Multiple Display Device

Abstract

A cathode ray tube is mounted in a substantially vertical position with a multiline display presented on an upwardly facing screen. The screen is partitioned into two discrete areas with the lines of the display associated one area presenting one message and that associated with the other presenting another, independent message. A pair of converging mirrors which each reflect one of the messages to a viewing location thereby permitting the screen to provide displays for a pair of independent devices.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to image display systems and more particularly to an image display system where a single display device is partitioned into discrete viewing portions to effect the function of multiple displays.

The invention is particularly useful where it is desired to provide an individual display for machine operators sitting along side or across from each other as in a data entry machine room environment. The operators in effect are sharing a single display device without the loss of display quality.

2. Description of the Prior Art

In the past, it has been the practice to provide each data entry machine operator with any individual display device without regard to the relative physical positions of the operators. Data entry machine operators sit at a keyboard which is used to enter data on storage media. As information is keyed into the keyboard, the data entered is displayed on the face of an image display device. This enables the operator to monitor the data entered.

Individual display devices are expensive irrespective of their size not only because of the duplication of the display apparatus, but also because of the necessary individual driver control and power circuitry. Hence, even though the electronic circuitry for furnishing the data to the display devices could be shared, in the past there has been no sharing of the apparatus for generating the display.

In the present invention, a single cathode ray tube functions as a multi-display device. The physical structure of the cathode ray tube is not changed. A single gun structure is still used and the deflection system is substantially the same. The images to be displayed in the discrete viewing areas are generated sequentially but at a rate which is timely for the viewer or machine operator. Using mirrors, it is necessary to provide controls whereby one display has its top line at the bottom of the display with the characters formed in mirror image, inverted and the first character of the line appearing at the left hand side of the line. The other lines of the one display or viewing area are appropriately spaced from each other and the bottom line is the top line of the display. The mirror associated with this one display makes the appropriate inversion of the characters and the lines so that the top line appears at the top of the display to the viewer and the lines read from left to right with the characters in the upright position.

The top line of the other display is at the top of the display and the characters are not inverted but also formed in mirror image with the first character in the line of characters at the right hand side of the line. The associated mirror reverses the lines so that they appear to read left to right to the viewer.

The displayed image is reflected from the cathode ray tube screen to an operator location through a shrouded passageway provided with non-reflective dark surfaces to afford the observing machine operator a brightened contrast between image and background. This display enhancement overcomes the deleterious effect of ambient light and ambient light reflections that tend to impair the quality of displays in the environment of a properly illuminated work area.

SUMMARY OF THE INVENTION

The principal object of the invention is to provide an improved image display system which: (a) eliminates ambient light reflections as usually occur on a CRT face; (b) occupies less space on operator's work surface; (c) is relatively inexpensive; (d) utilizes a single display device functioning as multiple display devices; and (e) provides high quality image displays by improving the apparent contrast of images on the CRT background.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation illustrating the preferred embodiment of the invention where the cathode ray tube is mounted in a generally vertical orientation and a pair of mirrors are at an angle with respect to each other and the viewing screen of the cathode ray tube;

FIG. 2 is an isometric view of a data entry device including the display apparatus shown in FIG. 1;

FIG. 3 is a schematic diagram of the control unit and interconnected devices of the apparatus shown in FIG. 2;

FIG. 4 is a block diagram of the deflection logic and deflection system for the cathode ray tube;

FIG. 5 is a schematic view illustrating the scanning sequence for a character generated in mirror image with a cursor underneath; and

FIG. 6 is a plan view illustrating the mirrors of FIG. 1 with the character lines appearing on the screen of the cathode ray tube shown in phantom view.

Between housing apertures 21, 22 and the cathode ray tube screen 11, all wall portions that define the passageways, such as housing walls 17 and 18, are provided with non-reflective, black surfaces. The shrouded passageways from each of apertures 21 and 22 to screen 11 eliminate ambient light reflections and enhance the contract between the illuminated image and the background.

