JPH049093A - Mesh filter for vdu screen - Google Patents

Abstract

PURPOSE:To prevent moire fringes from being generated by specifying the longitudinal line pitch, lateral line pitch, and tilt angle of a filter respectively. CONSTITUTION:The mean value of the apparent horizontal pitch of meshes formed of picture elements is denoted as p1, the number of the meshes as m1, the vertical pitch as p2, the number of meshes as m2, the pitch of longitudinal lines of the filter as P1, the number of meshes as M1, the pitch of lateral lines as P2, the number of meshes as M2, and the tilt angle of the longitudinal lines of the filter to the vertical line as beta (beta : 0 - 90 deg.). Then the longitudinal line pitch P1, lateral line pitch P2, and tilt angle beta of the filter are so set that the calculation results of Q, S, R, T, U, and V of inequalities are within specific ranges. Consequently, moire fringes are prevented from being generated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a VDU (visual display unit) in which both the horizontal and vertical pitches of the apparent mesh of pixels change depending on the measurement location on the screen. ) The present invention relates to screen filters, specifically mesh filters for VDU screens that prevent the occurrence of moiré fringes.

[Conventional technology]

In recent years, with the rapid transition to an information society, opportunities to use office automation equipment such as word processors and personal computers are increasing. In order to create an appropriate working environment in response to this situation, rV
V
It is expected that various problems related to DT work will be clarified and countermeasures taken.

Against this background, it is recommended that filters having various functions be installed not only in CRTs but also in display (hereinafter referred to as VDU) screens that have similar problems. The main functions of this filter are to prevent glare on the VDU screen, reduce flicker, adjust brightness contrast, and remove ultraviolet rays, and filters equipped with these functions have already been put into practical use. Furthermore, due to the structure of VDUs, it is unavoidable that static electricity is generated on the screen side.
．． Although it has been confirmed that static electricity of more than OKV is generated, and that electromagnetic waves are not emitted to the extent that they have a negative effect on the human body, there is a latent feeling of anxiety among some users about the radiation. For this reason, in response to the needs of users, filters for VDU screens have been provided which are equipped with the above-mentioned functions and also have a shielding effect against static electricity and electromagnetic waves. For example, those found in US Pat. No. 4,468,702 or Japanese Utility Model Application Publication No. 59-71344 fall under this category. Such multifunctional filters are usually applied using a conductive mesh fabric made of thin metal wires, carbon fibers, or metal-plated synthetic fibers, either directly or sandwiched between two transparent plastic sheets, and the number of meshes in the mesh fabric varies. Generally, the warp threads are 100 to 270 threads/inch, and the warp threads are normally used vertically.
No. 123 is used with the warp threads at an angle of 45 degrees with respect to the vertical.

[Problem to be solved by the invention]

