JPS5857750B2 - Interlace display method and device for display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device, and more particularly to an interlaced display method and device for obtaining good image quality without fluctuation of displayed characters in interlaced display (display using interlaced L7 scanning).

In interlaced display, as shown in Figure 1, character bits on the raster indicated by solid lines are displayed in even fields, character bits on the raster indicated by dotted lines are displayed in odd fields, and both fields are completely displayed. Obtaining images is well known.

In the conventional interlaced display method, raster numbers O12, 4, 6, 8 are used for even fields across all display lines.
Character dots with raster numbers 1.3.5.7.9 are displayed in odd-numbered fields.

By the way, the ratio of the number of bright spots in the even field and the odd field for the character "E I+" in Figure 1 is 4:21, and for the character n T 11 it is 6:11, and the ratio of the bright spots between both fields is 4:21. There is a numerical imbalance.

Similar imbalances exist for other characters, and even when viewed over the entire display screen, there is an imbalance of bright spots that is several times larger on average between even and odd fields.

Therefore, the beam current of the cathode ray tube changes in proportion to the imbalance in the number of bright spots.

Changes in the beam current cause fluctuations in the high-voltage power supply voltage of the cathode ray tube, which causes the screen size to vary between even and odd fields, causing undesirable "fluctuation" in displayed characters.

In a normal interlaced display, which portions of dots are displayed in even and odd fields will be explained with reference to FIGS. 2A to 2C.

FIGS. 2A to 2C show the case where the character E is displayed in two lines.

First, FIG. 2A shows a raster displayed in an even field.

As you can see, each row is raster 2.4
．． 6.1 dot in each of 8 (○ mark in the figure represents a bright spot of 1 dot.

) is displayed. That is, in an even field, the letter E
The bright spot is 4 dots.

The raster displayed in the odd field is shown in FIG. 2B.

In FIG. 2B, the bright spot of the letter E is 21 dots in each line.

The displays in Figures 2A and 2B are repeated alternately,
It is displayed as shown in Figure C.

However, as is clear from FIGS. 2A and 2B, there is an imbalance in the number of bright spots between even and odd fields.

As mentioned above, the greater the degree of this unbalance, the more "fluctuation" will occur.

The essential measure to eliminate the above-mentioned "fluctuation" is to stabilize the high-voltage power supply of the cathode ray tube against changes in the load (beam current), but this requires advanced technology and an appropriately expensive cathode ray tube. He leaves Tokyo.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a stable interlaced display method and apparatus without "fluctuation" of characters.

In the present invention, in order to eliminate the unbalance of bright spots of characters between even and odd fields, one line is divided into 2n+1
For example, in the case of a rask configuration, as shown in Fig. 3, in the even rows (even lines) of the even field, O12,
Generates raster addresses of 4, 6, ..., 2n, and 1.3 for odd lines in even fields.
．． Generates a raster address of 5,...2n1, and 1.3.5,... for even rows in odd fields.
・The reset timing of the raster counter and the output of the raster counter are adjusted to generate a raster address of 024.6, 2n-1 in the odd row of an odd field and a raster address of 2n. It is controlled by the evenness and oddness of the lines.

An example of display using this method is shown in FIG.

As you can see in Figure 3, the letter E in the even field
The number of bright spots of the letter E and the bright spots of the letter E in the odd field are the same when viewed in two lines.

That is, in this case, the ratio is 1:1, which is effective in eliminating character fluctuations.

Figure 4A shows the display example in Figure 3 in more detail.
It is C.

First, FIG. 4A shows a raster displayed in an even field.

The circle mark in the figure indicates a single dot bright spot.

As is clear from FIG. 4A, the number of bright spots on even-numbered rows is different from the number of bright spots on odd-numbered rows.

That is, the display of even rows in even fields displays bright spots corresponding to even rasters.

The display of odd rows in even fields displays bright spots corresponding to odd rasters.

Next, in the odd field, as shown in FIG. 4B, the raster display is reversed to that in FIG. 4A.

That is, the display of the even rows in the odd field (in the case of FIG. 4B) displays bright spots corresponding to the odd raster.

The display of odd rows in odd fields displays bright spots corresponding to even rasters.

These fields are repeated alternately and the characters are displayed as in FIG. 4C.

