, 10c, 10e, 10f, and 30. The printed smoked-area parts 30 are printed on front surfaces of the first printed area parts 10b, the second printed area parts 10c, and the printed background area parts 10e. A smoked lens is arranged on a front surface of the printed smoked-area parts 30. The other parts are constructed similarly to those of the switch 1 with the display device of the first embodiment.

0052In this embodiment, the first and second printed area parts 10b and 10c have filter transmission efficiencies similar to those of the first embodiment. A first and second light sources have luminous intensities similar to those of the first embodiment.

0053Non-display quality in a state that the light sources are turned off is further improved by usage of the printed smoked-area parts 30 and the smoked lens, in such a way that a user can not see the first and second printed area parts 10b and 10c that are subjected to the sunlight but not displayed.

0054Next, a switch with a display device of a fourth embodiment according to the present invention will be described with reference to the accompanying drawing of FIG. 15.

0055A color filter 10 has a transparent sheet 40 instead of the light-diffusion sheet 10a of the first embodiment. The other parts are constructed similarly to those of the switch 1 with the display device of the first embodiment.

0056According to configurations, dimensions, and/or colors of first and second displays, there are cases in which the transparent sheet 4 is superior to the light-diffusion sheet 10a in visibility: a case in which brightness is prior to others for drawing a user's attention because of a small display, and a case in which faded color is used for displaying, for example.

0057While there have been particularly shown and described with reference to preferred embodiments thereof, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

0058For example, the first and second light sources of the first and second embodiments are set to emit light having peak wavelength of about 500 nm and light having peak wavelength of about 600 nm, but they may use a light source capable of emitting light having characteristics of different peak wavelength, other colors, such as green.

0059The number of light sources and printed area parts of a color filter may be set arbitrarily.

0060Printed area parts, such as the first printed area parts 10b, the second printed area parts 10c, the background area parts 10e, and the printed dimmer area parts 10f and 10g may be formed by using any one of silk-screen print making, relief printing, or ink jet printing.

0061The printed dimmer area parts 10f and/or 10g are not limited to those shown in FIGS. 7 and 9. They may be formed by using negative/positive inversion of them.

0062The gradation of the printed dimmer area parts 10f and/or 10g may be obtained by changing at least one of diameter of a dot and a pitch of dots arranged in them.

0063The entire contents of Japanese Patent Application No. 2004 - 067976 filed Mar. 10, 2004 is incorporated herein by reference.