However, when the above-mentioned conventional mesh fabric is used as a filter for a VDU screen in which both the horizontal and vertical pitches of the apparent mesh of pixels change depending on the measurement location on the screen, moire fringes may occur depending on the VDU model. It was recognized that the situation was occurring. These moire fringes are caused by the interference between the horizontal and vertical components of the apparent mesh formed by the pixels and the warp and weft of the mesh fabric filter (hereinafter referred to as filter). Therefore, we investigated in detail the occurrence of moiré in the case of a 7-screen screen in which both the horizontal and vertical pitches of the apparent mesh of pixels vary depending on the measurement location on the screen. V
Measure the horizontal pitch and vertical pitch at several points at appropriate locations on the DU screen using a densimeter, and calculate the average value of the horizontal pitch of the apparent mesh by pixels as p1, the number of meshes as m1, and the vertical pitch as p1. The average value of the pitch in the direction is 1)2, the number of meshes is lT12, the pitch of the filter warp is Pl - the number of meshes is M1, the pitch of the weft is P2, the number of meshes is M2, the inclination angle of the filter warp with respect to the vertical line is β( However, β is 0 degrees or more and 90 degrees or less), and the ratio between the number of warp meshes of the filter and the number of meshes of the filter weft direction component of the apparent warp meshes on the U screen is Q, and the number of warp meshes of the filter is V
The ratio of the filter weft direction component mesh number of the apparent weft mesh on the DU screen to the filter weft direction component mesh number is R, the filter weft mesh number and VI) t,, the filter warp direction component mesh among the apparent warp mesh on the 7 screen. S is the ratio between the number of filter weft meshes and the filter warp direction component mesh number of the apparent weft meshes on the VDU screen, and T is the ratio between the filter warp mesh number and the apparent warp meshes on the VDU screen. The ratio of the number of filter weft direction component meshes and the average value of the filter weft direction component mesh number of the apparent weft meshes is IJ, and the ratio of the filter weft mesh number and the filter warp of the apparent warp meshes of the V D When the ratio of the direction component mesh number and the average value of the filter warp direction component mesh number of the apparent weft mesh is ■, the respective relational expressions are expressed as follows: 6ml = 25.4/
p+, m2 =25.4. /P2M 1=25.4
/ P + , M2 = 25.4/ P 2Q =
M t / (m 1COSβ) = p + / (P
1COSβ)R=M+/(m2SINβ)
= 1) 2 / (P + SINβ)S ”” M
2 / (m + SINβ) = P 1/ (P 2
SINβ)T-M2/(m2CO8β)=
p 2 / (P 2COSβ)2PI P2 P + (P 1SINβ+p 2cosβ)2PI
P2 p 2 (p , cos β to p 2 SIN β) Conventional theory of moire generation (for example, Journal of Textile Machinery Society (Textile Engineering) V
According to OL, 37, No. 6, 1984, pp. 253-262), moire fringes do not occur when the pitches of the two gratings match (at least the pitch of moiré fringes becomes infinite). Regarding the occurrence of Q, R
, S, T, (J, ■) was predicted to not generate moiré fringes when they were equal pitch and reciprocal tones. The average value of the horizontal pitch and the average value of the vertical pitch of the apparent mesh are calculated, and P1 of the filter is calculated.
, P2, change the inclination angle β, calculate the above formula 7, and test the filter by actually attaching it to the V D [7 screen.
, , each value of R, S, T is 0.50.0
．． 67. When the inclination angle β is set to 1.0.1.5.2.0 and 3.0, moiré fringes occur and Q
/R is in the range of 0.5 or more and 2.0 or less or S/T is 0
．． If the range is 5 or more and 2.0 or less, any value that includes Q, R, S, and T as well as U and V determined by the above formula is 0, 50.0.67.10, respectively.] ,,5,2.
It has been found that moiré fringes occur when the inclination angle β is set to 0.3.0. Special Public Service 1977-1980
Q, R, and S determined by the above formula also for those described in Publication No. 69 and Japanese Utility Model Application No. 49-79123, in which the warp threads are used at an angle of 45 degrees with respect to the vertical. , any value that includes U and ■ in addition to T is 0.50.0.67.1.0, 1.5, 2, respectively.
．． Moire fringes were observed when PI and β were set to 0.3.0. For example, the average value of the pitch in the horizontal direction and vertical direction of the 10-apparent mesh of pixels obtained by actual measurement is pH = 0.330 mm, p 2 =
NEC PC-KD351 (0.100mrn)
A 20 denier polyester monofilament mesh fabric is nickel-plated on the surface of a CRT (640x200 mode) to give it conductivity, and a filter (160
When a mesh (x160 mesh) was manufactured and tested on the model, moiré fringes were observed at an inclination angle β of 45 degrees.

The present invention provides a mesh filter for VDU screens to overcome these problems.

[Means to try to solve the problem]

The present invention relates to a mesh fabric filter consisting of ultra-fine warp and weft threads that is installed in a VDU screen in which both the horizontal and vertical pitches of the apparent mesh are changed depending on the measurement location of the screen. The average value of the pitch in the horizontal direction of meshes is P1, the number of meshes is m1, and the average value of the pitch in the vertical direction is p2.
, the mesh number is m2, the warp pitch of the filter is P1, the mesh number is MI, the weft pitch is P2, the mesh number is M2, the inclination angle of the filter warp with respect to the vertical line is β (however, β is 0 degrees or more) 90 degrees or less), and the ratio of the number of warp meshes of the filter to the number of filter weft direction component meshes of the apparent warp meshes on the VDU screen is Q.
, R is the ratio between the number of filter warp meshes and the filter weft direction component mesh number of the apparent weft meshes on the VDU screen, R is the ratio of the filter warp mesh number and the filter warp direction component mesh number of the apparent warp meshes on the VDU screen. S is the ratio between the number of filter weft meshes and the filter warp direction component mesh number of the apparent weft meshes on the VDU screen, and T is the ratio between the filter warp mesh number and the apparent warp meshes on the VDU screen. The ratio between the number of filter weft direction component meshes and the average value of the filter weft direction component mesh number of the apparent weft mesh is U, and the filter warp direction component of the filter weft mesh number and the apparent warp mesh of the VDU screen is U. When the ratio of the mesh number and the average value of the filter warp direction component mesh number of the apparent weft mesh is V, each value of Q, R, and i T expressed by the following formula is 0.50. ±5%, 0.67±5%, 1.
0±5%, 1.5±5%, 2.0±5%, 3.0±5%
If Q/R is in the range of 0.5 or more and 2.0 or less or S/T is in the range of 0.5 or more and 2.0 or less, Q, R, In addition to S' and T, all values including U and V are 0.50±5% and 0, respectively.
．． 67±5%, l.

