Ciao,
ho solo riordinato un po’ il tuo codice… caricando il tikz e scurendo un po’ il verde.
L’opzione ‘scale’ scala solamente la geometria e non i testi, per cui può essere usata tranquillamente.
`\documentclass{standalone}
\usepackage{tikz}
\colorlet{verde}{green!80!black}
\begin{document}
\begin{tikzpicture}[scale=0.7]
\draw (0,0) rectangle (5,7);
\draw[line width=1pt] (1,1) — (4,1);
\draw[line width=1pt] (1,6) — (4,6);
\draw[dashed] (5,7) — (14,7);
\draw[dashed] (5,6) — (13.5,6);
\draw[dashed] (5,1) — (13.5,1);
\draw[dashed] (5,0) — (13.5,0);
\draw (10,-0.5) — (10,7.5);
\draw[dashed] (13.5,0) — (13.5,7);
\draw[dashed] (12,0) — (12,7);
\draw[dashed] (8,0) — (8,7);
%Red
\draw[->,red] (14,7) — (14,6.3636);
\path[red] (14.5,6.5) node(yn1) {$y_{n_1}$};
\draw[red] (8,6) — (13.5,7);
%Orange
\draw[->,orange] (15,7) — (15,4.6667);
\path[orange] (15.5,6.5) node(yn2) {$y_{n_2}$};
\draw[orange] (8,3.3333) — (13.5,7);
%Green
\draw[->,verde] (16,7) — (16,3.1818);
\path[verde] (16.5,6.5) node(yn3) {$y_{n_\mathrm{b}}$};
\draw[verde] (8,1) — (13.5,7);
%Blue
\draw[blue] (17,7) — (17,4);
\draw[dashed,blue] (17,4) — (17,0.3);
\draw[->,blue] (17,0.3) — (17,-0.5);
\path[blue] (17.5,6.5) node(yn4) {$y_{n_4}$};
\draw[blue] (11.75,0) — (13.5,7);
%Names
\path (8,-1) node(-Ese) {$-\varepsilon_\mathrm{se}$};
\path (10,-1) node(E0) {$\varepsilon=0$};
\path (12,-1) node(Ese) {$\varepsilon_\mathrm{se}$};
\path (13.5,-1) node(Ecu) {$\varepsilon_\mathrm{cu}$};
\end{tikzpicture}
\end{document}`
Saluti.
R.