Rotating colour filter for a colour image display

Abstract: A coloring device for use, for example, in a color image display device, comprises a rotary filter (24, 124) rotated by a motor (30, 130) and includes color filter sections (FR, FG, FB) of the three colors which pass over the screen (12) of a monochromatic display device in a predetermined sequence as the rotary filter (24, 124) rotates. The coloring device may comprise two or more sets of color filter sections to enable reduction of the speed of rotation. For size reduction, a member (30) to be detected, used for detection of the rotation of the rotary filter (24, 124), may be provided on the rotor (35, 135) of the drive motor (30, 130), or the filter assembly (22, 122) having the rotary filter (24, 124) may be directly mounted to the rotor (35, 135) of the motor. The rotary filter (24, 124) may be in the form of a disk or a cone. In the latter case, it is advantageous that the color filter sections are formed of a transparent base provided with filter sheets attached thereto or coatings having a transparency only to the light of the respective color.

Description: BACKGROUND OF THE INVENTION The present invention relates to a coloring device used in combination with a monochromatic display device to form a color image display device or in combination with a monochromatic image pick-up device to form a color image pick-up device. Fig. 1 shows a conventional color image display device using a monochromatic image display means, such as a black-and-white CRT (cathode-ray tube). As illustrated, it comprises a black-and-white CRT 10 and a coloring device 20 including a filter assembly 22 and a D.C. (direct current) rotary motor 30. The filter assembly 22 has a disk-shaped rotary filter 24 formed of color filter sections FR, FG and FB permitting transmission of light of red (R), green (G) and blue (B) and each extending over an angular range of 120°, as illustrated in Fig. 2. In other words, the disk-shaped rotary filter 24 is divided by radially extending lines 24rg, 24gb and 24br into three equal sectors FR, FG and FB each having a vertex angle of 120° and respectively serving as color filters for red (R), green (G) and blue (B). The rotary filter 24 is fixed by means of a connection member 26 to a motor shaft 32 of the motor 30, and is rotated by the motor 30. As the motor 30 rotates, the filter sections FR, FG and FB sequentially pass over a screen 12 of the CRT 10. A rotation sensor 40, which may comprise a Hall element, detects the rotation phase of the rotary filter 24. A magnet 50 is attached to the shaft 32 of the motor 30 and serves as a detection member (member to be detected by a sensor) by the rotation sensor 40. That is, each time the shaft 32 rotates, the magnet 50 passes by the sensor 40, which thereby detects the passage of the magnet 50, on the basis of the magnetic field emanating from the magnet 50, and generates a rotation sync pulse P. The rotation sync pulse P is supplied to a control device 60. The control device 60 also receives a vertical sync signal VD directly and also via a frequency converter 62. The frequency converter 62 converts the vertical sync signal VD into a triple-frequency vertical signal V3 having a frequency three times that of the vertical sync signal VD. The control device 60 supplies the motor 30 with a drive signal. The rotation of the motor 30 is controlled such that the rotary filter 24 rotates once per vertical period, and the rotation sync pulse P is produced at a constant phase angle relative to the vertical sync signal VD. Another frequency converter 68 converts a horizontal sync signal HD into a triple-frequency horizontal signal H3 having a frequency three times that of the horizontal sync signal HD. Image signal memories 66R, 66G and 66B receive and store color image signals SR, SG and SB of red, green and blue together forming a color image. The memories 66R, 66G and 66B are supplied with a horizontal sync signal HD and the vertical sync signal VD as reference sync signals for writing, and are supplied with the triple-frequency horizontal signal H3 and the triple-frequency vertical signal V3, as reference sync signals for reading. The color image signals SR, SG and SB are sequentially written in the memories 66R, 66G and 66B. The color image signals for one field are stored at a time, and the color image signals SR, SG and SB