If this display method is adopted, in the case of Figure 4, the number of bright spots displayed in the even field (number of bright spots in the even numbered rows is 4 + the number of bright spots in the odd numbered rows is 21) and the number of bright spots displayed in the odd numbered fields is The number (21 bright spots on even rows + 4 bright spots on odd rows) is the same number.

In other words, the imbalance in the number of bright spots in even-odd fields can be reduced.

Since the beam current of a cathode ray tube changes in proportion to the imbalance in the number of bright spots, the above-described display method causes little change in the beam current.

Therefore, fluctuations in the high-voltage power supply voltage of the cathode ray tube are reduced, thereby reducing fluctuations in screen size between even and odd fields, and a display with less "fluctuation" can be obtained.

Next, one embodiment of the present invention will be described with reference to the drawings.

To explain FIG. 5, the rusk number register 100 contains 9, that is, the binary number "1001" or 8, that is, l.
If -1000J is set, the raster address shown in FIG. 3 is obtained.

Assume that 9 or 8 is currently set.

The time chart of FIG. 5 is shown in FIGS. 6 and 7, and will be explained together with them.

First, the operation of the raster counter 111 will be described.

A clock 200 with a 1/2 raster time period is input to the raster counter 111, and the raster counter output 201
is counted up as shown in FIGS. 4 and 5.

The match gate 105 compares the upper bits of the counter output 201 excluding the least significant bit with the upper bits of the rask number register 100 excluding the least significant bit, that is, "100".

Therefore, when the raster counter output 201 is 8 and 9, a match signal 204 is output.

Then, when it is an even number row in an even field and when it is an odd number row in an odd field (i.e., the row counter least significant bit output 2
02 and the even field signal 207 are different, and the output of the EOR gate 102 is at a high level.
vel ), the coincidence signal 204 is input to the one raster time delay gate 109 to obtain the maximum raster signal 205 delayed by one raster time.

When there is an odd number of rows in an even field and when there is an even number of rows in an odd field (i.e., the row counter least significant bit output 202
The level of the even field signal 207 becomes the same, and the output of the EOR gate 102 becomes a low level (Low 1e
vel ), the coincidence signal 204 becomes the maximum raster signal 205 as it is.

Table 1 shows the relationship between the row counter least significant bit signal 202, the even field signal 207, and the output of the EOR gate 102.

Note that whether it is an even numbered row or an odd numbered row is determined by the Low level and High level of the least significant bit output 202 of the row counter, respectively.
h level, and whether it is an even field or an odd field is determined by the High level of the even field signal 20γ.
It corresponds to level and Lww level.

The maximum raster signal 205 is input to a pulse width conversion gate 110, where the pulse width is converted into a raster counter reset signal 206 with the latter half width, and the raster counter 111 is reset.

Next, from the raster counter output 201 to the raster address 20
The conversion to 3 will be described.

The least significant bit of the raster counter output 201 is not used, and the upper bit is used as it is as the raster address 203.

The least significant bit of raster address 203 is inverter 11
Use the output of 2.

As can be seen from Table 1, the output of the inverter 112 is at a high level when the field is an even field and an odd row, and when it is an even field and an even row, and at other times it is a low level.

For example, as shown in FIG. 7, when the raster counter output 201 is 8 and 9 in an even row in an even field (2
When expressed in base numbers, 8 is "1000" and 9 is "1001".

), the output of the inverter 112 is rOJ, so the raster address is JlooOJ, that is, 8.

Therefore, a raster address 203 as shown in FIGS. 6 and 7 is obtained, and raster addresses as shown in FIG. 3 or FIG. 4 A-C are generated.

According to this embodiment, stable interlaced display without character fluctuation can be performed without using a cathode ray tube that requires advanced technology and is equipped with an expensive high-voltage stabilized power supply.
The effects of improving character quality in interlaced display and reducing cost of display devices are remarkable.

FIG. 8 shows another embodiment of the present invention, in which the same parts as in FIG. 5 are designated by the same reference numerals.

The difference from FIG. 5 is that the raster counter lock 300 is
By setting the raster time period, the raster counter 1
11 can be reduced by one bit, and the pulse conversion gate 110 of the reset signal generation circuit 113 is no longer necessary.

FIGS. 9 and 10 show time charts when 9 or 8 is set in the raster number register in FIG. 8.

This operation will be explained below. When 9 or 8 is set in the raster number register 100, the raster address shown in FIG. 3 is obtained.

