JPH0521293U - Display device - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to scroll a wide area as long as the capacity of the disk allows without increasing the cost and without causing flicker. A boundary detecting means for detecting that the scroll control circuit has scrolled to the boundary of the video memory and outputting a signal indicating the position of the boundary to the scroll control circuit. And a screen transfer means for receiving the boundary surface position signal output from the boundary surface detecting means in the drawing circuit and transferring the video memories for two screens of the CRT display screen to the side opposite to the boundary surface position at high speed. The scroll control means is provided so as to take out the video signal from the video memory portion transferred by the screen transfer means.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a display device applied to an operator station or the like of a process control device using a computer, and more specifically to a display device capable of scrolling a wide area as long as the capacity of the storage means permits. ..

[0002]

[Prior Art]

 An operator station of a process control device using a computer uses a display device such as a CRT to display various information, data, and graphics necessary for process control on its screen in order to facilitate man-machine communication. It is configured to be viewable. Recent process control devices have a tendency to increase, because their control objects range from plant control to factory control. For this reason, the various graphic screens displayed on the CRT screen have been devised so that the overall control status and driving status can be easily grasped, and the scroll function can be displayed vertically and horizontally on the screen. The screen can be moved.

FIG. 3 is a structural conceptual view of a conventional display device of this type having a scroll function. Reference numeral 1 is a disk device storing drawing data, 2 is drawing data reading means realized by an application program, 3 is a drawing circuit, and 4 is a video memory in which an image to be displayed on the screen is drawn by the drawing circuit 3. The drawing data reading means 2 reads the drawing data stored in the disk device 1 by the size of the video memory according to the request of the application program and passes it to the drawing circuit. Draw on. Reference numeral 5 denotes a scroll control circuit, which is configured to take out a portion to be displayed on the CRT screen 6 among the images drawn in the video memory 4 as a video signal.

[0004]

In the conventional device configured as described above, when the scrollable size is increased by the scroll control circuit 5, it is necessary to increase the size (capacity) of the video memory 4 accordingly. However, there is a problem that the cost becomes high. It is possible for an application to redraw the drawing data that is the continuation of scrolling without increasing the capacity of the video memory. However, in this case, the drawing time does not meet the refresh time of the video signal and the screen flickers. However, it becomes unsuitable as a display device for monitoring the process status.

The present invention has been made in view of these points, and increases the disk capacity of a video memory having a size four times as large as the display size of a CRT and an inexpensive disk device that is a bit unit less than the video memory. The purpose of the present invention is to realize a display device that enables scrolling over a wide area by using it, is inexpensive, and does not cause flicker.

[0006]

[Means for Solving the Problems]

 The present invention which achieves such an object is to display on a CRT screen in a video memory, a drawing circuit for drawing in the video memory according to a request of an application program, and an image drawn in the video memory. A scroll control circuit for extracting a portion as a video signal, wherein the video memory has a capacity four times as large as the capacity size of a CRT display screen, and the scroll control circuit scrolls to a boundary surface of the video memory. And a boundary surface detecting means for outputting a signal indicating the boundary surface position thereof is provided, and the boundary circuit position signal output from the boundary surface detecting means is received in the drawing circuit for two screens of the CRT display screen. Screen transfer means for transferring the video memory of the screen to the side opposite to the boundary surface at high speed is provided. A display device characterized by taking out a video signal know the video memory portion that is transferred by the feeding means.

[0007]

[Action]

 The boundary surface detecting means detects which of the four boundary surfaces of the video memory the scrolled screen reaches, and when the boundary surface is reached, whether the boundary surface position is above, below, right or left. A signal indicating the position of the boundary surface of is output. The screen transfer means provided in the drawing circuit receives the signal indicating the boundary surface position sent from the boundary surface detecting means. For example, if the boundary surface position indicates the top, the video memory for two screens of the CRT display screen is displayed. Is transferred at a high speed in the downward direction, which is the opposite side of the boundary position. The scroll control means realizes scrolling in a wide range by switching and taking out the video signal from the video memory portion transferred downward by the screen transfer means.

[0008]

【Example】

 Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of the present invention. In the figure, the same parts as those in FIG. 3 are designated by the same reference numerals. 1 is a disk device that stores drawing data, which is generally cheaper in bit unit price than the video memory 4 and has a large capacity. In this disk device, drawing data for n CRTs is stored separately for each CRT.

Reference numeral 2 is a drawing data reading means realized by an application program, and 3 is a drawing circuit for drawing an image in the video memory 4 according to the application program. Reference numeral 5 denotes a scroll control circuit, which is configured to take out, as a video signal, a portion of the image drawn in the video memory 4 to be displayed on the CRT screen 6. Reference numeral 7 denotes a scroll instruction means provided on the keyboard, for example, which also serves as a cursor movement key. The scroll instruction signal from here is received by the application program and outputs a scroll request to the scroll control circuit 5.

The video memory 4 has a capacity four times the capacity size (display size) of the CRT display screen 6. In the scroll control circuit 5, reference numeral 51 denotes a boundary surface detecting means for detecting that the boundary surface of the video memory 4 has been scrolled, and outputting a signal indicating the position of the boundary surface. The part corresponding to the display screen can be switched and taken out.