for one field are repeatedly read three times, each in a period of one third of the vertical period. The writing and reading are carried out concurrently. Thus, color image signals SR3, SG3 and SB3 of a triple rate, and repeated three times, each for a period of one third of the vertical period, are obtained from the memories 66R, 66G and 66B. Figs. 3A to 3C show the color image signals SR, SG and SB supplied to the memories 66R, 66G and 66B, and Figs. 4A to 4C show the color image signals SR3, SG3 and SB3 output from the memories 66R, 66G and 66B. The waveforms are shown schematically to facilitate distinction between the three color image signals. The reference marks R1, R2, G1, G2, B1 and B2 show that in reading the same color image signals are repeatedly read three times, at a triple rate. For instance, the color image signal R1 of red for one field is written over one vertical period, and is read three times, each in one third of a vertical period. The triple-rate color image signals SR3, SG3 and SB3 output from the memories 66R, 66G and 66B are supplied to the multiplexer 64, which is controlled by a switching signal S supplied in synchronism with the signal V3. As a result, one of the color image signals SR3, SG3 and SB3 corresponding to the filter section FR, FG or FB which is passing over the screen 12 of the CRT 10 is supplied from the multiplexer 64 to the CRT 10. The triple-frequency signal H3 is supplied from the frequency converter 68 to a horizontal deflection circuit 70, and the triple-frequency signal V3 is supplied from the frequency converter 62 to the vertical deflection circuit 72. Horizontal and vertical deflection signals are supplied from the deflection circuits 70 and 72 to horizontal and vertical deflection coils (not shown) in the CRT 10. The CRT 10 therefore conducts horizontal and vertical deflection scanning at a rate three times that of ordinary scanning. Figs. 5A to 5D show the relationship between the rotation phase of the rotary filter 24, the scan line SL of the CRT 10 and the switching of the multiplexer 64. The multiplexer 64 is controlled to operate in synchronism with the triple-frequency vertical signal V3 as described above, and is made to select the color image signals corresponding to the filter section that is passing over the screen 12 of the CRT 10, in accordance with the rotation sync pulse P. The multiplexing is so made that when when the boundary 24br between the filter sections FB and FR is passing over the center (the midpoint in the vertical direction) of the screen 12 of the CRT 10, supply of the blue color image signal SB3 for one field to the CRT 10 is terminated and supply of the red color image signal SR3 for one field is commenced (Fig. 5A). Similarly, when the boundary 24rg between the filter sections FR and FG is passing over the center of the screen 12 of the CRT 10, one third of the vertical period later, supply of the red color image signal SR3 for one field to the CRT 10 is terminated and supply of the green color image signal SG3 for one field is commenced (Fig. 5D). Similarly, when the boundary 24gb between the filter sections FG and FB is passing over the center of the screen 12 of the CRT 10, one third of the vertical period later, supply of the green color image signal SG3 for one field to the CRT 10 is terminated and supply of the blue color image signal SB3 for one field is commenced (not illustrated). With the above configuration, the triple-frequency signals SR3, SG3 and SB3 are sequentially supplied from the multiplexer 64 to the CRT 10, while the horizontal and the vertical deflection scans are conducted at a triple rate, so black-and-white images due to the color image signals SR3, SG3 and SB3 are sequentially displayed on the screen 12, each in a period one third that of the vertical period. As described above, the selection between the color image signals SR3, SG3 and SB3 is made in conformity with that one of the filter sections FR, FG and FB of the rotary filter 24 which is passing over the screen 12 of the CRT 10, so that as the image due to the color image signal SR3, SG3 or SB3 is displayed on the screen 12, the corresponding filter section FR, FG or FB is positioned over the screen 12 of the CRT 10. Accordingly, red, green and blue images by virtue of the color image signals SR3, SG3 and SB3 are obtained through the filter sections FR, FG and FB of the