1. Field of the Invention
The present invention relates to a light-emitting apparatus in which a plurality of light-emitting devices are allowed to emit light in different directions, and a method of producing the same.
2. Description of the Related Art
Major examples of conventional remote control coordinate indicators are cross-shaped cursor keys or ball pointers of remote controllers. Other major examples include controllers provided with a joy stick and planar coordinate input devices with switches disposed in a matrix arrangement.
The present applicant previously proposed the use of a light-emitting apparatus for the remote control coordinate indicator. In this light-emitting device, a plurality of light-emitting diodes are arranged so as to emit light in different directions. When such a light-emitting apparatus is used, the remote control coordinate indicator allows an operator at a distance to indicate the coordinates by intuitively moving the cursor in space. This type of remote control coordinate indicator has the advantage that it can be used over a wide region and that the detection angle range is wide, since the half value angle of a light-emitting pattern is wider and the light-emitting intensity is larger.
A description will now be given of this type of remote control coordinate indicator, with reference to FIGS. 7 to 12.
FIG. 7 is a schematic view illustrating a remote control coordinate indicator. FIG. 8 is a view illustrating the principle of angle detection of the remote control coordinate indicator. FIGS. 9A, 9B, and 9C are a front view, a side view, and a bottom view, respectively, of an arrangement of light-emitting diodes in a first conventional example of the remote control coordinate indicator. FIG. 10 is a diagram showing angle detection characteristics in the case where the half value angles of the light-emitting diodes of the remote control coordinate indicator have about the same values. FIG. 11 is a view illustrating an arrangement of light-emitting diodes in a second conventional example of the remote control coordinate indicator. FIG. 12 is a front view illustrating an arrangement of light-emitting diodes in a third conventional example of the remote control coordinate indicator.
Referring to FIG. 7, reference numeral 1 denotes a remote control operation member, reference numeral 2 denotes a monitor, reference numeral 3 denotes a controller, and reference numeral 4 denotes a light-receiving element such as a pin photodiode. Using FIG. 7, the coordinate detection and transmission methods of the remote control operation member 1 will be described.
Carrier production (described later) is performed at the remote control operation member 1 side, while an angle is detected by the controller 3. Transmission and reception of infrared light is performed unidirectionally from the remote control operation member 1 to the controller 3. The construction of the operation member 1 comprises five light-emitting diodes. The controller 3 is operated to compute the x and y coordinates of the remote control operation member 1 on the basis of the balance of the intensities of the quantity of infrared light received by one light-receiving element 4 from the remote control operation member 1. The computed x and y coordinate data is transmitted to the monitor 2, whereby a cursor 5 is moved. The transmission signal format of each light-emitting diode ordinarily consists of a remote control 40 kHz carrier portion and a 1-2 modulation signal 16 kHz carrier portion.
A description will now be given of the principle of detecting a uniaxial (for example, x direction) angle in the present invention, with reference to FIG. 8.
The x coordinate approximates angle .theta. between the optical axis (indicated by alternate long line and short dashed line) and a center line of the remote control operation member 1. The optical axis is formed by a line connecting the remote control operation member 1 and the light-receiving element 4.
The present invention utilizes the optical field of a light-emitting diode (LED). Light-emitting device A emits light, after which light-emitting element B emits light, causing the optical axis to become the point of observation, so that at the light-receiving element 4 the quantity of light emitted by the light-emitting device A and the light-emitting device B are detected in terms of current I.sub.A or I.sub.B, respectively. Using these values, the approximate projected x coordinate is found by Formula (1): EQU x.apprxeq.k((I.sub.A -I.sub.B)/(I.sub.A +I.sub.B)) (1)
Using this principle, the x and y coordinates are detected. The light-emitting diodes must emit light with a wide half value angle and a high intensity in order to allow light emission for a longer distance and a wider angle. In other words, the half value angle, being the angle at which the intensity of the light-emitting diode is halved, must be wide and the intensity must be high for practical purposes. However, when the half value angle is wide, the radiation intensity decreases. Accordingly, the present invention aims at providing an optical field with a wide half value angle and a high radiation intensity by combining the light-emitting diodes in a particular way, which is described below.
A description will now be given of a first conventional example, with reference to FIGS. 9 and 10.
As in FIG. 9, five light-emitting diodes are arranged so as to form the shape of a cross. More specifically, LED 10C is disposed at the center, LED 10U is disposed facing upward and above the LED 10C, LED 10D is disposed facing downward and below the LED 10C, LED 10R is disposed facing toward the right and to the right of the LED 10C, and LED 10L is disposed facing towad the left and to the left of the LED 10C. The LEDs emit light alternately. For example, the LEDs may emit light such that two sets, such as the LED 10C and the LED 10R, the LED 10C and the LED 10L, and the LED 10C and the LED 10D, alternately emit light. The LED 10C and the LED 10R emit light at the same time for a predetermined period of time, and then the LED 10C and the LED 10L emit light at the same time for a predetermined period of time. Thereafter, the LED 10C and the LED 10U emit light at the same time for a predetermined period of time, and then the LED 10C and the LED 10D emit light for a predetermined period of time. This process is repeated.
