JPH0477848B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a printed film applied to the back of the dial of an indicating instrument used mainly for automobiles in order to equalize the illuminance of night lighting of the indicating instrument. Regarding the manufacturing method.

[Prior art]

FIG. 1 shows a cross section of an indicating instrument that has been widely used in the past, and FIG. 2 is a front view of its dial. As shown in the figure, a dial 1 is fixed to an inner unit 3 attached to a case 2, and its surroundings are shielded by a facing plate 5. The dial plate 1 is made of a transparent resin such as acrylic, and the number 6, scale 7, etc. are printed on its surface with light-transmitting ink, and other parts are printed with black ink. 8 is an illumination lamp attached to the case 2. In addition, a printed film 9 for illuminance adjustment is provided on the back side of the dial 1, and as shown in FIG. It is made from a negative film 10 and a contact screen 11 that capture the unevenness of illumination at the position of the dial 1, but large dots are formed in areas with bright illumination, and small dots are formed in dark areas.
Equalize illuminance. Further, a curve 19 in FIG. 4 shows the printing characteristics of the back printing film 9, and is expressed by the relationship between print density and original halftone dot %. Here, halftone %
is an index indicating the size of the halftone dot, and the size of this numerical value corresponds to the size of the halftone dot. A curve 20 in FIG. 5 shows the relationship between the density of the negative film and the halftone dot percentage of the original 12, which is determined by the characteristics of the contact screen 11.

In the above configuration, a method for producing the back-printed film 9 necessary for uniformizing the uneven illuminance to a target illuminance is briefly described in Japanese Patent Publication No. 53-2065. However, in order to make the illuminance uniform according to the target illuminance, in reality, the printed density required for the back printing film 9 is calculated from the range of non-uniform illuminance and the target illuminance to be made uniform, and then the fourth After determining the required halftone percentage from the diagram, transfer original plate 12 to negative film 1.
0 and the contact screen 11, the original plate 12 having the required halftone dot percentage was produced by changing the exposure conditions through trial and error. Therefore, the production of the original plate 12 had the drawback of requiring a great deal of labor and time.

[Purpose of the invention]

In order to solve the above-mentioned drawbacks, the present invention focuses on a negative film, and adjusts a predetermined halftone percentage necessary to make the illuminance uniform according to the exposure conditions when the original is made from the negative film and the contact screen 11. The object of the present invention is to more easily and reliably obtain the required halftone dot percentage by photographing and developing a negative film at a predetermined density, rather than by trial and error.

〔Example〕

Examples of the method will be described in detail below. First, let the range of uneven illuminance before the formation of the illuminance adjustment printed film 9 be the minimum illuminance I ₁ and the maximum illuminance I ₂ , and let the target illuminance to be made uniform be I ₀ , then the illuminance will be illuminated at the target illuminance I ₀ The density of the printed film 9 necessary to make it uniform is:
From the definition of concentration, at the point of minimum illuminance I ₁ , N ₁ = log ₁₀
(I ₁ /I ₀ ), and at the maximum illuminance I ₂ N ₂ = log ₁₀ (I ₂ /
I ₀ ), densities from N ₁ to N ₂ are required, and the printing density range is determined. If this printing density range is 13 in Fig. 4, then from Fig. 4 this density range 1
The halftone dot % range 14 necessary to obtain 3 is determined. Next, the necessary density range 15 of the negative film 10 is determined from FIG. 5 based on this halftone dot % range. Next, if the target illuminance for uniformizing the illuminance is made brighter than in the above example, the required print density will be smaller as shown in Figure 4, 16, and the necessary original halftone dot % range will be 17.
Further, the negative film density changes to 18. Here, since the characteristic curves in FIGS. 4 and 5 are not the same, the density ranges differ between negative film densities 15 and 18. That is, in order to obtain a predetermined original plate 12, the negative film 10 is photographed and developed to have a predetermined density range, thereby making it possible to uniformize the illuminance to a predetermined illuminance.

Next, the characteristics of the negative film 10 are shown in FIG. 6, but since the characteristic curves 21, 22, and 23 vary depending on the type of negative film 10 and the developing conditions, the density required for the negative film 10 and Once the density range is determined, the exposure amount, that is, the photographing conditions, and the developing conditions are determined according to the characteristic curve shown in Figure 6.
The desired concentration or concentration range can be obtained.

To describe in more detail the method for producing the printed film 9 for illumination adjustment by the method described above, the non-uniform range of illuminance I ₁ ~ before forming the printed film 9 for illumination adjustment
The printing density range _{N 1 to N 2} of the printing film ₉ , that is, 13 in FIG. Find the concentration range 15 of 10. Next, the sixth
The photographing and developing conditions for the negative film 10 are determined from the figure. Then, a negative film 10 is placed in place of the dial 1 shown in FIG. 1, the illumination lamp 8 is turned on, and a photograph is taken and developed under the previously determined conditions.

Next, in the same way as the conventional method shown in Figure 3,
A previously photographed negative film 10 is subjected to mesh resolution using a contact screen 11 to produce an original plate 12. Then, from the original plate 12, a printing plate is produced by a generally well-known photolithography method, which will not be described in detail here, and a printing film 9 for illumination adjustment is formed on the back surface of the dial plate 1 using this printing plate. By printing, it becomes possible to make the illumination uniform at the target illuminance.

〔Effect of the invention〕

As described above, according to the present invention, in order to create a printing original plate for obtaining a printing film for adjusting night illumination to be applied to the back side of the dial of an indicating instrument, the printing film before forming the printing film for adjusting night illumination is prepared. It is set based on the relationship between print density and halftone dot %, and the relationship between negative film density and halftone dot %, depending on the unevenness of illumination and the illuminance that you want to make uniform after forming the printed film for adjusting night illumination. This method has an excellent effect in that it is possible to reliably obtain the required halftone percentage by simply photographing and developing a negative film within the density range of the negative film.

[Brief explanation of the drawing]

FIGS. 1 and 2 are longitudinal cross-sectional views and plan views showing an example of an indicator equipped with a printed film for controlling night illumination produced by the conventional method and the method of the present invention, and FIG. 3 is a plan view of the above printed film. Figures 4 to 6 are developed diagrams for explaining the method of producing the original plate, and the plots of print density - original halftone dots %, negative film density - original halftone dots %, exposure amount - negative film density applied in the method of the present invention. It is a figure which shows an example of each characteristic. DESCRIPTION OF SYMBOLS 1... Dial board, 8... Illumination lamp, 9... Printed film for adjusting night illumination, 10... Negative film, 11... Contact screen, 12... Original plate.

Claims (1)

[Scope of Claims] 1. In order to equalize the illuminance of the nighttime illumination of the indicator, a printing original plate with halftone dots formed using a negative film obtained by photographing and developing the unbalanced illumination as it is, and this printing original plate In the method for producing a printed film for night lighting adjustment consisting of halftone dots applied to the back of a dial of an indicating instrument using depends on the size of the halftone dots, and the print density range of the printed film is set according to the non-uniformity of the irradiation before the printing film is formed and the illuminance that is desired to be uniform after the printing film is formed. A density range of the negative film is set so that the halftone dots are formed as the printed film within a size range of the corresponding halftone dots, and the density of the negative film is within the density range. A method for producing a printed film for adjusting night illumination of an indicator, which comprises photographing and developing the negative film.