DESCRIPTION

Referring to the drawings and particularly to FIG. 1, the invention is illustrated including a conventional cathode ray tube 10 mounted in a generally vertical position. The axis of tube 10 is offset from vertical alignment to present the utilized portion of the screen 11 symetrically to the viewing station. The display is generated by using six of eight possible character line positions on the screen. The line locations are shown at 12a, 12b and 12c. Since it is desired to partition the display area into two separate three line displays, the two middle character line positions 12c were elected as the unused locations to permit maximum separation of the individual three line displays. Thus, the lines of information appearing on the screen are represented by the dotted lines 12a and 12b. The display area of screen 11 is surrounded by a generally rectangular gasket 14. A transparent glass dust seal plate 16 overlies and rests upon gasket 14.

Housing 20 overlies screen 11 and engages plate 16 by extending through an aperture 27 in the table top upper wall 28 of the machine console 29. Housing 20 is of molded construction and provided with viewing apertures 21 and 22. A pair of mirrors 25 and 26 are supported within housing 20 and are symetrically arranged with respect to the centerline of the housing. The reflective surfaces of mirrors 25 and 26 define a pair of planes that converge toward screen 11 and each forms an acute angle with the screen. Viewers observing screen 11 from the directions of arrows A and B respectively see lines 12a and 12b as the images 13a and 13b on the reflective surfaces of mirrors 25 and 26.

The display illustrated in FIG. 1 is mounted in a machine console 29 as shown in FIG. 2. The dual station device illustrated has keyboards 30 and 31 recessed at opposite sides of top surface 28. Display housing 20 is mounted through the top surface between the keyboards with the viewing apertures 21 and 22 respectively facing the positions occupied by operators seated at the keyboards 30 and 31. There is also a pair of data recording devices 32 and 33 normally associated with the keyboards 30 and 31 respectively. These data racording devices may be magnetic tape or disk drives or other data storage devices for recording electronically encoded information manually entered at the keyboards. Console 29 also encloses a control unit 35 to which, as shown in FIG. 3, are connected keyboards 30 and 31, the cathode ray tube 10 and the data recording devices 32 and 33.

The lines of information 12a and 12b appearing on screen 11 appear as lines 13a and 13b on mirrors 25 and 26 respectively. In FIG. 2, mirrors 25 and 26 are shown as overlying lines of information 12a and 12b on screen 11. The characters forming the lines of information 12a are reversed in mirror image with the character sequences progressing from right to left. The lines are oriented with the top line at the top and the bottom line at the bottom. Mirror 25 reverses the characters and lines so that the characters appear normal and the lines read left to right to a viewer observing from the direction of arrow A. The characters forming lines 12b are likewise formed in mirror image from right to left, but are inverted so that the first character of each line appears at the left hand side of the line. As viewed in FIG. 2, the bottom line is at the top of the display and the top line is at the bottom of the display. Mirror 26 inverts the characters and lines so that the top line appears at the top of the display to viewer observing from the direction of arrow B and the lines read from left to right with the characters in the upright position. The line inversion for lines 12b can be seen in FIG. 1.

The beam of cathode ray tube 10 is generated and deflected by the circuitry shown in FIG. 4. The beam is generated by an output signal from video amplifier 56. The characters are formed utilizing a wiggle sweep from wiggle ramp generator 71. The beam is swept horizontally by a single from horizontal ramp generator 73 and is positioned to the desired line position by signals from vertical digital to analog convertor 76.