In this case, the x coordinate is determined from Formula (2) which is obtained by substituting the current values I.sub.C+R and I.sub.C+L of the LED 10C and the LED 10R, and of the LED 10C and the LED 10L, respectively, at the observation points into the aforementioned Formula (1): EQU x.apprxeq.k((I.sub.C+R -I.sub.C+L)/(I.sub.C+R +I.sub.C+L)) (2)
The y coordinate is determined from Formula (3) which is obtained by substituting the current values I.sub.C+U and I.sub.C+D of the LED 10C and the LED 10U, and the LED 10C and the LED 10D, respectively, at the observation points into Formula (1): EQU y.apprxeq.k((I.sub.C+U -I.sub.C+D)/(I.sub.C+U +I.sub.C+D)) (3)
The tilting .beta. of each of the LEDs 10U, 10D, 10R, and 10L is set at about the LED half value angle.
FIG. 10 is a diagram illustrating angle detection characteristics in a conventional example, in which the horizontal axis indicates the deflection angle .theta. of the operation member 1, while the vertical axis indicates the normalized value when the maximum values obtained in Formulas (2) and (3) are 1. When the normalized value is 0, the quantities of light emitted from the left and right light-emitting diodes are the same. As is clear from the diagram, the characteristic curve increases monotonically, meaning that the gradient and the linearity can,be adjusted by the light-emission intensity and mounting angle of each LED. A wide mounting angle results in a small gradient, while a narrow mounting angle results in a steeper gradient. When the tilting angle is within the range of from -15 degrees to +15 degrees, the characteristic curve becomes substantially a straight line within this range.
If it is assumed that the size of a common television screen is about 20 to 50 inches, and that the person is about 2 to 3 meters from the television set, the angle at which the person points the operation member to the screen is about .+-.10 to 15 degrees. Ergonomically speaking, operation can be easily performed at an angle of about -15 degrees to +15 degrees. Therefore, operation is frequently performed at about this angle.
In the foregoing description, when each LED is mounted at about the half value angle, variations occur in the half value angle of each LED, which is very costly to eliminate. Even a small variation in the half value angle of the LED causes the graph to take the form of a wavy curve, as indicated by the dashed line of FIG. 10, resulting in the problem that the cursor moves in a curve on the monitor 2, even when the remote control operation member is moved straight. This is a particularly serious problem at the peripheries of the monitor screen.
When the half value angle of the LED 10C is larger than the half value angle of the outer LEDs, that is when the field of the center LED 10C is wider than those of the outer LEDs, the graph takes the form of a wavy curve as indicated by the dashed line of FIG. 10, resulting in poor linearity.
A description will now be given of a second conventional example, with reference to FIG. 11. Parts which are essentially the same as those of the previous conventional example are given the same reference numerals, and will not be described in detail below.
In the second conventional example, LEDs 10U, 10D, 10C, 10R, and 10L are disposed in a row from the left side, as shown in FIG. 11. Such an arrangement is called linearly independent angle type arrangement. Arranging the LEDs in a row makes the remote control operation member 1 thinner. The way in which the LEDs emit light is essentially the same as the way they emit light in the first conventional example.
A description will now be given of a third conventional example, with reference to FIG. 12. Parts which are essentially the same as those of the previous conventional example are given the same reference numerals, and will not be described below.
In the third conventional example, the LEDs are arranged on the basis of synthesized angles between two orthogonal coordinate axes. Such an arrangement is called a synthesized angle type arrangement. As shown in FIG. 12, LEDs 10LU, 10LD, 10RU, and 10RD are obliquely arranged around a center LED 10C.
The LEDs in the third conventional example may be allowed to emit light such that a set of three LEDs alternately emit light. The sets of three LEDs may be, for example: (1) LEDs 10C, 10LU, and 10LD, (2) LEDs 10C, 10RU, and 10RD, (3) LEDs 10C, 10LU, and 10RU, and (4) LEDs 10C, 10LD, and 10RD. In other words, LEDs 10C, 10LU, and 10LD are allowed to emit light at the same time for a predetermined period of time, and then LEDs 10C, 10RU, and 10RD are allowed to emit light at the same time for a predetermined period of time. Thereafter, LEDs 10C, 10LU, and 10RU are allowed to emit light at the same time for a predetermined period of time, after which LEDs 10C, 10LD, and 10RD are allowed to emit light at the same time for a predetermined period of time. This process is repeated.
In this case, the x coordinate is determined from Formula (4) which is obtained by substituting the current values I.sub.C+LU+LD, and I.sub.C+RU+RD of LEDs 10C, 10LU and 10LD, and LEDs 10C, 10RU, and 10RD, respectively, at the observation points into the aforementioned Formula (1): EQU x=k((I.sub.C+LU+LD -I.sub.C+RU+RD)/(I.sub.C+LU+LD +I.sub.C+RU+RD))(4)
The y coordinate is determined from Formula (5) which is obtained by substituting the current values I.sub.C+LU+RU and I.sub.C+LD+RD of LEDs C, LU, and RU and LEDs C, LD, and RD, respectively, at the observation points into the aforementioned Formula (1): EQU y=k((I.sub.C+LU+RU -I.sup.C+LD+RD)/(I.sub.C+LU+RU +I.sub.C+LD+RD))(5)
Arrangement of the LEDs as shown in FIG. 12 widens the light-emitting pattern field, and further widens the possible detection area and increases the angle detection range.