For VDU screens where the warp pitch P1, weft pitch P2, and inclination angle β of the filter are set so that they are outside the ranges of ±5%, 1.5±5%, 2.0±5x, and 3.0±5χ. It is a mesh filter.

Here, rrz=25.4/p+, rr+2=25.4/p
2M + =25.4/P1. M2=25.
4/ P 2Q = M + / (m 1cO8β)
=p+/(P1COSβ)R=M1/(m2SINβ
) = p2 / (P + SINβ)S = M2
/ (m + SINβ) = p + / (P z
sINβ)T = M2/(m2COSβ)
= 1) 2 / (P 2 COS β) 21) + f
)2 P 1(p l5INβ+p 2cosβ)2 pt
P2 P 2 (P IC09β+p 2SINβ).

If you know the average pitch of the apparent mesh in the horizontal and vertical directions on the VDLJ screen, and if the mesh fabric filter has already been designed, you can calculate the warp pitch P1 and the weft pitch P2 (or the number of warp meshes). Since M, and the weft mesh number M2) are known, it is possible to determine the inclination angle β of the filter that does not cause moiré fringes by calculation, and after setting the inclination angle β, it is possible to design the mesh fabric filter. can be determined by calculation.

[Function] A state is created in which the warp and weft of the filter do not interfere with the horizontal and vertical components of the apparent mesh formed by the pixels of the VDU screen, thereby preventing the occurrence of moiré fringes.

[Examples] Hereinafter, the present invention will be described in detail: (Example 1) In Example 1, the pitch in the horizontal direction and the pitch in the vertical direction were measured at several points using a density meter at appropriate locations on the VDU screen. Then, the average values of the horizontal and vertical pitches of the apparent mesh by pixels are r) 1=-0, 2, respectively.
68nun, I') 2 = 0.155mm NEC PC-8853N (640X 400 mode)
A 20 denier polyester monofilament mesh fabric was nickel-plated on the surface of the CRT to give it conductivity, and a filter (160 x 160 mesh) was manufactured and installed in the model, and the inclination angle β of the filter was changed. The presence or absence of moat formation was confirmed. 1l1 each
7) Table 1 shows the calculation results and visual test results for Q, Ima, S, 1', U, and ■ at angles.

(Example 2) In Example 2, the horizontal pitch and vertical pitch were measured at several points at appropriate locations on the VDU screen using a densimeter, and the horizontal direction of the apparent mesh by pixels,
The average value of the vertical pitch is P 1 = 0.26, respectively.
CR of NEC PC-8853N (640X 400 mode) which is 8 mm, l)2 = 0.155 mm
A 12 denier polyester monofilament mesh fabric is nickel-plated on the surface of the T to give it conductivity, a filter (200 x 200 mesh) is made and installed in the model, and the inclination angle β of the filter is changed to generate moiré. The presence or absence of was confirmed. Q at each angle
, R, S, T, U, V calculation results and visual test results are shown in Table 2.
Shown below.

(Example 3) In Example 3, the horizontal and vertical pitches were measured at several points at appropriate locations on the VDI screen using a densimeter, and the apparent horizontal and vertical pitches of the mesh by pixels were measured. If the average value of is different, p, = 0
．． 330 mm, I)2=O, ], 90 mm NEC PC-KD35] (640 x 200 motes) A 20 tenier polyester monofilament mesh fabric was nickel-plated on the surface of the CRT to impart conductivity. and filter (160x160 mesh)
A filter was manufactured and installed in the model, and the inclination angle β of the filter was changed to check whether moiré occurred. Table 3 shows the calculation results and visual test results for Q, R, S, T, U, and ■ at each angle.

(Example 4) In Example 4, the horizontal pitch and vertical pitch were measured at several points at appropriate locations on the VDtJ screen using a densimeter, and the average of the horizontal and vertical pitches of the apparent mesh by pixels was calculated. Each value is p 1=0.330
mm, P2 = 0.190mm NEC P
C-KD351 (640X 200 mode) CRT
A 20 denier polyester monofilament mesh fabric is nickel-plated on the surface of the fabric to make it conductive. A filter (110 x 120 mesh) was manufactured and installed in the model, and the presence or absence of moiré was confirmed by changing the inclination angle β of the filter. Table 4 shows the calculation results and visual test results for Q, R, S, T, U, and ■ at each angle.