As the beam sweeps horizontally across the screen 11 in this particular example, a line of forty characters can be formed. Each character position can be considered as a 10 .times. 11 matrix. The beam during its horizontal movement across screen 11 is vertically deflected up and down by wiggle ramp generator 71 at the rate of ten up and down excursions per character position. The up excursion is divided into 11 bit times. This provides the 10 .times. 11 matrix. The down excursion is for beam retrace and consists of five bit times. During the up excursion, as seen in FIG. 5, the first up bit time is reserved for displaying a cursor bit. The next bit time is blank to provide a space between the cursor and the bottom of the character. Thus, nine vertical bit times are used for forming the character. Further, only seven of the ten up excursions are used for forming a character. The remaining three up excursions provide for a blank space between characters. By this arrangement, the characters are formed by turning the video amplifier 56 on during a bit time where a dot is to appear. The character in FIG. 5 is a B underscored by a cursor and generated in mirror image such that the observer sees the character in normal form when viewing the reflected image.

In FIG. 4, control line 40 is energized from a control unit 35 (FIG. 3) during the time that lines 12a will be displayed to viewer observing from the direction of arrow A. Similarly, control ine 41 is energized during the time that lines 12b are being displayed to viewer observing from the direction of arrow B. Control line 40 provides a conditioning signal for AND circuit 51 for passing a cursor count from counter 58 which is advanced by pulses from oscillator 57. During the up excursion of the beam, the first bit is a cursor bit for normally oriented characters, i.e., characters forming lines 12a. However, for inverted characters, the cursor bit is at bit 11. Therefore, the output from the first position of counter 58 is applied to AND circuit 51 and the output from position 11 is applied to AND circuit 52 which is conditioned by the signal on conductor 41. Counter 58 is a conventional counter such as a right counter which counts to 16 and then resets.

The outputs of AND circuits 51 and 52 are passed via OR circuit 53 to AND circuit 54. The cursor bit itself is contained in character buffer 65 and the bit position for the cursor in this buffer is connected by conductor 42 to AND circuit 54. The output of AND circuit 54 is connected to video amplifier 56 via OR circuit 55. Thus, the cursor bit will appear upon the screen 11 of CRT 10 at either bit one or bit eleven during the up excursion of the beam if there is a cursor bit in character buffer 65. Buffer 65 is loaded with data from a data source, not shown, via data channel 43. Each character is represented in coded form in buffer 65 by six binary bits. Seven bits are required for the cursor. The characters in buffer 65 are transferred one at a time to character generator 66. In order to transfer a character from buffer 65 to character generator 66 in the proper orientation, control lines 40 and 41 are also applied to buffer 65.

As pointed out previously, the character is formed on screen 11 during seven up excursions. Vertical scan decode block 59 has an input from position 16 of counter 58 and inputs from conductors 40 and 41 to properly provide indications of the seven up excursions. Vertical scan decode block 59 has three binary outputs having binary bit values 1, 2 and 4 and binary bit values 4, 2 and 1 when conductors 40 and 41 are energized respectively. The three output conductors from vertical scan decode block 59 are applied to character generator 66.

Character generator 66 provides nine bits in parallel to serializer circuit 67. It will be recalled that during the up excursion of the bam, only nine of the eleven bits are used for generating the character. The serialized bits are passed by serializer 67 to video amplifier 56 via OR circuit 55. It should be noted that the nine bits passed in parallel by character generator 66 will have an inverse orientation when conductor 41 is energized. It should be further noted that the serializer 67 does not pass any bits to video amplifier 56 until bit three when displaying images to viewer A, i.e., when conductor 40 is energized but passes bits at bit one when images are being displayed for viewer B, i.e., when conductor 41 is energized. This control is accomplished by AND circuits 60 and 61.