Assume that 9 or 8 is currently set.

First, the operation of the raster counter 111 will be described.

A clock 300,6'' of one raster time period is input to the raster counter 111, and the raster counter output 201 counts up as shown in FIGS. 9 and 10.

The match gate 105 compares the counter output 201 and the upper bits of the raster number register 100 excluding the least significant bit, that is, "100J."

Therefore, when the raster counter output 201 is 4, a match signal 204 is output.

And when it is an even number field and an even number row, and when it is an odd number field and an odd number row, that is, 202 and 2 as shown in Table 1.
07 is different, and the output of the EOR gate 102 is H.
When at the high level, the coincidence signal 204 is input to the rask time delay gate 109 to obtain the maximum raster signal and raster counter reset signal 206 delayed by one raster time.

When it is an even field and an odd row, and when it is an odd field and an even row, as shown in Table 1, the levels of 202 and 207 are the same and the output of the EOR gate 102 is Low.
At the w level, the match signal 204 directly becomes the maximum raster signal and raster counter reset signal 206.

Note that whether it is an even numbered row or an odd numbered row is determined by the Low level or High level of the least significant bit output 202 of the row counter, respectively.
Corresponding to the gh level, whether an even field is an odd field is determined by the Hi level of the even field signal 207.
Compatible with gh level and low level.

Next, from raster counter output 20/1 to raster address 2
The conversion of 03 will be described.

The I' bit of the raster counter output 201 is used as the 2n+1 bit of the raster address.

Also, the least significant bit of the raster address is transferred to the inverter 11.
Use the output of 2.

As can be seen from Table 1, the output of the inverter 112 is at High level when the field is an even field and an odd row, and when the field is an odd field and an even row, and at other times it is a Low level.

Therefore, as shown in FIG. 10, for example, when the raster counter output 201 is 3 in an even row in an even field ("11" in binary representation), the inverter 112
Since the output of is rOJ, the last address is l-11
0J or 6.

Therefore, a raster address 203 as shown in FIGS. 9 and 10 is obtained, and raster addresses as shown in FIG. 3 or FIGS. 4A to 4C are generated.

According to this embodiment, not only stable interlaced display can be performed, but also the cost reduction of the display device due to the reduction in the amount of hardware is remarkable.

As explained above, according to the present invention, it is possible to reduce "fluctuation" in interlaced display and improve character display quality.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing raster addresses in a conventional interlaced display, FIGS. 2 A to C are diagrams for explaining a conventional interlaced display, and FIG. 3 is a diagram showing raster addresses in an interlaced display according to an embodiment of the present invention. 4A to 4C are diagrams for explaining interlaced display in an embodiment of the present invention, FIG. 5 is a diagram of a rask address generation method showing an embodiment of the present invention, and FIGS. 7
The figure is a time chart diagram for explaining FIG. 5, and FIG. 8 is a diagram of a rusk address generation method showing another embodiment of the present invention.
9 and 10 are time charts for explaining FIG. 6. 100... Raster number register, 111...
... Raster counter, 105 ... Match gate,
113...Reset signal generation circuit.

Claims (1)

[Claims] In a device that displays information by interlacing one frame with 12 fields, one field has 21 lines (i=o, 1.2, . . .
, n), scan the odd (or even) rasters of the raster group constituting 21+1 rows, and scan the 21+1 rows of the other field. An interlaced display method for a display device, comprising scanning odd (or even) rasters among a group of rasters that constitute a raster group, and scanning even (or odd) rasters among a group of rasters that constitute 21 rows. 2. A memory that stores information to be displayed and reads out the contents in synchronization with a timing signal, and inputs the output of the memory and display raster address, and outputs a video signal of the information according to each raster. A display device comprising a character generator, a display unit that displays information based on the output of the character generator, and a timing circuit that outputs timing signals necessary for the memory, the character generator, and the display unit, the timing circuit comprising: A raster counter that operates at a cycle of one raster time or faster, a raster number register that sets the number of rasters per line, and a signal that is sent when the output of the raster counter and the output of the raster number register match. a match gate that outputs, and a reset signal generating circuit that outputs a reset signal for the raster counter corresponding to each row from the output of the match gate and a signal indicating whether an interlaced even frame or an odd frame. An interlace device for a display device, characterized in that an output and a signal indicating whether the interlace frame is an even frame or an odd frame are output to the character generator as the display raster address.