JasonHelper.Escape変換文字列をjason形式コードに変換

public static class JasonHelper
{
    public static string Escape(string s)
    {
        if (s == null)
            return null;
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.Length; i++)
        {
            char ch = s[i];
            switch (ch)
            {
                case '"':
                    sb.Append("\\\"");
                    break;
                case '\\':
                    sb.Append("\\\\");
                    break;
                case '\b':
                    sb.Append("\\b");
                    break;
                case '\f':
                    sb.Append("\\f");
                    break;
                case '
':
                    sb.Append("\
");
                    break;
                case '\r':
                    sb.Append("\\r");
                    break;
                case '\t':
                    sb.Append("\\t");
                    break;
                case '/':
                    sb.Append("\\/");
                    break;
                default:
                    sb.Append(ch);
                    break;
            }
        }//for 
        return sb.ToString();
    } 
}