GB2228127A

GB2228127A - Display device

Info

Publication number: GB2228127A
Application number: GB8828863A
Authority: GB
Inventors: Hugh John Agnew; Roger Kenneth Wooley; Gwyn David Walter Parfitt
Original assignee: Qudos SA
Current assignee: Qudos SA
Priority date: 1988-12-09
Filing date: 1988-12-09
Publication date: 1990-08-15
Also published as: AU4757990A; GB8828863D0; WO1990006562A1

Abstract

A puck or cursor device for use with a navigation aid includes a digital display which can be selectively inverted to suit the puck being held in the right or left hand of the user and yet allow the display to still be easily read.

Description

DISPLAY DEVICES This invention relates to electro-optical display devices.

Display devices are used in a whole host of apparatuses, for example in clocks and watches, in radios, in electronic test equipment, in destination indicator boards, etc. Typically, the display has groups of segments which can be selectively activated to form a character, or an array of dots which can be selectively activated to form characters or other patterns.

The present invention provides a display device which can be selectively operated in either of two modes, in one of which the displayed data is displayed upside-down compared with the other mode.

The display device is of use in apparatuses which are handed. As one example, a conventional digital wrist watch may have more commonly used control buttons provided on the right-hand side of the watch and less commonly used control buttons located on the left-hand side of the watch. These control buttons are therefore suited to a person who wears the watch on the left wrist because the more commonly used control buttons on the right-hand side are more easily operated. A person who wears the watch on the right wrist has more difficulty in operating the more commonly used control buttons. However, when the invention is applied to the watch, the upside-down mode can be selected when the watch is worn on the right wrist, and the watch can be worn on the right wrist upside down compared with when worn on the left wrist, so that the display is still the correct way up, but the more commonly used control buttons are now on the left-hand side of the watch.

The invention is also applicable to a navigation aid of the type described in International patent application W087/07013 in which a digitising cursor may be designed to be held by a right-handed person in the left hand so that the cursor projects to the right from the hand and has a display on the projecting portion. Using the present invention, the cursor device can be held in the right hand by a left-handed person and the alternative mode can be selected so that the display appears the correct way up.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of one embodiment of the invention; Figure 2 illustrates the segments of one digit of the display of Figure 1; Figures 3 and 4 are tables illustrating the operation of the device of Figure 1; Figure 5 is a schematic diagram of a second embodiment of the invention; Figures 6A and 6B illustrate a digitising cursor which includes a display according to the invention.

Referring to Figure 1, a data source 10 such as a timer circuit addresses and supplies data to a display driver 12. The driver has four bytes of display memory which can be addressed on address lines 16 by the data source 10 and a four bit byte of data can be supplied on data lines 18 and stored in the addressed byte of memory.

The driver 12 employs hard-wired logic to drive a four-digit, seven-segment multiplexed display 20 having digits A, B, C, D by four digit lines 22 (one for each digit) which are scanned in succession and seven segment lines 24 for the seven segments a, b, c, d, e, f, g (see Figure 2) of each digit. As each digit is selected, the driver 12 activates the segments of the selected digit in accordance with the content of a respective byte of the memory 14. In this mode, the correlation between the digits and the memory addresses is as shown in columns 26 and 28 in Figure 3, and the correlation between the content of the respective memory nd the segments to be activated is shown in columns 30 and 32 of Figure 4.

In column 32, "1" indicates that the respective segment is activated, and "0" indicates that it is not. As described so far, the display device is conventional.

In accordance with the invention, two modes of operation can be selected. This is done by applying a signal to mode input 34 of the display driver. When the mode signal is "0" the device operates as described above. However, when the mode signal is "1" alternative logic is employed in the driver, as shown by columns 26 and 36 of Figure 3 and columns 30 and 38 of Figure 4. The effect in this alternative mode is that the display digits are scanned in the order D, C, B, A, rather than A, B, C, D, and the segments for each digit are activated as if rotated by half a turn compared with the case for mode 1. Thus, if in mode 0 segments a, b, f are activated (to represent the numeral "7"), then in mode 1 segments d, e, c are activated instead.

For simplicity, a four-digit numerical seven-segment display has been described above. It will be appreciated, however, that it is a straightforward extension of the principles described above to apply the invention to a display having more than four characters, perhaps arranged in a plurality of rows, and capable of displaying alpha-numeric characters using, for example, British flag or starburst type displays.

A further embodiment of the invention is shown in Figure 5. In this embodiment, a dot matrix display 120 is employed for displaying sixteen characters in an eight column by two row arrangement (A-P). Each character can be formed by a nine by seven array of dots. The driver 112 has a sixteen byte character code memory using a four bit address line 116 and a seven bit data line 118. The data is supplied in the form of the ASCII code of the respective character to be displayed. The device also includes a character generator 140, which contains, for each, ASCII code, a bit map of the respective character. The driver 112 also includes a display memory 142 having one bit for each dot of the display 120 so that the display memory can contain a bit map of the desired display. The driver is operable to look up the bit map for each character code stored in the character code memory 112 and to copy that bit map into the respective portion of the display memory. The display 120 then produces a display corresponding to the complete bit map in the display memory. As thus far described, this embodiment is not unconventional.

In accordance with the invention, however, two modes of operation can be selected. This is done by a signal to a mode input 134. When the mode signal is "0" the device operates as described above; however, when the signal is "1", the following changes are made. Firstly, a different bank 140B of the character generator 140 is used instead of the bank 140A used in the other mode. This bank 140B contains for each character a bit map which is upside down compared to the corresponding bit map in the bank 140A. Secondly, whereas the sixteen character codes in the memory 114 are used in one order to produce the display portions A to P in the display 120 when the mode signal is "0" when it is "1" the sixteen character codes are used in the opposite order to produce the display portions A to P. Thus, the character displayed in portion A in mode "0" is displayed upside in portion P in mode "1", the character of portion B in mode "0" is displayed upside in portion 0 in mode "1", and so on. Thus the whole display in inverted.

Referring to Figures 6A and 6B, a digitising cursor 200 of the type described in W087/07013 has a cross-wire portion 202 surrounded by four lights 204 to 210 for indicating a direction of required movement, a display and keypad portion 212 including a display 214 and a mode select key 216, and a portion 218 intended to be held by the left hand of a right handed person when in the orientation shown in Figure 6A. When it is desired that a left-handed person holds the cursor in the right hand, the cursor 200 is turned around to the orientation shown in Figure 6B, and the mode select key 220 is pressed. The display then displays data upside down compared with original mode, so that the data is the correct way up for the left-handed person. This function is provided by the arrangements described above with reference to Figures 1 to 4 or Figure 5. Additionally in the alternative mode, the direction indicator lights 204 to 210 are driven differently so the functions of lights 204 and 206 are reversed, as too are the functions of lights 208 and 210.

Claims

1. A display device adapted to be held by hand or worn on the arm and to be used in a first or second orientation in dependence upon whether the left hand/arm or the right hand/arm is used, the device comprising: a multi-segment display; means to drive the segments to display data; and means to select between display of the data in a first mode, or in a second mode in which the data is displayed upside-down with respect to the first mode.

2. A device as claimed in claim 1, wherein the drive means is operable to receive data codes and includes logic circuitry to drive the segments in dependence on the received data codes, the selection means being operable to cause the logic circuitry to employ different logic in dependence upon the selected mode.

3. A device as claimed in claim 1, wherein the drive means includes first and second character generators for receiving data codes and supplying character pattern data, the first or second character generator being selected in dependence up on the selected mode.