Abstract:
In a data display radio pager, light emitting diodes (LEDs) for alerting the user of the pager to an incoming call are disposed in a backlight together with LEDs for backlighting a liquid crystal display (LCD) for message display. The alert LEDs effect an alert via the LCD and flash in a striking color different from the color of light to issue from the backlight LEDs. The radio pager is miniature despite that the LCD and alert LEDs are arranged on the front of the casing of the pager.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a data display radio pager having a liquid crystal display (LCD) provided with a backlight and, more particularly, to a data display radio pager having a miniature configuration. 
     A data display radio pager having an LCD for displaying a message is extensively used today. The LCD is usually provided with a backlight which allows the user of the pager to see the LCD in the dark. Specifically, when the user operates a button switch provided on the casing of the pager, light emitting diodes (LEDs) are turned on to illuminate the LCD, so as to provide a backlight. Such backlight LEDs are also turned on when, for example, the power switch of the pager is turned on or when a call is received by the pager. In many cases, the backlight LEDs emit yellow-green light which brightly illuminates the LCD for easy recognition of messages displayed thereon. On the other hand, it has been customary to provide this kind of pager with alert LEDs in addition to the backlight LEDs. When the power switch of the pager is turned on or when a paging signal is received by the pager, the alert LEDs are turned on to inform the user of such a condition. The alert LEDs emit red light or similar striking light. 
     The problem with the conventional data display radio pager is that the alert LEDs, provided in addition to the backlight LEDs, have to be arranged on the surface of the pager together with the LCD. Specifically, the LCD for message display has a large area and has to be positioned on the front of the casing of the pager in order to facilitate recognition. Therefore, it is necessary to locate the alert LEDs next to the LCD on the front of the pager casing or on one side of the pager casing. For example, a radio pager having alert LEDs located next to a message display LCD is disclosed in Japanese Utility Model Laid-Open Publication No. 62-198735. 
     However, locating the alert LEDs next to the LCD on the front of the pager casing is undesirable for the following reason. In a card type pager available today, which is extremely thin and small, the LCD occupies a substantial area on the front of the pager casing. Hence, the alert LEDs cannot be positioned next to the LCD unless the front area of the casing, i.e., the horizontal and vertical dimensions of the pager are increased, which prevents miniaturization of the pager. On the other hand, when the alert LEDs are mounted on one side of the pager casing, they are difficult to see and, therefore, apt to cause the user to overlook an alert signal. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a data display radio pager which is miniature despite having an LCD with a backlight and alert LEDs arranged together on the front of the casing of the pager. 
     A data display radio pager of the present invention comprises an LCD provided with at least one backlight LED for illuminating the LCD, and a backlight structure for accommodating, together with the backlight LED, at least one alert LED for alerting a user of the radio pager to an incoming call in the LCD. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings in which: 
     FIG. 1 is a block diagram schematically showing a data display radio pager embodying the present invention; 
     FIG. 2 is a fragmentary exploded perspective view showing a specific backlight structure included in the embodiment; 
     FIGS. 3A and 3B are respectively a front view and a section view of the embodiment; and 
     FIG. 4 is a view similar to FIG. 2, showing another specific backlight structure. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 of the drawings, a data display radio pager embodying the present invention is shown. As shown, the pager, generally 10 has an LCD 12 provided with backlight LEDs 12a and alert LEDs 12b. Switching circuits 14 and 16 turn on and turn off the backlight LEDs 12a and alert LEDs 12b, respectively. Power sources 18 and 20 are respectively connected to the backlight LEDs 12a and alert LEDs 12b via the switching circuits 14 and 16. A control section 26 controls the switching circuits 14 and 16. The reference numerals 22 and 24 each designates a booster coil. The backlight LEDs 12a are disposed in the LCD 12. In the illustrative embodiment, the alert LEDs 12b are also disposed in the LCD 12. 
     FIG. 2 shows a specific structure of a backlight 32 accommodating the backlight LEDs 12a and alert LEDs 12b. As shown, in the backlight 32, the LEDs 12a and 12b are mounted on a printed circuit board 28. A rectangular saucer-like reflection frame 30 is formed with windows 30a through the bottom thereof. The circuit board 28 is fitted on the bottom of the reflection frame 30 such that the LEDs 12a and 12b each protrudes into the frame 30 via one of the windows 30a. A light conducting plate 32a is received in the reflection frame 30 over the LEDs 12a and 12b. Further, a diffusion sheet 32b is provided on the light conducting plate 32a. 