rotary filter 24, at the one-third vertical period. The net effect is that a color image is seen to the viewer observing the image through the filter sections FR, FG and FB. Because the color image display device in the prior art is configured as described above, the space between the main body comprising the stator and the rotor of the motor 30 and the filter sections FR, FG and FB of the rotary filter 24 must be wide to permit disposition of the rotation sensor 40 between the motor main body and the rotary filter 24, and this imposes a limitation to the size reduction. US-A-4 685 000 discloses rotary filters in which the rotary position of the filter wheels are detected using marks on the wheels which are sensed by detectors mounted adjacent the wheels. DE-A-2 835 210 and EP-A-0 161 032 relate to electric motors generally, and describe arrangements in which magnetic sensors are mounted in proximity to the rotor magnets so that the signals from the sensors can be used for commutation purposes. SUMMARY OF THE INVENTION It would be desirable to enable reduction of the size of the device. Aspects of the invention are set out in the accompanying claims. With an arrangement according to the invention, the detection member for detection of the rotation phase of the rotary filter is disposed on the outer circumferential surface of the rotor of the motor, so no space is required for disposing the rotation sensor between the main body of the motor and the rotary filter, and the size reduction is therefore possible. A coloring device of the invention may be further provided with a connection member for connecting the rotary filter to the motor ; wherein said motor has an output shaft ; said connection member is fixed to the rotary filter ; and said shaft of said rotary motor and the connection member are connected so that said detection member is positioned at a specific rotary position relative to the color filter sections. With such an arrangement, the coloring device is easy to manufacture and is less costly, and yet the rotation phase of the rotary filter can be accurately detected by the use of the rotation sensor. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a configuration diagram showing a conventional color image display device. Fig. 2 is a diagram showing the configuration of the rotary filter. Fig. 3A to Fig. 3C are diagrams showing the color image signals written into the image signal memories. Fig. 4A to Fig. 4C are diagrams showing the color image signals read out of the image signal memories. Fig. 5A to Fig. 5D are diagrams for explaining the relationship between the rotation phase of the rotary filter, the scan line of the CRT and the switching of the multiplexer. Fig. 6 is a configuration diagram showing an embodiment of the invention. Fig. 7A and Fig. 7B are a side view and a bottom view showing a filter assembly used in another embodiment of the invention. Fig. 8A and Fig. 8B are a top view and a side view showing a motor with its shaft used in the embodiment of Fig. 7A and Fig. 7B. Fig. 9 is a side view showing how the filter assembly of Fig. 7A and Fig. 7B is fixed to the motor of Fig. 8A and Fig. 8B. Fig. 10A and Fig. 10B are a side view and a bottom view showing a connection member in another embodiment of the invention. Fig. 10C and Fig. 10D are a top view and a side view showing a motor shaft used in combination with the connection member of Fig. 10A and Fig. 10B. Fig. 11A and Fig. 11B are a side view and a bottom view showing a connection member in another embodiment of the invention. Fig. 11C and Fig. 11D are a top view and a side view showing a motor shaft used in combination with the connection member of Fig. 11A and Fig. 11B. Fig. 12A and Fig. 12B are a side view and a bottom view showing a connection member of a filter assembly used in another embodiment of the invention. Fig. 12C and Fig. 12D are a top view and a side view showing an end part of a motor shaft used in combination with the connection member of Fig. 12A and Fig. 12B. Fig. 13A and Fig. 13B are a side view and a bottom view showing a connection member of a filter assembly used in another embodiment of the invention. Fig. 13C and Fig. 13D are a top view and a side view showing an end part of a motor shaft used in combination with the connection member of Fig. 13A and Fig. 13B. Fig. 14A and Fig. 14B are a side view and a bottom view showing a