In the drawing circuit 3, 31 receives the boundary surface position signal output from the boundary surface detecting means 51 and transfers the video memory for two screens of the CRT display screen to the opposite side to the boundary surface position at high speed. Screen transfer means.

The operation of the apparatus thus configured will be described below. When the scroll instruction is sent from the scroll instruction means 7 to the application program, the application program 2 outputs a scroll request to the scroll control circuit 5. Upon receiving this, the scroll control circuit 5 carries out scrolling. Here, the boundary surface detecting means 51 in the scroll control circuit 5 scrolls the screen and detects which of the four boundary surfaces of the video memory it reaches. Then, when the boundary surface is reached, a signal indicating the boundary surface position of whether the boundary surface position is above, below, right, or left is output to the screen transfer means 31 in the drawing circuit 3. Further, the information on the boundary surface position detected by the boundary surface detecting means 51 is held in the scroll control circuit 5 and the acceptance of the scroll request is prohibited.

The screen transfer means 31 receives a signal indicating the boundary surface position sent from the boundary surface detection means 51, and according to the boundary surface position, the video memory for two screens of the CRT display screen is opposite to the boundary surface position. When the transfer is completed, the transfer completion signal is returned to the scroll control circuit 5. Upon receipt of the transfer completion signal, the video signal take-out means 52 in the scroll control means 5 switches and takes out the video signal from the video memory portion transferred by the screen transfer means 31, and subsequently realizes scrolling. The switching here does not appear as flicker on the CRT display screen because the drawing content is the same as the transfer source.

FIG. 2 is a diagram showing a relationship between a boundary surface detected by the boundary surface detecting means 51, a transfer destination transferred by the screen transfer means 31 according to the boundary surface position, and a portion read by the video reading means 52. Is. For example, if the boundary surface detecting unit 51 detects “upper” as the boundary surface position, the screen transfer unit 31 stores the video memory for two screens of the CRT display screen in the downward direction on the opposite side to the boundary surface position. Transfer at high speed. That is, transfer from the upper half to the lower half. Then, the video signal extraction means 52 switches and extracts the video signal from the video memory portion transferred from the upward direction to the downward direction by the screen transfer means 31. Thereafter, in the same manner, according to the transfer relationship shown in FIG. 2, the transfer destination and the video signal extracting portion are switched according to the boundary surface position detected by the boundary surface detecting means 51.

During execution of scrolling, the scroll control circuit 5 requests the application program 2 to draw drawing data, which is a continuation of scrolling, in the video memory 4 for two CRT screens of the transfer source. Upon receiving this request, the application program 2 reads the drawing data for two screens from the disk device 1 and passes it to the drawing circuit 3. The drawing circuit 3 draws in the video memory 4 for two CRT screens of the transfer source by using the drawing data for two CRT screens, which is a continuation of scrolling. When drawing is completed, a drawing completion signal is sent to the scroll control circuit 5. When the scroll control circuit 5 receives the drawing completion signal, the scroll control circuit 5 accepts the scroll request again.

In this embodiment, the video signal output from the scroll control circuit is supposed to be sent to the CRT display means, but it may be sent to other display means using liquid crystal or plasma. Good.

[0017]

[Effect of the device]

 As described in detail above, according to the present invention, a video memory having a size four times as large as the display size of a CRT is prepared, and the capacity of an inexpensive disk device having a bit unit price is used as compared with the video memory, and the CRT2 screen is used. The minute video memory is transferred to the other side at high speed, and the video signal is taken out from the transfer destination. Therefore, it is possible to scroll over a wide area as long as the capacity of the disk allows without increasing the cost and without causing flicker.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a boundary surface detected by a boundary surface detecting unit, a transfer destination transferred by a screen transfer unit according to a boundary surface position, and a portion read by a video reading unit.

FIG. 3 is a conceptual diagram showing the configuration of a conventional display device of this type having a scroll function.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Disk device 2 Drawing data reading means (application program) 3 Drawing circuit 4 Video memory 5 Scroll control circuit 6 CRT screen 7 Scroll instruction means 31 Screen transfer means 51 Boundary surface detection means 52 Video signal extraction means

Claims (1)

[Scope of utility model registration request] 1. A video memory, a drawing circuit for drawing in the video memory according to a request of an application program, and an image drawn in the video memory,
A display device comprising a scroll control circuit for extracting a portion to be displayed on a CRT screen as a video signal, wherein the video memory has a capacity four times as large as the capacity size of the CRT display screen, and the scroll control circuit has a boundary of the video memory. A boundary surface detecting means for detecting that the surface is scrolled and outputting a signal indicating the boundary surface position is provided, and a CRT display screen is provided in the drawing circuit by receiving the boundary surface position signal output from the boundary surface detecting means. A screen transfer means for transferring the two screens of video memory to the side opposite to the boundary surface at high speed, and the scroll control means extracts a video signal from the video memory part transferred by the screen transfer means. And display device.