〔Effect of the invention〕

The mesh filter for VDU screens in which both the horizontal and vertical pitches of the apparent mesh of pixels of the present invention change depending on the measurement location on the screen not only reliably prevents the occurrence of moire fringes, but also It is possible to make a mesh fabric filter with the optimum specifications (number of warp meshes, number of weft meshes, angle) that can prevent the occurrence of moire fringes depending on the average value of the horizontal and vertical pitches of the mesh. In addition, if there is a mesh fabric with existing needles, in order to find out what angle of inclination should be used to prevent moire fringes, a large number of mesh fabrics are made as prototypes and tedious tests are carried out through trial and error. This method eliminates the need to repeatedly search for conditions that prevent the occurrence of moiré fringes, and the best conditions can be quickly and accurately determined through simulation.
In addition, it is a mesh fabric filter that prevents the generation of static electricity and shields electromagnetic waves, thereby avoiding eye fatigue and the effects on the human body.

Table [Note: 0.515K, 0.67f 5X, 1.0t
5%, ], 5t5L2.0±5%, within the range of 3.0±5χ (within the range where moire fringes appear).

[Notes are 0.5±5%, 0.67±5%, 1.0±5L1
．． 5±5L2.0±5%, within the range of 3.0±5χ (within the range where moire fringes appear).

Table [Note] Ne is 0.5±5%, 0.67±5%, 1.0±5%, 1.
5±5%, [Note: 0.5 f 5%, 0.67 f 5%, 1.0
f 5 Hiroshi, 1.5 i 5X:, 2.0±5%, 3.0
Those within the range of ±5χ (within the range where moiré fringes appear).

2.0±5%, 3.0±5χ).

Claims (2)

[Claims] (1) In a mesh fabric filter consisting of ultra-fine warp and weft that is installed on a VDU screen in a method in which the pitch of both the horizontal and vertical directions of the apparent mesh by pixels changes depending on the measurement location of the screen, the apparent mesh by pixels The average value of the pitch in the horizontal direction of the mesh is p_1, the number of meshes is m_1, and the average value of the pitch in the vertical direction is p_1.
_2, the mesh number is m_2, the warp pitch of the filter is P_1, the mesh number is M_1, the weft pitch is P
_2, the number of meshes is M_2, the angle of inclination of the warp of the filter with respect to the vertical line is β (however, β is 0 degrees or more and 90 degrees or less)
The ratio of the number of warp meshes of the filter to the number of filter weft direction component meshes of the apparent warp mesh on the VDU screen is Q, and the number of warp meshes of the filter and the VDU
R is the ratio of the number of filter weft direction component meshes among the apparent weft meshes of the screen, and S is the ratio of the number of filter weft meshes to the number of filter warp direction component meshes among the apparent warp meshes of the VDU screen. The ratio between the number of weft meshes and the number of filter warp direction component meshes among the apparent weft meshes of the VDU screen is T, the number of warp meshes of the filter and the number of filter weft direction component meshes among the apparent warp meshes of the VDU screen, and The ratio of the number of filter weft direction component meshes in the apparent weft mesh to the average value is U, and the ratio of the filter weft mesh number and the filter warp direction component mesh number of the apparent warp mesh on the VDU screen and the apparent weft mesh is When the ratio of the mesh number of the warp direction component mesh number of our filter to the average value is V, Q, R, S expressed by the following formula
, T values are 0.50±5% and 0.6, respectively.
7±5%, 1.0±5%, 1.5±5%, 2.0±5%
, outside the range of 3.0±5%, and Q/R is in the range of 0.5 to 2.0 or S/T is 0.5 to 2.0.
In the case of the following range, Q, R, S, expressed by the following formula,
Both values including U and V in addition to T are 0.5 each.
0±5%, 0.67±5%, 1.0±5%, 1.5±5
%, 2.0±5%, and 3.0±5%, the warp pitch P_1, weft pitch P_2, and inclination angle β of the filter are set to be outside the range of 3.0±5%. Here, m_1=25.4/p_1, m_2=25.4/p_2
M_1=25.4/P_1, M_2=25.4/P_2
Q=M_1/(m_1COSβ)=p_1/(P_1C
OSβ)R=M_1/(m_2SINβ)=p_2/(
P_1SINβ)S=M_2/(m_1SINβ)=p
_1/(P_2SINβ)T=M_2/(m_2COS
β)=p_2/(P_2COSβ)U=M_1/([m
_1COSβ+m_2SINβ]/2)=2p_1p_
2/P_1(p_1SINβ+p_2COSβ)V=M
_2/([m_2COSβ+m_1SINβ]/2)=
2p_1p_2/P_2(p_1COSβ+p_2SI
Nβ). (2) A mesh filter for a VDU screen, wherein the mesh filter according to claim 1 is a conductive mesh fabric made of thin metal wire, carbon fiber, or metal-plated synthetic fiber.