The primary factors which reduce the detection range and destroy, for example, the linearity in the light-emitting apparatus are variations in the axes, intensities, and half value angles (or field shapes) of the light-emitting diodes used as light-emitting devices.
A description will now be given of the construction of an LED with reference to FIGS. 13A and 13B which are a schematic front view and a schematic side elevational view, respectively, of the construction of an LED.
The LED 60 is formed by mounting a cup 62 at an end of one of the terminals, terminal 61, such that the opening of the cup faces upward, fixing an LED chip 63 in the cup 62, and connecting a gold leader wire from the LED chip 63 to an end of the other terminal 65. A mold case 66 is formed by molding such that the cup 62 is mounted between the ends of the terminals 61 and 65.
Therefore, variations such as those mentioned above occur due to the position of the LED chip 63 relative to an R surface of the mold case 66, or mounting condition of the cup 62. More specifically, during mounting, the cup 62 may be displaced laterally in the x direction, forwardly or backwardly in the y direction, or in the direction of the height in the z direction. In addition, the cup 62 may tilt laterally in the x direction or forwardly or backwardly in the y direction. Displacements in the x or y direction, or tilting in the x or y direction primarily cause axial variations. Displacements in the z direction primarily cause variations in the half value angles and intensities.
Displacements of the position of the LED chip 63 relative to the R surface of the mold case 66 occurs when the LED chip 63 and the cup 62 are being fixed to each other, and when the LED chip 63 with the cup 62 fixed thereto is being fixed to the mold case 66 resin.
A description will now be given of the LED 60 production process steps, with reference to FIGS. 14A to 14G which are schematic views of the LED 60 production process steps In FIG. 14A, a hoop with a plurality of pairs of terminals 61 and 65 is prepared, and a cup 62 is formed at an end of one of the terminals, terminal 61. Then, as shown in FIG. 14B, a conductive silver paste 67 is filled in the cup 62, and then, as shown in FIG. 14C, an LED chip 63 is placed on the silver paste 67 before the silver paste 67 hardens. The process steps illustrated in FIGS. 14B and 14C are called the die bond process steps. Then, the silver paste 67 is hardened, whereby the LED chip 63 is fixed within the cup 62, after which the wire bond process steps of FIG. 14D is performed in order to connect an end of the leader wire 64 to the LED chip 63, and the other end of the leader wire 64 to the upper end of the terminal 65. Thereafter, the mold process step is performed in order to set the cup 62 facing downward in a mold 68, after which synthetic resin 69 is filled therein, whereby the mold case 66 is formed.
Then, as shown in FIG. 14F, the frame joined to the terminals 61 and 65 is cut off, followed by inspection of the characteristics thereof or the like, and cutting off of the terminals from the frame, whereby an LED 60 illustrated in FIG. 14G is formed.
The LEDs 60 produced in this way are inserted into LED receiving holes 71 formed in an integral frame of FIGS. 15 and 16, and are affixed to the frame with an adhesive, as a result of which a light-emitting apparatus C as that shown in FIG. 7 is formed. (The order of the tilting angles of the LEDs 60 is different from that of the LEDs of FIG. 7.) The receiving holes 71 are formed at predetermined tilting angles in the integral frame 70 so as to allow the LEDs 60 to be mounted at their respective predetermined angles.
FIGS. 15 and 16 are views of the integral frame just before the LEDs 60 are inserted into their respective receiving holes 71 from below the integral frame 70. In the figures, reference numerals 72 denote mold lenses which are formed integral with the integral frame 70 so as to cover the upper portion of the receiving holes 71 in the frame 70. In FIGS. 15 and 16, the surface lines of the mold lenses 72 are drawn to show the surface shapes thereof.
In the above-described production process, displacement of the LED chip 63 relative to the R surface of the mold case 66 is thought to occur when the die bond process steps of FIGS. 14B and 14C are being performed, or most often during the resin hardening process step of FIG. 14E. As can be seen from the figures, it is difficult to achieve positional and angular precision, since the terminal 61 fixed to the LED chip 63 and the terminal 65 are inserted into the mold case 66 filled with synthetic resin 69, and then removed after hardening.
The above-described production process of a LED used for remote control operation (so-called shell-type LED) makes it difficult to reduce these variations. These variations can be reduced by producing a transfer-type LED, but this is very costly.
Consequently, in a light-emitting apparatus in which a plurality of remote control operation LEDs are disposed at predetermined angles, cheap LEDs must always be used, which results in considerable deterioration in the performance of the apparatus due to LED variations, so that, at present, attempts are being made to reduce the variations by a lens cap, aventurine means, or the like.