[R] using pdf(file="") encount a Chinese garbled

[PO SU]

Dear expeRts,
    When i use the following codes:
    pdf(file="1.pdf",width=15)
    plot(1:3,main="你好")
    dev.off()
#There were 12 warnings (use warnings() to see them)
  I find that "你好" can't show correctly in pdf file, but  i just  plot(1:3,main="你好") to R plot viewer, it's ok .
  Is there anyone happen to know the solution? BTW, i explore the encoding argument in ?pdf ,but still can't solve the problem.




--

PO SU
mail: desolator88 at 163.com 
Majored in Statistics from SJTU