connection member of a filter assembly used in another embodiment of the invention. Fig. 14C and Fig. 14D are a top view and a side view showing an end part of a motor shaft used in combination with the connection member of Fig. 14A and Fig. 14B. Fig. 15A is a side view showing a connection member, with a screw to be threaded thereinto, of a filter assembly used in another embodiment of the invention. Fig. 15B is a bottom view of the connection member of Fig. 15A. Fig. 16A is a top view showing an end part of a motor shaft used in combination with the connection member of Fig. 15A and Fig. 15B. Fig. 16B is a side view showing the end part of the motor shaft of Fig. 16A. Fig. 17 is a side view showing how the connection member of Fig. 15A and Fig. 15B is fixed to the end part of the motor shaft of Fig. 16A and Fig. 16B. Fig. 18A is a side view showing a connection member of a filter assembly used in another embodiment of the invention. Fig. 18B is a side view, as seen from a different angle, showing the connection member of Fig. 18A, with a pin to be inserted thereinto. Fig. 18C is a bottom view of the connection member of Fig. 18A and Fig. 18B. Fig. 19A is a top view showing an end part of a motor shaft used in combination with the connection member of Fig. 18A, Fig. 18B and Fig. 18C Fig. 19B is a side view showing the end part of the motor shaft of Fig. 19A. Fig. 19C is a side view, as seen from a different angle, showing the end part of the motor shaft of Fig. 19A and Fig. 19B. Fig. 20 is a side view showing how the connection member of Fig. 18A to Fig. 18C is fixed to the end part of the motor shaft of Fig. 19A to Fig. 19C. Fig. 21A is a side view showing a filter assembly used in another embodiment of the invention. Fig. 21B is a bottom view showing only the connection member of the filter assembly of Fig. 21A. Fig. 22A is a top view showing an end part of a motor shaft used in combination with the filter assembly of Fig. 21A and Fig. 21B. Fig. 22B is a side view showing the end part of the motor shaft of Fig. 22A. Fig. 23 is a side view showing how the filter assembly of Fig. 21A and Fig. 21B is fixed to the end part of the motor shaft of Fig. 22A and Fig. 22B. Fig. 24A is a side view showing a filter assembly used in another embodiment of the invention. Fig. 24B is a bottom view showing only the connection member of the filter assembly of Fig. 21A. Fig. 25A is a top view showing an end part of a motor shaft used in combination with the filter assembly of Fig. 24A and Fig. 24B. Fig. 25B is a side view showing the end part of the motor shaft of Fig. 25A. Fig. 26 is a side view showing how the filter assembly of Fig. 24A and Fig. 24B is fixed to the end part of the motor shaft of Fig. 25A and Fig. 25B. DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiment 1 Fig. 6 shows the configuration of an embodiment of a color image display device according to the invention. The components or parts identical or corresponding to those in Fig. 1 are given identical reference numerals, and description of the identical components and parts is omitted. In this embodiment, the rotary motor 30 has a disk-shaped stationary part or stator 33 mounted to a frame of the color image display device, not shown as such, rotatably supporting a shaft 32 extending therethrough, a disk-shaped rotary part or rotor 35 fixed to the shaft 32 and having a first surface 35a adjacent to and confronting a first surface 33a of the stator 33. The rotor 35 is mounted toward one end (upper end as seen in Fig. 6) of the shaft 32, while a filter assembly 22 comprising a rotary filter 24 and a connection member 26 is mounted toward a second end (lower end as seen in Fig. 6) of the shaft 32, opposite to the rotor 35 with respect to the stator 33. The motor shaft 32 of the rotary motor 30 and the filter assembly 22 are formed integrally. That is, the motor shaft 32 and the base material of the filter assembly 22 are welded together or bonded together by an adhesive where they are both made of metal or an alloy, or bonded together by an adhesive where one of them is made of a plastic material and the other is made of metal or an alloy. A detection member (member to be detected), e.g., a permanent magnet, 50 for permitting detection of the rotation phase of the rotary filter 24 in cooperation with a rotation sensor 40 is provided on the rotor 35 of the rotary motor 30. The rotation