     As shown in FIGS. 3A and 3B, the backlight 32 is received in the casing 10a of the pager 10 and extends along the rear of the LCD 12. When the backlight LEDs 12a are turned on, light emitted therefrom is extended to around the LEDs 12a by the light conducting plate 32a and then diffused by the diffusion sheet 32b. As a result, the light illuminates the LCD 12 from the rear uniformly. In the illustrative embodiment, the light from the LEDs 12a is yellow-green light which is high in visual sensitivity and, therefore, brightly illuminates the LCD 12. When the alert LEDs 12b are turned on, light from the LEDs 12b are diffused in the same manner as the light from the LEDs 12, thereby illuminating the LCD 12. In the embodiment, the light from the LEDs 12b is red light and, therefore, highlights the LCD 12 in red. Button switches 34 are arranged on the front of the casing 10a of the pager 10. 
     The pager 10 is operated in substantially the same manner as a conventional pager. Briefly, on receiving a signal, the pager 10 demodulates it while shaping the waveform, compares the demodulated signal with an address number, or identification number, assigned to the pager 10, and if the former is identical with the latter, causes the alert LEDs 12b to flash, causes a speaker to produce an alert tone, or otherwise alerts the user of the pager to the received call. 
     Assume that the pager 10 has received a call or that the user desires to see a message on the LCD 12. Then, as the user presses predetermined one of the button switches 34, the control section 26 sequentially delivers a high level signal and a low level signal to the switching circuit 14 via an output port LMPQ thereof. On receiving the high level signal first, the switching circuit 14 applies a voltage of 1 V from the power source 18 to the booster coil 22. The booster coil 22 boosts the input voltage. Subsequently, in response to the low level signal, a current stops flowing through the switching circuit 14 with the result that a current flows through the backlight LEDs 12a. As a result, the LEDs 12a are turned on to brightly illuminate the LCD 12, allowing the user to see a message on the LCD 12. On receiving a message, for example, the pager 10 drives the alert LEDs 12b in the same manner as it drives the backlight LEDs 12a, thereby alerting the user to the incoming call. The difference is that the control section 26 delivers a high level signal and a low level signal to the alert LEDs 12b via an output LEDQ thereof alternately at predetermined intervals. As a result, the LEDs 12 each flashes in red at the predetermined intervals, facilitating the recognition of the received call. 
     In the illustrative embodiment, the alert LEDs 12b are disposed in the LCD 12, as shown in FIGS. 3A and 3B. Hence, even if the LCD 12 mounted on the front of the pager casing 10a has a relatively large area, it occupies a minimum of area on the front of the casing 10a and, therefore, allows the casing 10a to be miniaturized, compared to a conventional pager having an LCD and alert LEDs arranged side by side. Further, the LEDs 12b, disposed in the LCD 12, effect an alert via the LCD 12 and, therefore, surely informs the user of the incoming call. 
     FIG. 4 shows another specific structure of the backlight. As shown, the backlight, generally 32A, has a rectangular saucer-like reflection frame 36 and a light conducting plate 38 which are formed integrally with each other. The light conducting plate 38 is formed with openings 38a and 38b at opposite ends thereof. The backlight LEDs 12a and alert LEDs 12b are securely received in the openings 38a and 38b, respectively. A diffusion sheet 40 is positioned on the light conducting plate 38. The backlight 32A is located at the rear of the LED 12 for illuminating it, as shown in FIG. 3B. The backlight 32A is simple in structure since it does not need a printed circuit board for supporting the LEDs 12a and 12b. 
     In summary, it will be seen that the present invention provides a data display radio pager having at least one alert LED disposed in a backlight together with at least one backlight LED and causes the alert LED to effect an alert via an LCD. Hence, when the LCD is mounted on the front of the casing of the pager, it is not necessary for the alert LED to be positioned beside the LCD. This provides the pager with a miniature configuration. Moreover, the alert LED does not have to be mounted on one side of the casing and, therefore, alerts the user to an incoming call without fail. 
     The backlight LED emits bright light while the alert LED emits light of red or similar striking color. This, coupled with the fact that the backlight LED glows continuously in the event of LCD display while the alert LED flashes, allows the flashing of the LED, i.e., an alert to be clearly recognized via the LCD. 
     Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.