The wiggle ramp generator 71 is controlled by signals from decode circuit 70 which has an input from position 16 of counter 58. Decode circuit 70 provides a signal to wiggle ramp generator 71 for the up excursion for 11 bits and a signal for the down excursion for five bits. The control for the ten up and down excursions for each character is provided by wiggle scan counter 68. Counter 68 has an input connected to position 16 of counter 58. The output of counter 68 is applied to AND circuit 63 and to character counter 69. Counter 68 has an output for every ten input signals from counter 58. The output signal from counter 68 is used for transferring six binary bits at a time from character buffer 65 and for advancing character counter 69. However, the first two character positions in a line are blank so as to provide sufficient time for the circuitry to settle down after character buffer 65 has been loaded. Thus, OR circuit 62 which conditions AND circuit 63 provides a conditioning signal from character position three time to character position 42 time, i.e., for 40 character positions. In this manner, a line of characters are generated. The beam must then retrace to the beginning of the next line. Retrace takes place during 14 character position times.

Counter 69 provides inputs to decode circuitry 72 for generating signals to energize horizontal ramp generator 73 whereby the beam is driven horizontally for 42 character positions and then retraces in a reverse direction. During retrace, the beam moves at a faster speed and retraces in a time allotted for 14 character positions. Position 56 of counter 69 advances line counter 74. The output of line counter 74 is decoded by vertical decode circuit 75 which provides three binary outputs to vertical digital to analog converter 76. The output of vertical to analog converter 76 positions the beam vertically to each line position as determined by the outputs from vertical decode circuit 75.

From the foregoing, it is seen that the invention provides an image display system incorporating a single display device partitioned into discrete viewing portions or information fields to effect the function of multiple displays. The viewers do not look directly at the face of the image display device. This is advantageous because glare is substantially eliminated and image contrast is enhanced. The optical components, and image i.e., the mirrors are relatively inexpensive as compared to lenses and fiber optic devices. Further, a single deflection system is used for controlling the generation of the images for the multiple display.

Claims

What is claimed is:

1. An image display apparatus comprising

a selectively controllable image display device having first and second unrelated multiline information fields presented on mutually exclusive first and second areas of a viewing surface; and

a pair of mirror surfaces converging toward one another and toward said viewing surface such that each defines an acute angle with said viewing surface,

said pair of mirror surfaces each being arranged to reflect the image formed on one of said first and second areas of said viewing surface in substantially opposite directions for observation from opposite sides of said display apparatus.

2. The image display apparatus of claim 1,

further comprising a pair of passageways extending from said viewing surface wherein said pair of mirror surfaces respectively form a portion of the wall surface of each of said passageways and the balance of the passageway wall surfaces are substantially all provided with dark, non-reflective surfacing, whereby the contrast between image and background is enhanced.

3. The image display apparatus of claim 1

wherein each of said information fields include characters generated on said viewing surface in mirror image with said first information field being inverted with respect to said second information field.

4. The image display apparatus of claim 3

further comprising a housing and means for mounting said image display device about a generally vertical axis and wherein said display device includes a cathode ray tube mounted about a generally vertical axis to present the viewing surface in a generally horizontal upwardly facing position and said pair of mirror surfaces are generally parallel to a common horizontal line.

5. In a data entry system comprising

a control unit and

a pair of keyboard entry units connected to said control unit,

the improvement comprising a multiline display device connected to said control unit and mounted about a substantially vertical axis to present a generally horizontal viewing surface,

a pair of mirrors each with a reflecting surface defining a plane which forms an acute angle with said viewing surface, and

each of said mirrors reflecting the image formed on a discrete portion of said viewing surface toward the position of one of said keyboard entry units.

6. The data entry system of claim 5,

further comprising a pair of passageways extending from said display device viewing surface wherein said pair of mirror reflective surfaces each form a portion of the wall surface of a respective one of said passageways and the remainder of the wall surfaces of said pair of passageways are substantially all provided with dark, non-reflective surfacing, whereby the contrast between the background and said image is enhanced.

7. The data entry system of claim 5

wherein said image display device is a cathode ray tube positioned with the screen thereof facing upward, and

said discrete portions form unrelated information fields upon which intelligible characters are generated.

8. The data entry system of claim 7

wherein the said characters generated in said information fields are formed in mirror image and the characters in one of said fields are inverted with respect to the characters in the other of said fields.