sensor 40 for producing a rotation sync pulse P is provided at a position to confront the permanent magnet 50. The rotation sensor 40 may be mounted on the stator 33 of the motor 30. The rest of the configuration is similar to that of Fig. 1. The operation of the present embodiment is identical to that of Fig. 1. That is, red, green and blue images by virtue of the color image signals SR3, SG3 and SB3 are obtained through the color filter sections FR, FG and FB, each for a period one third that of the vertical period, with the result that a color image can be recognized by seeing the screen 12 of the CRT 10 through the rotary filter 24. According to the above embodiment, the permanent magnet 50 is mounted on the outer circumferential surface of the rotor 35, opposite to the rotary filter 24 with respect to the stator 33, and the rotation sensor 40 is disposed at a position to confront the permanent magnet 50. As a result, the space between the motor 30 and the rotary filter 24 can be made narrow, and the size of the device can be reduced. Embodiment 2 In the embodiment of Fig. 8, the filter assembly 22 and the motor shaft 32 of the motor 30 are formed integrally. But this may be difficult to fabricate. It has been proposed to connect the rotary filter 24 of the filter assembly 22 to the motor shaft 32, but a special jig was necessary for such connection as to position the permanent magnet 50 relative to the filter sections of the rotary filter 24. Figs. 7A, 7B, 8A, 8B, and 9 show another embodiment of the invention. More specifically, Figs. 7A and 7B are a side view and a bottom view showing a filter assembly used in this embodiment. Figs. 8A and 8B are a top view and a side view showing a motor with its shaft used in this embodiment. Fig. 9 is a side view showing how the filter assembly of Figs. 7A and 7B is fixed to the motor of Figs. 8A and 8B. It should be noted that although the terms "top view", "bottom view", and "side view" are used, they are used for illustration purpose and do not necessarily reflect the orientation in the assembled coloring device. This also applies to description of other drawings. According to this embodiment, a cut-away portion 32d is provided at an end part 32c of the motor shaft 32, and an insertion bore 26b having a cross section conforming to the cross section of the end part 32c of the motor shaft 32 is provided on a connection member 26. The connection member 26 may be formed integrally with the rotary filter 24 to form a filter assembly 22 together. The motor shaft 32 is inserted in the insertion bore 26b of the connection member 26 for connection. Thus, the positioning of the permanent magnet 50 at a specific position or rotational phase angle with respect to the filter sections of the rotary filter 24 can be achieved without resorting to a special jig mentioned above. The motor shaft 32 of the motor 30 and the connection member 26 can be fixed by resilient pressure (when pressure insertion is adopted) or by an adhesive. Moreover, since connection is achieved by providing the cut-away portion 32d at the end part 32c of the motor shaft 32, and the insertion bore 26b having a cross section conforming to the cross section of the end part 32c of the motor shaft 32, deviation or shift of the rotary filter 24 in the rotational direction can be prevented. Furthermore, the shoulder 32e at the end of the cut-away 32d provided on the motor shaft 32 and the tip of the connection member 26 are in abutment with each other, so the distance between the filter sections FR, FG and FB and the screen 12 of the CRT 10 can be maintained at an appropriate value (Fig. 8). Where the length of the cut-away 32d of the motor shaft 32 in the axial direction is longer than the depth of the insertion bore 26b of the connection member 26, the tip of the motor shaft 32 and the bottom surface of the insertion bore 26b of the connection member 26 are in abutment with each other, so that the distance between the filter sections FR, FG and FB of the rotary filter 24 and the screen 12 of the CRT 10 can be maintained at an appropriate value. Figs. 10A to 10D, 11A to 11D, 12A to 12D, 13A to 13D, and 14A to 14D respectively show other examples of the end part of the motor shaft 32 of the motor 30 and the insertion bore 26b provided at the connection member 26. Figs. 10A, 11A, 12A, 13A and 14A are side views showing the insertion bore 26b in the connection member 26. Figs. 10B, 11B, 12B, 13B and 14B are bottom views showing the insertion bore 26b in the connection member 26. Figs. 10C, 11C, 12C, 13C and 14C are top views showing the end part 32c of the motor shaft 32. Figs. 10D, 11D, 12D, 13D and 14D are side views showing the end part 32c of the motor shaft 32. The structures shown in Figs. 11A to 11D and Figs. 12A to 12D permit the insertion of the motor shaft 32 in the insertion bore at a single rotational position. The structure shown in Figs. 10A to 10D permits the insertion of the motor shaft 32 in the insertion bore at either of two rotational positions, the structure shown in Figs. 14A to 14D permits the insertion of the motor shaft 32 in the insertion bore at any of three rotational positions and the structure shown in Figs. 13A to 13D permits the insertion of the motor shaft 32 in the insertion bore at any of four rotational positions. However, by providing a mark printed or engraved on the motor shaft 32 and the connection member 26 in the structures of Figs. 10A to 10D, Figs. 13A to 13D and Figs. 14A to 14D, one of the rotational positions permitted by the shape of the end part the motor shaft and the insertion bore of the connection member 26 can be selected to give the desired position. In addition, even without resorting to the marks, the structure of Figs. 10A to 10D can be used where the rotary filter 24 has two sets of filter sections, rather than one as in the above embodiments. Similarly, the structure of Figs. 14A to 14D can be used where the rotary filter 24 has three sets of filter sections, and the structure of Figs. 13A to 13D can be used where the rotary filter 24 has four sets of filter sections. Embodiment 3 In the embodiments of Figs. 10A to 14D, the cross section of the insertion bore 26b provided on the connection member 26 conforms to the cross section of the end part 32c of the motor shaft 32. Figs. 15A to 17 show another embodiment. More specifically, Figs. 15A and 15B are a side view and a bottom view showing a connection member 26, with a screw 27 to be threaded thereinto, of a filter assembly used in this embodiment. Figs. 16A and 16B are a top view and a side view showing an end part 32c of a motor shaft 32 used in this embodiment. Fig. 17 is a side view showing how the connection member 26 of Figs. 15A and 15B is fixed to the end part of the motor shaft 32 of Figs. 16A and 16B. In this embodiment, the insertion bore 26b is made to have a circular cross section while a tapped hole 26d is provided at a part corresponding to the cut-away 32d at the end part 32c of the motor shaft 32, and a screw 27 is threaded in the tapped hole 26d so that its tip is in abutment with the cut-away 26b for fixing. With the above configuration, the rotational position of the permanent magnet 50 with respect to the filter sections of the rotary filter 22 can be established, and the deviation or shift of the rotary filter 22 in the rotational direction or in the axial direction can be restricted. In place of the cut-away 32d at the end part of the motor shaft 32, the motor shaft 32 may be provided with a tapped hole (not shown), into which the screw 27 may be threaded into the tapped hole for tightening. Embodiment 4 Figs. 18A to 20 show another embodiment of the invention. More specifically, Figs. 18A to 18C are side views and a bottom view showing a connection member 26 of a filter assembly used in this embodiment, with a pin 28 to be inserted in the connection member 26. Figs. 19A to 19C are a top view and side views showing an end part 32c of a motor shaft 32 used this embodiment. Fig. 20 is a side view showing how the connection member 26 of Figs. 18A to 18C is fixed to the end part 32c of the motor shaft 32 of Figs. 19A to 19C. In this embodiment, pin insertion holes 26e and 32f are provided in the connection member 26 and the end part 32c of the motor shaft 32, and a pin 28 (in place of the screw 27 used in the embodiment of Figs. 17A to 19) having a pin head 28a and a stem part 28b having a circular cross section is inserted in the pin insertion holes 26e and 32f. The pin insertion holes 26e and 32f need not be throughholes. The stem part 28b of the pin 28 need not have a circular cross section, and the pin 28 need not have the pin head 28a. Embodiment 5 Figs. 21A to 23 show another embodiment of the invention. More specifically, Figs. 21A and 21B are a side view and a bottom view showing a filter assembly used in this embodiment. Figs. 22A and 22B are a top view and a side view showing an end part 32c of a motor shaft 32 used in this embodiment. Fig. 23 is a side view showing how the filter assembly of Figs. 21A and 21B is fixed to the end part 32 of the motor shaft 32 of Figs. 22A and 22B. In this embodiment, the end part of the motor shaft 32 has a threaded part 32g, and a nut 29 is used for fixing after the motor shaft 32 is inserted in the insertion bore 26b of the connection member 26. It is not necessary to insert a screw or pin from the side as in the embodiments of Figs. 15 to 17 and Figs. 18A to 20, and even when the rotary filter 24 is large in diameter, the fixing can be accomplished with ease. Embodiment 6 Figs. 24A to 26 show another embodiment of the invention. More specifically, Figs. 24A and 24B are a side view and a bottom view showing a filter assembly used in this embodiment. Figs. 25A and 25B are a top view and a side view showing an end part of a motor shaft used in this embodiment. Fig. 26 is a side view showing how the filter assembly of Figs. 24A and 24B is fixed to the end part 32c of the motor shaft 32 of Figs. 25A and 25B. In this embodiment, the motor shaft 32 is provided with a tapped hole 32h extending in the axial direction, and a screw 31 is inserted through the rotary filter 24 and the connection member 26 after the motor shaft 32 is inserted in the insertion bore 26b of the connection member 26. Embodiment 7 The features of the above embodiments may be combined with each other. Since the configurations of Embodiment 2 to Embodiment 6 are such as to prevent deviation or shift of the rotary filter 24 in the rotary and axial directions, they can be equally applied to the arrangement (Fig. 1) in which the permanent magnet 50 is provided on the rotary filter 24. The motor used in the above embodiments comprises disk-shaped rotor and a disk-shaped stator. In substitution, other types of motors may be used. As has been described, according Embodiment 1 to Embodiment 7-described above, the detection member, such a the permanent magnet, is disposed on the outer circumferential surface of the rotor of the motor, and a rotation sensor is disposed to confront the detection member mounted on the rotor of the motor. As a result, the space between the main body 34 (stator 33 and rotor 35) of the motor and the rotary filter 24 need not be wide, and the size of the color image display can be reduced. To position the detection member at a specific rotational position relative to the filter sections of the coloring member, the motor shaft 32 and the rotary filter 24 may be formed integrally. They may be formed separately and connected to establish the required positional relationship. The latter arrangement is advantageous with respect to the ease and cost of fabrication.

Claims: A coloring device comprising: a rotary filter (24) having color filter sections (FR, FG and FG) of three colors; a rotary driving means (30, 40, 50, 60) for rotating the rotary filter (24) in such a manner that the color filter sections of respective colors pass a predetermined position as the rotary filter (24) is rotated; wherein said driving means comprises: a rotary motor (30) having a stator (33) and a rotor (35) for rotating the rotary filter (24), a detection member (50) which rotates together with the rotary filter (24); a rotation sensor (40) for detecting said detection member, thereby to detect the rotation phase of the rotary filter (24); and a motor control means (60) for controlling the rotation of the rotary motor on the basis of the rotation phase detected by said rotation sensor; characterized in that said detection member (50) is disposed on the outer circumferential surface of the rotor of said rotary motor. The coloring device according to claim 1, wherein said stator (33) and said rotor (35) of the motor are disk-shaped and have first surfaces (33a, 35a) confronting each other; said motor further comprises a shaft (32) which extends through the stator (33); and said rotary filter (24) and said rotor (35) are fixed to said shaft (32) on opposite sides of said stator (33). The coloring device according to claim 1, further comprising: a connection member (26) for connecting the rotary filter (24) to the motor (30); wherein said motor has an output shaft (32); said connection member (26) is fixed to the rotary filter (24); and said shaft (32) of said rotary motor (30) and the connection member (26) are connected so that said detection member (50) is positioned at a predetermined rotary position relative to the color filter sections. The coloring device according to any preceding claim, wherein said rotation sensor comprises a magnetic sensor, and said detection member comprises a permanent magnet. A color image display system comprising: a monochromatic image display means (10) having a screen (12) for display of images; a rotary filter (24) comprising color filter sections (FR, FG and FG) of three colors; a rotary driving means (30, 40, 50, 60) for rotating the rotary filter (24) in such a manner that the color filter sections of respective colors pass over the screen (12) as the rotary filter (24) is rotated; a signal supplying means (64, 66R, 66G, 66B) for supplying the monochromatic display means (10) with color image signals of the color images of the respective colors in a predefined sequence: wherein said driving means comprises: a rotary motor (30) having a stator (33) and a rotor (35) for rotating the rotary filter (24), a detection member (50) which rotates together with the rotary filter (24); a rotation sensor (40) for detecting said detection member, thereby to detect the rotation phase of the rotary filter (24); and a motor control means (60) for controlling the rotation of the rotary motor on the basis of the rotation phase detected by said rotation sensor, such that each of the color filter sections passes over the screen (12) when the image due to the color image signal corresponding to said each of the color filter sections is displayed on the screen (12); characterized in that said detection member is disposed on the outer circumferential surface of the rotor of said rotary motor. A color image display system according to claim 5, wherein said stator (33) and said rotor (35) of the motor are disk-shaped and have first surfaces (33a, 35a) confronting each other; said motor further comprises a shaft (32) which extends through the stator (33); and said rotary filter (24) and said rotor (35) are fixed to said shaft (32) on opposite sides of said stator (33). The color image display system according to claim 5, further comprising: a connection member (26) for connecting the rotary filter (24) to the motor (30); wherein said motor has an output shaft (32); said connection member (26) is fixed to the rotary filter (24); and said shaft (32) of said rotary motor (30) and the connection member are connected so that said detection member (50) is positioned at a predetermined rotary position relative to the color filter sections. The color image display system according to claim 5, 6 or 7, wherein said rotation sensor comprises a magnetic sensor, and said detection member comprises a permanent magnet. A rotary filter arrangement comprising a rotary filter (24), a motor (30) having a rotor (35) and a stator (33), the rotor (35) being coupled to the filer (24) to rotate the filter about an axis so as to present differently coloured filtered sections in succession at a predetermined position, and a detection member (50) also arranged to be rotated by the motor (35) and capable of being sensed so as to indicate the rotational position of the filter (24), characterised in that the detection member (50) is mounted on the outer circumferential surface of the rotor (35) and the rotor (35), the stator (33) and the rotary filter (24) are disposed in succession along said axis in the named order. A coloring device as claimed in any one of claims 1 to 4, wherein the detection member (50) is functionally separate from the rotor (35). A color image display system as claimed in any one of claims 5 to 8, wherein the detection member (50) is functionally separate from the rotor (35). A rotary filter arrangement as claimed in claim 9, wherein the detection member (50) is functionally separate from the rotor (35).

Inventors: IDE TOMOAKI, KARIA SHIGEKI, KURITA KATSUMI, TSUKAHARA TOSHIRO, IDE, TOMOAKI, KARIA, SHIGEKI, KURITA, KATSUMI, TSUKAHARA, TOSHIRO, IDE, TOMOAKI, MITSUBISHI DENKI K.K., Karia, Shigeki, Mitsubishi Denki K.K., KURITA, KATSUMI, MITSUBISHI DENKI K.K., TSUKAHARA, TOSHIRO, MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1993
Main classification: H04N1
IPC codes: H02K7, H04N1, G02B7, H04N9